Charles A. Wenner

Estimates of Fishing and Natural Mortality for Subadult Red Drum in South Carolina Waters

Abstract Subadult red drum Sciaenops ocellatus were sampled in Charleston, South Carolina, from 1991 to 1999. Tagged individuals were subjected to either live recapture and release by research biologists or harvest and subsequent tag recovery by recreational anglers. Tag recovery data aggregated into 4-month periods were analyzed using Brownie models that were parameterized in terms of fishing effort and instantaneous rates of fishing (F) and natural (M) mortality. Within-year estimates of fishing effort were calculated from the U.S. National Marine Fisheries Services Marine Recreational Fisheries Statistics Survey and adjusted to reflect a 4-month harvesting period. The level of annual effort appeared stable over all years and was held constant for all analyses; however, the within-year seasonal pattern of fishing effort varied substantially. Estimates of F and M depended heavily on the values used for the tag-reporting rate (λ) and the tag-retention and immediate survival rate (φ). For age-1 fish, valu...

Stock identification of the sciaenid fish Micropogonias undulatus in the western North Atlantic Ocean using parasites as biological tags

Proper fisheries management of the Atlantic croaker Micropogonias undulatus is necessary in the United States due to the commercial and recreational importance of this fish species. Croaker stock structure in the western North Atlantic has been investigated in the past by various authors, with inconclusive results. In this study, macroparasites were used as biological tags to identify putative croaker stocks in the area between New Jersey and Florida, which encompasses the Mid Atlantic Bight and the South Atlantic Bight separated at Cape Hatteras, North Carolina. The macroparasite community of the fish was identified, showing the presence of 30 species in four phyla, of which several were new host records, and one species, a monogenean, was new to science. A canonical correspondence analysis was applied to determine the variables responsible for parasite species composition, to resolve the question of croaker stock structure in the western North Atlantic Ocean. This analysis showed that latitude was the deciding variable delineating the parasite community composition of the Atlantic croaker. Among the 30 parasites, 15 were identified as putative tags according to qualitative criteria, and then 10 out of those 15 were selected as being appropriate tags using quantitative criteria. These parasite tags support the presence of two stocks roughly separated at the known biogeographical barrier at Cape Hatteras.

Catch-and-Release Mortality in Subadult and Adult Red Drum Captured with Popular Fishing Hook Types

Abstract Saltwater anglers along the entire coast of the southeastern United States target red drum Sciaenops ocellatus more frequently than any other recreational fish species. The frequency of catch-and-release angling has increased dramatically for this species in the past two decades, but little is known about the survival of released fish. This study demonstrates that catch-and-release mortality rates for subadult and adult red drum differed significantly among the most popular types of fish hooks in each fishery. To investigate the effect of hook type on anatomical hooking location and short-term (48-h) mortality, we captured subadults (339–825 mm total length (TL)) by use of 2/0 J-hooks (n = 57 fish), 4/0 nonoffset circle hooks (n = 58 fish), and 4/0 offset circle hooks (n = 57 fish). Nonoffset circle hooks penetrated shallow regions of the body (jaw, tongue, or inside of mouth) significantly more frequently (90%) than did J-hooks (60%) or offset circle hooks (80%). Nonoffset circle hooks also resu...

Age, Growth, and Reproduction of Sheepsheads in South Carolina

Abstract The sheepshead Archosargus probatocephalus is a common estuarine and reef species that is found year round in South Carolina. Although not commercially important, the sheepshead is a significant recreational species, and most of the fishing pressure occurs in state waters. From 1990 to 2005, 5,692 sheepsheads were collected from fishery-dependent and fishery-independent monitoring programs in South Carolina. Fish ranged from 102 to 605 mm in fork length (FL) and were caught during every month of the year. Ages ranged from 0 to 19 years for males and from 0 to 23 years for females; the dominant age-classes were ages 2–5. Marginal increment analysis confirmed the formation of a single annulus per year, and annulus formation began in May. Males and females did not significantly differ in FL at age t(FLt) or total weight at age t (Wt); the pooled von Bertalanffy growth models were FLt = 498[1 - e-0.297(t + 110)] and Wt = 3,778[1 -e-0.165(t - 0.548)]2.997. Both males and females exhibited the first signs of sexual maturity at age 1, and 100% maturity was reached at age 4. Batch fecundity estimated late in the spawning season ranged from 18,400 to 738,500 oocytes/spawning event and averaged 235,000 oocytes/spawning event. Fork length, W, and age were positively correlated with fecundity. Although size was a better predictor of fecundity than age, the relationship was weak due to the high variability in size at age. Comparisons of growth parameters for sheepsheads studied in the southeastern United States indicated that South Carolina sheepsheads tend to have a larger maximum FL and a greater maximum age than fish found in the Gulf of Mexico.