Baby halibut
Juvenile halibut ready to be released into Mission Bay. Courtesy Hubbs Seaworld Research Institute

Hubbs-SeaWorld Research Institute, a 56-year-old marine science organization based in San Diego, is expanding its research into aquaculture as a means of replenishing depleted wild fish stocks.

The release of 2,300 juvenile California halibut into Mission Bay last month marks the second major species cultured and released into the wild by Hubbs-SeaWorld.

White seabass have been the primary focus of the California Ocean Resources Enhancement and Hatchery Program since 1983, with Hubbs-SeaWorld having released more than 2.5 million juvenile fish over the last 36 years. Both white seabass and California halibut are important for the sport fishing community, which has helped support both initiatives.

“We could not undertake this unprecedented program without support from key partners,” said Mark A. Drawbridge, senior research scientist and head of aquaculture initiatives at Hubbs-SeaWorld. “The Coastal Conservation Association California helped catch brood fish and release the juveniles, donors provided essential funding, and the California Department of Fish and Wildlife has provided the needed authorizations to conduct the pilot project.” 

This is the first release under the Dick Laub Fisheries Replenishment Program, which is named after the late fisherman and conservationist. Other major funders are Paul and Norma Fruchbom, and Chevron Corporation. 

“The Southern California saltwater angling community is very excited to see this next important hatchery effort,” said Wayne Kotow, Coastal Conservation Association California executive director.  “Hubbs-SeaWorld Research Institute has done incredible work with white seabass and we look forward to them being even more successful with California halibut.”

According to a 2011 stock assessment by the Department of Fish and Wildlife, the halibut population in southern California, “is estimated to be depleted to about 14% of its unexploited spawning biomass level. The population level is estimated to have been at a low level since the start of the modeling time period (1971)”. The central California population, by contrast, is not considered depleted.

The halibut program is similar to that for white seabass. Mature fish collected from the wild were spawned under controlled conditions. Juveniles were raised from eggs initially at Hubbs-SeaWorld’s Mission Bay headquarters and then transferred to raceways in a hatchery and nursery in Carlsbad until ready for release at four to six inches long.

Drawbridge emphasized that this is the first step in what could be a long process.

“We now know how to hatch, raise and release the halibut, but determining survival in the wild is the next crucial part of the study,” he said. “To track them, we implanted coded wire tags in their cheeks that can be scanned, and we marked them with a visible tag that we hope will last for a year or more. Our plan is to try to recapture some of the fish in Mission Bay after release, so we can begin to understand patterns of movement and rates of survival.  

“Our sampling efforts will give us initial indication of short-term survival, but long-term survival will depend on both commercial and sport fishing community members enabling us to scan halibut they catch to see which have wire tags that identify the fish as ours, and where and when they were released. As the saying goes, this is a marathon, not a sprint,” he concluded.