When you think of large concentration of whales, maybe you think of the Alaska coast. Or perhaps Hawaii. But the Mississippi River Delta probably isn't high on the list of places that come to mind, but researchers have found that endangered sperm whales frequent the deeper waters off the Mississippi Delta. Scientists estimate that at least 530 sperm whales can be found in the northeastern Gulf of Mexico.
In a Texas-Sea-Grant-funded project, Texas A&M University biologists Randall Davis and Bernd Würsig will use satellite tracking, direct observation, genetic analyses and photographic identification to learn more about these large marine mammals that live so close to the coast. Davis said coldwater eddies and the outflow of nutrients from the Mississippi River may enhance the production of food for these marine mammals and draw the animals nearer to coastal waters. The Mississippi Delta region of the Gulf also has water that's several thousand meters deep within 50 or 60 miles of the coast, he said, and sperm whales are typically found in these deeper waters along the continental shelf.
"The unique aspect of the Gulf is we have a continental shelf that is only about 25 miles wide off the Mississippi Delta, so we have this influx of freshwater nutrients into a deepwater environment very close to the coast," he said.
While this area of the Gulf of Mexico is popular with sperm whales, it is also home to a lot of oil and gas exploration. These activities, and the increasing boat traffic they bring, may be a cause for concern as far as their effects on the region's whales, he said.
"Basically, we probably have a breeding population of endangered sperm whales right in the middle of one of the hottest areas for offshore oil development in the continental U.S," Davis said.
As part of the study, researchers will tag whales with tracking devices that will follow the movements of the whales and record information on how often a whale dives -- which can be linked to feeding -- the duration of the dive and the depth of the dive. When the whale surfaces, the device relays the information back to researchers via satellite.
This information will help researchers learn more about the feeding behavior of sperm whales, Davis said. Currently, they can only get this information from observing sperm whales feeding and analyzing the stomach contents of a whale - neither of which is easily done.
"Without being able to make direct observations on these deepwater whales, it's surprising how little we know about their natural history," he said.