FAO Fisheries Circular No. 920 FIRM/C920
REVIEW OF THE STATE OF WORLD FISHERY RESOURCES: MARINE FISHERIES
Marine Resources Service,
Fishery Resources Division,
FAO, Rome, Italy
14. SOUTHWEST PACIFIC
FAO Statistical Area 81
This area encloses the Tasman Sea and the Pacific Ocean east to the 105E meridian (Figure B14.1). The types of habitats that are exploited in this area are most varied, from coastal continental fisheries to deepwater seamount fisheries. In fact, New Zealand has been a pioneer in profitable and sustained deepwater (>600 m) trawl fisheries. The fisheries resources consist of the coastal species of the Australian States of New South Wales and Northern Victoria, and of New Zealand, the pelagic resources of the South Western Pacific and the mesopelagic species (of which the most important are orange roughy and hoki) associated with the sea bottom rises of the Tasman Sea, and to the south and east of New Zealand and the deep water to the west of the South Island.
A development of interest in this area began with the industry-sponsored exploratory surveys for orange roughy in areas to the southeast of New Zealand. These surveys were noteworthy
as they required cooperation between otherwise competing companies. This had the benefit of spreading the risk of the venture in the event that no new resources were located. As it was, previously unknown resources of this species were discovered. Another event of considerable regional interest was the outbreak of a viral disease that caused massive mortalities of pilchard (Sardinops neopilchardus). This epidemic started in the Australian Bight, spreading to Western Australia and to Queensland, taking about 70 days to spread 6 000 km. The outbreak then appeared in New Zealand in June 1995. This epidemic was mostly specific to adults over 9 cm with the event happening quickly, over a period of a couple of weeks. Mortality could be patchy with apparently healthy schools among those that had been afflicted. The cause seems to be a herpes virus.
PROFILE OF CATCHES
Catches within the Southwest Pacific region increased relatively slowly up until the end of the 1960s. The relative isolation of Australia and New Zealand meant fisheries production was largely for domestic consumption only, where demand was low due to the traditional market preference, and low prices, for red meat. The main species caught during the 1950s and 1960s were the New Zealand dredge oysters, golden snapper, tarakihi and red rock lobster, all caught by New Zealand. These four species made up over 40% of total landings until 1970. Smaller quantities of cupped oysters and mullets were landed by Australia. In 1970 significant landings of species from other ISSCAAP Groups were first reported. By the mid 1970s catches of species from what are now considered the main ISSCAAP Groups had already trebled, and catches in total more than doubled. This rate of increase continued, with catches of the main ISSCAAP Groups nearly doubling every five years until 1991, at which point declines in catches of several of the Groups occurred (Figure B14.2, Table XIV).
One of the main "new" ISSCAAP Groups in the 1970s was Group 32 (cods, hakes, haddocks, etc.), with the main species being Southern blue whiting and blue grenadier (or hoki) (Figure B14.3). Catches of hoki peaked at 279 000 t in 1991, declined sharply in 1993 but rallied to 248 000 t in 1994 (with over 80% being caught by New Zealand). Catches of Southern blue whiting peaked in 1992 but have since declined to levels close to the average of the 1980s (~18 000 t).
|Figure B14.4||Figure B14.5|
RESOURCE STATUS AND MANAGEMENT
Thirty seven species are under quota management in the 1995-1996 fishery season. The Fisheries Act of New Zealand requires that, in respect of yields, management consider "The amount of fish ... that will produce from that fishery the maximum sustainable yield, as qualified by any relevant economic or environmental factors, fishing patterns, the interdependence of stocks of fish, and any generally recommended sub-regional or regional global standards". The assessment strategy uses an objective of Maximum Constant Yield (MCY). This is defined as "the maximum constant catch that is estimated to be sustainable, with an acceptable level of risk, at all future levels of biomass". MCY will depend on the current state of the fish stock: if the biomass falls below a certain level, the MCY would be reduced. The other management reference point used is that of Current Annual Yield (CAY). This is obtained by applying a reference fishing mortality, Fref, to the estimate of the biomass.
Many factors are taken into account before setting a Total Allowable Commercial Catch (TACC), and the TACC may be higher than would be indicated by the MCY or CAY. These factors include fishing patterns, the interdependence of stocks, non-commercial interests (e.g. Maori, traditional and recreational) and other relevant economic and/or environmental factors. For example, hoki catches have been lower than that which the stock is believed capable of supporting because it is thought that higher landings would result in fewer economic benefits being derived from the fishery.
With its entry into the New Zealand quota management system, stocks of red rock lobster (nine management units) have shown some signs of future possible recovery which has been reflected in the value of their quota rights. Landings for the 1994/95 season were 2 624 t, compared with 5 024 t in 1986/87. While stocks of the highly valuable orange roughy, the foundation of the export industries, continue to decline, this decline has been offset to some extent by the continuing discovery of new stocks and stocklets. Little is known about the relation between these apparent stocks. During the 1994-95 season, only 81.7% of the quota was taken for a catch of 22 449 t, down from a peak of 62 474 t for the 1988/89 season.
Another species gaining increasing prominence in export sales is blue grenadier (or hoki), which is managed in two stock units. At the industry's initiative (for marketing reasons) catches taken have been less than that believed to correspond to the sustainable yield. Only 79.4% of the quota was taken during the 1995-96 season for a total of 174 972 t, compared with 251 893 t during the 1989-90 season. The current size of the western stock is much larger than that which will support the MSY and it can sustain the current catch level. For 1995-96, the estimate of the (CAY) is much larger than the current catch level, which indicates that higher yields are possible from this stock. For both the current catch level and TAC increase of 100 000 t (with an increase of 75 000 t from the western stock), there appears to be zero risk to the stock and fishery from 1995 to 2000. For the eastern stock the assessment is less certain and the management model results are sensitive to most parameters. However, the current biomass appears to be above the level needed to maintain MSY, and the CAY is about the level of commercial catches. The risks associated with the fishery are unknown but would be reduced if harvesting were switched to the Western stock.
Being a country with a state-federal structure, Australia has two levels of fisheries management; traditionally States controlled the territorial waters (up to 3 miles offshore) and the Commonwealth Government controlled resources in the offshore (up to 200 miles). Many of the stocks in the Australian EEZ in Area 81 (i.e. essentially New South Wales) are shared with Queensland to the north (in FAO Statistical Area 71), particularly lutjanids and shrimp (eastern king prawn). About 25% (48 000 t) of fishery landings in the Australian EEZ in Area 81 are under Commonwealth control. These fisheries are managed under the Fisheries Management Act 1991 by the Australian Fisheries Management Authority. In terms of offshore fisheries, the general region of Area 81 contains the following: the East Coast yellowfin tuna fishery; the East Coast skipjack tuna fishery (resource probably underexploited with a declining catch trend); Southern bluefin tuna (overexploited with catches controlled by quota); Southern shark (schooling sharks overexploited, gummy sharks fully exploited); Southeast fisheries for eastern gem fish and orange roughy, the first being fully exploited, the second at or near full exploitation, and a Southeast fishery for 14 quota species of which only one is considered under exploited.
Total allowable catches were placed on silver gemfish in 1988 and on orange roughy in 1990. TACs were introduced for all 16 major species or species groups in the Southeast fishery in 1992. Prior to this time the fishery had been characterized by fleet over-capacity and effort leading to over exploitation of the species. Current catch from the fishery is around 23 300 t. Apart from silver gem fish and orange roughy, the most important species are flathead (Neoplatycephalus richardsoni), blue grenadier, and redfish (Centroberyx affinis). The Southeast fishery is shared among NSW, Victoria, Tasmania and South Australia. Since 1985 it has been compulsory for participants to keep log records by tow. Flathead have been a component of this fishery since trawling began and peak catches were recorded in 1928 (>5 000 t); current landings are around 1 150 - 3 800 t. High-grading may be a problem in this quota-controlled fishery. Redfish are a slow-growing species reaching more than 35 years of age. Problems have occurred with stocks straddling areas under state jurisdiction, and these have been compounded by growth overfishing and discarding of small individuals. Current biomass may be less than 30% of the unfished level and stock rebuilding is considered necessary.
The silver gemfish stock has been in decline since the late 1980s, largely as a result of poor recruitment during 1985-89. As a consequence, a zero TAC was set in 1993 which has since remained in place, and trip limits exist for gemfish bycatches. Despite the reductions in landings, the stock continues to decline as weak year classes pass through the fishery. For the other major trawl-caught species, orange roughy, stock biomass is now believed to be 25-35% of the unfished level and harvests must be reduced if the fishery is to be sustainable. The uncertainty regarding the stock structure of this species complicates its management. The extreme longevity of this species (~100 years) means that stock rebuilding will be a lengthy process.