WDCS biologist Sue Rocca is on a 2-week leg of a multi-discipline research cruise aboard the Greenpeace ship Arctic Sunrise in the Gulf of Mexico. While the media attention about the oil spill declines, WDCS attention to long term impacts of this oil spill continues.
With the possible exception of coastal bottlenose dolphin stocks, there are limited data documenting cetaceans in the Gulf of Mexico. According to the National Marine Fisheries Service Stock Assessment Reports, at least 20* cetacean species occur in the Gulf of Mexico, not including the rare, but confirmed, sightings of humpback and North Atlantic right whales in these waters. In addition, manatees are also known to inhabit the coastal waters of the Gulf. The vast majority of cetacean sightings occur in the deep
water canyons.
The population estimates for large whales in the Gulf of Mexico are remarkably small, with a minimum estimate of 1,409 sperm whales and as few as five Bryde's whales. As a result, the loss of as few as three sperm whales, or one Bryde's whale, resulting from the oil spill, can jeopardize the future of these populations in the Gulf.
Its likely that these losses have already occurred as a result of the spill but due to limited effort, and the likelihood that carcasses sink in deep water, these mortalities will not be documented. Of further and ongoing concern are the impacts from the use of chemical dispersants. Already, studies of blue crab larvae had revealed chemical traces in their shells indicating these toxins have entered the food chain.
WDCS believes that ongoing documentation of cetaceans exposed to dispersants will be valuable to determine long term effects. This documentation will be obtained through visual health and behavioral assessments. These baseline data can be used for comparison should annual surveys of habitat use and calving intervals be conducted.
For updates, check out Sue Roccas blog from the Gulf.