I’ve started to receive some questions about the Gulf of Mexico oil spill and how it may affect the supply of seafood in the near and distant future.  As some of you may know I went to graduate school in Louisiana and conducted all my research from fishing boats and oil rigs off the Louisiana coast so I’m familiar with the area and affected industries.  While I’m not an expert on oil spills I’ve been doing a lot of reading and research over the past few days – hopefully I can offer a little clarity in contrast to the rumors that are flying around the media and the general public.  If you have any further questions please don’t hesitate to call or e-mail me at mwestmeyer@scaquarium.org.

Q: Is seafood from the Gulf of Mexico safe to eat?

A: Yes, seafood harvested in the Gulf of Mexico is safe to eat.  On Sunday (5/2/10) the National Oceanic and Atmospheric Administration closed the potentially affected portion of the Gulf of Mexico to fishing for at least 10 days (see attached map).  This area is a relatively small portion of the Gulf stretching from the mouth of the Mississippi River to Pensacola Bay.  This area encompasses waters offshore of a portion of eastern Louisiana, all of Mississippi, all of Alabama and very little of the western Florida panhandle.  Louisiana closed some of their near shore waters to fishing as well, though waters within 20 miles of Alabama are still open to fishing for the time being.  Texas, most of Louisiana and nearly all of Florida are largely unaffected at this point and fishing is occurring as usual.  Federal and state government agencies are regularly testing the water quality in these areas and are inspecting seafood to ensure its safety.  Please keep in mind that while the affected areas are geographically limited in scope, the fishing communities within these areas, especially in Mississippi and Alabama, could be devastated because it might not be economically feasible for these fishermen to travel to fishable waters.

What seafood is likely to be affected by the oil spill?

A: The effects will vary depending on the species and their locations.  The surface oil (oil slick) is currently in a limited area east of the Mississippi River delta (eastern Louisiana) and south of Mississippi and Alabama.  These coastlines are the most likely to be affected at this time but very little oil has reached the coast so far.  Some species may be immediately affected (i.e. adult population could be damaged now) whereas others may be affected more in the future (i.e. reproduction could be affected).

  • Oysters are very likely to be affected by the oil slick that reaches the coast because they are immobile and cannot move to oil free areas.  The Gulf of Mexico produces 67% of the nation’s total oysters, with Louisiana vastly dominating harvest and Texas, Mississippi and western Florida producing smaller but significant amounts.  The affected portions of eastern Louisiana and Mississippi alone produce around half of the oysters consumed in the U.S.  You will probably see availability tightening and prices going up, for good reason.
  • Shrimp are likely to be affected in the short term.  During the spring and summer adult shrimp start to leave the salt marshes and move offshore to spawn.  This oil slick could affect both the adults (which would be harvested during this year’s shrimp fishery) and their offspring (which would be harvested during next year’s shrimp fishery).  The Gulf of Mexico produces about 73% of the U.S. harvested shrimp.  Again, Louisiana dominates harvest with Texas at a close second.  Alabama, Mississippi and western Florida produce smaller but still substantial amounts.  The currently affected portions of eastern Louisiana, Mississippi and Alabama produce about 20% of U.S. harvested shrimp.  The state of Louisiana did open a special shrimp harvesting season in their state waters at the end of April to allow shrimpers to harvest some of the adult population of white shrimp before the oil slick neared shore.  This special fishery was closed earlier this week when most of the marketable white shrimp in the near shore region were harvested.
  • Blue crabs are likely to be affected in the short term.  Blue crab harvest occurs in primarily near shore waters with harvest typically peaking during the summer and spawning peaking during the fall.  Most of the blue crab harvest occurs in Louisiana, which accounts for about 26% of U.S. caught blue crabs; though remember that only a portion eastern Louisiana is currently affected by the oil slick.
  • Adult snapper and grouper are less likely to be affected by the oil slick because they inhabit deeper waters.  Unfortunately many snappers and groupers have begun or are about to being spawning throughout the late spring and summer months.  Their larvae and juveniles tend to inhabit shallower and inshore waters, including salt marshes, bays and estuaries.  These larvae and juveniles are more likely to be affected by oil, potentially negatively impacting the next few years of snapper and grouper reproduction.
  • Tunas and other migratory species are much less likely to be affected because they spawn much further from shore.  At the same time, one of the largest seafood ports (especially for tuna) in the U.S., Empire-Venice, is right on the edge of the area closed to fishing in Louisiana.  I have not heard anything about boat traffic being limited by the oil slick but it could be a possibility.

What are the long-term consequences of the oil spill?

A: No one really knows.  Many scientists are watching and waiting.  Oil continues to leak from the deep sea well at an estimated rate of 210,000 gallons per day.  The true amount of oil leaked will probably never be known, but current estimates from BP and the Coast Guard put the amount just under 3 million gallons over the past two weeks.  To put this in perspective, the 1989 Exxon Valdez oil spill in Alaska was 11 million gallons.  The surface oil slick does not appear to be increasing in size anymore because emergency crews are piping oil dispersant to the seafloor near the leak.  The dispersant separates the oil into smaller droplets which are then dispersed throughout the water column instead of rising to the surface where it can coat animals, beaches and marshes and where it could do the most immediate damage.  This technique does not destroy or eliminate the oil, it just dilutes it until the oil naturally degrades.  Unfortunately it is difficult to predict where the diluted oil is going.  Sub-surface currents in the Gulf of Mexico can be very different than surface currents, thus the oil in the water column might be going in a different direction than the surface oil slick.   This is why the National Oceanic and Atmospheric Administration and the Food and Drug Administration continue to test water and monitor seafood.

Megan Westmeyer, Program Coordinator at the South Carolina Aquarium