Showing papers on "Fishing published in 1991"

The decline of Chesapeake Bay oyster population : a century of habitat destruction and overfishing

Abstract: The oyster population in the Maryland portion of the Chesapeake Bay has declined b y more than 38-fold since the early part of the century. Although the effects of fishing have been implicated, the decline has been attributed primarily to water quality and recently oyster disease. The decline has also been thought to have affected the biota and chemistry of the Bay. Our analysis provides a quantitative demonstration that the long-term declines are largely the result of habitat loss related to over fishing early in the century, stock over fishing, early in the century' through the recent times. Furthermore, the major ecological effects on Chesapeake Bay occurred well-before World War 1/, before industrialization and the prevalence of disease

Traditional fishing in the Torres Strait Islands

Abstract: Centuries of fishing and hunting have given Torres Strait Islanders an intimate familiarity with the sea and its inhabitants, including what may be an unparalleled understanding of dugong behaviour. And the waters around the islands are rich. Sea turtles and dugongs - endangered species in many other tropical waters - are so abundant that they form a large part of the islanders' diets. Coral reef fish and lobsters abound. But various impacts of the outside world have robbed the islanders of their ability to make a good living from their waters. The authors discuss how such Fourth World peoples (the islanders are Melanesian, but the islands are Australian) may find themselves at an even greater disadvantage than some Third World peoples in exploiting their natural resources for their own benefit. This text is based on five years of fieldwork. The book treats in detail the history of fishing in the islands; the practices of dugong hunting, turtle hunting and fishing; the islanders' detailed knowledge of the behaviour of marine animals; traditional fishing rights and their doubtful value today; the impediments to the islanders making effective use of their marine resources; and the very high consumption of local seafood, despite the high consumption of imported foods.

Incidental capture of seabirds in the New Zealand subantarctic squid trawl fishery, 1990

Abstract: Fisheries observers recorded incidental capture of seabirds during 338 days on Soviet squid trawlers in New Zealand subantarctic shelf waters around the Snares and Auckland Islands in 1990. Seven species were recorded entangled in fishing gear, including very high numbers of breeding adult White-capped Albatrosses Diomedea cauta steadi. The actual level of White-capped Albatross mortality was estimated at 2,300 birds in 1990, and is not considered sustainable. Nearly all albatrosses were killed by collision with the netsonde monitor cable. In New Zealand waters this equipment is carried only by Soviet trawlers, and is considered obsolete. Replacement of this cable by discrete netsonde transducers on Soviet trawlers should be a global seabird conservation priority.

The Status of Competitive Sport Fishing in North America

Abstract: Organized competitive sportfishing has been a growing use of fishery resources for at least the last 20 years. We conducted a survey of fishery agencies in Canada, the United States, District of Columbia, Puerto Rico, and U.S. Virgin Islands to estimate the numbers and types of competitive fishing events in inland and marine waters and to determine fishery agency perceptions of the benefits and problems associated with these events. Based on survey responses, there were 20,697 competitive fishing events annually. Adjusting for agencies that did not provide estimates and incomplete reporting, we estimated that there were at least 31,000 competitive fishing events annually. Most competitive fishing events were for black bass in inland waters and billfish in marine waters, but events targeted many species of fish. In inland waters, events for species other than black bass appear to be increasing. Prevalent problems of competitive fishing perceived by fishery management agencies were stimulation and ...

Resource and activity substitutes for recreational salmon fishing in New Zealand

Abstract: This article develops a typology of substitution alternatives to clarify the relationship between resource and activity substitutes. The present study examines anglers’ perceptions of resource and activity substitutes for salmon angling on the Rakaia and Waimakariri Rivers. Both rivers are noted for good quality fishing and are close enough for day trips from Christchurch, the major population center on New Zealand's South Island. For resource substitutes, most anglers indicated that rivers distant from Christchurch were not substitutes because the drive took too long; the expense and low salmon numbers were less frequently cited reasons. For rivers close to Christchurch that were not considered substitutes, fewer salmon and poor fishing conditions were the more common reasons. Anglers were also asked about trade‐offs between the Rakaia and Waimakariri. Responses indicated that the two rivers are not considered equal in value even though they are most often named by anglers as the best substitute...

Krill fishing activity in the southwest Atlantic

Abstract: Commercial krill fishing has been undertaken in the Southern Ocean for twenty years. Recently the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) introduced a reporting scheme to summarize catch data from half degree of latitude by one degree of longitude rectangles. These data demonstrate that commercial fishing in the southwest Atlantic is concentrated in the shelf zone. Certain krill predators are also restricted to this area whilst collecting food for their young during the summer. Krill fishing takes place year round, moving northwards in winter as the ice edge advances.

Fish and Fisheries Ecology.

Abstract: My paper on fish and fisheries ecology is offered to demonstrate a rich blending of applied and fundamental ecology, achieved by the intersections among fishery science, ichthyology, and ecology. The example, while specific, parallels practices and opportunities available in other areas of applied ecology. The emergence of fish and fisheries ecology as a discipline is evidence by such recent textbooks as Fisheries ecology by Pitcher and Hart (1982) and Ecology of teleost fishes by Wootton (1990). The ecology relevant to fish and fisheries includes not only marine and freshwater ecology, oceanography, and limnology, but also terrestrial study. Early work in fish and fisheries ecology came from Stephen A. Forbes > 100 yr ago in his books On some interactions of organisms (Forbes 1880) and The lake as a microcosm (Forbes 1887). These constitute one of the earliest conceptualizations of an ecosystem. By 1932 E. S. Russell concluded that fishery research was a study in marine ecology. I give examples of applications from six different categories of ecology. (1) Physiological ecology: The F. E. J. Fry school of fish physiology developed the concepts of temperature as a lethal, controlling and directive factor. More than 40 yr later, this knowledge is being combined with G. E. Hutchinson's concept of an n-dimensional niche to analyze potential influences of global climate warming on fishes. (2) Behavioral ecology: A. D. Hasler and students formulated and tested the hypothesis of olfactory imprinting as the mechanism by which Pacific salmon "home" to their natal spawning streams. Applications to reestablish salmon runs are as important to Hasler as the original scientific discovery; this is evident in his proposed "Salmon for Peace" for the river bounding USSR and China. (3) Population ecology: The realization that reproductive success of fishes depends more on larval mortality than on egg production emerged from the ideas of J. Hjort (1914). To this day inconsistencies between recruitment and reproductive stock size impart uncertainty into fishery management, while the search for explanatory mechanisms attracts the curious mind. (4) Community ecology: Species interactions are the grist of community ecology; predation and fishing are a natural for comparative study and application. Also, consumption by fish can control the dynamics of planktonic and benthic animal/plant communities; thus, apparent water quality of lakes depends on the consumer community as well as on nutrient inputs. (5) Ecosystem ecology: D. S. Rawson grouped external, abiotic influences on lakes into climatic, edaphic, and morphometric factors. The morphoedaphic index (Ryder 1965) predicts fish yields from this base, providing fish managers with a useful approximation and ecologists with a conceptual base for synthesis of production processes. (6) Landscape ecology: Regional ecology often incorporates land-water boundaries into the way ecological systems work. Application of island biogeography to lakes, as islands, has allowed predictions of fish assemblages for use by managers. Also, the extent and connectedness of lake and ocean "landscapes" offer insight into contrasts between marine and freshwater fishery research and management. In conclusion, the ecotone between academic and applied ecology seems an ideal place from which to advance both applied ecology and ecology in general.

The biology of the white musselcracker Sparodon durbanensis (Pisces: Sparidae) on the Eastern Cape coast, South Africa

Abstract: Aspects of the biology of the musselcracker Sparodon durhanensis, an important shore-angling species on the south-eastern coast of South Africa, are described from material collected between August 1984 and March 1987. Juvenile fish live in tidal pools and in shallow subtidal waters, where they feed on a variety of small invertebrates and chlorophytes. Larger fish are more common in deeper water down to about 30 m, but they also feed inshore, consuming large invertebrate prey such as gastropods, pelecypods, solitary ascidians, crustaceans and amphineurans. They are rudimentary hermaphrodites, mature at approximately 350 mm fork length and have a restricted breeding season between August and January, during which period they spawn small pelagic eggs. Growth studies based on 5ectioned sagittal otoliths reveal musselcracker to be slow-growing and long-lived. that both sex.es grow at a similar rate and that they can survive to at least 31 years of age. The specie, is likely to be highly susceptible to overexploitation even though the fish are not commercially exploited. and more stringent management measures are called for to ensure the survival of the species as a recreational angling resource.

Fishing Arctic foxes Alopex lagopus on a rocky island in west Greenland

Abstract: On a small barren island in Disko Bay, west Greenland, 195 hours were spent observing Arctic foxes at their den and the nearby coast. Their main food was found to be live, caught fish, and the activity of the foxes was correlated with the tidal height. S. M. Nielsen, Arctic Station, University of Copenhagen. DK-3953 Godhavn, Greenland.

Neritic squid resources and cuttlefish resources in Japan

Abstract: Knowledge concerning biology of two loliginids and three sepiids which are found in the Japanese waters was reviewed including unpublished information of the authors. The swordtip squid, Photololigo edulis, is one of the most important resources for the coastal fisheries of Kyushu and the prefectures facing the southwest Japan Sea. This species is the only species of genus Photololigo found along the Japanese mainland coast and is easily distinguished from other loliginids, by the light organs on the ink sac. The species is distributed from southern Japan to the Red Sea. The spawning season extends throughout the year. Egg cases are laid in clusters on the sandy bottom. The life span is about one year. In the juvenile stage they feed on Crustacea and after reaching pre‐maturity they prey mainly on fish, but many have empty stomachs. Most catches are made by jigging and trawler. The fishing season extends throughout the year. The fishing grounds are widely spread over the continental shelf. Annual catches ...

Changes in species composition of demersal fish fauna of Southeast Gulf of Carpentaria, Australia, after 20 years of fishing

Abstract: The changes in a tropical demersal fish community in the southeast Gulf of Carpentaria, Australia, were examined by comparing the results of a survey undertaken in 1964 before the area was fished, with two surveys in 1985 and 1986 after 20 yr of commercial trawl fishing. The numerical abundance of 52 of the 82 fish taxa had not changed significantly, but that of 18 had decreased while 12 had increased. One taxon (Paramonacanthus spp.) had decreased by more than 500 times and another (Saurida micropectoralis) had increased substantially in abundance. The changes occurred throughout the area surveyed, but the largest changes were offshore. In the pre-trawling community most taxa were caught mainly during the night, while in the post-trawling community most were caught in the same numbers during day and night. In 10 of the 30 taxa that changed in abundance, changes were within a family and could not be explained. For the remaining 20, the changes could be related to their position in the water column: benthic taxa decreased and bentho-pelagic taxa increased. The changes were assessed in relation to fishing effort, and changes in the mud content of the substrate in the study area. Although the changes did not correlate with the fishing effort among three zones in the study area, it is suggested that fishing effort and discarding of the by-catch caused the change in 18 taxa. The magnitude of the decreases of some species might be related to changes in the sediment or possibly other long-term environmental change. There was also a change in the diel behaviour in the fish community that perhaps may be related to the effects of fishing on a tropical multispecies fish community.

Exploitation and Survival of Black Crappies in Three Georgia Reservoirs

Abstract: During 1987–1989, population dynamics and fisheries for black crappies Pomoxis nigromaculatus were evaluated at three Georgia reservoirs that traditionally received substantial crappie-fishing effort. Exploitation rates and survival were estimated with mark–recapture studies relying on tag returns from anglers. Fishing pressure, harvest, and angler success were evaluated with nonuniform probability roving creel surveys. Growth rates were determined by scale analysis. Annual survival estimates ranged from 8 to 18% at all reservoirs; exploitation estimates ranged from 40 to 68%. Black crappies entered the fisheries at age 2 or 3 and numerically dominated the total angling harvest at all reservoirs. All populations were characterized by low survival regardless of angler exploitation, so standing crops of harvestable crappies would not be expected to increase appreciably if exploitation were reduced. Thus, anglers would not benefit from additional regulation of harvest.

Sociological, Economic, and Biological Aspects of Competitive Fishing

Abstract: Competitive fishing is a large and growing use of fishery resources that offers benefits and creates problems for fishery managers. Successful integration of competitive fishing with noncompetitive anglers and other aquatic resource users will require current and comprehensive data about competitive fishing events and additional information about sociological aspects, economic values, and biological effects of competitive fishing. In this paper we summarize available sociological, economic, and biological information about competitive fishing and suggest directions for future research. We suggest a permit system to obtain needed data about competitive fishing events and minimize social and biological problems associated with them. Competitive fishing provides communication channels between fishery managers and anglers. Integration of competitive fishing with other aquatic resource uses will require effective communication programs.

Net economic value of the freshwater recreational fisheries of New York.

Abstract: A statewide angler survey was conducted in New York in 1988 in part to estimate the net economic value of the state's recreational fishery. Willingness-to-pay questions from the National Survey of Fishing, Hunting, and Wildlife-Associated Recreation were adapted to a mail survey format and respondents were asked how much they would be willing to pay above current expenditures for a specific fishing trip. The net economic value estimated from the responses exceeded $284 million for the freshwater fisheries of New York in 1988. Although inland fisheries accounted for 76% of the statewide net economic value, $69 million was associated with the portion of the Great Lakes assigned to New York. Comparisons with a 1976–1977 analysis of the net economic value of New York's Great Lakes fishery, which used a variation of the indirect travel cost methodology, showed a major shift in net economic value from trips for warmwater species to trips for coldwater or for both warm and coldwater species. Baseline da...

Fishing a superfund site: dissonance and risk perception of environmental hazards by fishermen in Puerto Rico.

Abstract: Risk perception studies show that individuals tend to underestimate significant risks, overestimate negligible ones, and distrust authorities. They also rely on a variety of strategies or heuristics to reach decisions regarding their risk-taking behavior. The authors report on a survey of fishermen and crabbers engaged in recreational and substance fishing in a Puerto Rican estuary (near Humacao), which has been declared a Superfund site because of suspected contamination by mercury, and at ecologically similar control sites. Nearly everyone interviewed at the Humacao site was aware of the mercury contamination, but either denied its importance, believed the contamination was restricted to a distant part of the estuary, or assumed that the estuary would be closed by the authorities if the threat was real. All site-users consumed the fish and crabs they caught. At Humacao, the average catch was 7 fish per fishermen (mostly tilapia, Tilapia mossambica, and tarpon, Megalops atlantica) and 13 crabs per crabber (all blue crabs, Callinectes sapidus). On average, the site-users returned to the lagoons about 3-4 times per month. At control sites, fewer fish were eaten. The worst case consumption of tarpon, a species which concentrated mercury at Eastern Puerto Rico, provided an exposure exceeding the EPAmore » reference dose, whereas consumption of one tarpon per week did not entail excess exposure. Fortunately, few individuals caught tarpon exclusively. Unlike counterparts in the northeastern United States, they trusted authorities and indicated that they would have heeded warnings of mercury contamination posted where they fished.« less

A Bioeconomic Analysis of the Texas Shrimp Fishery and Its Optimal Management

Abstract: Overfishing in the Texas shrimp fishing industry by time period and fishing area is investigated. An optimal harvesting pattern is determined using a multiperiod mathematical programming model where prices, fishing effort, catch, and resource dynamics are treated endogenously. These results are then compared with actual effort. The comparison indicates substantial excess effort in spring and early summer, especially in the bays and shallow offshore areas. The peak fishing season also occurs later in the fall in optimal harvest pattern than in practice. The results indicate both producers and consumers gain from reduced fishing effort because of improved size composition of the harvest.

Fish Resources; Threats and Protection

Abstract: The status of fish species and fish resources is reviewed. Actual and potential threats are identified and, as far as possible, quantified in terms of their potential to cause local or general extinction. Excessive depletion by fishing alone has rarely, if ever, caused extinction, but the circumstances in which unrestrained fishing could potentially do so are identified. The harm to fish arising from deterioration of water quality caused by toxic pollutants and acidification is well documented and, for the most part, well understood. More subtle and potentially more dangerous conditions arise from excessive organic enrichment in low-energy systems such as deep lakes and semi-enclosed seas, which may lead to the creation or enhancement of an anoxic layer and its spead into shallower regions. The majority of introduced fish species have proved either non-viable or ecologically neutral. A small proportion have been beneficial, mainly in man-made water bodies. Some, notably general colonisers and powerful predators, have seriously harmed the native fish fauna. Most serious, because the fish have little or no natural protective response, is disruption of water flow or loss of habitat. Significant loss of genetic diversity can be caused even when these factors are not so serious as to cause total extinction. In reality, it is usual for two or more of the above threats to operate together; it is shown how the result may be more dangerous than the sum of their independent effects. In conclusion, it is suggested that a more rigorous and uniform definition of "threat" is needed. The established criteria and methodology of "risk assessment" could be used with advantage. Complete protection, except in special circumstances, is unattainable. A better strategy is to intensify efforts to convince the users of fish resources, whether for food, sport or the aquarium trade, that sustainable harvesting is to their long-term advantage as well as that of the fish. Above all, the need is to convince the general public that the conservation of fish is just as important as that of other more visible fauna and flora.

Population Dynamics of a Lightly Exploited Channel Catfish Stock in the Powder River System, Wyoming–Montana

Abstract: The population dynamics of a lightly exploited stock of channel catfish Ictalurus punctatus were assessed in the Powder River system, Wyoming–Montana, with special emphasis on evaluation of changes that may occur if the harvest is increased. The samples contained a substantial proportion of large fish, but growth rate was similar to that in other areas at lower elevations and latitudes. Fish up to 21 years old were collected. Annual exploitation was estimated to be only 1.9–2.0%. Maximum yield was predicted to occur at 18–22% annual fishing mortality, but this level of exploitation would be expected to cause a shift toward smaller sizes of fish and virtually eliminate fish in the large size-classes (>50 cm total length), which are the principal attraction for the current anglers.

Management Briefs: Effect of Catch‐and‐Release Angling on the Survival of Black Sea Bass

Abstract: We tested the hypothesis that black sea bass Centropristis striata captured and released by anglers experience zero mortality. Black sea bass captured by hook and line in Nantucket Sound, Massachusetts, were tagged and held in wire cages on site for 48 h. Hook location and physical condition were recorded for each fish. Concurrently, black sea bass used as controls were collected from commercial fish pots, tagged, and held under similar conditions. A preliminary experiment established that neither tagging nor densities up to 12 fish per cage caused mortality. During the 48-h posthooking period, 3 of the 64 fish tested died, resulting in an estimated hooking mortality of 4.7%. The three fatalities were among five fish hooked in the esophagus. We concluded that survival is high among small caught-and-released black sea bass (<27 cm standard length) and that release of hooked fish has little effect on total fishing mortality.

National estimates of the recreational value of streamflow

Abstract: This paper presents one practical method of valuing the recreational fishing benefits generated by a unit of water as it moves downstream. A cross-sectional analysis is employed to estimate the change in individuals' fishing behavior due to a change in availability of fishery resources. A proxy for the availability of stream fishery resources is derived from the link between changes in streamflow consumption to changes in the quality of fishing downstream. The results show that marginal increases in streamflow can generate recreational benefits that exceed the marginal value of water in agriculture in some regions of the country.