摘要:

Analyses of 36 fish and squid species sampled in standardized bottom-trawl surveys of the northwest Atlantic Ocean (1967–present) revealed a continuum of distributional responses associated with seasonal and annual variations in water temperature. Mean and maximum latitude of occurrence of the species were regressed against average surface- and bottom-water temperatures and indices of relative abundance from spring and autumn trawl surveys. Significant (P≤ 0.05) regression models were fitted for 17 of 36 species from spring and fall survey data. Variations in water temperature were significant in explaining changes in mean latitude of occurrence for 12 of 36 species in both seasons. Maximum latitude distribution responses to interannual differences in water temperatures occurred for pelagic species, including Atlantic mackerelScomber scombrusand Atlantic herringClupea harengus. Weighted mean catches of these species shifted poleward by 0.5–0.8 degree of latitude for each 1°C increase in average water temperature, Statistically significant poleward range extensions, associated with warmer water temperatures, occurred for five species in spring surveys and four in fall surveys. Different responses among species to changing thermal regimes of the northwest Atlantic Shelf have important potential consequences for trophic dynamics and fisheries yields of the ecosystem. Species found to be sensitive in distribution to temperature change include primary prey species of some predators that show limited seasonal or annual changes in distribution. Changes in distributional overlaps between some predators and prey therefore are a likely result of shelf warming associated with climate change.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0647:CCAMFD>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Allelic variation in nine polymorphic nuclear genes and restriction-site variation in mitochondrial DNA (mtDNA) were assayed among 194 adult red drumsSciaenops ocellatusfrom the northern Gulf of Mexico, Data were combined with those of previous studies in order to examine patterns of temporal genetic variation among four year-classes (1984–1987) and individuals spawned prior to 1984, Tests of heterogeneity among year-classes in both nuclear gene allele frequencies and mtDNA haplotype frequencies were nonsignificant, and estimated fixation (FST) values were 0.009 (nuclear genes) and 0.002 (mtDNA). Estimates of Nei's unbiased genetic distance (nuclear genes) and nucleotide sequence divergence (mtDNA) among year-classes also indicated the absence of temporal genetic differentiation, Estimates of average heterozygosity (nuclear genes) and nucleon and nucleotide sequence diversities (mtDNA) indicated that levels of genome-wide variation within and among year-classes of red drum are equivalent to (or higher than) those in most marine fish species examined to date. Estimates of effective female population size suggest that the total size of the female red drum population in the northern Gulf of Mexico could be 10 million individuals.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0659:TSONGA>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Restriction fragment length polymorphism (RFLP) analysis of mitochondrial DNA (mtDNA) was used to characterize stocks of striped bassMorone saxatilisand to estimate their relative contributions during the fall of 1989 to the mixed coastal fishery at eastern Long Island, New York. Mitochondrial DNA was obtained from reference samples of striped bass collected during the spring of 1989 from the Hudson River, New York, and four spawning areas of the Chesapeake Bay (Choptank, Rappahannock, and Potomac rivers and the upper Chesapeake Bay). Five mtDNA major length genotypes were detected in these fish, and significant differences in their frequencies were observed between the Hudson River and Chesapeake Bay samples. An mtDNA minor length genotype found in some fish (13%) from the Chesapeake Bay and absent from all Hudson River samples provided a second discriminatory character. By using a constrained generalized least squares approach, we estimated that the Hudson River and Chesapeake Bay stocks contributed 73% (95% confidence interval 50–87%) and 27% (95% confidence interval 13–51 %) respectively, of the mixed fishery sample. The probability of the Hudson River contribution exceeding the Chesapeake Bay contribution in this sample was more than 95%. These results suggest that the Hudson River contribution to the mixed coastal fishery was greater in 1989 than reported in earlier studies. We also found no differences in mtDNA major length genotype frequencies among as many as 11 year-classes within the Hudson River, Chesapeake Bay, or Roanoke River spawning systems. These results indicate that mtDNA RFLP genotypes in these striped bass stocks are temporally stable within a fisheries context. An advantage to mtDNA analysis over phenotypic approaches is that, because mtDNA genotype frequencies are not subject to environmentally induced variation, efforts subsequent to an initial survey can focus on characterizing the mixed coastal fishery.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0669:UOMDPT>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We investigated the amount and pattern of genetic variation expressed by the barramundi perchLates calcariferthroughout Queensland to identify and characterize population subdivision. Fourteen loci known to be variable in this species were screened in 2,912 fish from 24 different areas in Queensland by means of horizontal starch gel and slab polyacrylamide gel electrophoresis. Eleven loci were used in the statistical analysis of stock structure, Seven of these loci (EST-2*,ESTD*,mIDHP*,sIDHP*,LDH-C*,PGDH*, andPROT*) were polymorphic at the 0.95 level (frequency of the most common allele was 0.95 or less) in at least one collection; four loci (IDDH*,FH*,sMDH-A*, andPGM*) were polymorphic at the 0.99 level. Genotype proportions at these 11 loci exhibited close agreement with Hardy–Weinberg expectations. An overall chi-square test of allele frequencies revealed substantial genetic heterogeneity among the 24 collections. Successive rounds of contingency chi-square tests involving geographically adjacent pairs of collections were conducted to identify individual genetic stocks and to locate interstock boundaries. Seven genetically distinct stocks of Queensland barramundi perch were identified by this process. Similar tests demonstrated that Queensland stocks were distinct from neighboring stocks in the Northern Territory of Australia and in Papua New Guinea. The considerable genetic differentiation of barramundi stocks demonstrated by this analysis has important implications for fishery management, aquaculture, and conservation of this species.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0685:ECOMGS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Sustainable swimming speeds, defined as speeds maintained in 1-h tests, were measured for three size-classes (6–6.9 mm, 7–7.9 mm, and 8–8.9 mm) of larval striped bassMorone saxatilis. Probit analysis was used to find failure velocities (the water velocity at which 50% of the larvae fail to sustain swimming speed) and confidence intervals for each size-class. Failure velocities were 1.7, 2.1, and 3.0 cm/s for 6–6.9-mm, 7–7.9-mm, and 8–8.9-mm larvae, respectively. There was a general improvement in swimming performance with age, There was no difference in swimming ability due to the presence or absence of an inflated swim bladder. Striped bass larvae approached the upper range of swimming speeds recorded for other larval fishes and reached speeds of 3–4 body lengths/s, which are comparable to adult fish speeds. The relatively high speeds attained by striped bass larvae may improve feeding success rates by increasing the volume of water larvae are capable of searching for food.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0702:SSSOSB>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

We examined entrainment of ichthyoplankton associated with hydropower generation in 1988 and 1989 at the Pensacola Dam hydroelectric facility on Grand Lake in northeastern Oklahoma. To provide a basis for evaluating the effects of entrainment on the fish assemblage, we also estimated the total abundance of fish eggs and larvae in the top 10 m of the reservoir. Entrainment totaled about 10 million larval fish in 1988 and almost 100 million in 1989. Only nine taxa of larval fish were entrained during the study. Entrained eggs were almost exclusively those of freshwater drumAplodinotus grunniens. Although estimates of entrainment were large, they were generally low compared with the estimates of total abundance of ichthyoplankton in Grand Lake.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0709:EOLBAW>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

The gastric evacuation rates of brown troutSalmo trutta(0.9–1.6 kg) feeding on fingerling rainbow troutOncorhynchus mykiss(3.5–7.6 g) were measured in the laboratory at five temperatures (4.5, 9.0, 14.0, 19.0, and 22.5°C). Instantaneous gut evacuation rates (Re) increased exponentially with temperature (T): Re= 0.053·e0.073·T,r2= 0.98; they varyied from 7%·h–1at 4.5°C to 29%·h–1at 22.5°C. Linear regressions described the relationship between time and qualitative measures of fish digestion, thus allowing investigators to determine how long an ingested fish would be identifiable at different temperatures. An analysis of published evacuation rates (N= 121) of 22 fish species indicated that both temperature and prey size (PS, g wet weight) significantly affected digestion rate (Re): Re= 0.049·e0.072·T– 0.060 loge(PS)R2= 0.52. Predator size did not significantly affect rates of evacuation.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0717:AEMOGE>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Bioenergetics models define the mass balance relationship between the amount of food consumed by a fish and the fish's growth (somatic and reproductive), the energy it expends, and the waste it produces. The field of bioenergetics modeling has evolved rapidly from single-species studies of growth and food consumption to studies of food web dynamics, nutrient cycling, and predator–prey interactions at various spatial and temporal scales and to assessments of production potential at the ecosystem level. Much of this advance has been fostered by question-driven applications of bioenergetics models and by integration of bioenergetics approaches with new technologies and ecological theory. The accompanying papers in this issue exemplify such diverse and innovative applications. In future applications of these models to fish ecology and management, more attention must be focused on differences between model formulations, on model parameterization, and on assumptions used in model simulations and applications.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0731:IAWBMF>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

Elaborations of the mass-balance equation that partitions energy of consumed food into its various physiological fates have flourished in the past 15 years. These bioenergetics models have been converted to powerful simulation tools and used in fisheries science, most often for predicting consumption by predators or for projecting fish growth as a function of temperature and prey availability. New uses of bioenergetics models are proliferating and range from predictions of larval survival to analysis of ecosystem function. Companion technologies such as hydroacoustics and physiological telemetry promise to further broaden the spectrum of potential applications. However, the data demands and uncertain accuracy of multiparameter models may constrain their ability to address routine fish management questions. Field measures of consumption or growth failed to corroborate bioenergetics estimates consistently (differences of at least 50%) in four of six published tests. Poor agreement could be due to inaccuracies in field measures, bioenergetics estimates, or both. Errors in bioenergetics estimates will accrue when input values for internal parameters and external variables are deficient; problems can result from unknown activity costs, extrapolation of weight-dependent power functions, unjustified borrowing of physiological values from other species, and use of nonrepresentative field data. Remediation of these deficiencies will require a major concerted research effort and extensive field corroboration. Simpler individual and production-based models show promise for predicting long-term consumption or growth but also require substantiation of input parameters and more corroboration. In the interim, I suggest that bioenergetics models will remain better suited for making relative comparisons than for making precise quantitative predictions.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0736:BMTGPO>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor

摘要:

A bioenergetics model of fish growth was used to estimate phosphorus (P) cycling by the population of Lake Michigan alewivesAlosa pseudoharengusin the mid-1970s. The mean annual standing stock of alewives during the mid-1970s contained 1,500 tonnes of phosphorus, representing a substantial pool of particulate phosphorus unavailable to algae, An estimated 12,000 tonnes of phosphorus were egested and excreted annually by the Lake Michigan alewife population. Over half of the alewife-regenerated phosphorus was produced by larvae and age-0 alewives, which inhabit the nearshore epilimnion during summer. Seasonal aggregations of alewives – the dominant component of the Lake Michigan fish community during the mid-1970s – could have served as an important medium of phosphorus regeneration in comparison with more traditionally reported vehicles such as zooplankton. Expressed volumetrically, alewives regenerated 0.22 μg P·L–1·d–1during August, which is comparable to phosphorus regeneration rates previously estimated for Lake Michigan zooplankton. Use of a bioenergetics model provided a means to demonstrate that alewives played a substantial role in Lake Michigan phosphorus regeneration during the mid1970s.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1993)122<0749:PRBLMA>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1993

数据来源: Taylor