Showing papers on "Fishing published in 1983"

Fish stock assessment : a manual of basic methods

Abstract: Describes the scientific techniques used in assessing fish stocks, evaluating the effect of fishing on these stocks, and the probable impact of different policies for developing and managing fisheries. Covers the techniques developed starting with simple models and continuing to more complex methods.

Effects of depth and marine reserve fishing restrictions on the structure of a rocky reef fish assemblage in the north-western mediterranean sea

Abstract: SUMMARY (1) A visual scuba diving census, in which abundance and size class structure of conspicuous fish species were determined, was used to assess the effects of depth and marine reserve fishing restrictions on the structure of a Mediterranean rocky reef fish assemblage by comparing communities at sites from two depth ranges inside and outside a marine reserve. (2) The total assemblage had thirty-five conspicuous species and was dominated by Labridae (thirteen spp.) and Sparidae (nine spp.). (3) Mean species richness (number of species) and diversity (Shannon) did not differ significantly between sites. (4) Ordination of abundance data showed that occurrence and relative abundance of species was affected by depth (deep samples separated completely from shallow samples) and marine reserve status (samples from the marine reserve were significantly separated from those taken at the same depth outside the reserve). (5) Samples from the same depth were similar, because the majority of species showed a preference for either deep or shallow areas. The known biology of several species indicated that feeding requirements may be responsible for depth preferences. (6) Samples from reserve sites had signficantly higher densities of fish species sought after and/or vulnerable to local fishing methods, than those from non-reserve sites of similar depth. (7) Size frequency distributions of vulnerable species at reserve sites generally had a larger modal size class than distributions from non-reserve sites. (8) The data suggest that reduced fishing pressure in the reserve has provided effective protection for species vulnerable to fishing.

Bioeconomic Production Function in Fisheries: Theoretical and Empirical Analysis

Abstract: The traditional "fishing effort" approach to fisheries economics implies the existence of a production function with fishing effort and fish abundance as independent variables. It is shown how the ...

South African estuaries and their importance to fishes

Abstract: Environmental conditions typical of South African estuaries are contrasted with those of marine inshore waters. The life cycle of estuarine fishes is related to important physical and biological characteristics of estuaries. The fish fauna is divided into 6 categories according to the extent of their dependence on estuaries. This is followed by discussion of the effects of estuarine degradation on these groups. Continuing degradation will result in a decline in South Africa's estuarine fish fauna and consequently in recreational angling, in the yield of high-protein food and in economic activities dependent upon this natural resource.

Factors Influencing the Size of American Lobster (Homarus americanus) Stocks Along the Atlantic Coast of Nova Scotia, Gulf of St. Lawrence, and Gulf of Maine: A New Synthesis

Abstract: The general aspects of fluctuating American lobster (Homarus americanus) stocks are considered in an attempt to identify common principles controlling lobster populations in the Gulf of Maine, Gulf of St Lawrence, and the Atlantic coast of Nova Scotia Inshore fishing mortality is known to be precariously high in both Canadian and American waters yet only in the central Northumberland Strait region and along the Atlantic coast of Nova Scotia are stocks experiencing steep declines Existing regulations allow fishing of lobsters well below the size at which maturity can be expressed In western and central Northumberland Strait female lobsters are not protected by the 'berried' law because of the timing of the fishing season Climatic change, expressed as sea-surface temperature, is closely associated with the success of lobster recruitment in the Gulf of Maine, but nowhere else Huntsman's hypothesis that warm surface water of sufficient duration is essential for the successful completion of the larval st

Fish Bulletin 172. Life History, Environment, and Mariculture Studies of the Dungeness Crab, Cancer Magister, With Emphasis on The Central California Fishery Resource

Abstract: This report describes the results of the California Department of Fish and Game's Dungeness Crab Research Program (1974–1980) plus several related studies and provides a detailed history of the California fishery. The Dungeness Crab Research Program was developed in response to a severe and sustained decline in central California Dungeness crab landings; this decline is the primary focus of the investigations presented in this report. Research results are presented for life history, environmental, and mariculture studies relating to egg, larval, juvenile, and adult stages of the Dungeness crab. Specific areas of study include stock identification; larval and juvenile dynamics focusing on movement, distribution, relative abundance, age and growth, and predation; impacts of commercial trawl fishing; ocean climate and its effects on life cycle stages and fishery landings; reproduction; pollution such as chlorinated wastewater, toxic trace elements, pesticides and PCB's, and hydrocarbons; and laboratory culture techniques. This report concludes with a summary of the Dungeness crab life cycle and research results and a discussion of management options and further research needs.

A Method for Directly Estimating the Tag‐Reporting Rate of Anglers

Abstract: Tag-reporting rates for marine recreational boat anglers were estimated directly by surreptitiously implanting, during routine creel surveys, fish tags into fish that had already been caught during October 1976-September 1978. Twenty-nine percent (177) of the 600 implanted tags were returned. Ninety-five percent of all tags returned were received within 100 days after they had been implanted. Significant differences (P ≤ 0.05) were found among reporting rates by anglers from different fishing areas and for different species of fish. No significant differences were found for reporting rates by anglers among seasons or years. These results indicate that use of reward tags in other studies has not fully corrected for nonreporting of recovered tags and, consequently, fishing mortality estimates based on them have been underestimates. The vast majority of anglers (96%) correctly identified their fish to genus and they reported fish lengths that were within ±76 mm (SD) of those determined by agency sta...

Interrelationships between juvenile salmonids and nonsalmonid fish in the columbia river estuary

Abstract: Interrelationships between juvenile salmonids-coho salmon, Oncorhynchus kisutch; chinook salmon, 0. tshawytscha; and steelhead, Sa/mogairdneri-andnonsalmonid fish were studied in the Columbia River es­ tuary during 1980. Nonsalmonid species were numerically dominant in pelagic and intertidal areas of the lower estuary. In pelagic and intertidal areas ofthe upper estuary, juvenile salmonids, particularly subyear· ling chinook salmon were proportionally important Nonsalmonid species commonly associated with juvenile subyearling chinook salmon included American shad, A/osa sapidissima; Pacific herring, C/upea harengus pallasi; northern anchovy, Engraulis mordax; surf smelt, Hypomesus pretiosus; longfin smelt, Spirinchus tha/eichthys; peamouth, My/ocheilus caurinus; threespine stickleback, Gasterosteus acu/eatus; shiner perch, Cymatogasteraggregata; Pacific staghorn sculpin, Leptocottus armatus; and starry flounder, P/atichthys stellatus. Commonly associated species were generally defined only in reference to subyearling chinook salmon because, of all the juvenile salmonids, subyearling chinook salmon were clearly the most abundant and available in sizable numbers for the longest time. Predation on juvenile salmonids by non· salmonids andotherjuvenile salmonids was insignificant Significant diet overlap occurred among subyearling and yearling chinook salmon, coho salmon, and steelhead during the spring. American shad, threespine stickleback, and starry flounder had significant diet overlaps with juvenile salmonids. The Columbia River system is an important pro­ ducer of Pacific salmon (Oncorhynchus spp.) and steelhead, Salrno gairdneri, in North America (Chaney and Perry 1976; Bohn and Stockley 1981). Salmonids (wild and hatchery) originating from the Columbia River system provide fish for both river and ocean fisheries (recreational and commercial). Historically, the world's largest migration of adult chinook salmon, O. tshawytscha, occurred in the Columbia River (Van Hyning 1973). Dam construc­ tion, poor logging and agricultural practices, over­ fishing, and pollution have severely reduced adult salmonid returns to the Columbia River system. Ef­ forts to improve the runs, such as large hatchery releases ofjuveniles, collection and transportation of juveniles at selected dams, and the installation of dam spillway deflectors to reduce nitrogen super­ saturation have enhanced adult returns, but failed to increase them to historical levels. There is concern by some resource managers that significant losses of juvenile salmonids may be occurring in the ocean and!or estuary. They feel these losses may be due to predation or competition for the same food or­ ganisms by nonsalmonid fish. No published information is known to exist on the interrelationships between juvenile salmonids and

Potential Effects of Voluntary Catch and Release of Fish on Recreational Fisheries

Abstract: Anglers frequently release fish that are large enough to keep under prevailing fishing laws. However, fisheries managers usually estimate only fishing effort and number of fish harvested when assessing a fishery, and simply assume this voluntary release of fish is unimportant. In this study, I examined how the release of legal fish might affect a fishery. I modified the classical yield-per-recruit model so that the total mortality rate (Z) was partitioned into three components: natural (M), fishing (F), and hooking (H) mortality rates. I used another parameter (p), representing the probability a legal fish was released when captured, to modify the levels of fishing and hooking mortality. I applied the model to four fisheries with widely different characteristics of growth, mortality, and fishing: brook trout (Salvelinus fontinalis) in a small stream, largemouth bass (Micropterus salmoides) in a medium-sized reservoir, brown trout (Salmo trutta) in a medium-sized river, and northern pike (Esox luc...

Observations on the dietary habits of wild and stocked brown trout, Salmo trutta L., in Irish lakes

Abstract: The dietary habits and feeding rates of wild and stocked brown trout were compared for populations in a number of Irish lakes. Wild trout and stocked fish, which had been present in a fishery for 12 months or longer, tend to feed on the same dietary items at similar rates. Stocked fish in their immediate post-planting period (1–14 days) ate less than both the wild trout and established planted fish. In some instances recently stocked fish appear to have a preference for surface food items. They also consumed stones and detritic material. Data indicate that stocked fish adopted a natural diet in less than 5 months. Results are discussed in relation to angling crops of wild and stocked fish and the comparative success of autumn and spring plantings of salmonids.

Reconstruction of Stock History and Development of Rehabilitation Strategies for Pacific Ocean Perch in Queen Charlotte Sound, Canada

Abstract: Pacific ocean perch (Sebastes alutus) have undergone considerable over-exploitation in Queen Charlotte Sound, British Columbia, largely as a result of excessive removals by foreign fleets in the 1965-1974 period A new catch-at-age model is used to reconstruct the history of this stock through simultaneous analysis for all cohorts present in the time series of catch data The reconstruction extends from 1963-1977 and estimates that intensive fishing pressure reduced the stock from an initial size of 82,000 t to only 13,000 t by 1977 Numbers of fish at each age are estimated for the period of the data, together with estimates of fishing mortality The reconstructed stock status and the stochastic stock-recruit relation estimated by this analysis are used as inputs for a model to simulate stock behaviour over 30-year periods, under various exploitation strategies Results indicate that rehabilitation will be achieved only at fishing intensities about one-third of the terminal 1977 fishing mortalit

Fish and fisheries of wetlands

Abstract: SUMMARY The three major wetland types have characteristic fish communities. River-associated wetlands harbour a rich diversity of fishes which can either survive habitat desiccation during the dry-down, or migrate to and fro with the flood. Endorheic wetlands have a lower diversity of species which are typically ‘r’-selected relative to mainstream riverine or lacustrine forms. Marine wetlands have a variety of peripheral or marine forms, but are not discussed in this account. The dynamics of wetland fish communities are determined by periodically changing abiotic factors, especially water temperature and water level, and biotic factors, especially food availability. Water level fluctuations have several important functions and result in pulses of nutrient input and fish abundance. Wetland fish stocks can usually be sustained as long as the pristine flood regime is retained, but disruption of the flooding pattern interferes with fish breeding and nutrient flow. Fishing yields may be directly correlated wit...

Application of Angler Attitudes and Motives to Management Strategies at Missouri's Trout Parks

Abstract: The Missouri Department of Conservation manages four fishing areas on spring branches with water sources large enough to permit fish rearing and angling. These special areas, called trout parks, are stocked daily from March to October at a rate of 2.25 trout per anticipated angler. Each angler pays $1.50 for a daily fishing tag, an entitlement to keep five trout. Total revenues collected from the sale of daily tags and annual trout stamps are sufficient to defray costs of operating four trout hatcheries and one trout rearing station. Since 1960, visits to the trout parks have increased at an average annual rate of 4%; about 100,000 daily tags were sold at each park in 1980. In light of physical and fiscal constraints to stocking additional trout, a study was initiated with the goal of developing management responses to increased angler participation. Specific objectives were to determine anglers' motives and attitudes toward selected management alternatives, and catch and effort. About 16,000 ang...

How Many Traps Should a Crab Fisherman Fish

Abstract: A fisherman's choice between owning few traps and fishing them often, and owning many traps and fishing them less often can affect his profit. In a Newfoundland fishery for the snow crab (Chionoecetes opilio), a fisherman fishing 70% of the days of the season should own twice as many traps as he hauls per day, while a fisherman fishing 20% of the days of the season should own only the number of traps he hauls per day. Fishermen typically own more than the economic optimum number of traps. These conclusions were based on changes in catch with soak time, the cost of traps, and the number and spacing of fishing days during the season. An experiment comparing day and night catch rates provided no support for the popular view among snow crab fishermen that crabs trap better at night. Traps with 3 kg of bait caught about 50% more crabs than traps with 1 kg of bait when fished for both 1-day and 4-day soak times.

Carpe Diem: An Optimal Foraging Approach to Bari Fishing and Hunting

Abstract: Publisher Summary This chapter discusses a feature of Bari protein foraging strategy that contradicts one of the central tenets of optimal foraging theory. The Bari are a group of tropical forest horticulturalists who live in the southwestern most lobe of the Marcaibo basin. The tenet of optimal foraging theory of interest posits that a forager should exploit a resource when he cannot, on the average, get a better return for his time by exploiting some other resource(s). The chapter provides an overview of the Bari, focusing on subsistence activities. The hypotheses claim that the information gathered in hunting informs decisions as to where and when fishing should take place, in seasons when good fishing spots are rare. The hypotheses claim that hunting is not needed during the dry season good fishing months because rewarding fishing spots are abundant and there is no need to spend time seeking them out.

The demand curve for recreational fishing with an application to stock enhancement activities.

Abstract: McConnell and Sutinen (1979 and Bishop and Samples (1980) have developed models of recreational fishing and have derived conditions for optimal management policy both with and without joint commercial harvest While these models are correct, their structures do not explicitly consider the stock externality in terms of the demand curve for recreational fishing The effect each participant has on others, in terms of quality and quantity, is central to an intuitive understanding of recreational fisheries management and it can be clearly demonstrated in the demand curve model presented below The work is a synthesis of the above models and the Leibenstein (1950) bandwagon and snob goods concept, which has been used by a number of authors dealing with recreation (Anderson, L 1980a, 1980b; Anderson, F, and Bonsor 1974; Cicchetti and Smith 1973; Fisher and Krutilla 1972; Freeman and Haveman 1977; McConnell and Duff 1976) The model is applicable to a number of relevant problems, including joint recreation-commercial exploitation, but here it will only be applied to the optimization of enhancement, a topic that has not been treated previously The inverse demand curve of an individual for recreational fishing on a single independent fish stock can be expressed as:

Yield per recruit models of some reef fishes of the u. s. south atlantic bight

Abstract: Yield per recruit models for red porgy, Pagrus pagrus; vermilion snapper, Rhomboplites aurorubens; white grunt, Haemu/on p/umieri; red snapper, Lutjanus campechanus; black sea bass, Centropristis striata; gag, Mycteroperca micro/epis; scamp, M. phenax; snowy grouper, Epinephe/us niveatus; and speckled hind, E. drummondhayi,the most important species to both recreational and commercial fishing off North Carolina and South Carolina, are strikingly similar, and suggest that there is a single strategy for managing reef fishes in the South Atlantic Bight For all species, yield per recruit at median recruitment ages increased rapidly in response to increasing F (instantaneous fishing mortality rate) until F = 0.3-0.4. Thereafter, only small increases in yield resulted from large increases inFo Major gains in yield at all but very small values ofF (F:5 (J.15), resulted if recruitment to the fishery was delayed to age 3 or older. The value of M (instantaneous natural mortality rate) affected the magnitude of yield/recruit but had little effect on the shape of the re­ sponse surfaces. The annual total recreational and commercial catches ofreeffishes provides a preliminary estimate of max­ imum sustainable yield if the following assumptions are accepted: 1) F ? 0.3, 2) recruitment ages approx­ imate those required to produce maximum yield per recruit, and 3) recruitment is sufficient to saturate the available habitat. Preliminary estimates ofthe relative fishing power(per day) ofdifferent components ofthe fishery are headboats, 1.0; commercial handline boats, 1.3-1.5; and reef trawlers, 3.8-5.2. In this paper we examine the implications ofyield per recruit models to management of the reef fishery in . the South Atlantic Bight. We examined models for each ofthe several important species in this fishery to determine if there was a single pattern of yield re­ sponse that, in turn, would allow development of a coherent management philosophy. The Fishery Warm Gulf Stream-influenced water and irregular rocky substrates allow occupancy of the outer con­ tinental shelf ofthe U.S. South Atlantic Bight (Cape Hatteras to Cape Canaveral) by a community of primarily Caribbean, deep reef fishes. Principal species include groupers (Mycteroperca and Epi­ nephelus), snappers (Lutjanus and Rhomboplites), porgies (Calamus and Pagrils), and grunts (Hae­ mulon) (Huntsman 1976a). The black sea bass, Cen­ tropristis striata, is abundantat more temperate reefs nearer shore. Reef fishes support both recreational and commer­ cial fisheries in the area. About 40 headboats, about

An Analysis of the Hecate Strait Pacific Cod Fishery Using an Age-structured Model Incorporating Density-dependent Effects

Abstract: An age-structured model was used to analyze the Hecate Strait Pacific cod (Gadus macrocephalus) fishery for the years 1960–80. The data consisted of estimates of fishing effort, together with estimates of numbers of fish at age caught in each year. The latter estimates were derived from length–frequency analysis. A stock–recruitment relationship of the Ricker type with an additional environmental factor was estimated. The data is also analyzed for evidence of the existence of age-dependent trends in natural mortality, density-dependent trends in natural mortality and catchability, and for time-dependent trends in catchability. Evidence of a density-dependent trend in natural mortality was discovered. The average level of natural mortality was also estimated to be 0.65.

Optimal Foraging Group Size for a Human Population: The Case of Bari Fishing

Abstract: The Bari of the Maracaibo basin obtain most of the meat in their diet by spearfishing, usually in stretches of river which they dam off before fishing them. As the number of men in a fishing party increases, the time to build a dam decreases in approximately the same way that the catch per man decreases. The decrease in catch per manhour, as more men are added to a fishing party, is thus quite shallow. The interrelationship of these variables permits a prediction of the optimal number of men in a fishing party, based on the principle that below a certain number of participants, the addition of more men to the fishing party gains each individual more in time than it costs him in returns per man-hour. Data so far available indicate that the optimal number of men in a fishing party is about the same as the average number of adult men residing in a Bari longhouse.

Cocamilla Fishing: Patch Modification and Environmental Buffering in the Amazon Várzea

Abstract: Publisher Summary This chapter focuses on a hitherto unreported relationship between humans and fish in the Cocamilla Indian community of Achual Tipishca in the Huallaga River Basin in north-eastern Peru. The fishermen of Achual Tipishca exploit varzea lake and one aspect of their adaptation is to enrich its waters with garbage and human feces. In doing so, they are practicing a form of patch modification in which their lake resource is enhanced. Through an analysis of fishing data, it has been shown that the fertilized zone of the lake, that part nearest the community, becomes an important resource during the times when the lake is flooded, thus buffering the effects of an annual fluctuation in fish availability. The chapter discusses whether the Cocamilla fishing patterns can be explained by optimal foraging theory; whether the Cocamilla are time-minimizers or energy-maximizers in Schoener's sense; whether the view of Cocamilla fishermen as optimal foragers precludes a view of them as “managers” of their lake resources; and whether the data on varzea lake fish production and Cocamilla fishing patterns can shed light on the prehistoric Amazonian populations.

A Japanese fishing joint venture: worker experience and national development in the Solomon Islands

Abstract: THE NFD PHILOSOPHY 44 1 THE CONTEXT OF THE NFD PHILOSOPHY 45 Introduction POLICY AND OPERATIONS 47 5 THE POLITICS OF PRICING 48 The Solomon Islands 5 Local Processing a id the Development of SETTING 6 Noro Cannery 48 SOCIAL HISTORY GOVERNMENT AND POLICY 8 8 THE MECHANICS OF CANNING 49 INTRODUCTION 48 The Tuna Fishery THE TULAGI OPERATION 49 The Solomon-Taiyo Joint Venture 10 NORO CANNERY 50 WESTERN REGIONALISM 52 10 TAIYO AND THE NORO CANNERY 53 ORIGINS THE HISTORY OF SOLOMON-TAIYO 12 CANNERY WORKERS 54 POLITICS OF BAITFISHING 16 17 The Second Joint Venture 55 LONGLINING AGREEMENT 1978-1979 RENEGOTIATIONS 18 Conclusions and Recommenstions 55 Ethnicity and the Expatriates of Solomon-Taiyo 21 SOLOMON-TAIYO LIMITED 56 THE MANY DIVISIONS OF INTEREST 21 FOREIGN TRADE AND IMPORT THE STRUCTURE OF DIVISION 22 SUBSTITUTION 57 JAPANESE MANAGERS 22 BAITFISHING 58 58 OKINAWAN FISHERMEN 24 PUBLIC RELATIONS MANPOWER TRAINING 59 26 TECHNOLOGY TRANSFER 59 NATIONAL FISHEq1IES DEVELOPMENT 60 Workers INTRODUCTION 26 FORUM FISHERIES AGENCY 61 VILLAGE ECONOMY AND BEHAVIOR 27 EMPLOYMENT 28 References 62

Icelandic foremen and skippers: the structure and evolution of a folk model

Abstract: There are two folk models to explain differential fishing success in Iceland. One applies to the short term and is based on material factors; the other refers to the long term of seasons and careers and centers on the personal qualities of skippers, or the skipper effect. We show first that the skipper effect cannot account for differential fishing success. We then develop a sociological explanation for the ideology of the skipper effect and show how the ideology developed in response to historical changes in the social relations of production in fishing from the 19th century as labor and fish both became commodities, as Iceland gained independence from Denmark, and as new fishing technology developed. Finally, we describe the earlier conceptual scheme of fishing, which entailed foremen rather than skippers, and show how the role of skipper became elaborated as fishing developed into an autonomous economic field separate from other aspects of peasant production. [fishing, folk models, Iceland, social relations of production, history]