Showing papers on "Fishing published in 1989"

Abundance and distribution patterns of three temperate reef fishes (Teleostei:Sparidae) in exploited and unexploited areas off the southern Cape coast

Abstract: (1) Visual underwater census was used to determine the abundance and size structure of three conspicuous marine reef fish species, on the south-east Cape coast in 1984-86. Sites inside the Tsitsikamma Coastal National Park and outside the reserve at Cape Recife were compared to evaluate the effectiveness of the reserve as a management option for the fish. (2) Three sparids were studied: Chrysoblephus laticeps Cuvier, C. cristiceps Cuvier and Petrus rupestris Valenciennes. (3) Transect techniques suggested that point counts were best suited for mobile species and line counts best suited for more sedentary species that could hide within the reef. (4) Distribution within an area was correlated with depth and substratum relief, both factors reflecting feeding and habitat preferences of the fish. Fewer fish were found in shallow water and on flat reefs. (5) During cold upwelling, fish moved away from the study area, presumably following warmer water. Seasonal differences were observed in the abundance of C. laticeps; abundance was greatest in summer. (6) Sampling showed that the fish were significantly more abundant within the reserve, that there were more of the larger size-classes offish and that the maximum size offish was greater than outside the reserve. (7) The data suggested that the reserve is providing effective protection for species vulnerable to line-fishing.

Conceptual Origins of Rights Based Fishing

Abstract: In this paper, I consider some older institutions and ideas from which systems of individual quota rights to fisheries may have emerged. What makes such new systems appear? Can they be regarded as new property institutions? Does an economic approach throw light on their development?

The diet of Antarctic fur seals Arctocephalus gazella (Peters) during the breeding season at Heard Island

Abstract: Between September 1987 and February 1988, Antarctic fur seals Arctocephalus gazella (Peters) at Heard Island fed mainly on fish with an average 95.2% of scats in monthly collections containing fish remains. Pelagic myctophids constituted more than 50% of fish taken by fur seals at the beginning of the summer season and again at the end when there was an influx of non-breeding male seals. During the middle period from October to December, fish from the surrounding shelf area comprised the bulk of the diet. These included various benthic nototheniid species, the bentho-pelagic ice fish Champsocephalus gunnari Lonnberg and skate (Bathyraja spp.), the latter being found in over 60% of scats in October and November. The population of Antarctic fur seals at Heard Island is increasing at about the same rate as at South Georgia. There the increase is thought to be due to the high availability of krill E. superba, but in the present study no euphausiid remains were found, so the increasing population at Heard Island has been supported on a diet of fish. Whether this population increase can be sustained in future on a diet of fish is arguable. Trial fishing around Heard Island indicates that one of the major dietary items of the seals (C. gunnari) is of probable commercial importance and therefore any plans for the establishment of a fishery on Heard Island grounds must be considered in this light.

Impacts of artificial reefs on fishery production in shimamaki. japan

Abstract: The role of artificial reefs as a tool for increasing fishery production rather than just aggregating fish is addressed for two fisheries, octopus, Octopus dofeini, and flatfish, (Pleuronectidae), near Shimamaki, Japan. The time series of catch and effort data examined covers periods before and after two adjacent fishinggrounds received 8,645 and 40,766 m3 ofartificial reef. Octopus catches were increased by 4% per 1,000 m3 of artificial reef or by an average of I .8 kg/m3 of artificial reef. Artificial reefs aggregated flatfishes but did not increase catches in the regions. A survey of fishermen in the two regions revealed that the reefs generally are considered beneficial. Artificial reefs are widely advocated as a tool to enhance fishing. The U.S. Congress established a national policy to promote the use of artificial reefs (Stone, 1985). Japan has a long history of artificial reef usage, and its government currently spends about US$lO million annually on the construction and deployment of artificial reefs in its coastal waters. The Japanese Government has justified this program with reports of annual combined pelagic and demersal catches at the reefs of up to 16-20 kg/m3 of artificial reef (Sato, 1985). However, these catch rates do not measure the extent that artificial reefs increase fishery production in a region because, if the reefs were not present, many of these fishes might have been caught at the surrounding natural habitat instead. Evaluating the extent that artificial reefs can produce a sustainable increase in fishery production in a region, rather than just aggregate fish already present, is an important ecological question as well as a high priority research topic with important consequences for fisheries management (Bohnsack and Sutherland, 1985; Sato, 1985). This study compares annual catches and catch per unit ofeffort (CPUE) between two adjacent fishing grounds. Examining two regions rather than just one separates the effects of artificial reefs on catches from the effects of year-class strength, changes in fishing power, and market factors. Any changes in relative catch and CPUE, corresponding to differences in the magnitude of artificial reefs between the two regions, are likely due to the artificial reefs. This study is believed to be the first to quantify the extent that artificial reefs produce a sustainable increase in fishery production.

Symposium Review: Catch-and-Release Fishing, a Decade of Experience

Abstract: This paper provides a synopsis of the 1987 symposium “Catch-and-Release Fishing– A Decade of Experience,” gives a brief history of the catch-and-release concept, and presents related research needs. Twenty-three presenters provided current information concerning catch and release of a variety of freshwater and marine sport fish. Catch-and-release fishing was first tried in the Great Smoky Mountains National Park in 1954. Today, most states and provinces in North America have catch-and-release programs on some waters. Catch-and-release regulations must be selectively applied; productivity of the environment and longevity of the fish are important considerations and strict compliance with special regulations by anglers is necessary for success. Anglers will accept these regulations when professionals present sound biological evidence to demonstrate the need. An increased use of catch-and-release regulations was reported in nontrout fisheries, especially those for largemouth bass Micropterus salmoid...

Northern pike (Esox lucius L.) and aquatic vegetation, tools in the management of fisheries and water quality in shallow waters

Abstract: Species and size composition of fish communities in shallow stagnant waters appear to be associated with the type, abundance and pattern of the vegetation. Man-induced impacts as eutrophication, and suppression of vegetation for reasons of water quantity management or angling pleasure may induce irreversible changes in the aquatic ecosystem. Water quality management should aim at restoring former pike habitat. Submerged weeds are important to that effect. These habitats are characterized by relatively low densities of fish stocks. Stocking of bream and carp interferes strongly with these objectives. With respect to fish stocks, interests of water quality and fishery management may be opposed.

Assessment of the Implementation of Individual Transferable Quotas in New Zealand's Inshore Fishery

Abstract: In 1986, New Zealand implemented an individual transferable quota system (ITQ) for selected inshore fish species to promote conservation of stocks and to improve the economic efficiency of the fishing industry. The objectives of this study were to assess perceived problems and benefits of this new system and its effect on the fishing industry. Data were obtained through interviews with 62 industry participants from the Auckland region and 14 Ministry of Agriculture and Fisheries staff. Over 75% of the fishermen were making significant changes in their business because of ITQs. These changes included minimization of costs and maximization of price received for their catch, practices consistent with economic theory about ITQs. Industry and management agency interviewees generally recognized ITQ benefits of reduced competition, resource conservation, increased retirement security, reduced economic risk, possession of a valuable asset, improved ability to plan, and the professionalization of fishing....

River fisheries in Brazil: A review

Abstract: Riverine fisheries in Brazil are reviewed. There is a broad description of the environment and the fish, and arguments for the high diversity of fish fauna diversity are examined. The country is divided into five large river basins and the fisheries are described in relation to the main fish species caught, the main gear employed, and the fishing strategies. Exotic species introduction is discussed along with strategies for fish stock management. Effects of dams on resident fish stocks and consequences for the small scale fisheries are discussed and compared with the effects of pollution.

A Partially Observable Model of Decision Making by Fishermen

Abstract: This paper presents an application of a partially observable Markov decision process for the intraseasonal decisions of fishing vessel operators. Throughout each fishing season, independent vessel operators must decide in which zone or fishing ground of the fishery to fish during each period to catch the most fish with the highest return to fishing effort. Fishermen's decisions are assumed to be made to maximize net operating income. The decision model incorporates the potential fish catch, the cost of the fishing effort, and the unit price of fish. Catch potential is modeled by considering the abundance of the fish stock and the catchability of the fishing technique. Abundance dynamics not observed directly are modeled as a Markov chain with a parsimonious state-space representation, which renders the problem practicable. Dynamic decision policies are computed by the method of optimal control of the process over a finite horizon. The resultant policies are used to simulate distributions of fishermen's ne...

The theoretical basis of an access site angler survey design

Abstract: The theoretical basis is presented for a new design of angler surveys. The design was used in a survey to assess recreational fishing on New York's Great Lakes and tributaries. The large geographic area and budget constraints necessitated a survey design that could cover broad areas with the maximum efficiency of a limited number of survey agents. The model for the survey relates the amount of time that a survey agent has the angling party's car in view at an access site with the amount of time the party spent fishing. Geometric inclusion probability functions are developed and equations for estimating fishing effort are given. The special case when access sites are not limited to angler use (the case for many marinas) is also discussed and an estimator for fishing effort developed.

Offshore fishes of the Arafura Sea

Abstract: The species composition, zoogeographic affinities and importance to fisheries of the offshore fish fauna of the Arafura Sea is examined. A tot al of 527 species from 141 families are recorded. Most of the fishes are shallow-water, benthic species belonging to widespread Indo-Pacific families. Remaining fishes are deeper water or epipelagic forms with Indo-Pacific or Cosmopolitan distributions. The 10 most speciose families (Carangidae, Lutjanidae, Carcharhinidae, Leiognathidae, Nemipteridae, Platycephalidae, Serranidae, Scorpaenidae, Mullidae, Bothidae) contain about 34% of the total number of species. Greatest faunal affinity is seen with the fish fauna of the North-west Shelf of Western Australia. Fishing methods in the Arafura Sea include bottom trawl, gillnet, longline, and handline. Of the total species recorded, 491 (93.2%) were taken by bottom trawl; 108 species (20.5%) are retained as catch; and 163 by-catch species (30.9%), presently discarded, are potentially useful for food, bait, or processing as fish meal and petfood. Some 23 species (4.4%) are dominant in bottom trawls and 'Comprise about 70% of the total catch biomass.

A Public Ownership Resolution of the Tragedy of the Commons

Abstract: Imagine a society of fisherfolk, who, in the state of nature, fish on a lake of finite size. Fishing on the lake is characterized by decreasing returns to scale in labor, because the lake's finite size (and finite fish stock) imply that each successive hour of fishing labor is less effective than the previous one, as the remaining fish become less dense in the lake. In the state of nature, the lake is commonly owned: each fishes as much as he pleases, and, we might suppose, calculates his fishing plan by taking the labor of the others as given, as he sees it. Each knows that the distribution of fish will be proportional to labor expended among the fisherfolk: if I fish twice as long as you, I will end up with twice as much fish as you. This is not due to some kind of concern with equity (or the labor theory of value) among the fisherfolk; it is a technological fact, implied by the assumption that fishing labor is homogeneous, and all are equally likely to catch a fish in a unit of time. An equilibrium under common ownership can be thought of as a Nash equilibrium of the game where each computes his optimal fishing plan, given the labor of the others and knowing what the consequent distribution of fish would be. (A Nash equilibrium is an allocation of labor and fish to each fisherman, with the property that no one can increase his utility by deviating in his choice of labor, given what the others are doing.)

Assessment of multispecies cichlid fisheries of the Southeast Arm of Lake Malawi, Africa

Abstract: The multispecies cichlid fisheries of southern Lake Malawi have been managed by control of fishing effort, based on Gulland's (1961; Fishery Invest., Lond., Ser. 2, 23: 1—52) modification of the Schaefer (1954; Bull. inter-Am, trop. Tuna Commn, 1: 27-56) stock assessment model, together with continual monitoring and adaptation to changes in the fisheries as they occur. Schaefer yield estimates are updated in this paper. For the demersal trawl fishery, which exploits 160+ species, maximum sustainable yield (MSY) is estimated to be 1355 tonnes/year at an effort level of 620 boat days, and effort is controlled at a level of approximately 500 boat days. MSY for the Chambo (three Oreochromis spp.) ringnet fishery is estimated to be 2190 tonnes/year at an effort level of 11 360 ringnet pulls. Walter's (1986) equilibrium yield model has also been applied to the Chambo fishery and indicates maximum yields of between 1800 and 2500 tonnes at approximately 10000 ringnet pulls. Catch rates in both fisheries are influenced by a number of factors apart from fishing effort. In the demersal trawl fishery the effects of changes in species composition, variability in recruitment, a change in mesh size, and a decline in efficiency of certain fishing units can all be detected in catch and effort data. In the Chambo fishery, catches are related to changes in annual mean lake level three years previously. A hypothesis is proposed here which links wind-induced mixing of nutrientrich deep water with improved survival of planktivorous juvenile fish. The use of simple stock-assessment models combined with close observation and monitoring is effective in managing fisheries for tropical, short-lived species.

Alaska Pollack population, Theragra chalcogramma, of Japan and its adjacent waters, I: Japanese fisheries and population studies∗

Abstract: The present review starts with a brief history of Japanese Alaska pollack fishery and emphasizes its importance to that country. Alaska pollack fishery, including its history, fishing methods, fishing gears, fishing seasons, catch levels, migration of fish etc., in various parts of Japan and its adjacent waters is discussed. This is followed by a brief look at the present status of population studies, covering biological stocks in the Sea of Japan, the coast of Hokkaido, the west coast of Sakhalin and other important fishing grounds. Then successively, peculiarities of local fishery, problems of stock discrimination and interrelationships between other stocks, including Okhotsk Sea stock, Pacific ocean stock and Kamchatka stock, are taken up.

Tuna Purse-Seine Fishing with Fish-Aggregating Devices (FAD): Models of Tuna FAD Interactions

Abstract: A model is proposed for the analysis of fishing tuna from fish-aggregating devices (FAD), and parameters for the model are estimated Methods are described for determining the optimum number of FAD

Comparison between a fine mesh trap net and five other fishing gears for sampling shallow‐lake fish communities in New Zealand (Note)

Abstract: This paper describes the first tests of a fine mesh trap net suitable for sampling shallow‐lake fish communities in New Zealand. The catch from 2 shallow lower Waikato lakes of this and 5 other gear types frequently used in freshwater fisheries research in New Zealand are compared. The trap net caught the widest range of fish species and sizes, and was the least selective for species composition and relative abundance of any individual gear type. A combination of trap net and gill net caught the widest range of species and sizes for individual or pairwise combinations of gear types, and is recommended as being the best combination for sampling shallow‐lake fish communities in New Zealand.

Current Approaches to Multispecies Analyses of Marine Fisheries

Abstract: There is an increasing tendency to recognize that the dynamics of a fishery are not solely determined by intrinsic population factors, but that the external environment, which can include the effects of other species in the biotic community, plays an important role in determining the yield performances of marine fish stocks. Recognition of the role of external factors represents an important departure from the single-stock concepts of fishing theory, which have traditionally been used to manage marine stocks. We review a variety of examples of recent initiatives in the application of community concepts in marine fisheries, setting these in the context of four arbitrary categories which range from statistical description through multispecies extensions of single-stock fishing theory, to integral applications of community theory. Taken together, there is substantial evidence that the application of multispecies concepts to marine fisheries is now a major focus of international effort. The multispecies appro...

Managing nonrandomly varying fisheries

Abstract: Theoretical studies indicate that constant effort or constant escapement harvest strategies are viable long-term management policies for fisheries influenced by random environmental variability. Bu...

A survey of the recreational rock-angling fishery at Port Elizabeth, on the south-east coast of South Africa

Abstract: A recreational rock-angling fishery on South Africa's Eastern Cape coast was studied on the basis of random sampling which aimed at removing the sample bias usually associated with such studies. The fishery is primarily recreational and catch per unit effort is low (202,J g·angler-hour -1). A total of 27 teleosts was recorded, the most important of which were Pomatomus saltatrix (74,7 g. h-1). Sparodon durbanensis (30,3 g. h-1), Diplodus sargus capensis (19,4 g. h-1) and Pachymetopon grande (12,6 g. h-l). Seven cartilaginous species were caught, of which MUSlelus mustelus (I6,6 g. h-1) was the most important. Sharks were either discarded or returned to the sea. Catches of most species were seasonal, a result of both availability of fish and targeting of angler effort. Despite considerable overlap in the catch between this and the commercial sector of the linefishery, a number of species may be considered primarily recreational. Management of such species is discussed and the importance of long-term data series to the management of the resource is recognized.

Species Profiles: Life Histories and Environmental Requirements of Coastal Fishes and Invertebrates (South Atlantic). Black Sea Bass

Abstract: : Species profiles are literature summaries on the taxonomy, morphology, range, life history, and environmental requirements of coastal aquatic species. They are designed to assist in environmental impact assessment. The black sea bass, Centropristis striata, is an abundant species associated with the inshore sponge-coral habitat in the south Atlantic Bight (Cape Hatteras to Cape Canaveral). It is a protogynous hermaphrodite (each individual is first a female and then a male) that spawns from January to June on the Continental Shelf. Juveniles utilize estuaries, as well as offshore areas, for nurseries. It is a slow growing species with a life span of about 10 years. Juveniles and adults are bottom-feeding carnivores. Adults have been collected at temperatures as low as 6 C but are most abundant at temperatures of 8 to 10 C and above. Juveniles tolerate lower temperatures and greater salinity ranges than adults. Black sea bass are primarily harvested by the recreational hook and line fishery and the commercial trap fishery. Yield-per-recruit analyses indicate that the harvest of black sea bass is less than the maximum possible due to a combination of high fishing pressure and harvest of small fish. Keywords: Estuaries; Fishes; Fisheries; Salinity; Growth physiology; Temperature; Spawning; Sediments; Feeding habits; Life cycles; Contaminants; Black sea bass; Centropristis striata; Species profiles. (kt)

Monitoring the fish fauna in the Wadden Sea with special reference to different fishing methods and effects of wind and light on catches

Abstract: The seasonal and local distribution of fish in the Wadden Sea depends on the various modes of life of each species. To obtain nearly all species of the fish fauna and the stages of development in different spatial regions of the Wadden Sea-shallow and deep channels, puddles and pools, sedimentation fields and tidal flats—it is essential to use different fishing methods synchronously. During a two-year monitoring project in 1986 and 1987 on fish and fisheries in a restricted area of the Wadden Sea of Schleswig-Holstein, five types of fishing gear were used synchronously: handnet, push-net, 2-m beam trawl, commercial shrimp trawl, fyke net. In 822 samples of all gear 33 species were caught. No gear obtained the maximum number of species. Day and night samples show considerably different composition. Furthermore, force and direction of wind have an important effect on the distribution of fish in the coastal area. The advantages and disadvantages of the different gear for monitoring purposes are discussed from scientific and practical viewpoints.

An assessment of the Prochilodus platensis Holmberg population in the Pilcomayo River fishery, Bolivia using scale-based and computer-assisted methods

Abstract: . The catch from the fishery for the migratory Prochilodus platensis Holmberg on the Rio Pilcomayo shows considerable annual variation. Peaks were apparent in 1981 and 1982, followed by very low returns between 1983 and 1985 and a resurgence in 1986. The catch in 1986 was 1011t with the degree of annual variation probably lying between 500 and 2000t. In the Pilcomayo P. platensis is a rapidly growing short-lived fish with a maximum life expectancy of 6-7 years and an upper size approaching 61.5cm. The fish first migrate and appear in Bolivian’ waters when they are 21/2-3 years old, having spent the first 2 years on the nursery grounds, probably on the Argentine/Paraguay section of the river. Although fish of this age were numerous in the 1986 catches, the optimal market size is rather larger, and older fish are taken preferentially. The fishery actually depends upon very few age classes. A comparison of growth and mortality rates obtained from scale reading and from length frequency analysis by ELEFAN programs showed a close agreement. The considerable fluctuations in the fishery are largely due to the highly variable flood regime of the river rather than to fishing pressure, with the flood determining recruitment in 2 years’ time. Nevertheless, a combination of a sequence of poor flood years with sustained fishing pressure could seriously damage the fishery.