摘要:

Critical dissolved-oxygen levels and standard metabolic rates were determined for the bluegill, Lepomis macrochirus; largemouth bass, Micropterus salmoides; and the channel catfish, Ictalurus punctatus, at 25° C., 30° C., and 35° C. Two types of experiments were conducted: shock tests in which the dissolved oxygen was dropped rapidly from near saturation to a critically low point; and acclimation tests in which the dissolved oxygen was lowered gradually over a longer period of time. The minimal dissolved oxygen survived by fish in acclimation tests was lower than that survived in shock tests at any given temperature. In shock tests the minimum dissolved oxygen survived by bluegills was 0.75 p.p.m. at 25° C., 1.00 p.p.m. at 30° C., and 1.23 p.p.m. at 35° C. Slightly higher values were obtained for the largemouth bass at all three temperatures and for the channel catfish at 25° C. and 30° C. At 35° C. the channel catfish was more tolerant of low dissolved oxygen than either the bluegill or largemouth bass. In the acclimation tests the critical oxygen values obtained for bluegills were 0.70 p.p.m. at 25° C., 0.80 p.p.m. at 30° C., and 0.90 p.p.m. at 35° C. With the exception of the channel catfish at 35° C. slightly higher values were obtained with the largemouth bass and channel catfish. Within each species there was little difference between standard metabolic rates at the three temperatures. The standard metabolic rate of the bluegill at 25° C. was lower than that of the other species at the same temperature. Bluegills and largemouth bass weighing more than 15 grams showed no change in metabolic rate with increasing size, but below this weight, metabolic rate varied inversely with weight.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[377:DROTSO]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The toxicity of an endrin formulation to spring chinook and coho salmon, rainbow trout, bluegill, mosquitofish, guppies, and the marine threespine stickleback was determined at 20° C. Coho salmon were the most sensitive, with a 96-hour TLmof 0.27 parts per billion endrin; sticklebacks were the most tolerant. A volume effect was demonstrated; bluegills died at lower concentrations of endrin in aquaria with the smallest number of fish. Temperature had a marked influence on toxicity of endrin to bluegills, the toxicity increasing with rise of temperature. Tolerance of endrin by marine threespine sticklebacks was about the same in waters of different salinities. Developing eggs and early larvae of the stickleback are more tolerant than fully developed fish.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[394:TOETSP]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Fingerling brook trout (Salvelinus fontinalis) were force fed a capsulated food that contained P32-labeled phosphorus. A negligible direct effect of water temperature from 36° F. to 66° F. was measured on the recovery of the labeled phosphorus in the tissues of the trout through 4 days after feeding. Warmer water accelerated the rate of passage of the food through the digestive tract and the rate of digestion of the food equally. Consecutive daily feedings at water temperatures of 51°F. and 61°F. produced similar results for both water temperatures.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[398:RBWTAM]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Plantings that totaled 13,384 tagged, hatchery-reared lake trout (Salvelinus namaycush)—18, 25, 30, or 37 months old—were made at four Lake Superior localities in 1955-57 to: measure possible increases of return from rearing to greater size and age; study the effect of season of planting on the rate of return; compare returns from different types of tags; and follow the movements of hatchery-reared fish. The great advantage of spring over fall planting, demonstrated for fingerling lake trout in earlier experiments, did not hold for fish planted at ages of 18 to 37 months. The improvement of recovery rates with increase of age over the same 18- to 37-month interval appears to be too small to justify the cost of rearing to the higher ages. The recovery rates were closely similar (3.9 to 4.8 percent) for lower-jaw tags and two types of nylon-streamer tags but were much lower than the rate for Petersen tags (12.4 percent). The pins of Petersen tags render the fish highly vulnerable to entanglement in the webbing of gill nets, the principal gear in Lake Superior. Recoveries of Petersen tags also came earlier after planting than did those of other tags. The time between planting and recovery and the distance traveled by the fish were clearly but not closely correlated. Mean distance between points of planting and recovery increased with time out, and average time out increased with the number of miles traveled. More than half of the recoveries of fish that had been at liberty over 2 years were made within 25 miles of the point of release.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[404:ROTHLT]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Gill-net selectivity curves for ciscoes (Coregonus artedii), round whitefish (Prosopium cylindraceum), chub species (mainly Coregonus hoyi, with a few representatives of C. reighardi), yellow perch (Perca flavescens), and white suckers (Catostomus commersoni) were obtained from the analysis of catch statistics of experimental nylon gill nets fished in Georgian Bay in 1958 and 1959 and in South Bay during the period of 1954 to 1959 inclusive. The method for analysis of the data is similar to that developed by McCombie and Fry (1960). The relative efficiency of nylon and cotton gill nets in catching these species has been compared on the basis of catches of each material made in South Bay. Nylon gill net was found to be 1.3 to 3.6 times as effective as cotton, depending on the species. With the exception of yellow perch, the size composition of catches made with nylon and cotton nets does not differ significantly.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[413:SAEOEG]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The greater incidence of the giant trematode, Hirudinella marina Garcin, in skipjack tuna, Euthynnus pelamis (Linnaeus), from Hawaii than in skipjack from the Marquesas led to the hypothesis that this difference in infestation was due to area. Comparisons with respect to sex, size, and time led to the conclusion that a major source of variation could be attributed to time. The available data did not allow a conclusion on whether or not a real difference exists between the two areas.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[419:IOTGTH]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Various growth characteristics of the brook trout (Salvelinus fontinalis) were investigated by comparing the performance of three wild populations with five hatchery groups. Wild populations attained a total length at the end of 2 years of about 6 inches, which was less than half the size of the hatchery trout in the same period. Differences in weight between wild fish and hatchery fish for the same period were of the order of 10 times. Unfavorable temperature and lack of food were chief causes of slow growth of wild populations. Among the hatchery groups, inbreeding caused a decrease in growth. Randomly bred groups were very similar in size at all times up to 20 months of age. Growth rates of brook trout decline rapidly with increase in length or weight. Total length does not increase exponentially over long time periods, but growth in length more closely approximates a linear series with time. Different mathematical models were applied to growth data from the hatchery groups. The Walford-Ford concept was not applicable because the predicted ultimate sizes of the groups were unrealistic. The concept of Parker and Larkin appeared to describe adequately the growth curves obtained and was useful in measuring differences due to genetic factors. Weight-length curves were similar for fish of different strains grown under similar environmental conditions. Inbred groups had markedly different weight-length curves from those of randomly bred groups. A modification of LeCren's relative condition factor, derived from the weight-length data of the hatchery groups of brook trout, is proposed. It compares the observed weight of a fish with the weight expected to promote the optimum rate of growth of the species. Examples of its use for wild and hatchery groups are given.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[424:GOWAHS]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

The food of 159 young-of-the-year American smelt (Osmerus mordax) and 256 I-group and older fish from Saginaw Bay was examined. Thirty-one stomachs from the first group and 35 from the second were empty. Collections were made by bottom trawl and gill nets at seven localities in depths of 2 to 26 fathoms on 11 dates from July 21 to November 1, 1956. The O-group smelt contained mostly crustaceans which were present in all stomachs that contained food. Copepods were taken more frequently than cladocerans. Other food items were Rotatoria, small unidentified eggs, and algal remains. Crustaceans, insects, and fish made up nearly all of the food of the I-group and older smelt. Mean percentage frequency of occurrence and percentage of total volume were: crustaceans, 71 and 36 percent; insects, 31 and 44 percent; fish, 8 and 20 percent. Most important crustaceans were cladocerans and Mysis, the predominant insect was Hexagenia, and all fish were young Notropis or smelt. Saginaw Bay smelt compete for food with young of all associated species and with the adults of some. They did not eat commercially exploited fish other than smelt.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[439:FOTASI]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Juvenile brown bullheads (Ictalurus nebulosus) exposed to dilute solutions of zinc chloride tagged with zinc65showed an initially rapid uptake of zinc for the first several hours followed by a short period of decline. After about 12 hours the accumulation of zinc proceeded at a reduced rate. The highest concentrations in the tissues were found in viscera and gills, with lower amounts in the skin, muscle, and bone. Swallowed water does not contribute appreciably to the zinc in the gastro-intestinal tract. Nearly half of the zinc accumulated after prolonged immersion in a 6-p.p.m. solution was lost during the first day after transfer of the fish to flowing, fresh water, and only slightly more after 7 days. There was no apparent damage to the fish from exposure to zinc concentrations as high as 12 p.p.m. for 14 days, nor from the effects of the radiation from the zinc65in the solutions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[444:EOZWES]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor

摘要:

Movement of 248 marked and recaptured native smallmouth bass (Micropterus dolomieui), native rock bass (Ambloplites rupestris), and hatchery smallmouth bass released in a headwater tributary of the Little Miami River of Ohio during 1953 through 1957 is described. More than 91 percent of the native fishes of both species reported by anglers were taken within 1/2 mile of release points. Recaptures made with electric shocker and hoop nets indicated that appreciable numbers of native fish remained within limited areas of one to several pools between successive years. Considerable numbers of stocked smallmouth bass moved away from release points. A total of 35.7 percent of fish stocked in optimum habitat in 1953 and later recovered by anglers had moved distances greater than 1/2 mile. All fish stocked in submarginal habitat upstream in 1955 and later recovered by anglers moved more than 1/2 mile. Except for one recapture 6 miles upstream from the release point, all returns of stocked fish were from downstream at distances ranging up to 70 miles. The proportion of fish stocked in optimum habitat in 1953 and recaptured 11 to 50 miles downstream increased significantly from 1953 to 1954, suggesting a progressive downstream dispersal. Movement of hatchery smallmouth bass was independent of size at stocking in 1953. Rapid disappearance of the 1953-stocked fish may have resulted from higher mortality, as well as from movement.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1961)90[449:MONAHG]2.0.CO;2

出版商:Taylor & Francis Group    

年代:1961

数据来源: Taylor