Grantee Research Project Results
Abundance Trends and Juvenescence of Carcharhinus plumbeus in the Mid-Atlantic BightEPA Grant Number: U914968
Title: Abundance Trends and Juvenescence of Carcharhinus plumbeus in the Mid-Atlantic Bight
Investigators: Grubbs, Ralph D.
Institution: College of William and Mary-VA
EPA Project Officer: Just, Theodore J.
Project Period: January 1, 1996 through January 1, 2001
Project Amount: $68,000
RFA: STAR Graduate Fellowships (1996)
Research Category: Fellowship - Marine Biology , Academic Fellowships , Biology/Life Sciences
The sandbar shark (Carcharhinus plumbeus) represents approximately two-thirds of the commercial catch of large coastal sharks in the western North Atlantic and has been accepted as a keystone species for large coastal sharks. The objective of this research project is to investigate the largest pupping and nursery area for this species in the western North Atlantic, the lower Chesapeake Bay, to: (1) delineate inshore pupping and nursery grounds and analysis of stock and recruitment relationships; (2) determine age-related seasonal distribution of large coastal species; (3) generate a long-term fishery independent data set of abundance per effort for each species; and (4) estimate natural mortality at age.Approach:
A tagging experiment was conducted in the Chesapeake Bay last summer, marking 175 age 0 to age 5 sandbar sharks. I will continue the experiment this year by marking 2,000 sharks. Using recaptures, I will generate estimates of population size within the estuary to use in stock-recruitment dynamic relationships and to gain an understanding of age-specific migration patterns to and from the nursery area. I will use a stratified random-sampling scheme to delineate the age-specific extent of spacial utilization within the bay, as well as temporal recruitment to and from the estuary. I will investigate the levels of fishery and natural mortality on juveniles in the nursery and during winter migrations. In addition, I will use ultrasonic telemetry techniques to evaluate spatial and temporal habitat utilization within the estuary on tidal, diel, and lunar-temporal scales. I also will coordinate the Virginia Institute of Marine Science's longline program under Dr. Musick to maintain the monitoring of species-specific abundance trends in the coastal areas of the Mid-Atlantic Bight.Supplemental Keywords:
fellowship, sandbar shark, Carcharhinus plumbeus, North Atlantic, nursery, Chesapeake Bay, abundance trends, juvenescence.