摘要:

A 15-month study was conducted to describe the seasonal changes of total larval fish densities, fish egg densities, and species composition in the nearshore marine environment of Diablo Canyon, San Luis Obispo County, California.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<225:SLFAIW>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Otoliths of the gag grouper, Mycteroperca microlepis, sampled from the headboat fishery off the southeastern United States were examined to determine age. The oldest fish collected was age XIII and 1,201 mm total length. Back-calculated mean lengths of 136 fish ranged from 269 mm at end of year 1 to 1,080 mm at end of year 13. The von Bertalanffy equation describing theoretical growth in length is Lt= 1,290 (1 - e-0.12154(t+1.127)), where L = total length (mm) and t = years. The length-weight relationship is described by the equation W = 1.2 × 10-8L2.996, where W = weight in kg and L = total length in mm. Only slight differences were noted in length-weight relationships between geographical locations. The average fish landed by the recreational fishery was 825 mm total length and 6.56 kg. Approximately 34% of the gag landed were age × and older. Apparently the rate of natural mortality increases drastically after age XII.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<234:AAGOTG>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Two methods of measuring daily catches by headboats that fish the outer Continental Shelf off North Carolina and South Carolina are compared. Headboats are those commercial fishing boats where recreational anglers pay for a day's fishing on a per person, thus per head, basis. A dockside creel census estimated catches as only 47% to 87% of the catches, in numbers of fish, reported by crew members in logbooks. While the comparison suggests substantial bias in one or both techniques, low cost favors use of logbooks.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<241:MCITCH>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Gear catch efficiencies, q, are useful in achieving more accurate estimates of fish abundance. Twenty mark-recapture experiments using juveniles (50-80 mm) and yearling (90-140 mm) pinfish, Lagodon rhomboides, and spot, Leiostomus xanthurus, were conducted in an enclosed 5-hectare North Carolina estuarine embayment to estimate the catch efficiencies for a 6.1-m otter trawl. Catch efficiencies, defined as the percentage of fish in the path of the trawl that are captured, were calculated from the ratio of the average trawl estimate of marked fish density to the known density of marked fish. The trawl was towed at approximately 1.6 knots and sampled a path 5 m wide. Estimated catch efficiencies for the trawl during daylight were: juvenile pinfish 48%; yearling pinfish 49%; juvenile spot 32%; and yearling spot 32%. Precision for the efficiencies was relatively low with the standard error ranging between 9 and 58% of the mean. Catch efficiencies did not differ between day versus night recovery or appear to be related to fish density. Relative catch efficiencies for the 6.1-m trawl were greater than those for a 3.0-m and a 4.6-m otter trawl.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<246:CEOAMO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A roving creel survey with nonuniform probability sampling was conducted on West Point Reservoir, Georgia, for 24 months. The sampling design is described in detail. The assumption that catch per unit effort (CPE) for incompleted fishing trips is an unbiased estimator of CPE for completed trips is tested and verified. Coefficients of variation for monthly estimates of catch and effort are used to measure the precision of the sampling design. Precision was relatively high during the summer (April-October), but decreased markedly during the winter (November-March). This change is largely independent of sample size within the range of 5-10 sample days per month leading to the conclusion that sampling effort could be reduced 50% without impairing the precision of the survey. The method appears capable of detecting changes in the quality of fishing small enough for management purposes. The paper is intended to provide guidelines for the implementation, evaluation, and modification of statistically based creel survey programs.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<255:AEOTRC>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Stratified estimates of fishing intensity and harvest of paddlefish (Polyodon spathula) in the Yellowstone River at Intake, Montana were made during 1973 and 1974. An estimated 25.9 and 46.3% of the fishermen were contacted during 1973 and 1974, respectively. The fishery sustained an estimated 2,386 fisherman days of use in 1973 and 3,363 days in 1974. The seasonally pooled catch rates were 0.45 and 0.39 fish per hour in 1973 and 1974, respectively. The estimated total number of fish caught was 4,544 in 1973 and 4,359 in 1974. The weight of fish removed was estimated to be 45 and 39 metric tons in 1973 and 1974, respectively. The ratio of males to females in the run was estimated to be approximately 2:1 during 1973 and 1974. Males in the catch during 1974 averaged 0.889 kg more in weight, 6.4 cm greater in length, and the dominant age group was 1 year older than in 1964. Tag returns were 14.8% in 1974; however, only 8.2 and 9.5% of males and females were kept in 1974. It was concluded that the current rate of exploitation is not detrimental to the population.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<263:TFFPAI>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

A study was initiated to assess the mortality of larval fishes that were entrained in the condenser cooling systems of two nuclear power plants on the Missouri River in Nebraska. High mortalities were observed not only in the discharge collections but also in control samples taken upriver from the plants where no entrainment effects were possible. As a result, entrainment mortality generally could not be demonstrated.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<269:AAOSMO>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Twenty-nine white sturgeon (Acipenser transmontanus) were instrumented in 1975 and 1976 with separately identifiable radio transmitters to study seasonal movements in the mid-Columbia River, southeastern Washington. Tagged fish remained in free-flowing areas of the river and were inactive in winter. Movements occurred in summer and early fall. Activity appeared related to water temperature and sturgeon size.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<275:SMOWSA>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

Chinook salmon introduced into Lake Superior were sampled in Cherry Creek in 1971, in the Dead River during 1974 and 1975, and in Presque Isle Harbor during 1974 and 1975. A total of 80 males and 30 females were sampled. Analysis of the scales revealed that maturation could occur at ages I+, II+, III+, and IV+. All fish were found to have a planting check present; no fish were found having more than four annuli. There were no essential differences in age and growth between the sexes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<281:GAMOCS>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor

摘要:

An algorithm for modifying biological rates as a function of temperature has been developed using the basic form of the logistic equation. Versions of this basic algorithm are then used to modify growth, respiration, and mortality rates as a function of four characteristic temperatures.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1978)107<284:ATAFMB>2.0.CO;2

出版商:Taylor & Francis Group    

年代:1978

数据来源: Taylor