Small-scale deepwater fisheries usually occur along the continental shelf break and shelf slope where such fishing grounds are accessible to fishermen using smaller boats. Fishermen characteristically use drop lines that are retrieved using hand-powered, electric or hydraulic reels. These fisheries are particularly important to small-island states and because of the limited size of slope fish habitats, the associated fisheries resources are inevitably modest in size and of relatively low productivity. Fish that are targeted by these fisheries tend to have longevities of 30 to 50 years, and grow to sizes of 50–100 cm with slow growth rates. These species tend to be found in aggregations, which make them vulnerable to rapid depletion.
Many countries possessing slope-fishery resources have inadequate institutional and technical capacity to effectively manage them and the ‘boutique’nature of the resources requires the same management capacity and costs as that associated with large-scale fisheries. Small countries are less able to deal with IUU fishing because they lack surveillance capacity and learn of resource depletion long after the IUU vessels have moved elsewhere.
Among issues the workshop addressed were the need: to disaggregate data to show the geographical scale of fisheries; for data confidentiality; and for provision of generic log books and other data recording and collection logistics. Because many small-scale deepwater fisheries involve few vessels, providing appropriate log books is expensive and often beyond the capacity of small-country management authorities.
In addressing resource assessment, information on stock structure indicates that such resources may be highly restricted if not almost territorial. Thus fisheries, even in small areas, will exploit more than one stock. Management must account for this though resolving this problem will require taxonomic studies to investigate sub-population structures. Analysis of the population parameters shows that estimates for the ‘same’species from different areas may, in fact, differ widely, and that fish believed to be the same species, but found in different areas, may be different species.
The suitability of CPUE as an aid in such data-poor situations was recognized but examples were noted of fisheries prosecuted by only a few vessels where the arrival or departure of a single high-liner radically changed conclusions about resource abundance as implied by trends in the CPUE. This emphasized the need for care in undertaking trend analyses based on CPUE.
Experiences indicated that most slope-water fisheries caught several species of which two would be commercially abundant. Thus, single-species approaches would sub-optimize management of at least one species while multi-species approaches would be impractical. Further, the sustainability of less abundant species in catches must be monitored and investigated when harvesting decisions were based on one, or a few, more abundant indicator species. Risk adverse management approaches included that of basing harvesting decisions on the sustainability requirements of the slower growing and less productive species.
Scarcity of management funds means that harvest strategies must be simple, easily implemental, robust and understood by stakeholders. Given the speed at which these fisheries can develop and the difficulty of small and under-funded departments to rapidly implement management plans, the utility of developing “off-the-shelf and over-the-counter”management plans that could be rapidly implemented was noted. Such plans should cover data collection, resource assessment, control of harvesting and fishing down virgin fish resources. Such plans should include “move-on”criterion for when a resource has reached a limit level of depletion and effort must be relocated or stopped.
Current management paradigms need to consider the priorities of governance needs and it was agreed that the multiplicity of management and conservation requirements complicates efforts at governance and could be counterproductive to achieving less ambitious, but obtainable, objectives.
Western Australian Marine Research Laboratories
Department of Fisheries, Government of Western Australia
P.O. Box 20, North Beach, WA, 6920, Australia
The demersal fish resources off the northwest coast of Western Australia were first explored and fished by the Japanese in the late 1950s and were intensively fished by Taiwanese pair trawlers in the 1970s. The ratification of Australia's Exclusive Economic Zone (EEZ) in November 1979 allowed further foreign fishing in these waters but under a licence agreement with the Commonwealth of Australia. The northwest coast of Western Australia is at present split into two regional management zones along the continental shelf, the Pilbara region (114°E to 120°E longitude) and the Kimberley region (ca. 120 °E to 129 °E longitude) that extends to the border with the Northern Territory.
Fishing by Taiwanese and Chinese pair trawlers continued in the Kimberley region until 1990. The trawling effort by these foreign vessels in the Kimberley region was low compared to the adjacent Pilbara region (Nowara and Newman 2001). Following the departure of the foreign fishing fleets from the Kimberley region in 1990, a domestic trap and line-fishery has developed operating out of Broome and Darwin. The demersal trap and line-fishery in the Kimberley region of Western Australia is now known as the Northern Demersal Scalefish Fishery (NDSF).
The NDSF targets a multispecies group of fishes consisting primarily of snappers (Lutjanidae), emperors (Lethrinidae) and groupers (Serranidae). Snappers are the most important species group in the fishery (Newman 2002). Most of these species are considered to be only capable of sustaining low rates of exploitation because they are generally likely to be long-lived, have slow growth rates, a late onset of maturity and low rates of natural mortality.
This paper will use the NDSF as a case study to outline the research and management systems currently in use for all the tropical deepwater demersal fish resources of north-western Australia. A summary of available information is provided, detailing the species targeted and their distribution, knowledge of their stock structure and hence the appropriate spatial scales of management, their biology, a synopsis of the fishery including gear and equipment, the status of the demersal fish resources and the management and regulatory system including the innovative effort-quota allocation system developed for the NDSF and now applied elsewhere.
2. SPECIES TAKEN BY THE FISHERY AND THEIR DISTRIBUTION
The commercially important demersal fishes of the NDSF comprise three main families of reef fish; snappers (Lutjanidae), cods and groupers (Serranidae) and the emperors (Lethrinidae). The main target group is the snappers with the goldband snapper complex (consisting of 3 species, principally Pristipomoides multidens, and also P. typus and P. filamentosus) and red emperor (Lutjanus sebae) comprising over 50 percent of the total demersal finfish catch from the NDSF. The next largest component of the landed catch is the cods that consist of many species that are endemic to the Indian Ocean region, such as Epinephelus multinotatus and E. bleekeri, followed by the emperors, such as the spangled emperor (Lethrinus nebulosus).
These commercially important species are widely distributed across the continental shelf. The fishery principally operates in depths of 60–150 metres with effort concentrated along the old continental shelf coastline in approximately 100 metres of water (Figure 1). The target species inhabit hard bottom areas and areas of vertical relief and large epibenthos. The distribution of fishes tends to be concentrated in these specific habitat areas.
Spatial distribution of fishing effort in the NDSF showing the concentration of fishing effort along the old continental shelf coastline
The deeper continental slope waters of the NDSF, ranging from 150 m to 400 m depth, are only beginning to be explored. The fish fauna at these depths is diverse with variation in species composition between the continental shelf habitats and those of the offshore atoll reefs. To date many species of commercial fishing interest have been identified. These species include the deepwater snappers (Etelis carbunculus, E. coruscans, E. radiosus, Lipocheilus carnolabrum, Paracaesio kusakarii, Paracaesio stonei, Pristipomoides argyrogrammicus, P. zonatus, P. auricilla and Aphareus rutilans), the deepwater sparid (Dentex tumifrons), the deepwater emperor (Wattsia mossambica) and the deepwater cods (Epinephelus morrhua, Epinephelus radiatus and Epinephelus octofasciatus). Many of these species are already being landed in small quantities by the fishery.
3. STOCK STRUCTURE
Stock identity studies that examined populations of L. sebae and P. multidens in north-western Australia have revealed the presence of multiple functionally distinct assemblages of post settlement fish, indicating that adult populations are separate and therefore independent for most purposes of fisheries management (Newman et al. 2000, Stephenson et al. 2001). Thus, adult populations of both these species in the Pilbara region to the west and in the waters of the Northern Territory to the east are separate to those in the NDSF. There may also be low to very low rates of mixing between populations within the NDSF. The larvae of these species may move greater distances and thus mix among populations providing a conduit for gene flow. Therefore, while the NDSF region is likely to form part of one spawning stock (Ovenden et al. 2002), it is considered that management can be applied separately to each of the stocks at a regional (or location) level along the north-western Australian coast.
The presence of separate and distinct stocks of adult fish implies that the size of the total adult spawning stock (i.e. the combined sum of each of the separate functionally distinct assemblages of adults) could affect recruitment. Thus, fishing on any one stock could potentially indirectly affect yields from any other stock by affecting subsequent levels of recruitment should severe depletion of the total spawner biomass occur. However, impacts of fishing on one stock should not directly affect adjacent stocks (or any fishing effect should be negligible).
Knowledge of the stock structure of populations of L. sebae and P. multidens in the NDSF has provided fishery managers with a sound basis for the formulation of regional management plans that seek to ensure that adequate levels of the total adult spawning biomass of each species are maintained in each region.
4. BIOLOGY OF THE KEY SPECIES
Pristipomoides multidens, collected from commercial trap and line-fishers in the NDSF, were successfully aged by examination of thin sections of sagittal otoliths (Newman and Dunk 2003). The oldest fish examined was estimated to be at least 30 years of age. Age estimates were validated using marginal increment analysis with opaque and translucent zones each formed once per year. No significant differences were found in the growth curves between sexes. The von Bertalanffy growth parameters were L∞ = 598 mm, K = 0.187 yr-1 and t0 = -0.173, indicating moderately slow growth. Estimates of natural mortality were in the range 0.104–0.139. These instantaneous rates indicate that in the absence of fishing 9.9–13.0 percent of the population would die each year due to natural causes. The early life history of P. multidens is poorly understood. However, Newman (unpublished data) obtained juveniles from fish trawls over uniform sedimentary habitat with no relief in depths of 95–119 m off the Pilbara coast.
Newman and Dunk (2002) examined the age, growth and mortality of L. sebae from the commercial catches of fishers in the NDSF. Specimens ranged from 183 to 728 mm fork length (FL); males had a mean FL of 509 mm and were significantly larger than females, which had a mean FL of 451 mm. Ages were estimated from thin sections of sagittal otoliths. Marginal increment analysis of sagittal otoliths showed a single annual minimum during September and October and indicated that one annulus is formed each year. Male L. sebae (211–728 mm FL) ranged from age 2 to 30 years and females (183–584 mm FL) ranged from age 1 to 34 years. There was significant differential growth between sexes. Growth parameters for males were; L∞ = 628 mm, K= 0.151 yr-1 and t0 = -0.595 and for females; L∞ = 483 mm, K = 0.271 yr-1 and t0 = 0.065. The estimated instantaneous rate of natural mortality (M) ranged from 0.104 to 0.122.
The length at maturity of P. multidens was estimated to be 552 mm TL for females and 549 mm TL for males, corresponding to a mean age at maturity of approximately 8 years for females and males. The length at maturity for L. sebae was 461 mm TL for females and 491 mm TL for males, corresponding to a mean age at maturity of approximately eight years for females and males (Newman, Moranton and Lenanton 2001).
The protracted longevity, moderately slow growth, large size and age at maturity and low natural mortality rates of the key target species indicate that these species have a low production potential and are particularly vulnerable to overfishing.
The spawning characteristics of each of the key target species are different (Newman et al. 2001). The spawning period of P. multidens is during the mid-summer to mid-autumn months of January to April inclusive, with a peak during March. The co-occurrence of post-ovulatory follicles, hydrated oocytes and yolk-granule oocytes in some ovaries during the spawning period indicates that P. multidens is a multiple spawner (females spawn more than once during the spawning season) and also suggests that annual fecundity is indeterminate (i.e. unyolked oocytes continue to be matured and spawned during the spawning season). The overall sex ratio in catches collected from commercial fishing vessels was close to parity. The relatively large size of the ripe testes indicates that group spawning is likely to occur in P. multidens.
The spawning period for L. sebae was principally in mid-spring during the month of October with opportunistic spawning periods in January and March. Male L. sebae have small testes in relation to the female ovaries. Thus L. sebae are considered likely to be gonochoristic pair spawners.
The biology of the deeper slope species off north-western Australia is largely unknown, however, we have investigated the longevity of some of the larger species collected to date. At present, longevities of at least 56 years have been estimated for Epinephelus octofasciatus and at least 30 years for Etelis carbunculus using the bomb radiocarbon chronometer method of validating fish age (Kalish, Newman and Johnston2002).
5. FISHERY SYNOPSIS
The demersal fish resources of the NDSF have been exploited at varying levels for more than 20 years and have been reviewed by Nowara and Newman (2001). A foreign Taiwanese pair trawl fishery began in 1980 and lasted until 1990. The total annual catch of the Taiwanese vessels reached a peak in 1985 of 4 394 tonnes, corresponding to a peak in trawl effort of 14 896 hours (Nowara and Newman 2001). The total catch per unit effort of the Taiwanese pair-trawl fishery showed a significant decline over the duration of the fishery from 1980 to 1990 (Nowara and Newman 2001). Following the departure of the Taiwanese fleet, a domestic fishery developed primarily using fish-traps. The catch of the Taiwanese pair-trawl vessels includes many species that are not caught by the methods used in the current fishery. Therefore, the catch in the current fishery is much lower than that reported by the Taiwanese vessels.
During the period 1989 to 1992, the NDSF recorded a rapid increase in the level of exploitation with catches growing from approximately 50 tonnes in 1989 to approximately 730 tonnes in 1992. Managers introduced a control on the number of trap boats fishing in the fishery in 1993 because they had a limited knowledge of the capacity of the resource to sustain this increasing fishing mortality. The number of trap boats permitted to fish the NDSF was limited to nine boats in 1993. This stabilized the annual catches from 1992 to 1997 at an average level of approximately 817 tonnes. However, a limited number of line vessels were also operating in the fishery at this time that were not subject to the trap fishery management controls. The NDSF came under formal management on 1January 1998 and included the line vessels. Annual catches in the period from 1998 to 2002 have been lower at approximately 508tonnes on average. The number of licences to fish in the offshore waters of the NDSF was limited to 11 in 1998. The NDSF forms a major component of Western Australia's commercial production of high-quality finfish, contributing over 434 tonnes in 2002 for a catch value of approximately $ 2.41 million. Further expansion and development of fishing activities in deeper outer-shelf waters using trap and lines is likely to occur in the future.
The fishery is now managed by setting a notional total allowable catch in combination with a total allowable effort allocation to individual vessels as individual transferable effort (ITEs) to target that catch (see Section 7 for details). In 2002, five vessels fished the effort quota allocated to the 11 licences. The notional TAC in the NDSF is presently 800 tonnes.
At present there is little recreational or charter boat fishing effort directed towards the deeper-water fish species in the offshore zone of the NDSF that are the key species targeted by commercial fishers. Most of the recreational fishing effort targeting demersal finfish in the Kimberley region is concentrated in the Broome sector of the inshore zone of the NDSF that is closed to commercial fishing.
The main fishing method in the NDSF is the more efficient fish traps, although line-fishing methods such as handlines and, or, droplines are permitted under the ITE system. The use of longline, trotline and fish trawl gears in the NDSF is currently prohibited. The size of fish traps is controlled, with a maximum internal volume permitted equal to, or less than, 2.25 m3 to ensure the ITEs are equitably applied. The fish-trap design used in the NDSF has been modified from the initial O or cylindrical shaped trap that had been historically used in Western Australia. The shapes of fish traps are now roughly square in shape with a length of approximately 1.6 m, a width of approximately 1.5 m and a height of approximately 0.9 m. The entrance to the fish trap has incurving walls that taper to the vertical slit entrance that extends deep into the trap. The entrance is approximately 10–15 cm wide and extends from the top to the bottom of the trap. Trap frames are composed of steel rods and are covered with 50 mm square weld mesh. The whole trap is often zinc-dipped. Traps are baited with 1–2 kg of pilchards (Sardinops sagax). The soak time of traps varies with each operator, but in general ranges from 2–4 hrs during the day. Traps are also set overnight. There is no restriction on the number of traps that can be fished per vessel. However, as each licencee is allocated an annual effort quota in standard fishing days that is based on the use of 20 traps or less, when the number of traps being fished increases, the number of allowable standard fishing days declines. Fishers are allowed to leave traps on the fishing grounds for extended periods, but they must be unbaited and have open doors.
The line gear consists of either hand-hauled or hydraulic reels. The main line of each reel has a terminal weight of 2–4 kg with 6–30 hooks attached at approximately 1 m intervals above the weight. The preferred hook size is a 13/0 tuna circle hook. Line-fishers use a combination of squid and pilchards as bait.
Commercial fishers in the NDSF utilize vessels varying from 15–23 m in length. Vessels are equipped with colour depth echo sounders, radar systems, satellite navigation systems and plotters. Some vessels also have sonar. The electronic equipment now available to fishers allows operators to gather detailed plots of all trap and line sets. These data allow operators to determine the most productive areas available in the fishery. In addition, the size of vessels and the associated electronic navigation and plotting gear provides the fleet with an extensive and flexible capacity to fish throughout the area of the fishery.
Fishing in the NDSF is carried out in all months of the year with most fishers trying to provide a consistent year-round supply of fresh fish to the markets. The landed catch from the NDSF is highly valued and is marketed whole, usually fresh on ice, via road transport from the regional ports of Broome and, or, Darwin for on-shipping to markets in most state capital cities and is occasionally exported.
6. STOCK STATUS AND REPORTING
An integrated age-structured model has been developed for two of the important species in the NDSF, Lutjanus sebae and Pristipomoides multidens, which includes the estimation of spawning biomass. The model estimates are calculated from (a) known catches by all sectors (commercial, recreational and charter), (b) catch rates from the trap fishing vessels and (c), age composition data from samples collected throughout the NDSF. The specific relationship between stock size and recruitment is not known for either of these two target species. Evidence from other fisheries on similar species suggests that a biomass limit of 30 percent, with a target of 40 percent, of the virgin biomass is appropriate to ensure sustainability of this fishery (Mace 1994, Mace and Sissenwine 1993, Die and Caddy 1997, Gabriel and Mace 1999). The spawning biomass of L. sebae and P. multidens in 1980 are assumed to represent the virgin stock levels. Spawning biomass levels of less than 40percent are considered to be exposed to a significant risk of recruitment overfishing. The current stock assessment analyses indicate that the optimum yield of the two target species can be obtained at current effort levels.
The two major target species, L. sebae and P. multidens, are considered to be representative of other long-lived species (i.e. Pristipomoides typus, Lethrinus nebulosus and Lutjanus malabaricus) present in the landed catch of the NDSF that are similarly vulnerable to overexploitation. In addition, they comprise greater than 50 percent of the total landed catch, consequently they are used as indicator species for this entire group of long-lived species. Thus, management action is focused on ensuring catch levels for these two indicator species are sustainable given that they are assumed to be the most vulnerable of the main species landed. Therefore, if adequate levels of the spawning biomass of the two indicator species are maintained, it is considered likely that the management arrangements will be affording similar protection to other long-lived species, and conservative yields from any shorter-lived species.
In 2002, the total spawning biomass of the two indicator species, red emperor and goldband snapper, in the NDSF were estimated to be at 54 percent and 41 percent of the estimated virgin levels. These levels were both above the recommended target level of 40 percent of the virgin spawning biomass and their breeding stocks were considered adequate at the current levels of catch. The level of harvest of the demersal fish resources in the NDSF is in the general range of maximum yields and thus the assessment of the current status of the NDSF stocks is that they are fully exploited.
Catch levels and catch rates in the NDSF are likely to be good indicators of changes in fishing practices that affect the key target species. However, catch rates of trap and line vessels in the fishery are considered to be only moderate indicators of stock size due to the likelihood of ‘hyperstability’ in the catch rate data. Hyperstability may occur due to the (a) targeting of aggregating fish species, (b) high mobility of the fishing fleet and (c), the relative ease with which fish can be located (they are strongly associated with hard bottom habitats). Under these conditions, the catch rate may remain relatively constant while stock biomass is declining and mask a decline in the true abundance of the stock.
Catch rate data are also likely to be affected by the small number of vessels fishing (5vessels in 2002 fishing 11 licences). A small number of vessels operating in the fishery (i.e. a small sample size) results in a high level of variability in the catch and effort data. In particular, catch rate is critically dependent on the number of skilled operators in the fishery, which may vary from year to year.
A time-series of age structure data for each of the key species provides a more robust indictor of stock status than is provided by catch data alone. Age structure data, used in combination with catch and catch rate data, will provide highly robust indicators of stock status for future stock assessments. Nevertheless, the level of robustness of current indicators is considered adequate to manage stocks of L. sebae and P. multidens in the NDSF at a sustainable level, given the effort controls that are in place take into account effort creep and the fact that no other fishing sector catches significant quantities of these species in the Kimberley region.
The status of the NDSF is assessed each year and forms the basis of a report to parliament (Newman 2002). This is part of the annual reporting cycle for all fisheries in Western Australia. However, undertaking annual stock assessments of key target species are not logistically feasible, and as such, detailed stock assessments of the key target species are undertaken every three years. This reporting cycle is illustrated in Figure 2. The NDSF is also currently in the process of undergoing an Ecologically Sustainable Development (ESD) assessment by the Department of Environment and Heritage (DEH). DEH is a Commonwealth of Australia Agency that has jurisdiction on issuing export permits for Australian fisheries. All export fisheries in Australia must now comply with an ESD assessment.
Flow diagram showing the annual reporting cycle and timing of stock assessment reviews for the NDSF
The ESD assessment includes a detailed report on the status of target species and byproduct species, and measures used to assess the fishery against management objectives, such as performance indicators, performance measures and the associated management responses (see Fletcher et al. 2002 for details). The report also includes an examination of non-retained species (discards) and more general impacts on the environment. The ESD assessment requires the formulation of a set of performance indicators for the fishery that allow it to be assessed on a 5-year basis to allow fishers to continue to export fish products.
7. THE INDIVIDUALLY TRANSFERABLE EFFORT MANAGEMENT SYSTEM
The area of the NDSF is divided into an inshore zone (Zone 1) and an offshore zone (Zone 2) that operate under two different management regimes (Figure 1). The inshore zone is regulated by a limit to a total of 4 on the number of licences authorizing fishing in this zone in conjunction with a limit on the type and quantity of handlines that may be fished. Zone 1 licence holders may use up to five handlines with no more than six hooks per line. There is a prohibition on the use of automated line hauling gear in Zone 1 of the NDSF. In addition, there is an area closure around the town of Broome to reduce the potential for conflict between commercial operators, recreational fishers and charter boat fishers.
The offshore zone of the NDSF is regulated by means of individually transferable effort allocations. The only fishing methods allowed in this zone are demersal fish trapping and demersal line-fishing. The numbers of licences available to fish in the NDSF is also restricted in this zone. Additional management arrangements pertaining to Zone 2 licencees include a restriction on the maximum number of hooks (30) that can be fished per handline or dropline; a restriction on the maximum internal volume of a fish trap (equal to, or less than, 2.25 m3) and a restriction on the size of the mesh used in the trap (not less than 50 mm square mesh with the diagonal corners of each square being not less than 70 mm). Furthermore, the management plan for the fishery allows for the Executive Director of the Department of Fisheries, Western Australia to close the fishery if the notional TAC is exceeded and catches are considered to threaten the sustainability of the resource. In data-limited situations a notional TAC can also be tested within an adaptive management framework in the ITE system.
Requirements for the ITE allocation system include
The notional target TAC was initially set based on historical levels of total catch and more recently from specific stock assessment advice. The notional TAC in the NDSF is presently set at 800 tonnes of demersal scalefish.
From 1993 to 1997 the numbers of fish traps that fishers were allowed to fish was limited to 20 fish traps a vessel a day. Following the formal implementation of the effort quota system in the NDSF in 1998, a number of fishers have chosen to fish more than 20 fish traps a vessel a day through the purchase of additional effort quota with the number of fish traps used a vessel a day having varied between 20 and 40. To use these data fishing effort needs to be calibrated so that it is comparable to the fishing effort used in previous years. The calibrated fishing effort is referred to as a standard fishing day.
Fishing effort is transformed to the equivalent number of vessels that operated 20fish traps a vessel a day. This calibrated effort may be calculated by multiplying the number of days fished by the average number of traps used a day by that vessel, then dividing by 20. For example, if a fish trap boat uses on average 30 fish traps a day and fishes for 14 days in any one month, then the calibrated fishing effort for that month is obtained by multiplying the nominal effort (14 days) by 30 and then dividing by 20, therefore the resultant calibrated fishing effort is 21 standard fishing days.
A similar effort calibration procedure is used to calibrate line-fishing effort, with line-fishing effort transformed to the equivalent number of vessels that operated five lines a vessel a day. For example, if a line boat fishes for 14 days but uses on average 10lines a day, then the calibrated fishing effort for that month is obtained by multiplying the nominal effort (14 days) by 10 and then dividing by 5, therefore the resultant calibrated fishing effort is 28 standard fishing days.
The setting of the annual ITE in the NDSF is based on the catch rate of trap vessels, as this measure of effort has been more consistent and less variable throughout the history of the fishery. Fishers then have a choice to use either traps or lines depending on their fishing operation.
The ITE allocation process is determined by the following relationship:
ITE = a ÷ (b × c)
ITE = number of standard fishing days (SFDs) to be allocated a boat
a = recommended notional TAC
b = catch rate (kg a boat day) in recent years
c = number of licences with access in the fishery
ITE [No. SFDs/boat] = TAC ÷ (No. licences × catch rate)
(Note: This allocation mechanism provides for an equitable effort allocation among all licences in the fishery).
The industry members are consulted each year prior to the allocation of fishing days for the following year. In the calculation procedure defined above the number of licences that allow vessels to operate in the fishery is fixed, along with the recommended notional TAC. The TAC can be changed on an annual basis if required, but is generally left fixed from one detailed stock assessment to the next. Therefore, by varying the projected future catch rate, the allocation of standard fishing days can vary. Usually a number of catch rate scenarios (see below) are presented to industry and fishery mangers for their consideration. The projected catch rate (kg/boat/day) is determined from the catch and effort statistics from the previous year, based on the information supplied by all licence holders in the NDSF that is submitted on a monthly basis. Effectively, the allowable effort in terms of the total number of days fishing in the fishery can vary on an annual basis.
Catch rate scenarios generally include the following
All catch rate scenarios assume that each boat with an effort allocation will achieve the specified catch rate. The catch rates and the corresponding fishing days access are provided to industry and managers along with an assessment of the probability of exceeding the notional TAC. The standard fishing day is calibrated to a number of gear units, for example 20 traps a day. This allows flexibility for fishers (vessels) who may then choose to fish more gear units, for example say 40 traps and thus the amount of time they have in the fishery is then halved. That is, the effort allocation is in standard fishing days. Using more gear units reduces the number of days a vessel can fish in the fishery. The ITE allocation process is illustrated in Figure 3.
Licensed vessels may choose to fish using either traps or lines in the fishery. This provides flexibility for the fishing operation and the ability to target species or species groups of interest to the market. At present, both gear types cannot be used simultaneously in the fishery, although this option is to be further investigated.
The number of licence holders within the fishery is fixed. However, licencees have the capacity to either temporarily or permanently transfer ITE units and thus adjust their unit holding to suit their fishing operations. This option allows fishers to increase their economic efficiency without affecting the sustainability of the resource. In addition, this mechanism also allows internal restructuring of the fishery with operators able to sell and buy ITE units to maximize their economic viability. This has resulted in fewer boats fishing in the fishery, but with each boat having a larger ITE unit holding.
Flow diagram of the management process illustrating the ITE allocation procedure for the NDSF
A vessel’s time in the fishery is monitored through a satellite-based vessel monitoring system (VMS). Each vessel is required to install a VMS in order to operate in the fishery. The VMS tracks a vessels movement within the fishery via satellite to a remote base station. The amount of time within the fishery is then calculated from this data record. The operators of each vessel are required to nominate the quantity of gear they are fishing with. The VMS allows the amount of effort and gear used in the fishery to be calculated on a trip-by-trip basis. The amount of effort used in each trip is then deducted from the total allowable effort for each operator in a given year. When an operators ITE allocation has been exhausted, fishing must cease or additional unused units acquired from other operators.
The life history of deep-slope reef fish species are characterized by slow growth, long life spans, low rates of natural mortality and large size and age at maturity. These life-history characteristics imply that deep-slope reef fish have a low production potential and may be vulnerable to over-exploitation. In addition, the apparent low survival rate for released fish that have been caught in depths greater than 40 m of water indicates that the traditional use of legal minimum sizes to increase survival to spawning sizes and hence increase overall yields is not a practical option (Newman and Dunk 2003).
Conservation of deep-slope reef fish species requires low frequency or low intensity harvest strategies. In addition, harvest strategies that include appropriately targeted spatial or temporal fishery closure systems may provide a useful additional means of controlling effort and hence of the exploitation rate, thus preserving the spawning stock biomass of these fish to protect against recruitment overfishing (Newman et al. 2003). The use of indicator species in the assessment of the NDSF is a cost effective method of monitoring the status of the demersal fish resources.
The primary benefit of the ITE management system is that it encourages vessels to maximize their return for each day fished in the fishery. Thus, there is no dumping or high grading of the catch such as that experienced in output control fisheries under individual transferable quota systems. In the NDSF, the notional TAC has not been exceeded since the introduction of the ITE system. In all years a large proportion of the allocated effort has remained unutilized, due to the operators choosing to maximize their economic performance by operating below the estimated MSY.
The underlying concern for resource managers in any multispecies fishery is how to minimize exploitation of long-lived vulnerable and less productive species and maximize the exploitation of the more productive species. The use of the ITE system and regulation of the fishery through using a VMS allows flexibility in future management arrangements. More specifically, the adoption of VMS technology has facilitated opportunities to regulate the spatial distribution of fishing effort and thus direct fishing away from vulnerable areas and, or, species of concern.
The NDSF is located in a remote area of north-western Australia where the resources available for direct compliance checks are limited. The use of the VMS-based ITE management system allows for the sustainable development of these fisheries by reducing the costs associated with enforcement. The transferability of ITE units among licence holders allows for free market trading of effort units and provides operators with the market system to adjust their level of entitlements to suit their fishing operation.
The notional TAC-based ITE system is similar to a TAC-based individually transferable quota system but directly controls fishing capacity while keeping fishing effort relatively constant for research purposes. The ITE system removes latent effort and automatically adjusts for changes in technology and efficiency increase. The ITE system allows for a constant exploitation rate harvest strategy as opposed to the hard TAC found in ITQ systems. The primary benefit of the constant exploitation rate harvest strategy is that in years of increased availability of the demersal fish resources, more fish can be removed and hence landings increase, while in those years of reduced availability of the demersal fish resources, less fish are removed and landings decrease. Thus the ITE system allows exploitation rates to remain stable while the size of the standing stocks of demersal fish resources in the region may change due to natural cycles.
For example, managers set ITQs as an absolute harvest quantity, often resulting in a total catch that does not respond dynamically to changing catchability and stock availability from year to year. It is sometimes politically harmful for elected officials to lower ITQs until the stock is reduced to such a low level that serious economic consequences are evident. The ITE system does not have the same economic and financial consequences to fishers, as the notional TAC often remains the same and the effort quota is all that is adjusted. Monitoring of effort days is straight forward using the satellite vessel monitoring system.
Illegal under reporting of the catch in ITQ systems is common and difficult to detect or quantify, as fishers are reluctant to risk reporting illegal activities even to researchers who do not have any compliance or enforcement role. In terms of overcapitalisation of the fleet, a common problem with effort controls, the fully tradeable ITE system has many of the attributes of ITQs and in this fishery has resulted in a significant reduction in fleet size (i.e. approximately two-thirds) and capitalisation. The allocation of the ITQs at implementation is often highly divisive among licence holders whereas under the ITE system described above there is an equitable allocation of the effort quota and this allows good fishermen to continue to perform well relative to less efficient operators. Most importantly, the ITE system has desirable features for achieving the objectives of ecosystem-based management.
9. LITERATURE CITED
Die, D.J. & J.F. Caddy 1997. Sustainable yield indicators from biomass: are there appropriate reference points for use in tropical fisheries? Fisheries Research 32: 69–79.
Fletcher, W.J., J. Chesson, M. Fisher, K.J. Sainsbury, T. Hundloe, A.D.M. Smith & B. Whitworth 2002. National ESD Reporting Framework for Australian Fisheries: The ‘How To’Guide for Wild Capture Fisheries. FRDC Project 2000/145, Canberra, Australia. 120pp.
Gabriel, W.L. & P.M. Mace 1999. A review of biological reference points in the context of the precautionary approach. In Restrepo, V. (ed). Proceedings of the 5th national stock assessment workshop. National Marine Fisheries Service, Office of Science and Technology, 1315 East-west Highway, Silver Spring, MD 20910.
Kalish, J.M., S.J. Newman & J. Johnston 2002. Chapter 18. Use of bomb radiocarbon to validate the age estimation method for Epinephelus octofasciatus, Etelis carbunculus and Lethrinus nebulosus from Western Australia. pp. 281–298. In Kalish, J.M. Use of the bomb radiocarbon chronometer to validate fish age. Final Report to the Fisheries Research and Development Corporation (FRDC) on Project No. 93/109. The Australian National University, Canberra, Australia. 384pp.
Mace, P.M. 1994. Relationships between common biological reference points used as thresholds and targets of fisheries management strategies. Canadian Journal of Fisheries and Aquatic Sciences 51: 110–122.
Mace, P.M. & M.P. Sissenwine 1993. How much spawning per recruit is enough? In Smith, S.J.M., Hunt, J.J. and Rivard, D. (eds). Risk evaluation and biological reference points for fisheries management. Canadian Special Publications in Fisheries and Aquatic Sciences 120: 101–118.
Newman, S.J. 2002. Northern Demersal Scalefish Fishery Status Report. pp. 70–75. In Penn, J.W. (ed.). State of the Fisheries Report 2000–2001. Department of Fisheries, Government of Western Australia, Perth, Australia. 198pp.
Newman, S.J. & I.J. Dunk 2002. Growth, age validation, mortality, and other population characteristics of the red emperor snapper, Lutjanus sebae (Cuvier, 1828), off the Kimberley coast of North-Western Australia. Estuarine, Coastal and Shelf Science 55(1): 67–80.
Newman, S.J. & I.J. Dunk 2003. Age validation, growth, mortality and additional population parameters of the goldband snapper (Pristipomoides multidens) off the Kimberley coast of northwestern Australia. Fishery Bulletin 101 (1): 116–128.
Nowara, G.B. & S.J. Newman 2001. A history of foreign fishing activities and fishery-independent surveys of the demersal finfish resources in the Kimberley region of Western Australia. Fisheries Research Report No. 125. 84pp.
Newman, S.J., M.J. Moran & R.C.J. Lenanton 2001. Stock assessment of the outer-shelf species in the Kimberley region of tropical Western Australia. Final Report to the Fisheries Research and Development Corporation (FRDC) on Project No. 97/136.127pp.
Newman, S.J., G.A. Hyndes, J.W. Penn, M.C. Mackie & P.C. Stephenson 2003. Review of generic no-take areas and conventional fishery closure systems and their application to the management of tropical fishery resources along north-western Australia. pp. 75–85. In Beumer, J. P., Grant, A. and Smith, D. C. (eds) 2003. “Aquatic Protected Areas - What works best and how do we know?”, Proceedings of the World Congress on Aquatic Protected Areas - 14–17 August 2002; Cairns, Australia. University of Queensland Printery, St Lucia, Queensland.
Newman, S.J., R.A. Steckis, J.S. Edmonds & J. Lloyd 2000. Stock structure of the goldband snapper, Pristipomoides multidens (Pisces: Lutjanidae) from the waters of northern and western Australia by stable isotope ratio analysis of sagittal otolith carbonate. Marine Ecology Progress Series 198: 239–247.
Ovenden, J.R., J. Lloyd, S.J. Newman, C.P. Keenan & L.S. Slater 2002. Spatial genetic subdivision between northern Australian and southeast Asian populations of Pristipomoides multidens: a tropical marine reef fish species. Fisheries Research 59(1–2):57–69.
Stephenson, P.C., J.S. Edmonds, M.J. Moran & N. Caputi 2001. Analysis of stable isotopes to investigate stock structure of red emperor and Rankin cod in northern Western Australia. Journal of Fish Biology 58:126–144.
This paper benefited from discussions with Dr J.W. Penn, Dr W.J. Fletcher and Dr R.C.J. Lenanton (Department of Fisheries, Government of Western Australia).
Department of Business, Industry and Resource Development
GPO Box 3000, Darwin NT 0801, Australia
The Timor Reef fishery is a multi-species trap and dropline fishery operating in an area between 128° 10' and 131° E longitude and extending from 11° S latitude northwards to the boundary of the Australian Fishing Zone (AFZ) (Figure 1). Fishing occurs primarily in the 100–200 m depth range. The target species is goldband snapper (Pristipomoides spp.), which is a high-value fish, primarily aimed at the interstate restaurant markets. Other important target species in this fishery are red emperor (Lutjanus sebae), saddletail snapper (L. malabaricus), red snapper (L. erythropterus) and various ‘cods’(Family Serranidae).
Area of the Timor Reef fishery
Although fishing occurs during the entire year, there is less activity during the dry season months of June–August when strong northerly winds often prevent fishermen going to sea. The boats range in size from 15 to 24 m and carry sophisticated electronic fish-finding and bottom-sounding equipment. Many operators also have onboard computers. Therefore participation in this fishery requires considerable capital outlay in both the size of the vessel required for operating in exposed offshore conditions and electronic equipment for finding fish schools.
There are currently 12 licence holders who are required to fill out detailed daily logbooks on a shot-by-shot basis. As goldband snapper have a patchy distribution, good spatial data is regarded as essential for monitoring this fishery.
In addition to Australian fishers, Indonesian fishermen also target these resources on the adjacent side of the AFZ. In an effort to more effectively manage this straddling stock fishery, Indonesian and East Timor fisheries managers have been included in the northern Australian fisheries managers’workshops that are conducted on an annual basis in Darwin.
2. THE FISHERY
2.1 Target species
The target species of this fishery is goldband snapper, however there are three species which are grouped together for marketing purposes under this name. These are Pristipomoides multidens, P. typus and P. filamentosus. Onboard monitoring has revealed that of the three Pristipomoides species, P. multidens is the most commonly caught, comprising around 73 percent of the Pristipomoides catch, while P. typus accounts for 21 percent and P. filamentosus, 6 percent. Together these three species account for 63 percent of the total catch. Other key species in this fishery are red snappers (Lutjanus malabaricus, L. erythropterus), red emperor (L. sebae) and ‘cods’ (Family Serranidae) (Figure 2). There are minimal byproduct and bycatch species and in total they contribute less than 5percent of total catch. The total catch for 2002 was 340t of which the goldband snapper catch component was 213 t. Both goldband snapper and total catch have remained relatively constant over the past three years. For 2002 the Timor Reef fishery catch was valued at A$2.3 million.
Composition of the catch from the Timor Reef fishery for 2002
2.2 Fishing method
2.2.1 Fishing practices
Although legislation has permitted the use of both traps and droplines, until 1999droplines were almost exclusively used as the preferred fishing method. However, in 1999, a trap boat originally from Western Australia, began fishing in the Timor Reef fishery with great success. This instigated a rapid change in both fishing gear and fishing methods, from targeting schools of fish with droplines to targeting specific bottom types with traps. Within 12 months nearly all Timor Reef operators had changed from droplines to traps.
Operators have found that there are a number of advantages in using traps compared with droplines. These include:
2.2.2 Trap design
The majority of operators use “WA style traps”. These weigh around 85 kg, are constructed of steel mesh (75 mm × 50 mm) and have one funnel (Figure 3). A trap door is located opposite the funnel entrance to allow easy removal of fish and for refilling the bait box. The bait box is located near the funnel entrance and is secured to the bottom of the trap. Pilchards are the most commonly used bait, although tuna, mackerel heads and trevally are also used.
WA style fish trap used by the majority of operators in the Timor Reef fishery
The fishing grounds are approximately 150nm from Darwin, and the average boat takes between 18–24 hours to reach the area. Traps are generally set in the 90–120 m depth range, but can be set as deep as 200m. Fishing commences where traps were left from the previous trip, usually five days earlier. No dead fish have been observed in unattended traps during monitoring trips. However legislation is currently being implemented to avoid “ghost fishing”by lost traps. It is proposed that an anode be attached to the trap door, which will corrode and release the door should the trap be lost.
Traps are deployed in lines and are set in such a way that the funnel entrance is facing in the lee of the current, which makes it easier for fish to enter the trap. Traps are normally set at least 400 m apart, and have a soak time of 3–4 hours (Figure 4a). Operators aim to setting at least 90 traps a day, with fishing commencing at 4 a.m. and finishing at 11 p.m. Operators normally experience best catch rates during the spring tides, as these tides are more effective in dispersing the odour of the bait further and more rapidly owing to the strong tidal movement.
FIGURE 4 (a)
Trap ready to be deployed
Once fish are landed (Figure 4b), they are bled and held in an ice-slurry for a short period to reduce body temperature quickly. The catch is then packed in insulated storage containers with ice. Upon arrival in Darwin the catch is sent to east coast interstate markets, mainly Brisbane and Sydney, usually by road. Little product is sold in Darwin as the market is small.
FIGURE 4 (b)
Fish being retrieved from the trap
Droplines consist of a single line with a 5 kg weight attached. The lower section of the line has 30–40 tuna circle hooks (size 11/0 to 13/0) each attached to the mainline with a short line (Figure 5). Squid is the preferred bait for dropline fishers.
Fishing occurs in depths of 80–200 metres. Fishers use echo sounders to search for schools of fish that have a distinctive pattern indicative of goldband snapper. Once a school of fish is located, a signal is given to set the lines. Generally 2–6 lines are deployed at a time and the soak time can vary from 2 to 10minutes. Landed fish are handled in the same manner as described above for trap-caught fish.
Lower section of dropline rig
3. ROLE OF THE NORTHERN TERRITORY FISHERIES DIVISION
3.1 Developing the Timor Reef Fishery
During the 1970s and 1980s Australia’s northern offshore resources were heavily fished by foreign vessels, mainly Thai and Tawainese trawlers. By the late 1980s the Northern Territory government was looking for ways to encourage Australian fishers to develop these resources. This led to the implementation of a number of development initiatives such as the fishing gear loan scheme, where the Division loaned fishing gear to local operators for a period of several months so they could “try their hand”in a new fishery, without the high cost of purchasing equipment.
The NT Fisheries Division also implemented a number of marketing initiatives as goldband snapper was not well known in Australia at the time. Marketing played a key role in the development of the Timor Reef fishery as Darwin is several thousand kilometres from Australia’s main population centres and premium prices were essential to make this fishery profitable. Market research showed that there was a niche market for fresh fish, which led the Division to initiate a study to determine the optimal methods for handling, processing and storing reef fish in order to achieve a high quality product. One of the key findings from this work was that with correct handling techniques, reef fish could be stored for more than three weeks (Poole, Roberts and Knight 1990, Poole et al. 1991). Promotional work in interstate capitals was also undertaken in conjunction with this initiative and by the early 1990s Territory reef fish were well accepted in the Sydney and Brisbane markets.
3.2 Early development phase of the fishery
Originally logbooks were filled out on a monthly basis using 60-by-60 mile grids, a standard grid size for all Northern Territory fisheries. Unfortunately this spatial scale was too broad for management of this fishery, which was concentrated in a small area. Hence obtaining better logbook information was a priority, but for this to be successful industry cooperation and support was needed. This was begun through extensive wharf visits where the reasons for requiring better information were explained. Then a voluntary daily logbook was tested by operators who asked for information on each fishing shot. This logbook design was regularly modified to make the logbooks as “user friendly”as possible. Compulsory daily logbooks were introduced in 1995.
3.3 Present situation 2003
Development of gas fields in the Timor Sea
In recent years there has been considerable exploration of the Timor Sea by petroleum companies as this area has been identified as an area of significant natural gas reserves. A gas-to-methanol conversion plant is soon to be constructed at Tassie Shoal, one of the prime fishing spots in this fishery. The plant will consist of a concrete structure 165 m long by 85 m wide and weighing 174000t. This plant is due to begin production in 2006. What effect this will have upon the fishery is not known, however careful monitoring of this area will continue to determine whether the fishery is being effected by this production plant.
4. STATUS OF THE TIMOR REEF FISHERY
While catch per unit effort for the Timor Reef fishery has remained relatively stable in recent years (Figure 6), one of the main concerns has been the possibility of serial depletion. When this occurs falling catch rates at valued fishing sites are masked by fishers moving into new areas where catch rates are higher, or fish from surrounding areas recolonize depleted areas.
Catch per unit effort for the Timor Reef fishery
Three well-known fishing areas were examined to determine whether catch rates had declined over time on a finer spatial scale. In this analysis, no allowance was made for improvements in fishing power due to improved fish finding equipment, introduction of fine-scale bathymetric charts, or increased knowledge and skill over time. Likewise, no allowance was made for variations in catch rate from year to year due to environmental conditions. During 1995 many operators were still getting used to the new daily logbooks and consequently not all the spatial data was recorded for that year.
All three areas showed an overall decline in catch rates over the period 1996–2002, although there were some fluctuations in catch rates for one area. Due to confidentiality constraints (less than five operators per site in some years), areas cannot be identified on graphs (Figure 7).
Declining catch rates have occurred at three well-known areas in the Timor Reef fishery
These areas combined account for 15–30 percent of the effort in the Timor Reef fishery, therefore a decline in catch rates in these areas is of concern. While the argument may be put forward that there is always a fishing down of biomass at the start of a new fishery before it stabilises to a sustainable level, this usually happens during the first few years. Therefore we would have expected catches to have stabilized prior to 1996, at which point the fishery had been in operation for seven years.
Analysis of spatial data shows trends that are of concern for this fishery. While catch rates (Figure 6) for the entire fishery have increased since 1995 and appear to be relatively stable, this masks a contrary trend occurring on a finer spatial scale: prime fishing areas have shown a decline over this same period (Figure 7). Another way to express this is that the relatively stable overall catch rates for the Timor Reef fishery are the sum of declining catch rates from the established areas being compensated by higher catch rates as operators find new areas. The recent trend from 1999 onwards for operators to increase fishing effort in the Demersal Fishery immediately adjacent to the Timor Reef fishery also suggests that good catches may be harder to maintain in the Timor Reef fishery. Computer modelling results (which have not been presented in this paper) also show that biomass is declining.
6. FUTURE RESEARCH
To obtain a better picture of the dynamics of this fishery future research needs to be undertaken in the following areas.
Continue dialog with Indonesia and East Timor to obtain better information on catch and effort in their sectors.
7. LITERATURE CITED
Poole, S., R. Roberts & C. Knight 1990. The storage lives of selected commercial inshore and offshore reef fish from Northern Territory waters. Fishery Report, 23a. Northern Territory Depatrtment of Primary Industry and Fisheries. Darwin.
Poole, S., R. Roberts, D. Williams, A. Ford & C. Knight 1991. The effects of trapping on the storage lives of selected iced commercial reef species caught in waters off the Northern Territory. Fishery Report, 23b. Northern Territory Depatrtment of Primary Industry and Fisheries. Darwin.
Malta Centre for Fisheries Sciences
Fort San Lucian Marsaxlokk, Malta
Maltese fisheries are of a typically Mediterranean artisanal type, which are not species selective and are frequently described as multi-species and multi-gear fisheries, with fishermen switching from one gear to another several times throughout the year. There are over 2200 fishing vessels registered in Malta with more than 92 percent measuring less than 10 m in length which, in regional terms, are considered as small-scale vessels. Annual landings recorded at the central fish market normally reach about 1000 tonnes with more than two-thirds of this weight attributed to large pelagic species. Most of the fish brought to this market are caught by the larger vessels. While a long time series of data on these landings is available, the activities of the small-scale fleet have seldom been monitored.
The collection of reliable catch and effort data for various fleet segments is widely recognised as being essential for scientific assessments of stocks and responsible fisheries management. In this context, a catch assessment scheme for the small-scale fleet has been set up in Malta to complement the monitoring of larger vessels, which is undertaken through a logbook scheme.
2. MATERIALS AND METHODS
Fleet and gear statistics were obtained from the database and information system of the Maltese fishing fleet register, MaltaStat (Camilleri et al. 2003), which contains data collected by a census and is updated on a daily basis.
Catch and effort estimates for the small-scale fleet were obtained using a sampling scheme (Coppola, Camilleri and Scalisi 2003) applied in six representative ports, which together contain 42.5percent of the national small-scale fleet. Surveys took place in each port for six consecutive fishing days every other month between January and September, on a 12–24 hour basis resulting in a total of 881 interviews. The sampling frame for each port was adjusted each month according to the number of operational vessels. Data on catches, fishing effort, vessel activity and fishing zone were recorded by gear and species using purposely formulated interview and activity record sheets (Appendix 1). Fishing zones were recorded using a pre-set geographical grids of 5'by5'.
Results for each port and the entire country, by day, month, species and gear were obtained by applying time and area raising factors to the sampled data (Coppola et al. 2003). Selections of these results were summarized in order to give a general description of the activity of the small-scale fleet. An evaluation of slope (i.e. over 200 m depth) fisheries was also carried out using the available data.
3.1 Gear statistics of the small-scale fleet
The total number of registered vessels under 10 m in length overall (small-scale fleet) was 2 074 with more than 60 percent using either trammel nets or bottom-set longlines as the main gears. Almost 15 percent of the vessels used hand-trolling lines and more than eight percent used pots and traps. Figure 1 gives summary statistics on the main gear registered for this fleet category.
Registered main gear of small-scale fleet
3.2 Activity of registered vessels
On average, about 67 percent of registered vessels were operational at any given time. Further, the fraction of operational vessels that went out fishing daily was limited with an average of only 20 percent being observed as active over the whole sampling period of the sampled ports. Table 1 summarizes the operational status and activity of vessels by registered gear.
Estimates of vessel activity by gear based on data collected from all sample ports during the whole sampling period
|Gear||Operational vessels* %||Daily activity of operational vessels ** %|
|Hooks and lines||47.21||6.06|
* number of vessels present in port/number of
registered vessels present in port *100
** number of vessels fishing daily /number of operational vessels *100
3.3 Vessel production
In general, small-scale vessels using trammel nets and hooks and lines had the highest daily catches averaging 9.86 kg and 10.79 kg/vessel respectively. However, the catch per vessel for the hook and line category reached 21.43 kg in July because of the use of surface longlines targeting large pelagic species, which have high individual weights. Catches of vessels using traps were found to be under 5 kg a vessel on average, while vessels using trolling lines reached a maximum monthly average of 2.15 kg a vessel except in the month of September when the average vessel catch reached 5.04 kg, largely owing to the occurrence of Coryphaena hippurus and other migratory pelagic species in Maltese waters at that time of year. Figure 2 summarizes the results obtained on the average daily catches per vessel by gear for the five sampled months.
Average daily catches per vessel by gear and month
3.4 Estimates of landings
The average monthly landings for the whole sampling period was about 24 tonnes with the highest value being obtained in the month of July for which a total landing of almost 39 tonnes was estimated. The elevated production of the small-scale fleet in July and September is largely attributed to the landings of large pelagic species and other migratory species which are caught during this time of year. The landings of Phycis spp., conger eel (Conger conger), Lophius spp., Helicolenus dactylopterus, hake (Merluccius merluccius) and Lepidopus caudatus, which are normally abundant in fishing grounds deeper than 200 m depth (i.e. the slope), were found to be limited and averaged about 1 tonne a month. Estimate values of monthly landings are shown in Figure 3.
Estimates of total landings by month
3.5 Relative importance of gears
Trammel nets and demersal hooks and lines were generally the most important gears in terms of production with an average of 54 percent of landings and almost 90percent of the landings originating from these two gears for the whole sample period and for the month of March respectively. Traps and trolling lines both contributed significantly to landings in all sample months, while surface hooks and lines and trolling lines jointly caught 52 percent of the catch in the month of September. More than 38 percent of the catches in July were caught by surface hooks and lines. Contributions from the Coryphaena fish aggregating device (FAD) fishery were detected in the month of September when the fishery commences. Figure 4 illustrates the percentage distribution by gear or fishery during the sampling period.
Percentage distribution of catches by gear or fishery
3.6 Operational statistics of main demersal gears
Summary statistics related to trammel net and bottom longline fishing operations are listed in Table 2. Results show that fishing trips were typically of less than one day and the gear dimensions were relatively small. Landings of both gears were of a highly multi-species nature.
Gear dimensions, fishing time and number of species landed
|Trammel nets||Bottom lines|
|Average fishing time||13 h 42 mn||10 h 30 mn|
|Average length of net||128 m||-|
|Average height of net||1.2 m||-|
|Average number of hooks||-||646|
|Average number of species landed*||23||15|
* Excluding unidentified and mixed box category.
3.7 Spatial distribution of fishing effort of main demersal gears
Rough estimates of the spatial distribution of the fishing effort of vessels operating from the six sample ports using bottom longlines and trammel nets are given in Figures5 and 6 respectively.
Despite the large number of registered small-scale vessels, the results obtained clearly suggest that the fishing effort exerted by this fleet category is relatively small and is a function of the operational status and daily activity of the fleet, their effective fishing time, as well as of the dimensions and other physical parameters of the fishing gear used. It is also evident that the amount of activity, the gear used, the production and species composition vary seasonally.
Spatial distribution of fishing effort of vessels operating from six sample ports using bottom longlines
Spatial distribution of fishing effort of vessels operating from six sample ports using trammel nets
The landings estimates obtained in this survey indicate that the annual production of the small-scale fleet is less than one third of annual landings recorded at the central fish market. However, the great variety and quality of valuable species landed by this fleet category makes its contribution to the Maltese fishing industry significant.
The spatial distribution of fishing effort of the two main demersal gears show similar patterns. Fishing operations seem to be concentrated within areas close to the base port of the vessel, which, in the case of the investigated ports, occur almost exclusively in waters less than 200 m deep (i.e. on the shelf). A limited exploitation of slope fisheries resources was detected off the island of Gozo where the sample ports are within close range of the 200 m isobath. Similarly, small-scale slope fisheries would also be expected off the western coast of Malta, however, the fishing effort in this area is probably low since there are only four ports along this coast harbouring less than seven percent of the national small-scale fleet.
Although the estimates of catches of deep water species by the small-scale fleet may be slightly underestimated, because of the absence of a sampling port on the west coast of Malta it could be concluded that deepwater small-scale fisheries are responsible for only four to five percent of the landings of this fleet category. However, there is evidence from recent trawl surveys, which have been carried out within the framework of a regional programme (Bertrand et al. 1997), that the abundance of demersal resources in Maltese waters on the slope (and shelf), is relatively high in comparison to other areas in the region and that they have not been adversely affected by excessive fishing pressure. This suggests that the areas where the small-scale fleet operates are not determined by the spatial distribution and abundance of the resources but by the geographical location of the base ports. This situation points to the fact that there may be fishing grounds, even in coastal areas, which are slightly exploited or maybe even not exploited by the Maltese small-scale fishing fleet.
5. LITERATURE CITED
Bertrand, J., L. Gil de Sola, C. Papaconstantinou, G. Relini & A. Souplet 1997. An international bottom survey in the Mediterranean: the MEDITS programme. ICES CM 1997/Y: 03:16 pp.
Camilleri, M., R. Spiteri, S.R. Coppola, M. Spinelli & F. De Rossi 2003. MaltaStat -National Statistical System: Part 1 -Fishing vessel register. Serie Informes y Estudios -FAO-Copemed Project. Rome, February 2003.
Coppola, S.R., M. Camilleri & M. Scalisi 2003. The review of the fishery statistical system in Malta. Part 2 - Catch and Effort Assessment Survey. Serie Informes y Estudios -FAO-Copemed Project. Rome, May 2003.
|MINISTRY OF AGRICULTURE AND FISHERIES - MALTA|
Department of Fisheries and Aquaculture
Smallscale fishery ( < 10 m. L) Catch and Effort Sample Survey of Smale Scale Fishery
|Daily Landings of Sampled Fishing Units|
|(a) Interviewer's Name: Code: (b) Stratum: (c) Site Name: Code: (d) Date: / / Time:|
|(e) Sampled Unit Type: Code: (f) Registry Number: (g) Auxiliary Boats: (h) Prof. Fishermen: (i) Part art Time:|
|(l) Number of Trips in the Day (m) Fishing Area: Code: (n) Time Spent in Fishing: (Hrs) Boats ample N:|
|Ref. H.||(o) Gear Name||(P) Gear Code||(q) Number of Sets||(r) Size, Length (m) or Number of units||Total (q*r)*o||(s) Gear Ref.||(t) Species Name||Species Code||(u) Number of Boxes (B) or Number of Animals (A)||(v) Box Weight (Kg) or Average Weight of the Animal (Kg)||(z) Total Weight (Kg)|
|1||Trammel Nets||Number of Net used||Length (m) of each net||(q*r)*o||Number of boxes||B||Box Weight|
|height (m):||Number of Flsh||A||Average Weight|
|2||Long Lines||Number of Lines||Number of Hooks per line||(q*r)|
|3||Traps||1||Number of Traps per line||(q*r)|
|4||Trawls||Number Trawls used||Mouth opening of the net (m)||(q*r)|
|5||Gill Nets||Number of Net used||Length (m) of each net||(q*r)|
|6||Trolling Lines||Number of Lines||Number of Hooks per line||(q*r)|
|7||Surrounding Nets||Number of Net used||Length (m) of each net||(q*r)|
|8||Kannizzati Fisheries||1||Number of Kannizzati fished||(q*r)|
|Number of boats sampled:|
|Comment:||MaltaCas Form 23||Restricted data - For statistical purpose only|
|MINISTRY OF AGRICULTURE AND FISHERIES - MALTA|
Department of Fisheries and Aquaculture
Smallscale fishery (< 10 m. L.) - Monthly Sample Activity Data Sheet
|Stratum||G1||Site name||Marsalfom||Code||G1||Reference period (month/year):||January 2003|
|Number of fishing days in the month:||29||Number of sampled days||6|
|Sample day||day 1||day2||day 3||day 4||day 5||day6||day 7|
|Date||25/1/2003||26/01/2003||30/01 /2003||10/01 /2003||12/01/2003||20/01/2003|
|Number of boats||Total /Daytime||Total /Daytime||Total /Daytime||Total /Daytime||Total / Daytime||Total / Daytime||Total / Daytime||All days|
|Landed by gear class|
|Total Boats Landed||0||0||0||1||1||0||2|
|Total Boats Sampled||0||0||0||1||1||0||2|
|Comments||N.B. number of fishing days per month is let blank due to that by the end of January the 6 day sample period was incomplete due to bad weather.|
|Source: Malta Stat CAS database: Malta 2003 cas||MaltaCas Form 2.4||30/05/2003|
|Insert total landings for 24hrs periods, and insert dayitime landings from 7.00 ta16:00;|
Secretariat of the Pacific Community
BP D5, 98848 Noumea Cedex, New Caledonia
Fishing for deepwater snappers in depths from 100 to 400 m, and sometimes deeper, has been practised for generations in some of the remote island communities of the Pacific (Preston et al. 1999). Traditionally, Polynesian fishermen used coconut fibre line, with a stone sinker and several wooden, bone or shell hooks attached (Figure 1) to fish for these species.
Traditional Polynesian deep-bottom fishing rig
Since the introduction of more modern materials in the 1970s, Polynesian and other fishermen have experimented with a range of gears throughout the region in an attempt to harvest deepwater snapper species. From the late 1970s, the SPC has assisted most Pacific Island countries and territories in the region (Figure 2) to fish for these species using a range of fishing gears and methods.
In addition to the SPC’s work in the region, other development organizations, including the FAO, UNDP, USAID, Japan, the European Union have funded fishing trials and development projects based on the harvesting of deepwater snappers. This paper summarizes the different fishing gear and techniques trialled or used over the last 25 to 30 years to target deepwater snappers in depths from 100to 400 m and draws heavily on the information presented in Preston et al. (1999).
The Pacific Island countries and territories in the region
2. HAND REELS
The simplest reel introduced to the Pacific region in the late 1970s for deepwater snapper fishing was the FAO-design Samoan hand reel (Figure 3). The reel can be made from locally available materials and allowed small-scale fishermen to make them at minimal cost. The reel post was mounted to the side of small-scale vessels, while the spool with line and the rocker arm were removable for ease of storage.
FAO design Samoan handreel
Other commercially made hand reels have also been available for local fishermen. However, the cost of these reels has limited their use in the Pacific region. Commercially manufactured reels have been designed and built in Australia, Japan and the US (Figure 4) to name a few locations.
Commercially manufactured handreels used for deepwater snapper fishing
Other variations of low-cost handreels have been developed in the region. In Vanuatu, a French fisherman mounted a reel spool to a bicycle frame to come up with the ‘velo’design (Figure 5). Other designs were merely modifications of the original wooden handreel, made larger from steel for larger boats (Figure 6), or smaller for mounting on traditional outrigger canoes (Figure 7).
Velo design deep-water snapper reel
Steel version of a handreel
Modified handreel mounted on a traditional outrigger canoe
3. RIGS USED FOR FISHING
The mainline used for fishing with handreels can be either monofilament or braided lines, such as super-toto. The line is wound onto the reel, with usually 400 to 500 m used depending on the size of spool and the depth of water to be fished. A terminal rig is attached to the end of the mainline. The terminal rig can be made of wire or monofilament and usually has three to five hooks attached (Figure 8). A chum bag can also be attached to the top of the terminal rig.
3.2 Anchor gear and use
The anchor gear used for deepwater snapper fishing is simple in construction and consists of a grapnel anchor made from rebar (Figure 9) and around 400 to 500 m of polypropylene rope. The size of the rebar and rope used depends on the size and weight of boat using the gear. A large PVC balloon buoy or float (Figure 9), or several longline floats tied together, are used in the retrieval of the anchor at the end of fishing
At the end of fishing a simple method is used to retrieve the anchor. The slack rope is pulled in until the rope is taught and vertical in the water. The rope is then secured to the boat as it speeds up and over the anchor, breaking it free from the bottom (Figure 10). As the rope streams out behind the moving boat, the buoy is attached to the rope and so slides back until it is trapped by the no-return barb that is whipped to the rope. With the rope floating on the surface, the boat is turned and motored along as one person pulls the rope in (Figure 10). When the anchor is reached, it too is pulled onboard.
Terminal rigs used for deepwater snapper fishing
Anchor gear used for deep-water snapper fishing
Retrieving the anchor after fishing
An alternative to anchoring to fish for deepwater snapper is to use a controlled drift. To do this a parachute sea anchor is needed (Figure 11). The size of the sea anchor will be determined by the size and weight of the boat it is used on.
Parachute sea anchor used for controlled drifting
To set a sea anchor, it is simply lowered over the bow of the boat. The trip-line and float attached to the apex of the sea anchor are also paid out as the sea anchor fills, and allowed to float free with no tension. Once some resistance is felt, the anchor rope is paid out to the desired length and secured. Hauling the sea anchor is the reverse of setting. The trip-line is hauled in to turn the parachute around so it is pulled in by the apex. Once this is retrieved, the anchor line is pulled in.
4. POWERED REELS
In some locations, handreels have been replaced by powered reels. The same principle applies; however, electric motors or hydraulics are used to wind the reel, and hopefully fish, up to the boat. There is a range of commercially made reels available. In the 1980s and 1990s, these reels were simple, with either the line wound onto a spool (Figure 12) or a pinch-puller (Figure 13) used to haul the line, with the line coiled into a basket.
Electric and hydraulic reels used with spools
Pinch-puller used for hauling braided line
Powered reels are becoming more sophisticated by the year, and newer versions have computer technology where they can be programmed (Figure 14) to lower the line to a specific depth, jig the line if desired, and automatically haul up when weight is put on the line, such as a fish being hooked. The reel will also stop winding when the terminal rig reaches the surface, as this is all programmed into the reel as well.
One type of programmable electric reel used for deepwater snapper fishing
The types of terminal rigs used with powered reels are the same as for the handreels. The anchor gear and the sea anchor are also the same.
5. BOTTOM LONGLINES
5.1 Gear configuration
The next step up from using handlines is to use some form of longline, whether it be set horizontally or vertically. With bottom-set longlines, the mainline and baited hooks are set along and in contact with the ocean floor. The mainline is generally made from negatively buoyant rope so that it rests on the bottom. Sometimes additional weights are attached to the mainline to reduce the chance of fish or currents moving the mainline and getting it tangled on the bottom (Chapman 1990). The mainline usually has a haul-in line on each end with a float to mark the position and support the weight of the haul-in line (Figure 15). The mainline is generally 250 to 350 m long, although this can be altered to suit the operation of the boat and the depth of water being fished. A general rule is to have the mainline shorter that the depth of water being worked, so that when the first hook reaches the surface the fisherman knows the last hook is off the bottom. The hooks are on individual snoods around 30 to 40 cm long, with a longline clip on the other end. The snoods are snapped onto the mainline at around one-metre intervals. This type of gear is generally used on a flat bottom with few obstacles, to reduce the chance of the mainline becoming stuck on the bottom. This type of gear has not been very successful in the Pacific due to the rough nature of the bottom being fished, which has resulted in considerable gear loss.
One type of bottom longline with a haul-in line at each end
An alternative type of bottom-set longline is being used in some locations in the Pacific because of the rough bottom being fished. In this case, a short mainline of 100 to 150 m in length is used and the mainline is made from polypropylene rope, which is positively buoyant (Figure 16). The snoods and spacing along the mainline are the same as other bottom longlines, and there is generally only one haul-in line as the mainline is so short. This type of gear has been more successful in the Pacific as it is short and can be better targeted, and there is less chance of getting the gear snagged on the bottom with less gear loss.
Alternative bottom longline using polypropylene rope mainline
5.2 Setting a bottom set longline
The most common and safest way to set bottom longlines from small craft is to use a shooting rail. The rail is a piece of aluminium ‘U’or channel beam or equivalent. The snoods are prepared by baiting each hook and placing it in the ‘U’or channel beam. The snap is allowed to hang down from the beam (Figure 17). The snap of each snood is then attached to the mainline in order, with around one metre of mainline between snaps (Figure 18). When all the snaps are attached to the mainline, it is ready for setting. The anchor or weight at the end of the mainline is let go and it starts to pull the baited hooks of the shooting rail in order as the boat motors forward. When all the snoods are set, the mainline is tied off and the boat stretches the mainline out to stop in settling in a pile on the bottom. When the mainline is stretched, the second anchor or weight is released and the haul-in line paid out. The float is then released and the gear allowed to settle and soak.
Baited snoods lined up ‘U’or channel beam
Snood snaps attached to the mainline in the ready for shooting the gear
5.3 Hauling the gear
The gear is easily hauled using a line hauler that is mounted close to the side of the boat (Figure 19). The float is retrieved and the haul-in line passed over the line guide (Figure 19) or block and on to the hauler. The rope is then closely monitored as it is hauled until the first anchor or weight is reached. The hauler is stopped, the anchor or weight removed and the hauling continued slowly with each snap being removed from the mainline as it comes into reach. When larger fish are on the line, the hauler is stopped to allow the fish to be gaffed and boated.
One type of line hauler used to haul bottom longline
Trotlines are an alternative to bottom-set longlines. The main difference is that the mainline is suspended horizontally above the bottom, so it does not come in contact with the ocean floor and become stuck. There have been several types of trotline arrangements used or trialled over the years in the Pacific.
The ‘Florida fish stick’uses short lengths of PVC tubing with a weight on one end and a pressure float and snap attached to the other (Figure 20). Holes are drilled through the PVC and a snood is passed through and secured, with a hook placed on each end. The fish sticks are then attached to the mainline as it is paid out during setting, so that the weight of each stick is on the bottom with the pressure float keeping it vertical in the water (Figure 20). Although this method has been used in several locations in the Pacific, it has not been successful as the fish sticks are costly, easily broken and difficult to handle on the boat. Consequently they are no longer used in the region.
The ‘Florida fish stick’type of trotline
Other trotline arrangements have the trots or droppers made of monofilament, wire or light cord rather than PVC pipe. The basic design is the same; however, the trots are much easier to handle on the boat and easily stored. Another small difference is that the weight at the bottom of each trot is usually sacrificial, and is attached to the trot by a light cord. This is to allow it to break off if it gets stuck on the bottom. Figures 21 and 22 show two trotline arrangements.
The length of each trot is usually around 1.5 to 2 m, so that the three to five hooks are kept relatively close to the bottom. Trotlines are set and hauled in the same manner as bottom-set longlines. The main difference is that the trots are generally attached to the mainline as it is being paid out (no shooting rail used). Like bottom-set longlines, the length of the mainline is shorter than the depth of water being fished. These types of trotlines are still used in a few locations in the Pacific, especially some Melanesian countries.
A trotline arrangement with the mainline attached to the anchor or weight
A trotline arrangement with the mainline attached to the haul-in lines
A few species of deepwater snappers are known to school and rise off the bottom. For these species, a dropline can be used. A dropline is a single line (haul-in line and mainline) set vertically, with a weight on the bottom and a marker float on the top (Figure 23). From 5 to 50 snoods can be spaced at 50 to 80 cm intervals along the bottom portion of the line from the bottom up (Figure 23). Just above the top hook, a small pressure float is attached to ensure the mainline is kept vertical and the hooks are kept off the bottom.
Droplines are generally set using a shooting rail the same as described above for bottom-set longlines. The difference is that the boat is stationary so the weight takes the hooks straight down so the mainline is vertical. A rope line hauler is used to retrieve the gear, with the hooks unsnapped from the mainline as they come aboard. This method has been tried in the Pacific, but has not become popular and is rarely used at present.
The ‘Z’trap (Figure 24) has been trialled in several countries in the region with limited success. The design of the trap is such that it guides fish to one of two entrances in the wire mesh cage. Once inside, the fish find it difficult to escape. Although the catch rates for deepwater snappers have been low, it has been reported that in some locations large numbers of nautilus have been caught as well as some deepwater shrimps (when fine wire mesh is used). This method is not used in the Pacific at present due to the high cost of the gear, the low catch rates and the potential for gear loss.
Basic ‘Z’trap design
Trawling in the Pacific for deepwater snappers has been tried on a couple of occasions, especially on offshore seamounts where the trawl just passes over the top of the seamount where the fish tend to congregate. This is a method that is not used in the Pacific at present for fishing deepwater snappers. However, several countries in the region are looking at the possibility of deepwater trawling in depths of 500 to 2 500 m for other species and this may occur in the future.
The main gear used in the Pacific region for deepwater snappers continues to be the handreels and powered reels. This is due to the low cost of the equipment, their ease of maintenance and repair of the equipment and the generally limited fishing area for these species. This type of gear would be used to some degree in all Pacific Island countries and territories.
Bottom longlining and trotlining are the next most common methods used in the region for deepwater snappers, although these are mainly used in some of the Melanesian countries where there are larger fishing areas for these species. The boats used are equipped with hydraulics and the gear is more expensive. In Pacific locations demand in both local and export markets provides high prices for the fish, which warrants the increased cost of the boats and gear used.
11. LITERATURE CITED
Chapman, L. 1990. Certificate in Fishing Operations -fishing technology course notes for year one. Australian Maritime College, Launceston, Tasmania. 220 pp.
Preston, G., P. Mead, L. Chapman and P. Taumaia 1999. Deep-bottom fishing techniques for the Pacific Islands -a manual for fishermen. Secretariat of the Pacific Community, Noumea, New Caledonia. 82 pp.