A recent study led by scientists from the University of Miami’s Rosenstiel School of Marine and Atmospheric Science (RSMAS) provides new insight into the migratory patterns of the great hammerhead sharks.
Using satellite tag technology, the research team was able to track one of these nomadic sharks for 62 days to discover its 1,200 kilometer (745 mile) journey from the coast of South Florida to the middle of the Atlantic off the coast of New Jersey.
“This animal made an extraordinary large movement in a short amount of time,” said Rosenstiel School Research Assistant Professor Neil Hammerschlag. “This single observation is a starting point, it shows we need to expand our efforts to learn more about them.”
Hammershlag and colleagues assume that the shark was following food, such as mahi-mahi or jacks, off the continental slope and into the Gulf Stream.
This study is part of a much larger effort led by Hammerschlag who directs the R.J. Dunlap Marine Conservation Program at RSMAS. Other studies will track tropical sharks via satellite in order to identify hotspots that are important for feeding, mating, and pupping. They also hope to uncover other unknown migration routes.
In just the last year, the R.J. Dunlap team has tagged the fins of more than 50 large and environmentally threatened sharks in Florida and the Bahamas, including the great hammerhead, bull, and tiger sharks.
The great hammerhead shark is listed as an endangered species in the northwest Atlantic and Gulf of Mexico by the International Union for Conservation of Nature (ICUN) primarily due to a population decline of nearly 50 percent over the last 10 years. The shark is threatened by overfishing for its large (and tasteless) fins for sharkfin soup, and from accidental bycatch from commercial fishing operations. DNA analysis of great hammerhead fins sold in the Asian shark fin market has proved that a large majority of the sharks come from Atlantic waters.
“This study provides evidence that great hammerheads can migrate into international waters, where these sharks are vulnerable to illegal fishing,” said Hammerschlag. “By knowing the areas where they are vulnerable to exploitation we can help generate information useful for conservation and management of this species.”
The paper, titled “Range extension of the Endangered great hammerhead shark Sphyrna mokarran in the Northwest Atlantic: preliminary data and significance for conservation” was published in the last issue of the journal Endangered Species Research. The paper’s co-authors include Hammerschlag, Austin J. Gallagher and Dominique M. Lazarre of the University of Miami and Curt Slonim of Curt-A-Sea Fishing Charters.
Copyright © 2011 by Marine Science Today, a publication of OceanLines LLC