Biologists Tackle Big Job: Restocking the Pacific Ocean

Restocking lakes and streams with fish bred at hatcheries is a time-tested practice with a proven record of success. But a group of marine biologists from local institutions are embarking on uncharted waters, as they attempt to restock Pacific Ocean coastal waters with two species of fish whose numbers have declined drastically in recent years.

If the $500,000 state-funded restocking program is successful, the biologists say, sport and commercial fishermen in Southern California could begin finding larger schools of white sea bass and California halibut in coastal waters.

In 1983 the Legislature approved the program after hearing reports that in recent years fewer than 1,000 white sea bass were being caught in Southern California annually.

Marine biologists say the fish were being caught by the tens of thousands as recently as the late 1950s.

Oceanographers say they believe the colonies are shrinking because of years of overfishing and a reduction in natural habitat for the fish.

Marine biologists at Scripps Institution of Oceanography, Hubbs Institute at Sea World, and San Diego State University say they hope to eventually stabilize the colonies by releasing into the ocean tens of thousands of young fish.

The project, introduced by Assemblyman Larry Stirling (R-San Diego), is financed with a $1 surcharge on licenses for sport fishermen and a $10 charge for commercial fishermen in Southern California, said Michael Mullin, professor of biological oceanography at Scripps Institution of Oceanography. The project should be reviewed for possible renewal in five years, he said.

Don Kent, asst. director of operations at Hubbs Institute, said he believes that if all goes well, at least 10,000 young white sea bass could be released by year’s end.

Kent cautioned, however, that people should not become overly optimistic about the project, because there is limited knowledge about raising white sea bass, and scientists have never before attempted to restock an ocean.

If the technology and money were available, he said, biologists estimate they would have to release more than 70,000 white sea bass just to replace those caught by fishermen.

A full-time staff at Hubbs Institute is carefully monitoring about 100 adult white sea bass that should begin spawning by late April, Kent said. The fish weigh about 20 pounds each, and one female is capable of laying about 1 million eggs.

However, biologists say they do not know the sexual makeup of the breeding fish because tests to determine sex would be too traumatic and could kill the big fish.

During the next few weeks, biologists will gradually increase the water temperature and available light for the fish. The light and water conditions should be similar to summer days to encourage the females to spawn, Kent said. Soon after the eggs are laid, the males should begin fertilizing them as they float in the water.

Once the eggs are hatched, it should take more than six months before the fish grow large enough to be released into the ocean, said Refik M. Orhum, senior mariculturist at the hatchery. It will then take another four to five years before they grow to about 28 inches, the minimum legal length for them to be caught.

A similar program for the California halibut is being conducted at Occidental College in Los Angeles, Mullin said. Hubbs Institute officials said they also will soon begin catching halibut for breeding in San Diego.

Neither species of fish is very important to the commercial markets, Mullin said. However, in recent years they have become prized catches for sport fishermen.

Several sport fishing boat owners said their patrons have all but given up trying to catch the two species in Southern California waters--from Santa Barbara to Mexico. All said they see less than 10 white sea bass caught each month, and only slightly larger numbers of California halibut.

Local market and restaurant owners say they buy as many pounds of the two species as possible, but are usually unable to get more than 700 pounds each month. They said they often pay as much for the local fish as they pay for other species shipped from foreign oceans.