摘要:

We conducted laboratory experiments in the summers of 1986 and 1987 to examine the effects ofDaphnia pulexbody size and ration level on growth of age-0 yellow perchPerca flavescens.Daphnia pulexrations were set at 25 and 40% of yellow perch dry weight. Specific growth rate tended to be higher for smaller fish and decreased with fish size at both ration levels. For the 25% ration, the highest growth rates, 0.023 to 0.024 g/d, were observed when yellow perch were fed meals ofD. pulexbetween 1.4 and 1.8 mm long; growth declined for prey sizes outside this size range. For the 40% ration, no relationship was found between body length ofD. pulexand specific growth rate; the mean specific growth rate for the 40% ration was the same as the peak rate for the 25% ration. Multiple-regression analysis was used to examine the dependence of specific growth rate of yellow perch on initial fish length, prey size, and temperature. For the 25% ration, prey size and the square of prey size were the only variables that contributed significantly (P< 0.05) to the prediction of specific growth rate. For the 40% ration, initial fish length was the only significant predictor (P< 0.05) of specific growth rate. Our results clearly indicate linkages between prey selection and growth and demonstrate the importance of prey size to growth of age-0 fish.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0001:IBPBSA>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We assessed the effect of sampling schedule on estimates of diet composition of an age-II+ cohort of largemouth bassMicropterus salmoidesin a small lake in Michigan's upper peninsula. Our objectives were to determine the effects of sampling frequency on diet variance and on estimated prey consumption by the fish population. Sampling frequency ranged from 2 to 30 samples per 45-d sampling period in summer 1987. We determined the mean variance of an index of relative importance for each of six prey types as a function of sampling frequency. Estimates of mean rates of total population food consumption (based on percent wet weights of each prey type) were calculated with a generalized bioenergetics model. Feeding on each of three prey items (i.e., zooplankton, chironomids, and trichopterans) fluctuated irregularly over time, and intervals of 3–18 d between feeding bouts were determined from the data. Sampling frequency influenced the accuracy of consumption rate estimates. A minimum sampling frequency of three times per 45 d was necessary for accurate estimates of consumption rates forChaoborusspp., for odonate naiads, and possibly for ephemeropterans. However, accurate estimates of consumption rates for zooplankton (Daphniaspp. andHolopedium gibberum), trichopterans, and chironomid pupae required more frequent sampling. Increased sampling did not decrease the intersample variance, but the error in estimates of consumption rates decreased with increased sampling frequency.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0011:EOSFOI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Little is known about the growth of male stone crabsMenippe mercenariain Florida waters. For the most part, information from laboratory and tagging data has not been analyzed thoroughly to obtain a growth curve for the species. In this paper, I synthesized existing and new methods to construct a growth curve from available data. Two components of growth were estimated in detail: the relationship between postmolt and premolt size and the relationship between intermolt period and premolt size. The first relationship was estimated from data from captive crabs by relating the sizes before and after ecdysis with a segmented regression model. The relationship between intermolt period and premolt size was estimated from data from laboratory studies in which crabs were allowed to molt once and the subsequent intermolt periods were recorded exactly. Because long exposure to laboratory conditions may affect growth rates, the molt–frequency relationship also was estimated with methods that require one of two types of information that can be gathered in a shorter period of time: the time to first molt in captivity or the proportion of crabs that molt after an observation time of arbitrary duration. The intermolt period–size relationship also was estimated from mark–recapture data from wild crabs that comprised individual records of initial size, time from release to recapture, and a binary variable that indicated whether or not each animal had molted. I then used simulation analysis to develop a growth curve for a hypothetical stone crab cohort; individual (stochastic) variability in the two components of growth was considered in the analysis. The simulation used growth increments predicted by the estimates from the laboratory data and molt frequencies predicted by the estimates from the tagging data. The results suggested that, on the average, male stone crabs are recruited into the fishery at age 2.25 years and can live to be at least 8 years old.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0020:GEFMSC>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Young and adult southern flounderParalichthys lethostigmawere subjected to decreasing temperature (1°C every 24 h) in fresh and salt water in the laboratory to study their lower temperature tolerances. Survival of adult southern flounder overwintering in fresh- and saltwater ponds was also observed. Young and adults in the laboratory were more tolerant of cold in salt water than in fresh water. Sixty percent of young fish died in fresh water, but only 10% in salt water, as temperatures declined to 2°C; all adults died in fresh water and 63% died in salt water after temperature declined to 1°C. Young died sooner than adults in fresh water, but later in salt water, during temperature decreases. Mortalities continued after water rewarmed. Some young and all adults ceased feeding when temperatures dropped below 6.4°C. In ponds, a minimum temperature of 8°C in fresh and salt water resulted in 14% mortality of adults, whereas a 5°C minimum temperature in a freshwater pond caused 100% mortality. Temperatures below about 10°C in fresh water and 7°C in salt water are judged to put southern flounder at risk of cold-induced death.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0030:LTOSFI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Arctic charSalvelinus alpinusthat were sympatric with lake troutSalvelinus namaycushin three northern Quebec lakes had faster growth rates, lower survival, and shorter longevities and yielded lower catches per unit effort than a population of Arctic char that was sympatric only with threespine sticklebacksGasterosteus aculeatus. In lakes that contained lake trout, Arctic char were not piscivorous, whereas lake trout were. In the absence of lake trout, Arctic char were piscivorous, the rate of consumption of prey fish was positively correlated with length of Arctic char and, from the age of 6 years onward, each age-class of Arctic char exhibited a bimodal length distribution. We concluded that the growth rate of a small proportion of small, slow-growing Arctic char accelerated when the fish became piscivorous. Internal parasite load was significantly greater in Arctic char when the threespine stickleback was the only other fish species in the community; parasite loads were positively correlated with length and negatively correlated with maturity of Arctic char. Beyond the juvenile stages, lake trout in northern Quebec do not appear to be at risk from the introduction of Arctic char. In Arctic char populations that exist only with threespine sticklebacks, the introduction of lake trout should reduce both the density and parasite loads of Arctic char and increase Arctic char growth rates. Lake trout should be experimentally introduced into some lakes that contain Arctic char to determine if this will increase the value of the fishery resource in those lakes.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0036:IOLTOL>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We examined Chinook salmonOncorhynchus tshawytschapopulations in the Yukon Territory for variation in age and size of spawning adults, juvenile morphology, and biochemical genetics during 1985–1987. Yukon River Chinook salmon spent at least one winter in fresh water as juveniles; about 6% of the returning adults had spent two winters in fresh water as juveniles. Males matured at younger ages and generally at smaller mean lengths at age than did females. We observed differences in juvenile morphology among populations: juveniles in habitats with faster water velocities had larger fins and thicker bodies than those in habitats with slower water velocity. We also observed genetic differentiation among populations; the greatest difference was between those populations in the Yukon River drainage and an Alsek River population. Within the Yukon River drainage, Chinook salmon from the Whitehorse fishway and Takhini River were distinct from other populations surveyed. We noted some variation in allelic frequencies between adults and juveniles sampled from the same location and found annual stability of allelic frequencies for the 16 variable loci examined.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0046:AMABGV>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We used quinacrine hydrochloride and chromomycin A3staining techniques to examine chromosome-banding polymorphisms in lake troutSalvelinus namaycushfrom seven wild populations and two hatchery stocks from the Great Lakes region. Although considerable variation in the number of bands occurred among individuals examined by both staining techniques, banding patterns were constant for all cells of a given individual. The populations were differentiated into three groups on the basis of the number of chromomycin A₃ bands: a group from the northern shores of Lakes Superior and Huron and the inland lakes north of Lake Superior; a group from the southern shore of Lake Superior; and a group that comprised one wild population and one hatchery stock from Wyoming that were both originally transplanted from a Lake Michigan stock. Each population within these three groups had a unique distribution of chromomycin A3bands on specific chromosomes. Results for a given population were consistent when sampled for two consecutive years. The populations were very similar in the frequency of Q-band (quinacrine-stained) variants except for one polymorphism found in the Michipicoten Island, Ontario, population and another polymorphism, which was rare in the Seneca Lake, New York, population. The cytogenetic results were compared with allozyme results from the same populations. The populations were similarly differentiated by both the allozyme and cytogenetic data.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0064:PDICPI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

Juvenile steelheadOncorhynchus mykiss(formerlySalmo gairdneri) that were homozygous for two alternative alleles at the dipeptidase locus were released into stream sections of the Palouse River drainage, Idaho, to test the neutrality of the alleles with respect to survival or growth. After 4 months in the stream sections, juveniles homozygous for either of the two major alleles did not differ in mortality, length, or weight.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0074:SAGOSS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

We used radiolabeled DNA of bacteriophage M13 to probe Southern blots of restriction enzyme-digested genomic DNA of rainbow troutOncorhynchus mykiss. We found a high level of polymorphism for restriction fragment lengths by analysis of DNA from a single-pair mating between individuals of an outbred strain of this species. Each of the offspring of this mating exhibited a unique banding pattern. Similar polymorphic patterns were found in chum salmonO. keta, coho salmonO. kisutch, and Atlantic salmonSalmo salar. This technique shows great promise for demographic analysis and unabiguous genetic tagging of individual fish.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0078:DFIRTD>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor

摘要:

The postlarva (larval stage IV) of the American lobsterHomarus americanusis very different in form and behavior from earlier larval stages. Recruitment to the benthic population occurs during the postlarval period. Field observations in Rhode Island nearshore waters showed most postlarvae to be swimming in northerly to easterly directions. Average swimming speed in the field was 18 cm/s. Swimming speeds in the laboratory averaged 13.2 cm/s for field-captured and 10.7 cm/s for hatchery-reared postlarvae. Sustained directional swimming could have a considerable effect on postlarval distribution, and thus on patterns of recruitment to benthic populations.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1989)118<0082:SADOSB>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1989

数据来源: Taylor