Filling In the Gaps
You can see Narragansett Bay from marine biologist David Taylor’s office at Roger Williams University in Rhode Island. On his walls are framed scientific illustrations of fish, and a rack of well-appointed fishing rods stands in front of academic books and journals dealing with fisheries ecology, habitat restoration and environmental toxicology. Here in the Ocean State, Taylor says, “it seems like everyone fishes – and the majority eat what they catch.”
Taylor’s research focuses on mercury contamination in fish caught and eaten by Rhode Island’s recreational anglers. When Taylor started his work, there was a lot of research on mercury levels in freshwater fish and in some well-known commercial saltwater species, like swordfish and tuna. But there was surprisingly little research on mercury contamination in commonly consumed saltwater species such as striped bass, tautog, bluefish and summer and winter flounder.
In 2009 he began investigating dogfish. He wasn’t motivated, at first, by health concerns. Dogfish has never been a popular food choice among American anglers; if not handled properly, the flesh has a foul taste because dogfish essentially urinate into their own flesh.
Existing data on mercury concentrations in dogfish were, at best, sparse.
Rather, Taylor turned to dogfish to better understand how mercury moves through ocean food webs. He found that the existing data on mercury concentrations in dogfish in the
Northwest Atlantic were, at best, sparse. He was going to need to start collecting.
Since then, Taylor has collected and archived almost 300 dogfish samples, probably the most robust data set for mercury levels in dogfish in the Northwest Atlantic to date. His data, which will appear in a forthcoming article in Marine Environmental Research, suggest that species of dogfish, as well as age and size, can have a significant effect on mercury concentrations. In the Atlantic spiny dogfish he tested, Taylor says he found mercury levels “exceeding the EPA action level for mercury in seafood” (0.30 ppm) in more than 50 percent of market-size samples. For the closely related smooth dogfish, that figure was 90 percent – a relevant statistic since sometimes different dogfish species are caught and sold generically as dogfish in areas where the species’s ranges overlap.
According to Taylor, even a liberal reading of his data would likely place dogfish in a category where, based on joint FDA-EPA advice, he would recommend no more than a single serving of dogfish per month for men. Women of childbearing age and children would be advised to forgo dogfish altogether.