Black bear (Ursus americanus) populations have expanded in Maryland since the late 1970s. Previous attempts to estimate bear numbers have been hampered by access to private land and manpower shortages. The development of hair snaring techniques, coupled with genetic fingerprinting, provides a more efficient technique than traditional mark-recapture methods to estimate black bear numbers in Western Maryland. In May-June 2000, we established 108 grids throughout occupied bear range in Garrett and western Allegany counties in western Maryland. We established hair traps in each grid for 4 week-long sampling periods. Hair samples that were snagged on barbed wires were collected after each sampling period and kept for DNA analysis. We subjected 330 hair samples to DNA analysis and identified 92 individual bears. We identified 45 males and 43 females; the gender of an additional 4 bears could not be determined. We used Program CAPTURE to estimate the bear population in western Maryland, and a total of 227 bears (95% C.I. 166-337) were estimated to occupy the 2,152 km(2) area, 10.5 bears/100 km(2) (95% C.I. 7.7-15.7). We found this technique to be more practical for estimating bear numbers in western Maryland than the traditional mark-recapture technique of running trap lines. Costs were substantially less per bear marked in 2000 than in previous attempts.

Nine polymorphic nuclear‐gene (allozyme) loci were surveyed among 491 red drum (Sciaenops ocellatus) sampled in 1988 and 1989 from nearshore localities in the northern Gulf of Mexico (Gulf) and the Atlantic coast of the southeastern United States (Atlantic). Data were combined with those from a previous study to generate a data set of 762 individuals representing 11 sample localities in the Gulf and 175 individuals representing five sample localities in the Atlantic. The combined data set included individuals from the 1986 and 1987 year classes and permitted rigorous testing of both temporal and spatial genetic heterogeneity. Average heterozygosity‐per‐locus values (estimated using 33 assumed monomorphic loci) were 0·048 (Gulf red drum) and 0·046 (Atlantic red drum). Tests of heterogeneity in allele frequencies between year classes at individual localities and across regions (Gulf and Atlantic) were non‐significant. Tests of spatial (geographic) heterogeneity indicated that red drum are weakly subdivided: genetically‐differentiated subpopulations occur in the northern Gulf and along the south‐eastern Atlantic coast. Genetic data were consistent with the hypothesis that red drum within the Gulf and along the Atlantic coast comprise singie subpopulalions. Genetic differences between Gulf and Atlantic red drum seem likeiy to stem from historical or recent interactions between dispersal and impediments to gene flow.

Bay scallops (Argopecten irradians) were discovered in 0.4- and 0.8-hectare earthen research ponds at the Texas Parks and Wildlife Department's Perry R. Bass Marine Fisheries Research Station near Palacios, Texas. These ponds were filled with unfiltered Matagorda Bay water during April 1990 and were drained on 19 September and 8 October 1990, respectively. Mean surface water temperatures and salinities were 27.1-degrees-C and 27 parts per thousand for the 0.4-hectare pond and 26.6-degrees-C and 28 parts per thousand for the 0.8-hectare pond. Mean total shell lengths of bay scallops harvested were 37 mm in the 0.4-hectare pond and 53 mm in the 0.8-hectare pond. One thousand live bay scallops were moved to the bottom of another 0.4-hectare pond for overwintering, and four 6-mm-mesh plastic cages containing 50 scallops each were suspended in the pond. By April 1991, 50% of the caged scallops had survived, but survival was 0% by May. When the pond was drained on 6 December 1991, none of the 1,000 bay scallops stocked on the bottom had survived.

Allelic variation in nine polymorphic nuclear genes and restriction-site variation in mitochondrial DNA (mtDNA) were assayed among 194 adult red drums Sciaenops ocellatus from 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 (F(ST)) 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.

Variation in mitochondrial (mt)DNA was examined among 473 red drum (Sciaenops ocellatus) sampled in 1988 and 1989 from nearshore localities in the northern Gulf of Mexico (Gulf) and the Atlantic coast of the southeastern United States (Atlantic). Data were combined with those from a previous study to generate a total of 871 individuals sampled from 11 localities in the Gulf and 5 localities in the Atlantic. Individuals assayed were from the 1986 and 1987 year-classes. A total of 118 composite mtDNA genotypes (haplotypes) was found. The percentage nucleotide sequence divergence among the 118 haplotypes ranged from 0.184 to 1.913, with a mean (±SE) of 0.878±0.004. MtDNA nucleon diversities and intrapopulational nucleotide-sequence divergence values were similar over all Gulf and Atlantic localities, and were high relative to most fish species surveyed to date. These data indicate that the perceived decline in red drum abundance appears not to have affected the genetic variability base of the species. Significant heterogeneity in the frequencies of at least four haplotypes was detected between pooled samples from the Gulf vs pooled samples from the Atlantic. No heterogeneity was found among localities from the Gulf or localities from the Atlantic. High levels of gene flow among all localities were inferred from FST values (a measure of the variance in mtDNA haplotype frequencies) and from Slatkin's qualitative and quantitative analyses. Parsimony and phenetic analyses revealed no strong evidence for phylogeographic cohesion of localities, although there was weak support for cohesion of four of five localities from the Atlantic. These data indicate that the red drum population is subdivided, with weakly differentiated subpopulations (stocks) occurring in the northern Gulf and along the Atlantic coast of southeastern USA. Spatial autocor-relation analysis and heterogeneity tests of haplotype frequencies among regions within the Gulf supported the hypothesis of increased gene flow among neighboring localities; i.e., migration of individuals within the Gulf may be inversely related to geographic distance from an estuary or bay of natal origin. Estimates of evolutionary effective female-population size indicate that the red drum subpopulations may be large.

FisheriesVolume 18, Issue 2 p. 1-40 Article Full Issue Article Volume 18, Issue 2 First published: February 1993 https://doi.org/10.1577/1548-8446-18-2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Volume18, Issue2February 1993Pages 1-40 RelatedInformation

Hatching success of spotted seatrout (Cynoscion nebulosus) eggs was examined after embryos were exposed to various temperature (20-32-degrees-C) and salinity (30-70 parts per thousand) combinations. Spotted seatrout eggs were obtained from temperature-photoperiod induced spawns. Eggs held at 26-degrees-C exhibited a higher overall hatching success than eggs held at other test temperatures when salinities exceeded 40 parts per thousand. Hatching success at salinities below 40 parts per thousand was highest at 23-degrees-C. For eggs held at 26-degrees-C, both the median lethal salinity (LC50) and the near-total lethal salinity (LC99) were higher than they were for eggs held at other test temperatures, suggesting that incubation of eggs at salinities above 30 parts per thousand may be more successful at this temperature.