Showing papers on "Fish migration published in 1993"

Nutrient and energy transport between estuaries and coastal marine ecosystems by fish migration

Abstract: Biomass accumulation and changes in body energy and nutrient (carbon, nitrogen, and phosphorus) composition were evaluated relative to the migration pattern of gulf menhaden (Brevoortia patronus) t...

Recycling of Elements Transported Upstream by Runs of Pacific Salmon: II. δ15N and δ13C Evidence in the Kvichak River Watershed, Bristol Bay, Southwestern Alaska

Abstract: Biota δ15N and δ13C values (deviations from recognized isotope standards) from lliamna Lake (a major anadromous sockeye salmon (Oncorhynchus nerka) nursery lake supporting peak-year runs > 10 milli...

Implications of diadromy for the structuring and modelling of riverine fish communities in New Zealand

Abstract: Development of models to describe the distribution and abundance of salmonid fishes depends on understanding the suitability of local, small‐scale, critical habitat parameters such as water depth, flow velocity, and substrate characteristics. The success of such models in predicting trout abundance depends on the populations not being limited by additional constraints on abundance by wider, large‐scale parameters, such as recruitment and migratory access. Extension of these models for use in evaluating the impacts of flow modifications to New Zealand rivers on indigenous fish populations would significantly advance biologically sustainable management of rivers. Many of New Zealand's native fish species are diadromous, requiring access to and from the sea to complete their life cycles. For this reason, abundance of native fishes is likely to be constrained by a combination of large‐scale variables such as: elevation, slope, distance from the sea, the presence or absence of explicit barriers to ups...

Migration, growth and survival of wild and hatchery-reared anadromous Arctic charr (Salvelinus alpinus) in Finnmark, northern Norway

Abstract: Two groups of anadromous Arctic charr (Salvelinus alpinus) (size 200–350 mm) reared in heated water (6–12° C) under simulated natural photoperiod were individually tagged and released in spring 1988. The fish were released at two sites, in the estuary of the River Halselva and in the fjord, 2 km from the river mouth. Growth, timing of migration and survival of these hatchery-reared fish was compared to that of wild anadromous charr of the same size over a 4-year period. The hatchery-reared charr had poorer growth than the wild fish during their first year in sea water. They also resided longer in the sea and had a slightly lower survival than wild fish. During the second year, hatchery-reared charr displayed good growth, and after the third sea-season the fish were ready for slaughter at a size of approximately 800g. The results suggest that the successful development of Arctic charr ranching will be dependent upon production and release strategies that lead to improved migratory and feeding behaviour of the fish during their first season at sea.

The Norwegian Gene Bank Programme for Atlantic Salmon (Salmo salar)

Abstract: Norway has about 400 rivers which supported anadromous Atlantic salmon (Salmo salar). In 79 of these rivers the salmon population is either extinct or threatened by extinction. Acid precipitation has been the main cause of salmon mortality in the southern part of the country and 25 stocks are now virtually extinct (Hesthagen and Hansen, 1991). The parasite Gyrodactylus salaris has caused extensive fish kills in 34 salmon rivers in the middle region of the country.

Fish ecology and management of the Sepik-Ramu, New Guinea, a large contemporary tropical river basin

Abstract: The ichthyofauna of the Sepik-Ramu basin is composed of diadromous species and the freshwater derivatives of marine families. Fish species diversity, ichthyomass and fish catches are low even by Australasian standards. Three major factors have produced the depauperate ichthyofauna and restricted fishery within the basin: First, the zoogeographic origins of the ichthyofauna. Australasian freshwater fishes, being mainly derived from marine families, generally exhibit ecological characteristics that have evolved for life in estuaries, not rivers. This has led to peculiarities in river fish ecology and explains the probable low fish production from rivers in this region in general. Several important riverine trophic resources are not exploited by the Australasian freshwater ichthyofauna. The modes of reproduction amongst the Australasian freshwater ichthyofauna have limited the colonisation and exploitation of floodplain habitats. Second, Sepik-Ramu lowland habitats, especially floodplains, are very young. This has resulted in low fish species diversity in lowlands, whilst diversity at higher altitudes is equable, in comparison to river systems in southern New Guinea/ northern Australia. Third, the Sepik-Ramu lacks an estuary in sharp contrast to river systems in southern New Guinea or northern Australia. Most of the 18 families of Australasian fishes missing from the Sepik-Ramu are probably absent because of this factor alone. In particular, the Sepik-Ramu has not been colonised by any family of fishes having pelagic eggs, resulting in the loss from the fauna of the few Australasian fish taxa with high reproductive rates. Consequently, the general problems with river fish ecology in Australasia are exacerbated within the Sepik-Ramu by the particular development and morphology of the basin. Fish species diversity in the Sepik-Ramu is low, even in comparison with those taxa representative of marine families resident in rivers in nearby zoogeographic regions (S.E. Asia) whose ichthyofaunas are otherwise dominated by freshwater dispersant groups. The Sepik-Ramu ichthyofauna is considered noteworthy for what is absent, not what is present. Ichthyomass and fish production can be increased by fish species introductions whilst, in theory, biodiversity of the native fish fauna can be maintained. The directions in which ecological evaluations of proposed introductions might proceed in practice for the Sepik-Ramu are discussed but are constrained by the lack of knowledge on species interactions from other areas.

Production and dispersion of freshwater, anadromous, and marine fish larvae in and around a river plume in subarctic Hudson Bay, Canada

Abstract: From 1988 to 1990, fish larvae were sampled before, during, and after ice breakup within and outside the plume of the Great Whale River off Kuujjuarapik, southeastern Hudson Bay, Canada. Arctic cod (Boreogadus saida) and sand lance (Ammodytes spp.) were the most abundant larvae. Half of the larval fish taxa emerged before the ice broke up in the Bay. The highest densities of Arctic cod, sand lance, slender eelblenny, and gelatinous snailfish larvae were in salinities exceeding 25 practical salinity units (p.s.u.). Arctic shanny, sculpins, and capelin larvae were more abundant at salinities between 1 and 25 p.s.u.. Burbot and coregonid larvae were clearly associated with fresh or brackish waters even when caught in the Bay. The timing and extent of the Great Whale River freshet influenced the distribution of marine fish larvae in southeastern Hudson Bay and determined the moment when the larvae of anadromous and freshwater species entered the Bay.

Abundance of Juvenile Atlantic Salmon and Brown Trout in Relation to Stocking and Natural Reproduction in the River Laerdalselva, Western Norway

Abstract: Since the regulation of the river Laerdalselva in 1974 many juvenile Atlantic salmon Salmo salar and brown trout S. trutta have been stocked above the natural reach of anadromous fishes to compensate for possible loss in Atlantic salmon production. The parental material for the stocking was obtained from the lower parts of the river. In 1988 the numbers of fish stocked were drastically reduced. The density of Atlantic salmon (all year-classes) was 75–80% less in years of light stocking than in years of intensive stocking. For Atlantic salmon, a strongly significant (P < 0.001) correlation was found between the numbers of young-of-the-year parr (age-0 fish) stocked in the river and the corresponding density of age-0 fish. The reduction in Atlantic salmon density occurred even though the fish ladders allowed fish migration to the spawning grounds. However, few of the Atlantic salmon moving up through the fish ladders were females, so natural recruitment was severely limited.

Implementation and Evaluation of the Water Budget

Abstract: The Northwest Power Act established the Northwest Power Planning Council to coordinate hydrosystem operations by developing a program “to protect, mitigate, and enhance” the Columbia River basin's anadromous salmonid resources. The language and legislative history of the act demonstrate the intent of Congress that the basin's power planners consider anadromous fish “co-equal partners” with hydrosystem operations and planning. An important and controversial element of the council's Fish and Wildlife Program is the water budget, a program that allows fish and wildlife agencies to help determine flow levels in the basin during the peak of juvenile downstream migration. Execution of the water budget has been difficult due to its lack of an authoritative management strategy, limited scope, and the absence of firm implementation guidelines. Implementation problems that have plagued the water budget since its inception make judging the efficacy of the program difficult. Evaluation of the water budget co...

Distribution, growth and movement of River Usk brown trout (Salmo trutta)

Abstract: The River Usk catchment in South Wales supports mainly freshwater resident brown trout, with few anadromous fish. Electric fishing and netting revealed that age-class distribution differed between main river and tributary habitats, the latter environment acting as a nursery area for young fish. Few fry were found at main river sites. Age-class distribution also differed between tributary systems, and possible reasons are discussed. Trapping experiments indicated that trout move to main river habitat at 2+ yr. Lengths at age (back-calculated from scale reading) were similar for main river and tributary resident fish at 1 and 2 year, but main river fish were larger at 3 and 4 yr. This habitat shift and size difference is discussed with reference to current angling regulations.

Glochidia of the freshwater mussel,Anodonta anatina, affecting the anadromous European smelt (Osmerus eperlanus) from the Eider estuary, Germany

Abstract: During a 2-year survey on external disease conditions of fish between January 1988 and December 1989, 0.2% of 40011 smelt,Osmerus eperlanus, from 30 stations in the German Wadden Sea and estuaries of tributary rivers, were infected with glochidia of the freshwater mussel Anodonta anatina. Seasonality was marked, with glochidia only being observed in March and April 1989, when prevalences were 37% and 15% respectively, in fish 10–20cm long at the most heavily infected site. A marked increase in prevalence in fish 15cm in length and longer, suggested that only temporarily resident spawning fish (as opposed to resident juveniles) were infected. Infection was almost exclusively restricted to the Eider estuary, where prevalence decreased with increasing salinity. It is concluded that the glochidia carried by smelt returning from their freshwater spawning sites in the Eider River to the sea would have died, thus representing a loss to the 1989 cohort of A. anatina from the Eider. The potential importance of the smelt–A. anatina relationship as indicator for the detection of (a) spawning mussel populations and of (b) possible ecological effects of climate changes is noted.

Successful Maturation and Spawning of Captive Chinook Salmon Brood Stock

Abstract: Brood stock of chinook salmon (Oncorhynchus tshawytscha) cultured from egg to maturity had low prespawning mortality and highly viable offspring when fed a formulated brood diet and matured in a seawater net-pen with a surface freshwater lens. The brood fish were cultured in freshwater raceways as fry, reared in seawater net-pens from the juvenile (4.7 g) stage until 2 months before spawning, and then transferred into the seawater net-pen modified with a 1-m-thick freshwater lens. Diet was changed 12 months before spawning from a basic formulated commercial diet to a commercial brood-fish diet. The average egg viability to the eyed stage (72% for the progeny of nine females, each crossed with a single male) compared favorably with that of anadromous fish produced at the same facility. Although cultured fish matured younger and smaller, and thus produced smaller eggs and fry, than did wild or anadromous fish of the same stock, juvenile size did not differ after 6 months of freshwater rearing.

Umatilla River Basin Anadromous Fish Habitat Enhancement Project : 1991 Annual Report.

Abstract: The Umatilla habitat improvement program targets the improvement of water quality and restoration of riparian areas, holding, spawning,and rearing habitats of steelhead, spring and fall Chinook and coho salmon. This report covers work accomplished by the Confederated Tribes of the Umatilla Indian Reservation from April 1991 through May 1992. This program is funded under the Northwest Power Planning Council's Columbia River Basin Fish and Wildlife Program (Measure 704 (d)(1) 34.02) as partial mitigation for construction of hydroelectric dams and the subsequent losses of anadromous fish throughout the Columbia River system.

Stream habitat assessment project: Afognak Island. Restoration study number 47. Exxon Valdez oil spill state/federal natural resource damage assessment final report

Abstract: The Alaska Department of Fish and Game, Habitat and Restoration Division, conducted surveys of anadromous fish streams on Afognak Island from July 6 to September 1, 1992. These surveys focused on Afognak Native Corporation and Afognak Joint Venture lands in order to document anadromous fish distribution and habitat on private lands throughout the spill area. 167 new anadromous fish streams were documented totalling approximately 56 km (35 miles). Dolly Varden and coho salmon were the principal fish species found, followed by pink salmon, sockeye salmon, chum salmon, rainbow trout, stickleback and sculpin. The study additionally found 34 streams that have a high potential for rehabilitation.