Program brings global attention to decline in shark numbers
The VIMS’ shark survey, established in 1973 by VIMS Emeritus Professor Jack Musick, stands as the longest-running fishery-independent study of shark populations in the world.
It fortuitously began two years before the 1975 blockbuster film Jaws, which sparked a sport fishery that first began to take significant numbers of large sharks from Atlantic waters.
The survey, part of VIMS' larger Shark Research Program, is now directed by Professor Rob Latour. The program has brought global attention to significant declines in shark populations due to overfishing, and led to the first U.S. management plan for sharks, in 1993.
Data from the annual survey show that the population of sandbar sharks, Virginia's most common species, had declined to just less than 50% by 1990. Since then the yearly index has varied, but the overall trend has continued down. These data prompted the National Marine Fisheries Service (NMFS) to close the commercial sandbar shark fishery in 2008. Other species like sand tiger and dusky sharks showed larger declines and have been on the protected list for several years. Dusky sharks have shown some signs of recovery, but sand tigers have not.
Sharks are susceptible to over-fishing because they grow slowly, don’t reach sexual maturity until 5-20 years old, and produce only 8-10 pups every other year.
The scientists and students of the VIMS program continue to provide detailed information on habitat use, age, growth, reproduction, food-web dynamics, and demographics of sharks. Their work has identified Chesapeake Bay and Virginia’s seaside lagoons as the principal nursery area for sandbar sharks in the whole western North Atlantic, and has helped establish VIMS as one of four members of the National Shark Research Consortium.
Musick and Latour stress that sandbars and other sharks are a key part of the marine ecosystem. “Sharks are at the top of the food web,” says Musick, “and when you remove the apex predators, it throws everything out of whack. Their prey items become more abundant, and tend to overeat things below them.”
The researchers stress the rarity of shark attacks. “You are 30 times more likely to be killed by a dog than to be bitten by a shark,” says Musick. There were an average of 34 shark attacks per year in U.S. waters between 1990 and 2008. Of the 658 attacks during this18-year span, 13 were fatal.