DNA to the Rescue
Dr. Mahmood Shivji, director at the GHRI, along with his graduate students have pioneered a process for rapidly identifying sharks using DNA markers. The technique allows researchers and law enforcement agencies to identify both the species of shark and the population it came from based on tiny tissue samples. The technology is now routinely used to assist NOAA’s Office for Law Enforcement officials to investigate and prosecute illegal fishing cases, and was put to use late last year to document for the first time that some fins in the Hong Kong fin trade originated from endangered scalloped hammerhead populations in the western Atlantic. The research is going to be used to  by U.S. officials to push for stronger international regulations on trade in hammerhead shark body parts at the upcoming Convention on International Trade in Endangered Species (CITES) in March 2010.

Grouper by Any Other Name

The old adage, “you get what you pay for” is not always true, at least when it comes to dinner at your local seafood restaurant. Prompted by consumer activists, GHRI has used its expertise in genetics to identify food samples from more than 100 restaurants around the country. In more than half the cases, fish sold as grouper or red snapper turned out to be something else much less expensive such as catfish or tilapia. In addition to the basic issue of consumer fraud, the practice of fish swapping also poses a health risk for consumers with seafood allergies and conservationists say it makes it harder to track the consumption of over-fished species.

Confirming a Virgin Birth
The fact that a hammerhead shark gave birth in a Nebraska zoo was not all that unusual. The fact that there had been no exposure to male sharks in three years was. At first, scientists thought it was an extreme case of sperm storage, something female sharks have been known to do for up to six months, but genetic analysis of the newborn by GHRI and collaborators revealed the incident was a case of asexual reproduction and a legitimate virgin birth. Although documented in some other bony- fish species, the ability for a female to reproduce without a male was previously unknown among sharks. This ground-breaking discovery has now been confirmed in two other shark species suggesting that this ability may be more common in sharks generally.

Two Instead of One
Spotted eagle rays are globally distributed and until very recently listed as a single species. But GHRI research has now shown that there are at least two distinct species. Populations found in the Indo-Pacific regions are different than those in the eastern Pacific and Atlantic regions and the populations do not mix. This discovery means that the population size of each species is smaller than previously believed for one globally distributed species, making each species more susceptible to over-fishing, a problem spotted eagle rays may face in the western Pacific where they are caught for food.

Mistaken Marlin

In 2007 GHRI worked with NOAA scientists to determine that many of the white marlin caught off the U.S. Atlantic coast are not really white marlin at all, but a new species dubbed the roundscale spearfish. The improper identification of these fish as white marlins throws in doubt previously accepted population figures and has heightened the concern for protecting the popular game fish.

RELATED RESOURCES

Leave a Reply