摘要:

The hypothesis that juvenile anadromous salmonids which are migrating to sea have higher levels of gill (sodium and potassium) adenosine triphosphatase ([Na+K]-ATPase) activity than nonmigrants was examined for wild and hatchery spring and fall chinook salmon (Oncorhynchus tshawytscha) from the Rogue River, Oregon. Although migrant juvenile chinook salmon captured at river km 173 had elevated gill (Na+K)-ATPase activity, migration from the more upstream portions of the Rogue River occurred without significant changes in gill (Na+K)-ATPase activity. High water flows stimulated migration without increasing gill (Na+K)-ATPase activity. Tributary-to-main-stem migration of juvenile fall chinook salmon did not result in elevated gill (Na+K)-ATPase activities. Juvenile spring chinook salmon released from Cole Rivers Hatchery (km 254) migrated rapidly to km 18 on the Rogue River without changes in gill (Na+K)-ATPase activity. We conclude that, although the relationship between seaward migration and elevated gill (Na+K)-ATPase activity is demonstrable in chinook salmon in many cases, such elevated ATPase activity is not a prerequisite for seaward movement of juvenile chinook salmon.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<349:SMOJCS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

We examined salmonid habitat and biomasses in 50–70-m pairs of altered and control sections of small (discharges less than 0.3 m3second-1) streams around Puget Sound in western Washington in 1978–1979. Altered sections had been channelized or used by livestock. Channelization significantly reduced overhead cover, sinuosity, wetted area, and woody bank cover while increasing bank grasses. Total habitat area declined in altered areas. These impacts most damaged the quality of habitat for cutthroat trout (Salmo clarki) over 70 mm in length. Biomass of coho salmon (Oncorhynchus kisutch) did not decline significantly in altered sections except in areas severely damaged. Zero-age trout (cutthroat and steelhead, Salmo gairdneri) suffered no loss of habitat quality, although larger trout did, except in areas of severe physical impact. Short-term effects of machinery operation in the one stream for which data were obtained included biomass depletions of all salmonid species and size classes. Channelization and livestock use appeared to reduce quality of winter habitat for salmonids. In altered sections with stable bottoms, no recent damage history, relatively little silt and sand, and adequate riffle areas, the reduction in overhead cover appeared to lead to higher standing crops of salmonids, suggesting that fish production in many streams of the Puget Sound area may be light-limited.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<357:CALIOS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Over four seasons the movement and distribution of radio-tagged smallmouth bass (Micropterus dolomieui) were evaluated relative to water temperature, current velocity, turbidity, surface light intensity, reservoir elevation, bottom contours, substrate, and cover. Water temperatures always were within the range of tolerance by smallmouth bass, but late summer temperatures of 31 C probably reduced movement. Fluctuations in water velocity and reservoir elevation influenced depth distribution and movement of individual fish. Bottom relief was a major variable governing distribution and movement patterns of smallmouth bass. Dropoffs of 30–45° slope from the overbank into the original river channel or inundated creek channels were preferred. Bottom contours influenced both the shape of residence areas and movement pathways outside of residence areas. Smallmouth bass utilized all forms of submerged cover—rocks, stumps, sunken trees, and crevices in hard clay banks—without apparent preference for one type.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<364:HOASBI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A 12-year study of the smallmouth bass population, Micropterus dolomieui, in a pumped storage reservoir revealed an accelerated growth that was related to the abundance of gizzard shad, Dorosoma cepedianum. Prior to the gizzard shad introduction, the growth of smallmouth bass was generally poorer than that reported for the mid-Atlantic region. Large drawdowns (9 m per day, 15.6 m per week) may have increased the vulnerability of gizzard shad by concentrating both prey and predator. In the lower reservoir, where water levels fluctuated irregularly and much less (up to 1 m per day), smallmouth bass growth was not greatly improved following the introduction of gizzard shad.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<371:AGOSBI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The natural log of catch per unit of effort (CPUE) calculated for successive fish ages during the lifetime of a cohort, is related to the size of the cohort and to the fishing and natural mortality rates. After a simple linearization procedure, regressions of logeCPUE against effort and age can give estimates of natural mortality rate, catchability coefficient, and size of the cohort. The method is applied to Lake Opeongo trout data.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<378:EOMRIF>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A cartilage and bone staining technique was employed to study the developmental osteology of the striped bass (Morone saxatilis) and white perch (Morone americana). Special attention was given to those osteological characters that appeared to be unique to the larvae of each species. Larval striped bass and white perch exhibited diagnostic differences in the position and shape of the median ethmoid, predorsal bones, dorsal- and anal-fin pterygiophores, vertebral column, and caudal skeleton. These differences were discernible at the earliest appearance of these elements as cartilage, and allow identification of striped bass and white perch larvae above a length of about 7.5 mm.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<387:EODOWP>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Brook silverside (Labidesthes sicculus) eggs, larvae, and juveniles were collected with a plankton net from the Peace River, Florida. Eggs had two or three attachment filaments (mode = 2) and a mean diameter of 1.2 mm. Oil globules were present in the yolk, and decreased from a mean of 22 after fertilization to one by the late embryo stage. Recently hatched protolarvae ranged from 4.7 to 5.6 mm total length and had six to seven and 28 to 31 postanal myomeres. The ratio of preanal length to total length increased as the anus migrated posteriorly during the metalarval phase; preanal myomere counts increased while postanal counts decreased. Pectoral anlages were present at hatching. By 8.0 mm, the base of the second dorsal and anal fins began to develop, and fin ray anlages were present in the caudal fin. Pelvic fin anlages appeared by 10.3 mm and all median fin rays were visible by 11.3 mm. The first dorsal fin developed between 11.3 and 15.5 mm. Metalarvae transformed into juveniles between 15.5 and 20.1 mm. Atherinid eggs were distinguished from those of other families, except the cyprinodonts, by the presence of attachment filaments. Atherinid larvae were distinguished with larval-fish keys. Identification of brook silverside eggs and larvae was based on systematic analysis and the absence of other atherinids. Species similar to brook silversides are discussed. Geographical comparisons of brook silverside eggs, larvae, and juveniles revealed differences in the number of attachment filaments, larval pigmentation, metalarval and juvenile myomere counts, and the number of first dorsal spines.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<407:EALDOB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Pulsed direct current, square-wave alternating current, alternating current, and direct current, at voltages similar to those currently in use for electrofishing, induced drift by Ameletus dissitus, Baetis spp., Cinygmula par, Hesperoperla pacifica, Psychoglypha subborealis, Hesperophylax occidentalis, and Epeorus longimanus under simulated stream conditions. Of nine species of insects shocked at these voltages, only Simulium jacumbae did not drift. There was an inverse relationship between the propensity of an individual to drift and the minimum level of voltage required to induce drift. Threshold body voltages varied among and within species at different body sizes and at different temperatures. Temporary reductions in productivity with potential loss of species will occur in areas that are electrofished so frequently that rates of insect displacement are greater than rates of insect recolonization.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<417:EOEOSB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Dominance hierarchy was monitored over a 2-week period in triplicated groups of six parr of coho salmon (Oncorhynchus kisutch) by recording a variety of behavioral activities. Indices of stress were subsequently determined and compared with dominance statuses. Social position fell into three main categories: (1) the dominant fish; (2) two or three intermediate fish; and (3) two or three subordinate fish. Plasma cortisol concentration, interrenal nuclear diameter, and tail-beat frequency were lowest in the dominant fish and highest in the subordinate fish. Fish held alone had levels of plasma cortisol, interrenal nuclear size, and tail-beat frequency similar to those of the dominant fish. Hepatic glycogen varied directly with social position. It is plausible that dominance status is inversely related to a low-level, chronic state of stress in the fish, the dominant individuals being the least stressed.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<423:SASHRI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Eggs of the kelp greenling, Hexagrammos decagrammus; painted greenling, Oxylebius pictus; whitespotted greenling, H. stelleri; and larvae of these species and of lingcod, Ophiodon elongatus, were subjected to tests that simulated thermal stress associated with steam-powered electric stations using seawater for cooling in a once-through system. Ambient temperatures for holding the eggs and larvae were 8 C for the lingcod, 9 C for the kelp and whitespotted greenlings, and 13 C for the painted greenling. Embryos subjected to daily 4-hour exposures where temperature changes were gradual, as could occur with thermal plumes passing over egg nests, survived a maximum temperature of 22 C but not 24 C. Unfed larvae were subjected to conditions simulating passage through heat exchangers (held at elevated test temperatures for 10 or 20 minutes with an abrupt increase and decrease from ambient) or mixing with thermal plumes (held at test temperature 1–8 hours with temperatures gradually rising and decreasing from ambient). Lingcod, the most sensitive species, had a 48-hour, 50% survival at 24 C for the 10-minute test and at 22 C for the 20-minute test. However, lingcod and kelp greenlings became torpid at 18 C for the 10- and 20-minute tests. The 48-hour 50% survival of the greenlings subjected to the thermal plume test ranged from 26 C for the 1-hour test to 16 C for the 8-hour test. The maximum termperature increase that would not cause death or torpor to the least resistant species is 8 C.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1980)109<427:STROHE>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor