Tiger shark - Credit: Richard Ling

The people in attendance mowed down on cheese and crackers, celery and crisps. But as soon as Greg Skomal, a state shark expert, opened up his mouth, he told them what it really meant to chow down.

Skomal, who was the guest of honor at the Harwich Conservation Trust’s yearly get together this past Sunday evening, gave the people in attendance at Wequassett Resort the low down on great white sharks. He told of tagging them off Chatham’s coast near Monomoy. He explained how they weren’t very discriminant about what they chowed down on, and how they hunt a myriad of fish. Given that there is an abundant supply of gray seals in the area, and it’s ever increasing, more and more great white sharks are going to be making their way to the waters of the Cape every summer.

“You can eat as much popcorn you want or you can have one big steak,” Skomal commented, which accurately depicts why great white sharks like to pick out the gray seals in the area, especially near Monomoy. Just one gray seal can satisfy a great white shark for one to two months.

According to Skomal, who happens to be a shark expert with the state Division of Marine Fisheries, has commented no one can know for sure just how many great white sharks make an appearance every year, but it is becoming quite a “hot spot” off the Cape.

Researchers at Woods Hole Oceanographic Institution (WHOI) unveiled a hazardous cocktail of pesticides when analysing the brain matter of 12 marine mammals; eleven cetaceans and one gray seal stranded near Cape Cod, Massachusetts.

This is the most extensive study of pollutants in marine mammals’ brains and it confirms suspicions of marine mammals being the carrier of a vast array of different chemicals that have found their way into marine ecosystems.

Lead author Eric Montie analyzed the cerebrospinal fluid and the gray matter of the cerebellum in the twelve animals and found them to contain a long row of different man-made chemicals, including a group of especially widespread substances labelled “the dirty dozen” by environmentalists. Many countries banned the “the dirty dozen” as early as the 1970s due to their adverse effect on human health, but they are unfortunately still present in our environment.

Montie didn’t just test for the presence of certain chemicals; he also measured their concentration and found one instance where it was surprisingly high.

“The biggest wakeup was that we found parts per million concentrations of hydroxylated PCBs in the cerebrospinal fluid of a gray seal”, says Montie. “That is so worrisome for me. You rarely find parts per million levels of anything in the brain.”

PCBs are neurotoxicants known to disrupt the thyroid hormone system. Other examples chemicals found in the tested mammals are DDT (diklorodifenyltriklorethane), which can cause cancer and disturb reproduction, and PBDEs (polybrominated diphenyl ethers); a type of flame retardants known to impair the development of motor activity and cognition.

Co-author Chris Reddy, a senior scientist in the WHOI Marine Chemistry and Geochemistry Department, describes the new study as “groundbreaking because Eric measures a variety of different chemicals in animal tissues that had not been previously explored. It gives us greater insight into how these chemicals may behave in marine mammals.”

The results of this study was published online April 17 in Environmental Pollution.