Blocking of lagoon/sea access channels by fixed or movable fishing gears appears to be a universal problem where lagoon fisheries are intensive, particularly when practised indiscriminately on outward or inward bound migrations for reproduction and on inward bound migrations of larval shrimp or fishes. Examples of this problem are known in the Chilka (Jhingran and Natarajan, 1969) and Pulicat (Menon and Raman, 1977) lagoons in India. In the latter, fixed stake nets are said to “choke” the lagoon mouth during high tide and to filter out prawns and finfishes, irrespective of size. In the former, concern has been expressed because of interference with the seaward spawning migrations of Mugil and Lates. Fishing close to the lagoon mouths on inward and outward migrations has also been recognized as inimical to the lagoon finfish fishery in the Laguna Madre de Tamaulipas (Mexico) by Meza (1980) and to the shrimp fishery there by Martinez Mata (1980). Numerous fish weirs completely block the channel interconnecting the lagoons of the Inharrime River (Mozambique) with the sea. Abundance of fishes of marine origin in the system is apparently inversely related to the number of weirs which the fish must pass through on inward migrations (Matthes, 1981).
The locations of various kinds of fishing gears used mainly for shrimp fishing in various connecting water courses of the Lagoa de Araruama, Brazil, have been plotted by Slack-Smith et al. (1977) (Fig.1). Here, too, blockage of channels by gears is recognized as one of the factors which has caused a decrease in shrimp yields in recent years. One trap so tightly blocked waterflow that there was a 10 cm difference in water level between the lagoon and the channel, a condition which would prejudice the entrance of post-larval shrimp to the lagoon which takes place throughout the year.
Other problems identified in relation to the operation of fishing gears in lagoons are fishing in parts of the lagoon known to be nursery areas where juvenile shrimps are concentrated (Slack-Smith et al., 1977: Martinez Mata, 1980). This practice is usually combined with the use of small mesh sizes (Barrera Huerta, 1976). Meza (1980) also notes that the use of active gears which are fished along the lagoon bottom for finfishes in Laguna Madre de Tamaulipas leaves paths bare of vegetation and also destroys natural oysters beds.
Among the management solutions proposed by Slack-Smith et al. (1977) to reduce the overfishing of shrimp by the artisanal fisheries of Lagõa de Araruama was the removal of fishing gears which completely blocked the access channels to the lagoon (those allowing some area of free passage could remain as long as their numbers would not be increased). Matthes (1981) proposed a similar solution for the blockage of fish migrations in the Inharrime lagoon system. A trap configuration was designed that permits passage of fishes on inward and outward migrations as a replacement for the weirs (Fig.2).
Additional management measures advocated by Slack-Smith et al. (1977) were the registration of the some 1 000 fishermen and their gears. Based on this registration no new fishermen or gears were to be permitted to enter the fishery. Also recommended was a restriction which would limit the use of some active gears to deeper areas of the lagoon.
Fig. 1. Locations of various kinds of fishing gears in the connecting channels of the Lagoa de Araruama, Brazil (from Slack-Smith et al., 1977)
Fig. 2. Existing fish weirs, and recommended replacement by fish traps with capture chambers which permit migrations (from Matthes, 1981)
Limitation of mesh sizes for shrimp fishing was not recommended because of a lack of information on gear selectivity and also because an earlier attempt to enforce a minimum size limit for shrimp caused a decline in fishermen's income to such an extent that their economic survival was threatened. Further, gears using meshes smaller than those than prevalent would be made inoperable because of clogging by the abundant plant material of the lagoon.
In Bardawil lagoon along the Mediterranean in Egypt, amelioration of a hypersalinity condition in 1970, through maintaining continuous connections with the sea led to an increase in stocks but also stimulated a rapid expansion of the fishery. This led to overexploitation of the valuable Sparus aurata resources of the lagoon (Ben-Tuvia, 1979). In the late 1960's the fishery was largely subsistence- oriented and fishing was from 50 sailboats. By 1972, the number of boats had increased to 179, of which 68 were motor-powered (Pisanty, 1980). Cotton nets were replaced by synthetic fibres, and net numbers and lengths increased. Subsequent biological investigations showed an urgent need for regulation of the fishery and a number of fishery management measures were adopted. These included mesh-size regulation, establishment of a minimum legal length, a closed season to protect the seaward spawning migration of Sparus and also to provide protection for the non-migrating younger year class which remains in the lagoon over winter (Ben-Tuvia, 1979). Additional fishery management measures adopted were licensing of fishermen, boats, and gears, a permit system regulating fishing effort on a rotational basis, and restrictions on gear dimensions (Pisanty, 1980).
As a result of the hydraulic and fishery management programmes the yield from the lagoon was doubled and the value of the fishery was increased tenfold over the period 1968-78 (Pisanty, 1980).
It is noteworthy that the tax of about 15 percent imposed on the gross value of the catch was ample to support the hydraulic management of the lagoon as well as the cost of research, administration and management of the lagoon fishery.
Another factor which must have contributed to the success of the fishery, in addition to the comprehensive fishery management programme itself, though not mentioned specifically by Ben-Tuvia (1979) or Pisanty (1980), is that the lagoon is somewhat isolated and therefore management regulations were more easily enforced. Additionally, management measures were formulated and imposed before the fishery got out of hand, and the management measures selected proved to be quite appropriate from the outset.
On Lake Borullus, one of five Nile Delta coastal lagoons in Egypt, regulations on the fishery include prohibition of fishing in the area of the lake-sea connection, minimum mesh sizes on gears, restrictions on some gear types and speed limit on trawling. However, Libosvarsky, Lusk and El-Sedfy (1972) state that these regulations are not adhered to, presumably for lack of enforcement.
Chilka Lake, in India, varying in surface area from 96 500 to 116 500 hm², supports an incredibly complex conglomeration of fishing gears in the broad types: nets, traps, and “janos” (impoundements). Jhingran and Natarajan (1969) list 13 different kinds of nets in use there which are variations of drag, gill, and castnets. Netting is carried out both on leased grounds (exclusive fishing rights) and in other unleased areas on a fee basis. There are 112 jano impoundment fisheries which are leased out and which total 13 550 hm² (13 percent of average lagoon surface area) and 67 leased prawn fisheries (traps). A map of the entire lagoon and of several sections of the lagoon at a larger scale (Fig.3) provide an idea of the density of fishing gears used there in leased areas.
The fishery is based on ten principal commercially important finfishes and two species of shrimps, as well as crabs. The resources are somewhat overexploited as suggested by the small size of individuals, their young age at capture, and by relatively high fishing mortality rates.
Among the management measures suggested for this fishery by Jhingran and Natarajan (1969) were limiting fishing on the seaward reproductive migration of mullets and the banning of fishing on lagoonward migrating mullet fry, both of which occur in the narrow channel linking the lagoon to the sea.
Inside the lagoon, Jhingran and Natarajan (1969) suggested that minimum sizes be set for the commercially important finfishes with those of less than minimum size returned to the lagoon alive. Minimum size restrictions would be enforced through monitoring at markets. With such a diversity of gear types, minimum mesh size restrictions were considered unworkable. Other management measures recommended were induced breeding of mullet for lake stocking and for culture, use of shallow portions of the lake for aquaculture with some of the seed to be supplied from the lake, thinning of prawn traps located in areas affecting fish and prawn migration routes, and hydraulic engineering to maintain the lagoon/sea connection.
Fig. 3. The distribution of various kinds of fishing grounds and fishing areas in Chilka Lake, India (adapted from Jhingran and Natarajan, 1969)
A management technique favoured in Mexican lagoon shrimp fisheries is the closed season, “veda”, which is timed to protect shrimp during their period of rapid growth in lagoons, before their seaward migration for reproduction. Considerable research has been exerted to rationalize the timing and duration of the veda (Castro Melendez and Santiago Villalobos, 1976; Barrera Huerta, 1976, for example) and to properly phase the operation of shrimp trapping devices (“tapos”, “atravesadas”) with the seaward migration of shrimp (Reyna Cabrera, 1976; Gezan Soto, 1976). However, facilitating the entry to the lagoons of shrimp post-larvae, eggs and juveniles of finfishes, and crab larvae while simultaneously avoiding excess escapement of seaward migrating shrimp of fishable size (Barrera Huerta, 1976) and without excess loss of water from the lagoon (Edwards, 1978a) have remained a problem. For example, Barrera Huerta (1976) mentions that in lagoon systems of Oaxaca (Pacific Coast), operation of the structure favouring the first pulse of lagoonward migrating shrimp would have it open for entrance of post-larvae until the end of June and closed thereafter. However, in September there occurs another pulse of lagoonward migration of shrimp post-larvae which coincides with a seaward migration of harvestable-sized shrimp from the lagoon. Edwards(1978a) has proposed a scheme whereby two tapos would be operated in tandem in the same channel, with alternating openings and closings. This would permit both access by in-migrating shrimp post-larvae and the capture of out-migrants. However, he observes that such management would require liaison between the fishing cooperatives owning each of the tapos.
An artisanal fishery for Penaeus duorarum developed on the Casamance Estuary (Senegal) with the stimulus of the installation of a shrimp processing factory there in 1960. Historically, the development of the shrimp fishery had been marked by a more or less regular increase in shrimp yield and in fishing effort up until 1968. However, from the period 1968 through 1976 effort increased progressively while catch varied. In the period 1974–76 the catch decreased by about one-third, causing official concern that the resource was endangered.
The problem was believed to be that the increase in fishing effort had been accompanied by an extension of shrimp fishing into areas not traditionally fished beforehand, and that these newly-fished areas harboured small-sized shrimp which had previously not been included in the fishery. Thus, it was thought that the decrease in catch was caused by an overexploitation of juvenile shrimp.
In line with this hypothesis, a number of regulatory management measures were adopted in 1977. These included setting aside mangrove creeks as closed areas, limiting shrimp fishing to a well-defined portion of the main channel of the Casamance River, a prohibition on the use of drag-seines along the shoreline, and the setting of a minimum mesh size for the gears which were not restricted.
However, Le Reste (1980, and MS), in a study subsequent to the institution of the regulations, has found that annual shrimp yields in the estuary were governed much more by historical variations in salinity than by the effects of the fishery on shrimp resources. In particular, the results of the analysis showed that the timing of the outward migration of shrimp from the estuary, and most importantly for the fishery, the size at which shrimp migrate, are controlled by annual variations of salinity. Furthermore, salinity variations affect the spatial distribution of shrimp within the estuary.
Given that the present objective of management of the shrimp fishery in the Casamance estuary is to maximize the value of the catch which, in turn, implies that management be directed toward a strategy which maximizes the quantity of the large-sized, most valuable shrimp, Le Reste (MS) advocates that the minimum mesh-size regulations should remain in force. However, with regard to the closed areas, he notes that biological responses of shrimp to annual changes in salinity will be reflected in varying shrimp distribution patterns within the estuary. Therefore, it is not realistic to expect that large-sized shrimp will always be found within the estuarine areas now open to fishing, and he recommends some flexibility in the legislation governing the geographic limits of the closed areas along with implementation of a system to monitor shrimp fishing.
In a somewhat different perspective than the direct regulatory techniques that have been mentioned above is an “administrative” approach to the management of small-scale fisheries through the creation of fishing franchises. The franchise is thus a vehicle to moderate or remove the condition of common property (Christy, in prep.). By granting exclusive rights for the exploitation of fishery resources there is an incentive to self-regulate and to self-enforce to maximize resource benefits by the organization granted the franchise.
Leasing of estuarine and lagoon fishing grounds appears to be common practice in India as in Chilka Lake (Jhingran and Natarajan, 1969) and the Mahanadi estuarine system (Shetty, Chakraborty and Bhattacharya, 1965), but the extent to which this is used as a management tool is unclear from the literature available, although the impression is given that leasing is viewed predominantly as a source of government revenue.
Shetty, Chakraborty and Bhattacharya (1965), in connection with the fisheries of the Mahanadi estuarine system (Orissa), mention exploitation of the fishermen through the leasing system by the “Mokaddams” (landlords) in former times during which fishermen had to give over one-half of the value of their catches for fishing rights. Subsequently, the allocation of fishing rights through leases was brought under government control; however, at least in some areas leases have been taken up by the wealthy “landlords” once more and fishermen are once again forced to pay dearly for fishing rights.
The leasing system of the Mahanadi estuary seems to be similar to that presently practised for inland water fisheries in Bangladesh. In former times, on the floodplain lake/river systems wealthy landlords leased fishing rights directly to the fishermen for periods of up to 20 or 30 years. Under these conditions there was considerable incentive for the fishermen to manage exploitation to ensure a high and sustainable output year after year. Care was taken to preserve nursery areas, and channels and dikes were maintained for hydraulic control to benefit fish production. However, with the breaking up of large estates through agrarian reform after independence, leasing of fishing rights came under the public domain. Leases for fishing rights were shortened to one, two,or three years. As a result, the exploitation strategy changed toward extracting the maximum in the shortest possible time and catches decreased, as well as revenues to government (Kapetksy, unpublished).
Given the proper set of conditions, leasing of fishing grounds can be a powerful fishery management tool which also can provide considerable socio-economic benefits for fishermen while reducing somewhat the costs of management. Among the conditions which have to be met are: (1) relatively long-term leases as an incentive toward rational exploitation; (2) geographically well-defined limits on the lease (lagoon, arm of an estuary); (3) a fishery preferably based mainly on stocks which complete their life cycle within the leased area, or provision of areas closed to fishing or closed seasons so that migratory fishes have an opportunity to complete their life cycles, and so that each leased fishing ground has a more or less equal opportunity of receiving migratory juveniles and adults; and (4) a strong, uncorruptable local or central government infrastructure to administer the leasing system for the benefit of fishermen.
The examples presented above have illustrated a variety of perceived needs and some applications of different kinds and combinations of regulatory management techniques for a number of coastal lagoon and estuarine fisheries.
This brief perspective has been added to call attention to some additional and important aspects of the management of coastal lagoon and estuarine fisheries which have not been explicitly covered in these examples.
Implicit in nearly all of the examples is that the objectives of regulatory management is to ensure maximum yield or maximum economic value of the yield. In fact, in the great majority of coastal lagoon and estuarine fisheries of developing countries, socio-economic conditions -- mainly underemployment and lack of alternative employment opportunities for fisherman -- dictate that fisheries have to be managed in such a way as to ensure maximum employment, even if this objective results in marginal economic benefits to the individual fisherman and even if total fishery output suffers. Therefore, one of the most potent of regulatory management tools, limitation of entry, either in terms of direct regulation of total numbers of fishermen, indirect regulation of entry by gear type, or by closed seasons, may not be acceptable in many coastal lagoon and estuarine fishery situations except where fishermen have other employment opportunities, or where these opportunities can be created.
In addition to socio-economic situations which militate against the limitation of entry to coastal lagoon and estuarine fisheries as a means of management, there are other factors which also limit management options. In terms of the formulation of appropriate management policy an d strategy , lack of sufficient information such as on basic fish biology, yield, effort, economic and environmental data, may constrain the design of management programmes or result in the application of inappropriate management regulations. Le Reste's (1980 and MS) studies of the Casamance estuary shrimp fishery cited in the previous section, provide a case in point of the establishment of a set of management regulations based on insufficient or inaccurate information.
As a result of the same lack of information almost invariably the fishery situation has already gotten out of hand before the need for regulatory management is officially recognized, and therefore the implementation of an appropriate management programme under these circumstances is all the more difficult.
Still other characteristics of lagoon and estuarine fisheries limit the alternatives to the application of regulatory management techniques. Among these characteristics are that fishermen are widely dispersed and that fishing grounds, fishing times and landing sites may vary widely. Thus, regulatory techniques which would involve monitoring of fishermen while they are engaged in fishing, or at landing points, would of necessity be expensive in terms of the numbers of enforcement personnel required. Therefore, governments would find difficulty in funding such expensive enforcement activities.
Another factor which complicates regulation of fishing or of fishing gears on the fishing grounds is the often complex and varied nature of the fishing gears utilized, as exemplified by the Chilka Lake fisheries (Section 2.2). In this situation measurement of gear selectivites and efforts cannot be easily accomplished and therefore gear specification and effort cannot be practically regulated unless a specific gear type is entirely eliminated from the fishery through legislation.
Within the context of coastal lagoon and estuarine fisheries as they presently exist in most developing countries, management of fisheries is probably most easily applied (and has the best possibility of becoming more effective in the future) when regulation is aimed first at the most destructive of fishing practices. In this situation the majority of fishermen themselves can then readily appreciate the benefits of regulation. An example of such a situation in which regulatory management can be readily implemented is the blockage of inbound and outbound reproductive migrations and the fishing of juveniles by fixed gears set in lagoon/sea access channels.
Another possibility which seems workable at first sight is the maintenance of minimum size or length regulations through monitoring of the marketed catch and by holding marketers responsible for maintaining the size standards through penalties. This method has the advantage of requiring a relatively small and thus inexpensive enforcement staff for maintenance of a straightforward management objective. However, even such a low-complexity management method might present difficulties in some fisheries, namely that in many artisanal fisheries a significant proportion of the catch may go for subsistence or local sale, and may not enter formalized marketing channels. Another draw-back is that in some fisheries processing may be undertaken by the fishermen themselves and size-regulated fishes or crustaceans may be unidentifiable for measurement after processing. Examples of extreme cases are the practices of using undersized fishes and shrimps for sauces or pastes, but sun-drying, prevalent as a preservation method almost everywhere in the tropics and sub-tropics, would have a similar effect. Thus, enforcement of size regulations would have to be undertaken at usually widely dispersed fish landing sites. This regulatory method is therefore best applied to high value fishes, crustaceans and molluscs where quality maintenance demands centralized processing and where monitoring can be relatively easily undertaken.
An alternative to the regulation of lagoon and estuarine fisheries through central government intervention is the possibility that traditional fishery management practices could be revitalized or reinforced. Such traditional fishery management practices have evolved over centuries to conserve fishery resources while at the same time providing an equitable distribution of resource wealth among fishing communities.
Fishery management by traditional means is probably fast disappearing; however, there are indications that these traditions still remain in force in some areas. For example, “self-regulation” by traditionally engendered controls still works in parts of the Ghanian lagoon system. There, lagoon ownership is held by the adjacent village or town and the lagoon itself has a religious status. Regulation of fishing is controlled by a Chief Fetish Priest and is exercised in the form of closed seasons (Mensah, 1979). Fetishes also play a role in the regulation and allocation of fishing in the lagoon systems of Benin (Welcomme, pers.comm.). In Nigeria, where lagoon oyster fisheries have been in decline for some time, to safeguard against further depletion, the villagers themselves have enforced management regulations including licensing, closed seasons and quotas (Ajana, 1980).
Although the traditional fishing industry in the Lagune Ebrié in Ivory Coast has been disrupted by the influx of expatriate fishermen,gears, and capital, in another lagoon in the same country fishermen themselves decided not to permit the entry of new gears(Garcia, pers.comm.).
In the estuarine fisheries of the Bahia State of Brazil, Cordell (1974; 1978a and 1978b) has shown that a complex of factors has been evolved over four centuries to match traditional canoe fishery exploitation to the resources available to the fishery. Among the means which have been evolved to ensure rational exploitation of the resources is a system of keeping the detailed knowledge for prediction of tides and currents, necessary for fishing success, within tight-knit family groups which are limited in number. The establishment of proprietary fishing rights to certain fishing areas which are passed from one generation to the next was probably the most important development to rationalize exploitation. Other factors included a cooperative attitude within the fishing community, and community social pressure.
In order to revitalize traditional fishery management where its practice is fast disappearing, or to reinforce it where it is still in force, would , however,require indepth studies of the sociological/anthropological/economic aspects of traditional fisheries such as those conducted by Cordell mentioned above. But it seems that this approach, if successful, could be quite viable, and in the long run, economic when compared to the costs and difficulties of management programmes instituted and wholly enforced by central governments. After the mechanisms involved in traditional fishery management had been studied and understood, steps could then be taken by central government authorities to formally legalize traditional regulatory institutions and to reinforce traditional regulatory authority. For example, the first attempt at a unified fishing law for Japan in 1901 recognized and legalized a major part of the existing traditional fishing institutions and practices (Asada, 1973).
In summary, many “classical” regulatory fishery management techniques have been proposed to solve the various kinds of fishing problems identified in the lagoons and estuaries of developing countries -- closed seasons, closed areas, limited entry of gears and fishermen, and gear regulations; however, the literature is much less replete with examples of the successful employment of these regulations which are accompanied by measurements of the benefits which have accrued to fishermen and the costs which are incurred for the management strategies adopted. Bardawil lagoon was the only exception found. There it was demonstrated that classical regulatory approaches to fishery management can be successful if implemented in the near ideal circumstances of high-value resources, strong but benevolent administration, adequate and appropriate research on which to base management strategies, and sufficient means for strict enforcement of management regulations. However, in what is the more usual circumstance in the coastal lagoon and estuarine fisheries of developing countries, the most potent forms of regulatory management may be inappropriate or inapplicable for a complex of sociological, economic, and political reasons, or the information may not be sufficient to formulate appropriate management policies. Nevertheless, in this situation a start can be made by attempting to address the most serious management problems through regulation of the most destructive fishing practices. As an alternative to the imposition and enforcement of management regulations by central government authority, or as a supplement to such management, it may be possible to revitalize or reinforce those features of traditional fishery control which historically conserved fishery resources while providing fishing communities with an equitable share of resource wealth.
