摘要:

The value of the classical blood variables (erythrocyte count, hemoglobin, hematocrit) and their derivatives (mean erythrocytic volume, mean erythrocytic hemoglobin, mean erythrocytic hemoglobin content) as indicators of fish health is assessed from the viewpoints of measurement precision and the distortion of information content by sampling procedures and storage conditions. So also is the concept of hematological norms and their validity in relation to natural fish populations. Few of the assumptions underlying the use of hematological data for health assessment purposes can be regarded as other than marginally valid. Of the primary indices, erythrocyte numbers and hemoglobin, if corrected for nonviable cells and accompanied by information on isomorph abundances, appear to be the more useful indicators of O2carrying capacity. Hematocrit and hematocrit-dependent Wintrobe indices emerge as suspect. Higher-order indices describing red cell anisocytosis and yielding an “erythron profile” provide additional and more sensitive means for assessing blood status.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0879:RATCHV>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We examined fish distribution and abundance in erosional habitat units in South Fork Roanoke River, Virginia, following a fish kill by using a reachwide sampling approach for 3 species and a representative-reach sampling approach for 10 species. Qualitative (presence–absence) and quantitative (relative abundance) estimates of distribution and abundance provided consistent measures of fish recovery for 2 of 3 species at the reachwide scale and 8 of 10 species at the representative-reach scale. Combining results across scales and estimator types showed that distributions and abundances of 5 of 11 species in the Teach affected by the kill were similar to those observed in unaffected upstream and downstream reaches 8–11 months following the perturbation. Differences in distribution and abundance between the affected Teach and unaffected reaches indicate that 4 of 11 species had not fully recovered during the same time period; results were equivocal for 2 other species. We attribute differences in recovery rates between these two groups to differences in parental investment in offspring. Species exhibiting rapid recovery either engage in extensive spawning site preparation or guard the spawning site following egg deposition and fertilization; species that had not recovered in the year following the kill show limited spawning site preparation and do not guard the spawning site.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0895:FISFRF>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We examined scales of wild striped bassMorone saxatilisto determine whether scale morphology differs systematically among three Atlantic coast stocks and thus could be used for stock discrimination. Morphological variables investigated included Fourier coefficients, ratio shape descriptors (circularity, rectangularity), truss networks, perimeter landmarks, width and spacing of the first 10 circuli, and angular measurements of the scale interior. A variable was considered potentially useful for stock identification if it could be corrected for size variation, did not show year-class effects, and showed significant stock-of-origin effects in a multivariate analysis of variance. Fourier shape descriptors, rectangularity, and angular measurements of the scale interior showed the greatest potential for discrimination of Atlantic striped bass stocks. In addition, circulus patterns showed some usefulness. The remainder of the morphometric variables appeared less useful either because of failure to meet statistical assumptions for size correction (truss networks and perimeter landmarks), significant year-class effects (circulus patterns), or a paucity of significant stock-of-origin effects (truss networks, circulus patterns, circularity). Relatively few strong correlations (r≥ 0.70) were evident among morphological variables of different types.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0908:SSVISM>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

We used scale morphology to discriminate wild Atlantic striped bassMorone saxatilisfrom the Hudson River, Chesapeake Bay, and the Roanoke River. Morphological features used were perimeter shape as described by Fourier analysis, rectangularity, width and spacing of the first 10 circuli, and patterns of partitioning of the scale interior. Performance of discriminant functions was evaluated by examining the percent correct classification of known-origin samples (precision) and the bias in resulting stock composition estimates (accuracy). Correct classification rates ranged from 57% to 84%, varying with the number of stocks and year-classes included. Lowest rates were for three stocks with multiple year-classes; highest rates were for single-year-class analysis of the most geographically distant stocks. Despite some poor classification rates, bias and variance in stock composition estimates were low in four of five discrimination problems, suggesting that corrections based on the classification matrix could be applied with some confidence to unknown samples. However, we used bootstrapping to evaluate bias stability; further evaluation of independent samples would be useful.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0919:UOSMFD>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The Tustumena Lake drainage in southcentral Alaska is glacially turbid and geologically young (<2,000 years old). Previous field studies identified at least three subpopulations of sockeye salmonOncorhynchus nerkaat Tustumena Lake, based on the distribution and timing of spawners. The subpopulations included early-run salmon that spawned in six clearwater tributaries of the lake (mid August), lake shoreline spawners (late August), and late-run fish that spawned in the lake's outlet, the Kasilof River (late September). Our objective was to determine the degree of genetic differentiation among these subpopulations based on restriction enzyme analyses of the cytochromebgene of mitochondrial DNA and analyses of four polymorphic allozyme loci. Mitochondrial DNA haplotype frequencies for outlet-spawning sockeye salmon differed significantly from those of all other subpopulations. The most common (36%) haplotype in the outlet subpopulation did not occur elsewhere, thus suggesting little or no gene flow between outlet spawners and other spatially close subpopulations at Tustumena Lake. Allele frequencies at two allozyme loci also indicated a degree of differentiation of the outlet subpopulation from the shoreline and tributary subpopulations. Allele frequencies for three tributary subpopulations were temporally stable over approximately 20 years (based on a comparison to previously published results) despite initiation of a hatchery program in two of the tributaries during the intervening period. Collectively, our results are consistent with the hypothesis that significant genetic differentiation has occurred within the Tustumena Lake drainage since deglaciation approximately 2,000 years ago.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0926:GDOSSS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Introductions of black bassesMicropterusspp. beyond their native ranges have led to hybridization within the genus. In the southeastern USA, the potential for hybridization appears high because species introductions have been common in reservoirs. We determined the extent of hybridization between smallmouth bassM. dolomieuand spotted bassM. punctulatusin reservoirs in which introductions of either species into the native range of the other species had occurred. Three allozyme loci were used to distinguish the two species and their hybrids. Significant hybridization occurred in two of three reservoirs where introductions had been reported. In Lake Chatuge, Georgia–North Carolina, where the Alabama subspecies of spotted bassM. p. henshalliwas introduced, 77 of 276 fish had hybrid genotypes, and only 2 fish had genotypes of the native smallmouth bass. In Thurlow Reservoir, Alabama, where smallmouth bass were introduced and Alabama spotted bass were native, 3 of 17 fish had hybrid genotypes. Only I fish with a possible hybrid genotype was identified in two reservoirs containing native smallmouth bass and northern spotted bassM. p. punctulatus.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0939:HBISBA>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

The intermediate filaments (IFs) are a multigenic family of 10-nm cytoskeletal polypeptides that have been partially classified according to their cell-specific expression patterns in mammals. Since the IFs have been highly conserved during vertebrate evolution, the objective of the present study was to evaluate the immunological cross-reactivity and tissue distribution patterns of IF types I, II, and III in the common carpCyprinus carpio. A panel of six heterologous antibodies were evaluated with a streptavidin–biotin–peroxidase complex detection system. The monoclonal antibody AE3, specific for human cytokeratins 1–8 (type II IFs), stained a wide variety of epithelial and nonepithelial tissues. Staining with the AEI monoclonal antibody, specific for human cytokeratins 10, 14–16, and 19 (type 1 IFs), resulted in similar, although generally less intense, staining of all tissues relative to the AE3 antibody. However, the AE1 antibody stained myocardial and skeletal muscle fibers in contrast to the pattern achieved with the AE3 antibody. The polyclonal antibody 68–121, specific for mammalian vimentin (type III IFs), stained a variety of nonepithelial tissues that included various connective tissue cells (fibroblasts, muscle cells, and chondrocytes), glial cells, neurons, lymphohematopoietic cells, and chromatophores. The 68–121 antibody also resulted in the restricted staining of simple and stratified epithelia. In contrast, staining with the antimammalian vimentin monoclonal antibody V9 was restricted to the cells and fibers of the retinal ganglion layer, basal lamina of the integument, lens epithelium, meninx, and choroid plexus epithelium, whereas the antimammalian vimentin monoclonal antibody Vim 3B4 did not stain. Staining with the monoclonal antibody 33, specific for mammalian desmin (type III IFs), was negative except for an intense staining pattern of the ocular lens epithelium. The localization of vimentin and the cytokeratins in various epithelial and nonepithelial tissues of the common carp indicates that IF expression in teleosts is fundamentally different than that in mammals relative to cell type specificity and expression.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0948:ICROTI>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

SplittailPogonichthys macrolepidotus, an endemic cyprinid of the Sacramento–San Joaquin estuary, has been proposed for listing as threatened under the U.S. Endangered Species Act. Almost continuous low outflow conditions in the estuary from 1987 to 1994 led to reduced abundance of young splittails, but adult abundance did not decline consistently except in the downstream portion of the species' range. This range had decreased primarily as a result of historical levee and dam construction but did not appear to have changed substantially in the past 20 years. The distribution of young splittails appears to be relatively plastic on an interannual basis. Evidence of the resilience of the species was seen when high freshwater outflows in extremely wet years (such as 1982, 1983, 1986, and 1995) resulted in high numbers of young splittails. Splittail year-class strength was positively related to freshwater outflow during the spawning season. High outflow inundates the floodplain, which provides spawning, rearing, and foraging habitat. The relatively long life span, high reproductive capacity, and broad environmental tolerances of splittails are contrasted with delta smeltHypomesus transpacificusand longfin smeltSpirinchus thaleichthys, other native species of special concern in the system.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0961:ROSITS>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

Current water chemistry and fish communities in 70 Pennsylvania streams were compared with historical records to determine whether fish species richness had declined and, if so, the possible role of acidification. First-, second-, and third-order streams were selected, and stream sites sampled during the 1961–1971 survey were resampled during May and June 1994 in the Appalachian Plateaus province and during June 1995 in the Valley and Ridge province. Streamflow was measured and a habitat assessment was completed at each site. Dominant bedrock types influencing the stream sampling site were determined for the Appalachian Plateaus streams. Episodic water chemistry was collected for 39 of the 50 Appalachian Plateaus streams and 14 of the 20 Valley and Ridge streams during the winter and spring of 1996. Thirty-eight (76%) streams of the Appalachian Plateaus province and 13 (65%) streams in the Valley and Ridge province had a loss of fish species since the 1961–1971 sampling period. Habitat scores were not related to losses of fish species. Of the 53 streams sampled during runoff episodes 22 (42%) increased in total dissolved aluminum by more than 50 μg/L, and 31 (58%) streams decreased in pH by 0.5 units or more. Minnows (Cyprinidae) and darters (Percidae) are sensitive to acidity and were the species most often lost. Streams draining watersheds of the Appalachian Plateaus province dominated by Pottsville bedrock had more acidic water quality during base flow and storm flow sampling periods than streams dominated by Pocono bedrock. The results of this study indicate that many Pennsylvania streams have undergone an alarming reduction in fish diversity during the past 25–34 years. In many of these streams the loss in fish diversity may be attributed to episodic acidification.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0977:EAACIF>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor

摘要:

To improve survival of stocked fish, field and laboratory tests were conducted to evaluate the survival and stress response of rainbow troutOncorhynchus mykissafter exposure to waters with various combinations of high temperature and high pH. For each of four laboratory experiments, fish were transported by truck for 90 min. Fish were then put in replicate tanks for each of four treatments per experiment: (A) controls, pH 7.8, temperature 14°C; (B) control pH and high temperatures (19°C, experiment 2; 22°C, experiments 1, and 4) or low temperatures (7–9°C, experiment 3); (C) control temperature and fluctuating high pH (8.4–9.6); and (D) a combination of high or low temperature with high pH. Blood was sampled at 1.5, 3, 6, and 24 h after stocking. At 1.5 h, plasma glucose, chloride, and cortisol levels in all fish indicated a stress response from hauling and stocking. High temperatures (19°C, 22°C) alone did not produce additional changes in the stress indicators. However, high pH induced significant additional rises in glucose and cortisol levels in both high- and control-temperature tanks. At low temperatures the stress response was delayed; low temperature (7–9°C) alone produced significant elevations in glucose and cortisol compared with controls at 24 h, suggesting that cold water acted as a stressor, albeit with a delayed reaction. Cold water combined with high pH induced higher cortisol concentrations after 24 h than high pH alone. Warm temperatures combined with high pH did not synergistically affect the stress response, but they significantly increased mortality at 22°C. Mortality in the field occurred at pH levels greater than 9.3–9.4 and temperatures of 19.9–22.8°C. Diel fluctuations in pH measured in four reservoirs ranged 0.1–0.5 units. Laboratory and field tests indicated that pH values greater than 9.4 resulted in mortality, especially at higher temperatures. There was also a significant stress response to pH 9.0 or greater.

ISSN:0002-8487    

DOI:10.1577/1548-8659(1997)126<0985:CEOTAH>2.3.CO;2

出版商:Taylor & Francis Group    

年代:1997

数据来源: Taylor