Mark R. Collins

Genetic structure of Atlantic sturgeon populations based on mitochondrial DNA control region sequences

Abstract The Atlantic sturgeon Acipenser oxyrinchus oxyrinchus has a latitudinally broad distribution along the east coast of North America, with extant populations occurring from the Saint Lawrence River to rivers in southern Georgia. This species once supported intensive caviar-based fisheries that resulted in overharvest and sharply reduced population abundances; presently, directed commercial fishing for Atlantic sturgeon is banned in U.S. waters. We sequenced a 203-base-pair section of the mitochondrial DNA (mtDNA) control region of 322 Atlantic sturgeon specimens from 11 river systems across their range to elucidate their stock structure. We found a pronounced latitudinal cline in the number of composite mtDNA haplotypes and in haplotypic diversity, which increased from north to south, from previously glaciated and subsequently recolonized systems to the portion of their range unglaciated during the Pleistocene. The observed number of haplotypes per population ranged from 1 haplotype in each of the ...

Habitat Utilization and Biological Characteristics of Adult Atlantic Sturgeon in Two South Carolina Rivers

Abstract Thirty-nine adult Atlantic sturgeon Acipenser oxyrinchus oxyrinchus (136–234 cm total length) were caught in gill nets fished at historical sturgeon-fishing locations in the Combahee and Edisto rivers (South Carolina) during spring and fall 1998. All fish were tagged (with passive integrated transponders and darts), and radio and acoustic transmitters were surgically implanted in 29 fish. When possible, gonad biopsies were taken for sex and maturity-stage determination. Locations of telemetered fish were determined several times per week from airplanes (radio) and boats (radio and acoustic). Nominal ages, based on microscopic examination of pectoral spine cross-sections, ranged from 7 to 20 years. Of the 28 fish for which sex was definitively ascertained, 21 (aged 7–15) were male and 7 (aged 15–20) were female. All fish moved out of the rivers during the period extending from October to November. Twelve fish returned the following spring (most in March), and many took up residence at the same sit...

Swim Bladder Deflation in Black Sea Bass and Vermilion Snapper: Potential for Increasing Postrelease Survival

Abstract Although some anglers regularly deflate swim bladders of demersal fishes being released, it is not known whether this practice actually increases postrelease survival of reef fishes. Benefits of deflating the swim bladder of black sea bass Centropristis striata and vermilion snapper Rhomboplites aurorubens before release were evaluated; survival of fishes deflated with one of two tools was compared to survival of nondeflated controls. Capture depths were 20–22 m, 29–35 m, and 43–55 m. Fishes were deflated with a 16-gauge hypodermic needle (99 black sea bass, 64 vermilion snapper) or with a Sea Grant tool consisting of a sharpened stainless steel canula (119 black sea bass, 64 vermilion snapper). Deflated fish were held in cages and observed in situ for 24 h. Controls (108 black sea bass, 89 vermilion snapper) were first segregated in a live well and then held in situ for 24 h in cages. Deflation, especially with the hypodermic needle, provided very significant reductions in mortality of black sea...

Sturgeon Fin Ray Removal is Nondeleterious

Abstract Marginal pectoral fin rays were removed from cultured shortnose sturgeon Acipenser brevirostrum and wild Atlantic sturgeon A. oxyrinchus oxyrinchus to evaluate the impact on growth and survival. Shortnose sturgeon were examined after 98 d and Atlantic sturgeon were examined after 183 d. There were no significant differences between control (no fin ray removed) and treatment fish in growth (weight or length) or survival of either species, and all wounds had healed. Removal of pectoral fin rays for age analyses had no apparent deleterious effects on these sturgeon species.

Retention of Oxytetracycline-Induced Marks on Sagittae of Red Drum

Abstract In a pilot-scale stocking program, juvenile red drum Sciaenops ocellatus were immersed for 4 h in a 500-mg/L active solution of oxytetracycline hydrochloride (OTC) and 15-g/L salinity water at a temperature of 26.2°C to mark the otoliths before release. A portion of the treated fish was retained to determine marking success and mark retention. Retained fish were held in outdoor tanks supplied with flow-through estuarine water from Charleston Harbor, South Carolina, and fed commercial trout diets daily. During a 4.4-year period, subsamples of treated fish were regularly sacrificed, and their sagittae were removed, sectioned, and examined under an epifluorescent microscope to validate presence of a mark. Because of interference from autofluorescence, OTC marks were not detectable on sagittae from fish sampled 56 d after immersion (N = 4). However, a mark was visible on 100% of sagittae examined from treated fish sampled on nine occasions from 73 to 1,618 d after immersion (N = 46). In a blind test,...

Habitat Use and Movements of Juvenile Shortnose Sturgeon in the Savannah River, Georgia-South Carolina

Abstract During 1999-2000, 28 juvenile (<56 cm total length) shortnose sturgeon Acipenser brevirostrum were captured in the lower Savannah River, Georgia−South Carolina, and acoustic transmitters were implanted in or attached to 15 of them. The juveniles were located only between river kilometers (rkm; measured from the mouth of the river) 31.2 and 47.5, in salinities of 0.1‰ to (briefly at high tide) 17.6‰, and at depths of 2.1-13.4 m. The fish used two small areas very intensively. When water temperatures were above 22°C, the fish moved upriver; they aggregated particularly at rkm 47.5 when temperatures were greatest, and the average salinity at this location was 0.1‰. When water temperatures were below 22°C, the fish moved downriver into Savannah Harbor and used approximately 2-km segments of the Front and Middle rivers just upriver of their confluence at rkm 31.5. Here they encountered higher salinities (mean, 5.4‰) than during warm months. During the period of lowest water temperatures, the fish aggr...

Effectiveness of Six Methods for Marking Juvenile Shortnose Sturgeons

Abstract The shortnose sturgeon (Acipenser brevirostrum), an endangered species, was the subject of a stock enhancement trial. Some standard methods of marking individuals for later identification as cultured fish appeared to be ineffective. Therefore, six marking techniques were tested on several groups of cultured juvenile shortnose sturgeons (mean total lengths, 115–500 mm) during 1989–1990. The methods evaluated were: (1) coded wire tags implanted in the snout cartilage, (2) dorsally implanted T-bar tags, (3) dorsally implanted dart tags, (4) abdominally implanted T-anchor tags, (5) abdominally implanted disk anchor tags, and (6) barbel clipping. After 2 years, 100% of the clipped barbels were partially or completely regenerated. Retention of coded wire tags was highly variable (70–100%) in trials of 62–410 d. Retention was greater for the T-anchor tag (92%) than for any of the other tag types. However, in most cases, tag incisions and wounds persisted for the duration of the experiment.

Management Briefs: Distributions of Shortnose and Atlantic Sturgeons in South Carolina

Abstract Records of 662 Atlantic Acipenser oxyrinchus oxyrinchus, 1,024 shortnose A. brevirostrum, and 59 unknown sturgeons in South Carolina were acquired from various sources. Shortnose sturgeon were 25.6–129.0 cm total length (TL) and were reported from 10 rivers, 3 bays or sounds, 2 reservoirs, and the Atlantic Ocean. Atlantic sturgeon were 10.1–245.0 cm TL and were reported from 11 rivers, 3 bays or sounds, 1 reservoir, and the Atlantic Ocean. All ocean records of shortnose sturgeon were from near shore, primarily in the vicinity of river plumes, while juvenile Atlantic sturgeon were recorded in depths up to 40 m. During the spawning season, adult shortnose sturgeon were recorded at upriver locations in the Savannah, Cooper, Waccamaw, Santee, and Congaree rivers. The Congaree River records add credence to the hypothesis that there is a landlocked population in the Santee–Cooper Lake system (Lake Moultrie, Lake Marion, and the Congaree River). There is also apparently a population in the ACE Basin (As...

Temporal and Spatial Differences in Life History Parameters of Black Sea Bass in the Southeastern United States

Abstract During 1978–1998, 80,558 black sea bass Centropristis striata were caught with blackfish and chevron traps off eastern Florida, Georgia, South Carolina, and North Carolina at depths ranging from 9 to 55 m. Black sea bass were found to live for at least 10 years, but most were ages 1–5. There were latitudinal differences in the size at age, significantly larger size at age occurring in the southern segment (31°20′N to 32°40′N) than in the northern segment (32°41′N to 34°00′N). Males were found in all size-classes and age-classes and were most frequently encountered at sizes greater than 220 mm standard length (SL) and greater than age 4 in the southern segment and at sizes greater than 240 mm SL and greater than age 5 in the northern segment. Sexual transition and maturity of females occurred at smaller sizes and younger ages in the southern segment than in the northern segment. Probit analysis indicated that between 1978–1982 and 1987–1998 the size at 50% maturity (L 50) for females fell from 137...

Year-Class Component, Growth, and Movement of Juvenile Red Drum Stocked Seasonally in a South Carolina Estuary

Abstract Red drum Sciaenops ocellatus have been classified by the Atlantic States Marine Fisheries Commission as overfished in the Atlantic off the southeastern USA. A study was conducted to evaluate stocking hatchery-reared fish as a management tool to increase abundance of red drum in South Carolina estuaries. Multiple groups of juveniles, at mean sizes of 22–56 mm total length, were released after being marked by immersion in 15 g/L salinity brackish water containing oxytetracycline HCl (500 mg/L active). Fish were released into a small (535-ha) part of the available nursery habitat (total = 25,000 ha) in the Port Royal Sound estuary each fall and spring from fall 1995 through spring 1997. During fall 1995 and spring 1996, 347,000 fish were stocked; during fall 1996 and spring 1997, the number was 1,228,000. Movement of hatchery fish from the release site was monitored for at least 2 years after release. Overall, hatchery fish accounted for 19.0% of the 627 fish (age 0 to age 2) captured from the 1995 ...