Abstract: Birds are the most conspicuous, wide-ranging, and easily studied organisms in the marine environment. They can be both predators and scavengers, and they can be harmed by and can benefit from fishing activities. The effects of fishing on birds may be direct or indirect. Most direct effects involve killing by fishing gear, although on a lesser scale some fishing activities also disturb birds. Net fisheries and hook fisheries have both had serious negative effects at the population level. Currently, a major negative impact comes from the by-catch of albatrosses and petrels in long-lines in the North Pacific and in the Southern Ocean. High seas drift nets have had, prior to the banning of their use, a considerable impact on seabirds in the northern Pacific, as have gillnets in south-west Greenland, eastern Canada, and elsewhere. Indirect effects mostly work through the alteration in food supplies. Many activities increase the food supply by providing large quantities of discarded fish and wastes, particularly those from large, demersal species that are inaccessible to seabirds, from fishing vessels to scavengers. Also, fishing has changed the structure of marine communities. Fishing activities have led to depletion of some fish species fed upon by seabirds, but may also lead to an increase in small fish prey by reducing numbers of larger fish that may compete with birds. Both direct and indirect effects are likely to have operated at the global population level on some species. Proving the scale of fisheries effects can be difficult because of confounding and interacting combinations with other anthropogenic effects (pollution, hunting, disturbance) and oceanographic factors. Effects of aquaculture have not been included in the review. 2000 International Council for the Exploration of the Sea

Abstract: The world's most endangered marine cetacean, the vaquita ( Phocoena sinus ), continues to be caught in small-mesh gillnet fisheries throughout much of its range. We monitored fishing effort and inciden- tal vaquita mortality in the upper Gulf of California, Mexico, from January 1993 to January 1995 to study the magnitude and causes of the incidental take. Of those factors studied, including net mesh size, soaktime, and geographic area, none contributed significantly to the incidental mortality rate of the vaquita, implying that the principal cause of mortality is fishing with gillnets per se . The total estimated incidental mortality caused by the fleet of El Golfo de Santa Clara was 39 vaquitas per year (95% CI 5 14, 93), over 17% of the most recent estimate of population size. El Golfo de Santa Clara is one of three main ports that support gillnet fisheries throughout the range of the vaquita. Preliminary results indicate that fishing effort for San Felipe, Baja California, is comparable to that of El Golfo de Santa Clara, suggesting that this estimate of incidental mortality of vaquitas represents a minimum. We strongly recommend a complete and permanent ban on gillnets in the area. Alternative or supplemental mitigation strategies include (1) a maximum annual allow- able mortality limit of vaquitas; (2) mandatory observer coverage of all boats fishing within the Upper Gulf of California and Colorado River Delta Biosphere Reserve; (3) extension of the Upper Gulf of California and Colorado River Delta Biosphere Reserve to encompass all known vaquita habitat; (4) rigorous enforcement of new and existing regulations; and (5) development of alternative sources of income for gillnet fishers.

Abstract: POLICY The American Fisheries Society (AFS) recognizes the need for conservative and robust management of Pacific rockfishes because of naturally low population growth, the overfished state of many of the stocks, and complex nature of the mixed-stock fisheries (60-plus species). The AFS recommends that catch information be collected on a species-specific basis, and that management targets also be established on a species-specific basis including species taken as bycatch. Such management will require accurate studies of discards at sea. Reduction in rockfish discards should be a management priority in all fisheries which capture significant numbers of rockfish. The AFS further recommends establishment of adequate fishery independent surveys to more accurately assess and monitor rockfish stocks. The AFS supports the establishment of systems of Marine Protected Areas to protect the habitat of Pacific rockfish and to promote recovery of stocks. Such areas should be established along with traditional management measures to control fishing mortality. Regardless of the management strategy used, substantial decreases in fishing mortality must be achieved soon to avoid stock collapses. The AFS encourages its members to become involved by providing technical information needed for protection of rockfish to international, federal, state, and provincial policy makers so decisions are made on a scientific, rather than emotional or political, basis.

Abstract: Food and feeding ecology of black-browed albatrosses Diomedea melanophrys rearing chicks was studied during 2 austral summers (1994 and 1995) at the Kerguelen Islands. Dietary analysis and satellite tracking were used to estimate potential interactions with commercial fisheries in the area. Fish comprised 73 % by fresh mass of albatross diet; other significant food items were penguins (14%) and cephalopods (10%). Twenty-one species of fish (232 individuals) were identified and included mainly nototheniid and channichthyid species. The most important were Dissostichus eleginoides (18.3% by reconstituted mass), Channichthys rhinoceratus (16.9%), Lepidonotothen squamifrons (11.6%), and to a lesser extent, Bathyraja sp. (4.5%) and Notothenia cyanobrancha (4.5%). The cephalopod diet was dominated by 3 taxa, the ommastrephid squids Todarodes sp. (7.6%) and Martialia hyadesi (3.6%), and the octopus Benthoctopus thielei (2.4%). Satellite tracking indicated that during trips lasting 2 to 3 d, albatrosses foraged mainly over the outer shelf and inner shelf-break of the Kerguelen Archipelago. Birds moved to northern, eastern and southern waters, but never to the western Kerguelen shelf where there was a commercial longline fishery for D. eleginoides. Interactions with trawlers targetting D. eleginoides and Champsocephalus gunnari were of minor importance in the northern shelf. There, offal from D. eleginoides was available to the birds; fish and cephalopod bycatch were negligible. Most of the natural prey of black-browed albatrosses are primarily benthic and semipelagic organisms not known to occur near the surface. Since we demonstrate that most of them were not scavenged behind fishing vessels, the way albatrosses catch demersal organisms remains a mystery.

Abstract: ‘The American Fisheries Society (AFS) recommends that regt the Indian River Lagoon area of Florida; Puget Sound, Washington and adjacent Canadian waters; and the Gulf of California. Further AFS analyses show that certain groups of fishes are particularly vulnerable because they have slow growth and late maturity Severe population declines have been documented for several snappers and groupers (Lutjanidae, Serranidae) in the Atlantic and the Gulf of California, several rockfishes (Sebastinae) in the Pacific, and some sharks (Selachei), skates (Rajidae), and sawfishes (Pristidae). Regulatory agencies should be apprised that these groups are extraordinarily vulnerable, and priority management should be given to these species, The greatest threat to many long-lived marine species may be bycatch (including regulatory discard) in fisheries,targeting other, often more-productive species. Regulatory,agencies must monitor bycatch of long-lived species and move to implement conservation actions if population declines are recorded. The most effective management strategy for some species taken as bycatch and for targeted species such as deeper-water groupers and Pacific rockfishes, may be establishment of large, protected marine reserves to supplement traditional management practices outside of the protected areas. The AFS supports the development, use, and evaluation of large marine reserves or Marine Protected Areas to protect and rebuild vulnerable populations. These reserves must have clearly defined goals, include a wide variety of environmental conditions, be of sufficient number to protect marine ecosystems within each region, allow adaptive management, and be large enough to be self-sustaining. The AFS encourages its members to become involved by providing technical information needed for protection of at-risk marine stocks to international, federal, state, and provincial policy makers, so decisions are made on a scientific, rather than emotional or political, basis.

Abstract: We investigated the effects of a purse-seine fishery with drifting fish aggregating devices (FADs) in the South Sherbo area of the Equatorial Atlantic, located between 0–5N and 10–20W. There had been no surface fishing activity in the area until 1975. Since 1991, fishing operations on schools of tuna associated with FADs has become widespread and this offshore area has developed into a major fishing zone. Exploitation rates are high between November and January. The fishery exploits multispecies concentrations of skipjack (71%), bigeye (15%), and yellowfin (14%) tunas of similar size (mode: 46-cm forklength). The use of FADs increased the vulnerability of small tunas and induced changes in fishing patterns. The mean individual weight of skipjack caught has decreased since 1991, due either to overfishing or to a growth change. Data from scientific observers were used to estimate discards and by-catches generated by FAD fishing during 1998. Discards of tunas (including frigate and little tunas) represented 7.6% of the total catch. Other by-catch (dominated by wahoo, billfish, triggerfish, sharks, barracudas, and dolphinfish) represented 2.3%, including 0.4% discarded at sea. Stomach content analysis showed that a mesopelagic species, Vinciguerria nimbaria (Photichthyidae), which during daylight concentrated in the upper layers in dense schools, was the main prey of all small tunas. The South Sherbro area appears to have exceptional environmental conditions. It is suggested that the FAD fishery may have wide-ranging effects on the migration of tunas in general and on the productivity of the skipjack population in particular.

Abstract: We used stage-within-age based matrix models of Atlantic croaker (Micropogonias undulatus) in the Gulf of Mexico and the South and Mid-Atlantic bights to explore the population-level impacts of shrimp trawl bycatch on estuarine-dependent fishes and to investigate tradeoffs between directed adult fisheries and bycatch mortality. The Gulf model reflected a rapidly declining population, while the Atlantic population showed a modest decline. Elasticity analyses indicated that both populations were more sensitive to the summed survival of adults than first-year survival, particularly in the Gulf. Contrary to our expectations, bycatch mortality on late juveniles was not the most important factor affecting either population of Atlantic croaker, and this result was robust to uncertainty in both adult and late juvenile mortality estimates. Both populations were most sensitive to ocean larva mortality, followed by mortality of estuary larvae and adults in the Gulf and of early juveniles and adults in the Atlantic. ...

Abstract: In New England waters, many fish stocks are in precipitous decline while others are already at historically low levels. Bycatch and discard of non-target species is a major contributor to fishing mortality and is a key factor in the observed decline of stocks. In recent years, there have been many initiatives, both globally and locally, to improve selectivity of fishing nets, or more correctly, to reduce the capture and discard of non-target fish. However, it has also become clear that the natural behavior patterns of many species prevent effective selection. For a trawl gear to be truly selective, every fish that enters the net should be tested to insure that those that are small enough to pass through the meshes escape and those that are above the minimum landing size are retained. In general there are two main techniques to aid fish escapement. The first technique is based on making use of species-specific behavior patterns, whereas the second technique involves a process of mechanical sorting on the basis of size. This paper outlines the most widely used bycatch reduction techniques and, where applicable, provides examples within each category where such techniques have been shown to reduce bycatch and discard. The role of bycatch reduction in conservation of fish stocks is discussed.

Abstract: In recent years shrimp bycatch has become one of the most important issues in fi shery management in the southeastern United States, including the U.S. Gulf of Mexico. In 1990, the U.S. Congress requested a 3-year research program to assess the impact of bycatch by the shrimp fi shery on federally managed fi shery resources along the south Atlantic and the U.S. Gulf of Mexico coasts (Public Law 101-627, sec110c1). As a result, the National Marine Fisheries Service (NMFS) created the Cooperative Shrimp Bycatch Characterization Project (NOAA1), a four-year program which focused on 1) characterizing onboard shrimp trawl bycatch, 2) developing and testing bycatch reduction devices (BRDs), and 3) evaluating alternative bycatch management options. Among the major objectives identifi ed in this project were those of updating and expanding temporal and spatial bycatch estimates (offshore and inshore waters) (NOAA1). Since 1987, the NMFS has provided bycatch estimates for several fi nfi sh species in the Gulf of Mexico by using a catch-per-unit-of-effort (CPUE) method, where bycatch CPUEs are estimated following a general linear approach (Nichols et al.2). Briefl y, a bycatch CPUE rate is estimated for each fi sh species by year (1972–95), area, season, and depthzone stratum. These bycatch CPUEs An alternative method for estimating bycatch from the U.S. shrimp trawl fi shery in the Gulf of Mexico, 1972–1995

Abstract: This study estimates the effect of a sea lion (Phocarctos hookeri) population management plan on both the sea lion population and the associated squid (Nototodarus sloanii) fishery. The goal of the management plan is to rebuild the sea lion population and involves closing the squid fishery when a threshold level of sea lions have been caught. The threshold level is calculated from a generalized simulation analysis which conservatively allows for adequate population rebuilding for a number of different species and populations. Our analysis uses Bayesian theory to describe uncertainty in the sea lion population site and squid catch under the implementation of the management plan. The priors represent this particular sea lion population, and the analysis represents expectation rather than calculating conservative levels of safe fishing-related mortality. The results show that the squid catch is very sensitive to whether or not the squid fishery is closed when it exceeds the threshold level for sea lion bycatch. The sea lion population size is much less sensitive to the closure of the squid fishery. For an economically important fishery, the estimates of uncertainty in both loss of catch and increase in sea lion population are needed to allow informed decision-making about trade-offs between sea lion conservation and full exploitation of the fishery.

Abstract: Mandatory release to the sea of Pacific halibut Hippoglossus stenolepis incidentally harvested in Alaskan and Canadian groundfish fisheries has the potential to close fisheries or to close fishing to individual fishermen or vessels that reach Pacific halibut bycatch mortality limits. Tagging experiments of Pacific halibut from longline gear demonstrated that Pacific halibut with similar types of injuries experienced lower mortality following release from small (13/0) circle or autoline hooks than from large (16/0) circle hooks. As a result, the current viability criteria for individual Pacific halibut overestimate discard mortality rates. Proposed, simplified four-category viability criteria based on injury codes increased accuracy of bycatch mortality calculations over the present three-category criteria. The new criteria may reduce calculated discard mortality of Pacific halibut released from longlines by 20%. Use of the new criteria would result in more accurate estimates, which in turn could ...

Abstract: The influences on catches and bycatches due to 1) an increase in size of mesh and 2) a reduction in twine diameter in the body of prawn trawls were investigated in Gulf St. Vincent, Australia. Compared with a conventional trawl body (mesh size 45 mm) attached to a composite square-mesh codend, two new trawl bodies, made with 53-mm mesh but with different twine diameters (1 and 1.7 mm, respectively) and each attached to identical composite square-mesh codends, were equally effective in significantly reducing the numbers of a range of small fish (by between 23.7% and 67%) and in not significantly reducing the weight of targeted prawns. Because there were no significant differences in the selectivity parameters of both new trawl bodies, these results indicated that the main cause of bycatch reduction was the increase in size of mesh in the body of the trawl. The escape of large numbers of unwanted small fish and prawns is discussed in terms of their probable behavior in the body of the trawl and the extent to which this behavior was influenced by the operational characteristics of the gear.

Abstract: This paper collates unpublished and published data on the fish faunas of the large basin and Collie River regions of the Leschenault Estuary in 1982/83 and 1993/94, and provides information on the commercial and recreational fisheries in that estuary. The most abundant of the 42 fish species recorded in eight six-weekly samples collected from the nearshore, shallow waters of the basin in 1994, were the long-finned goby Favonigobius lateralis , the sandy sprat Hyperlophus vittatus and the atherinids Leptatherina presbyteroides and Atherinosoma elongata ; these four species collectively contributing 83.0% to the total number of fish caught. Of the 42 species, 20 were marine species which use the estuary as a nursery area (marine estuarine-opportunists), whil e 13 complete their life cycles in the estuary, of which seven are also represented by marine populations. The contribution made to the total number of individuals by marine estuarine-opportunists and marine stragglers collectively (32.1%) was far lower than that of species which complete their life cycles in the estuary (67.9%). The presence in shallow waters of large numbers of representatives of species that spawn in the estuary, which parallels the situation found in other south-western Australian estuaries, is probably related to the maintenance of stable conditions and high salinities during late spring and summer when these species, which generally have marine affinities, typically spawn. The composition of the fish fauna of the shallows of Leschenault Estuary differs markedly from that of comparable waters in Koombana Bay into which this estuary discharges. Indeed, the most abundant species in the bay, the flathead sandfish Lesueurina platycephala , which contributed ca 25% to the total numbers in those marine waters, was never recorded in the estuary. The fish catches in offshore, deeper waters of the estuary basin and Collie River comprised larger species and, unlike the situation in shallow waters, were dominated by marine estua- rine-opportunists and the semi-anadromous Perth herring Nematalosa vlaminghi . However, the composition of the fish fauna in offshore, deeper waters of the basin differed markedly from that in corresponding waters in the Collie River. This was mainly due to the presence in the basin of far more species and relatively greater numbers of species, such as yellow-eye mullet ( Aldrichetta forsteri ), tailor ( Pomatomus saltatrix ) and Australian herring ( Arripis georgiana ), and to the occurrence in the river of relatively greater numbers of Perth herring and sea mullet ( Mugil cephalus ). Length-frequency data provide strong evidence that, within the estuary, the small species F. lateralis, L. presbyteroides and A. elongata spawn mainly in summer and typically have a one year life cycle. The small juveniles of the marine species A. forsteri and M. cephalus are recruited into the estuary between mid- or late autumn and early spring, which is consistent with the fact that the spawning period of these two species is very protracted, extending through autumn and winter. Both of these mugilids were represented in some months by three or more age classes. Recruitment into the estuary of King George whiting ( Sillaginodes punctata ) occurs in spring, while that of yellow-finned whiting ( Sillago schomburgkii ) and prickly toadfish ( Contusus brevicaudus ) takes place in summer and autumn, respectively. This reflects spawning occurring in winter and early spring in the case of the first species and in summer with the second and third species. These three species were apparently represented mainly by only two age classes. While length-frequency data show that P. saltatrix also uses the estuary as a nursery area, the modal size classes did not follow such consistent trends throughout the year, possibly reflecting a recruitment, in some years, of the 0+ age class of both the spring and autumn-spawning cohorts. The growt h of all of these species essentially ceased during the cold winter months. The feeding mode of each of the most abundant species can be allocated to one of the following categories. (1) herbivores which feed mainly on the algae associated with seagrass, e.g. Hyporhamphus melanochir, Pelates sexlineatus. (2) detritivores, e.g . M. cephalus, N. vlaminghi . (3) omnivores which feed on algae and a range of invertebrates, e.g. A. forsteri, Amniataba caudavittata . (4) lower-order carnivores which feed on small benthic inverte- brates, e.g. A. elongata, F. lateralis, L. presbyteroides, S. punctata, S. schomburgkii, Torquigener pleurogramma . (5) higher-order carnivores whose prey includes larger and more active invertebrates and fish, e.g. Argyrosomus japonicus, P. saltatrix . The former commercial fishers in Leschenault Estuary, who were restricted to fishing in the basin, shifted from gill nets to haul nets in recent years to reduce the amount of bycatch. Aldrichetta forsteri, M. cephalus, S. schomburgkii and S. punctatia were the main commercial fish species, contributing 55.5, 20.2, 11.1 and 6.6%, respectively, to the total wet weight of all fish species caught between 1981 and 1997. The recreational fishery is dominated by three species of whiting ( S. punctata, S. schomburgkii and Sillago burrus) and tailor P. saltatrix.

Abstract: A total of 4378 sea snakes (14 species; 5 unidentified specimens) were collected from 21 082 h of sampling effort by trawlers of the Northern Prawn Fishery. Most species (12) were collected from the southern Gulf of Carpentaria. Hydrophis elegans and Disteira major were caught frequently in all areas. The catch rates of H. elegans and Lapemis hardwickii were highest in the eastern gulf and in depths of 31–40 and 27% of specimens from most areas. Other species that represented ≥20% of specimens from one or more areas were: L. hardwickii, H. ornatus, D. major and Aipysurus eydouxii. Catch rates of all species of snakes combined did not differ significantly between 1984–86 and 1989–90, and were moderately high around Groote Eylandt where the fishery is centred. Most by-catch species occur in areas that are not subjected to extensive trawling, and there are no data to suggest that this fishery seriously threatens any population of sea snake. However, sea snakes may be more vulnerable to trawler-induced effects than most other by-catch species, and formal assessment of the status of populations is needed.

Abstract: ibut bycatch limits are reached and, as a result, substantial quantities of ground­ fish remain unharvested each year. Flatfish fishermen have long been in­ terested in developing gear modifica­ tions to reduce this bycatch and allo w increases in fishing time and harvests. Some have developed their own de­ signs for halibut excluders. 1 Most of these excluders put a size selection panel across the trawl a short distance ahead of the codend. Holes in the panel are large enough to allow smaller target species to pass but will exclude the much larger halibut, which are guided toward an escape slot. The performance of these excluders had not been sci­ entifically evaluated. Although the ad hoc experience of these fishermen con­ vinced some that these excluders were effective in particular fisheries, the need was seen for scientific evaluations of at least one excluder’s selectivity. Costs associated with the intensive catch sam­ pling and experimental design, which were necessary for such evaluations, were well beyond what any single fish­ ing operation could reasonably manage during an open fishery. In 1998, the Groundfish Forum, an organization representing groundfish trawl catcher/processors that fish in Alaska waters, obtained a National Marine Fisheries Service (NMFS) ex­ empted fishing permit to test system­ atically the exclusion of halibut from flatfish trawls with a selected industry device. The work was done in coopera­ tion with NMFS, which provided assis­

Abstract: Tristan da Cunha and Gough 1slands in the central South Atlantic Ocean support globally important seabirdpopulations. Two longline fisheries occur within Tristan's Exclusive Economic Zone: a pelagic fishery for tunas and a demersal fishery for bluefish and alfoncino. Fishery observers have accompanied all three licensed demersal cruises. Despite attracting considerable numbersofbirds and setting lines during the day, only one bird (a Great SheawaterPuffinus gravis) was killed (mortality rate 0.001 birds per 1000 hooks). By comparison, the pelagicfishery) for tuna, which exceeds demersalfishing effort, probably has a much greater impact. Observations aboard one vessel in mid-winter suggest a bycatch rateof>1 bird killed per 1000hooks; this could be even higher in summer when more birds are breeding at the islands. Stricter regulations are required for pelagic vessels, including routine placingofobservers on board. The gravest threat posed bylonglinefishing to Tristan's seabirds comes from vesselsfishing illegally in Tristan waters, as well as vessels in international waters that do not use basic mitigation measures. There is a pressing need for better policing of Tristan's waters.

Abstract: Baited branchlines were set from a tuna longlining vessel using an underwater setting device and their sink patterns compared with those of baited branchlines that were hand‐thrown. Using a paired /‐test at an hypothesised mean difference of 2 m, at a point 100 m astern of the vessel, baited branchlines set using the device were significantly deeper than those that were hand‐thrown. Baited branchlines set using both methods showed a high variation in then‐sink patterns; on some sets they sank faster than others. The underwater setting device has potential to reduce seabird bycatch substantially with minimal intrusion on the normal operation of a longline fishing vessel. It delivers baits underwater (removing the visual cue of a hand‐thrown baited hook to seabirds) and immediately places baited hooks outside the diving range of some vulnerable albatross species (Diomedea spp., Phoebastria spp., Thalassarche spp., and Phoebetria spp.).

Abstract: Sizewell A and B Nuclear Power Stations are located on the Suffolk coast of East Anglia. The A station is a 650 MWe Magnox plant, completed in 1966 and operated by British Nuclear Fuels; the B station is a 1258 MWe pressurised water reactor (PWR), commissioned in 1995 and operated by British Energy Generation Ltd. Both power stations are direct cooled and rely on abstractions of cooling water (CW) from the North Sea: together they can abstract some 80 m3 s-1 . The water is passed around the plant condenser circuits and returned to the sea, along with reject heat and any chlorine residues from antifouling treatment. The abstraction of this water is accompanied, to some extent unavoidably, by entrained fish present either as ichthyoplankton (eggs, larvae and postlarvae of fish), or as fully-formed juvenile or adult fish which have to be removed by mechanical screening systems ('drum' screens) to avoid CW condenser blockage. The entrained ichthyoplankton passes through the entire cooling system and is discharged back to sea along with the heated water. The later life stages of fish and other material that become impinged upon the drum screens are removed from the water. At Sizewell B provision is made to return the more robust species of fish back to the sea alive. In the late 1970S the Central Electricity Generating Board (CEGB), then owner of the whole Sizewell site, announced plans to build the PWR power station which was to become known as Sizewell B. Local fishermen lodged an objection to the scheme on the grounds that the mortality of juvenile fish on the drum screens might be increased to an unacceptable level. Between 1981 and 1982 a joint study of the fish catch was carried out by the CEGB and the Ministry of Agriculture, Fisheries and Food (MAFF). This study showed that the losses on the A station of commercially important species, including plaice (Pleuronectes platessa), sole (Solea solea), dab (Limanda limanda), cod (Gadus morhua), whiting (Merlangius merlangus) and herring (Clupea harengus), amounted to 66 tonnes per year (t y 1 , then valued at £28 000 per annum. This estimate included an allowance for the potential yield of fish which were below the statutory minimum landing sizes when captured, assuming that the rates of growth, mortality and exploitation would have been similar to those experienced by other fish within the North Sea fisheries. The catch rate was summarised by observing that it was 'less than that of a single small, inefficient trawler' and therefore of minor significance. It was also concluded that no impact on local fisheries could be defined, as stocks within the North Sea tend to migrate over large distances. Nonetheless, it was agreed between CEGB and MAFF that a number of reasonably practicable opportunities existed for reducing the catch of the B station, such as appropriate location and design of the cooling water intake and the incorporation of the 'trash' return system. It was also agreed that, following commissioning, the predictions on fish catch would be validated and the relative success of the various mitigative measures assessed. This report is the result of that agreement, but also provides the opportunity of summarising and incorporating other Sizewell-related impingement and entrainment studies to give an updated assessment. With the construction of the B station, and plans (now dropped) to build a C station, the CEGB's successor and British Energy Generation Ltd.'s predecessor, Nuclear Electric Ltd., commissioned studies both to satisfy the prior agreement with MAFF and further evaluate the actual or potential impact of the Sizewell power stations on North Sea fish- eries. So, from 1991 onwards: the original survey data were re-analysed to assess any likely changes resulting from trends in North Sea stocks; assessments were made of losses due to ichthyoplankton entrainment at the A station; experimental studies were undertaken to determine mortality rates of ichthyoplankton passing through the CW system; on the commissioning of the B station, catch rates were compared with the A station to determine whether design and positioning improvements in the B station intake were beneficial; survival rates on passage through the fish return system on the B station were measured; comparisons of losses of juvenile fish due to the power stations with those due to other sources, such as the East Coast shrimp fisheries, were undertaken, to provide an alternative context within which to view the findings; an expert system known as PISCES was used to make estimates of impingement rates for other English East Coast power stations, so that the combined effects of these stations acting in concert could be determined; other fish-related studies were undertaken to determine, for example, any possible impact of fish losses on the availability of food for fish-eating birds at the neighbouring Minsmere nature reserve. The results of these studies are frequently presented in this report in terms of Equivalent Adult values (EAV's). The EAV method is a procedure where the nurnbers of fish of any age are standardised to the number that would be expected to be alive at the age when 5O% of the stock would mature. Thus, if a fish matures at 3 years old, many millions of eggs or larvae may represent a single 'equivalent adult', and the EAV will be a tiny fraction of unity, whereas a fish older than 3 years will have an EAV of greater than one. The purpose of the EAV method is to allow fish captured at any stage of their life cycle to be compared on an equal footing with fish of commercial size. It is important to note that the EAV method does not take account of density-dependent factors (such as rates of predation, parasitism, feeding success) that might tend to increase the survival, growth and reproductive rates of individuals left in the population when some of their competitors are removed. The values given should therefore be regarded as overestimates.

Abstract: Marine crabs belonging to the family Portunidae form bycatch of shrimp trawlers in India They are sold at low prices and consumers discard eggs and consume the meat The paper details the nutritional value of eggs of Portunus pelagicus