THEY HAVE A NOSE FOR DOLPHINS

By JACK KASKEY Staff Writer, (609) 272-7213

CAPE MAY - More than 50 dolphins are on the move, their gray, glistening bodies surfacing farther and farther north.

Aleta Hohn, a biologist with the National Marine Fisheries Service, or NMFS, follows them along the Wildwood coast with a contingent of six boats.

When the dolphins turn south, the researchers are ready for them.

"Wetsuits on!" Hohn calls over the radio, and everyone scrambles to obey.

Hohn is in town this month hoping to net as many as 30 of the mammals for the first-ever study into health and migration patterns of New Jersey's bottlenose dolphins. Bottlenose dolphins reach their northern limit in New Jersey, but scientists know very little about the New Jersey population, including where they spend the winter.

"Some go to North Carolina, but where do the rest go?" Hohn asks. "There is lots of information that we can get only if we catch the animals."

Three times already this Friday morning, the researchers have circled dolphins with a net, only to have them escape.

But when the nets are deployed this time, four dolphins are captured amid the breakers. NMFS researchers, joined by scientists from Hawaii and Sweden and veterinary students from North Carolina State University swim to the dolphins, holding them up so they don't get tangled and drown.

It's not easy work. People often are bruised grappling with the 400-to 500-pound mammals.

A 41-inch processing boat on loan from the state Department of Environmental Protection moves close to lift the dolphins on board, but the researchers decide instead to work on the nearby beach.

The beach, they soon learn, is part of the Cape May National Wildlife Refuge that is closed until Oct. 1 for piping plovers and migratory birds. The U.S. Fish and Wildlife Service denies use of the beach, so the researchers must float the netted dolphins a quarter-mile north to the boundary of the refuge, at Diamond Beach in Lower Township. Before the arduous trip is over, they are forced to release two of the animals.

Plastic boxes and coolers marked "biopsy kit" and "blood" are hurriedly unloaded from the processing boat in waist-high surf and carried to the beach. The remaining two dolphins, a male and a female, are carried on stretchers to mats spread on the white sand.

For the next two hours, a dozen people embrace the two animals, holding them still while they wet the taut, smooth skin with seawater-soaked sponges. Men crouched beside the dolphins' powerful tails hold especially tight.

Hohn, meanwhile, leads researchers in a variety of measurements and probes. Some procedures are innocuous - a measuring tape tells us the male is 8.5 feet long - while others are fairly invasive.

Using a scalpel, a biopsy of skin and blubber is taken off each animal's back. A catheter is inserted in the urethra to draw urine samples. Blood is drawn with a needle. Hohn freeze-brands the animals on the dorsal fin and back with identifying numbers. And a veterinarian pulls a back tooth from each animal's mouth.

Local anesthetics numb the animals prior to the biopsy and tooth removal, and the beached animals seem generally calm. During the dental procedure, the vet allows the dolphins to bite down on his towel-wrapped forearm, and they endure with their wide-set eyes tightly shut.

The various samples will help the researchers get a picture of each animal's health. The collective data from the two-week mission also will allow researchers to see how the health of New Jersey's dolphins compare to others along the coast, Hohn said.

The blood is analyzed overnight at Burdette Tomlin Memorial Hospital in Cape May Court House, telling the researchers if a dolphin is fighting off any disease, said Teri Rowles, a NMFS veterinarian who coordinates the Marine Mammal Health and Stranding Response Network.

Additional blood work will reveal what diseases New Jersey's dolphins have been exposed to and how those diseases differ from other populations, Rowles said.

Bob Schoelkopf, executive director of the Marine Mammal Stranding Center in Brigantine, said the health assessment is essential to protect against the kind of disease that devastated dolphin populations in the late 1980s.

"Even though it's a little rough sometimes watching, I think it's necessary to do," Schoelkopf said. "It's done in a clinical way that is safe for the animal."

NMFS researchers began intensively studying bottlenose dolphins after a 1987-88 outbreak of morbillivirus, a kind of dog distemper in marine mammals that killed half the inshore bottlenose population.

Since, then, NMFS has studied the health of dolphins off the coasts of Texas, Florida, Virginia, South Carolina and North Carolina, but they didn't intensively studied New Jersey's dolphins until now.

Although bottlenose dolphins sometimes are spotted as far north as Long Island, N.Y., New Jersey is regarded as the northern end of their range, with perhaps 500 to 1,000 mammals returning here each summer, Schoelkopf said.

The skin from the biopsies will help geneticists determine how similar or distinct New Jersey's dolphins are from others.

"We know there are at least four genetically different populations along the Atlantic coast," Hohn said.

The dolphins' blubber, meanwhile, will tell researchers how much pollution the mammals have absorbed through the weakfish, croaker, spot and other fish they eat. Certain pesticides, such as chlordane and DDT, as well as industrial products, such as polychlorinated biphenyls, or PCBs, do not break down quickly in the environment. These contaminants become concentrated at the top of the food chain - in dolphins as well as people - potentially affecting health.

The researchers take one of the dolphin's 88 teeth to estimate the age, Rowles said. Researchers need to know the age of each mammal to put other data in perspective, particularly the accumulation of contaminants, Hohn said.

Because people eat from the same waters as dolphins, the researchers note, assessing dolphin health might provide warnings about environmental threats facing humans.

Independent researchers from outside NMFS, meanwhile, are doing their own studies on New Jersey dolphins.

Swedish researchers are studying echolocation by attaching a device that records dolphins "talking" with sonar and using sonar to locate fish.

Researchers also are force-feeding some dolphins a small device that transmits data from the stomach on when and where the animal feeds. After about 12 hours, the device is regurgitated.

Kristi West, a doctoral candidate from the University of Hawaii, on Friday wielded a hand-held ultrasound device to study the dolphins' blubber thickness for research on dolphin nutrition.

West also uses the device to check for pregnancies. When she detects amniotic fluid in the female, which may be a sign of early stage pregnancy, Hohn exempts the animal from the final procedure, and the dolphin is set free.

The final procedure involves drilling a series of holes through the dorsal fin, and then bolting a pair of custom-fit transmitters to either side. One transmitter sends the mammal's location to a satellite, which will relay the information to Hohn's office in Beaufort, N.C. The other transmitter emits a VHS signal that researchers on the water can use to pinpoint the dolphin.

When New Jersey dolphins follow their prey south next month, researchers will be able to see exactly where they go, Hohn said. By following the VHS signal, they also will be able to see whether they mix with other dolphin populations, she said.

The transmitters should fall off within a year when the bolts corrode, she added.

Once the transmitters are securely fastened, Hohn calls for volunteers from the crowd of vacationers to help haul the male dolphin back to the water. Wetsuit clad researchers and bare-chested tourists take their spots at the stretcher and walk him into waist deep water. As the dolphin swims free, people on the beach cheer.

To e-mail Jack Kaskey at The Press: JKaskey@pressofac.com