Population of Dolphins Found Steady

Populations of various dolphin species in the Eastern Pacific appear to have remained steady in recent years amid concerns that deep-sea nets used by tuna fishing boats are killing large numbers of the mammals, the lead scientist of a dolphin-counting project said Thursday.

Two ships from the National Oceanic and Atmospheric Administration docked in San Diego Bay on Thursday after completing the fifth annual voyage of the six-year project to monitor dolphin populations in areas where the mammals are at risk of being killed in the purse seine nets of tuna boats.

“Our primary interest is, are the dolphin populations declining, and, if they are, does it have to do with the purse seine?” said Tim Gerrodette, the chief scientist for the project.

“We have found no evidence that the dolphins are declining in abundance,” Gerrodette said. “But they are still considerably below what they were when the (purse-seine) fishing started.”

The welfare of dolphins has been a major issue among environmentalists as well as commercial fishermen, who say they take great pains to protect dolphins but are being driven out of their traditional fishing grounds by the new labeling practices of American canners.

Purse seines, introduced by the Southern California fleet about 1960, trap the air-breathing dolphins along with the tuna, drowning them and sometimes crushing them in the machinery that reels in the net.

The major tuna companies have vowed to no longer buy fish unless they were caught using “dolphin-safe” methods that don’t trap the mammals in the nets.

A new federal law requiring tuna cans to carry dolphin-safe labels goes into effect in April.

Catching tuna without endangering dolphins means American boats must sail thousands of extra miles to areas in the South Pacific and Atlantic where dolphins and tuna do not swim together.

“There is a lot of sensitivity to the numbers on the part of environmentalists and fishermen,” Gerrodette said.

The vessels McArthur and David Starr Jordan left San Diego in late July and covered about 45,000 miles of open sea in a triangular area stretching from Peru and Baja California west to Hawaii.

Observers using yardlong sets of binoculars and a helicopter made a visual tally of dolphins and will try to estimate how many they failed to see, using a complex series of mathematical computations.

Thousands of dolphins of a variety of species live in the area, including eastern spinner dolphins and northern offshore spotted dolphins, the two species most frequently affected by tuna fishing.

Gerrodette said the processing of the data will be completed in about six months, shortly before the sixth and final counting mission sets sail.

The information will be used to compile a study that will be used by Congress when it considers reauthorization of the Marine Mammal Protection Act in 1992.

“I think there is a heightened interest in this these days, but this study was planned six to seven years ago, before tuna-labeling,” Gerrodette said.