Studies toward growing tiny algae and crustaceans as fish larva food

[USA] Mississippi-Alabama Sea Grant is getting nearly $1 million to figure out how to raise tiny crustaceans called copepods (KOH-pee-pahdz) for large-scale use in hatcheries for saltwater fish.

Red snapper, tuna, many groupers and many ornamental tropical fish are among those that are hard to raise in aquaculture because, when they’re still tiny larvae, they eat copepod larvae, said Reginald Blaylock, assistant director of the University of Southern Mississippi’s Thad Cochran Marine Aquaculture Center.

And copepods are finicky critters.

“They have complicated life cycles. So in order to get the population going, everything about every stage of the life cycle has to be perfect,” Blaylock said in a telephone interview. In addition, he said, “you need a lot of space for a relatively small number of copepods.”

USM researchers will be working with colleagues at Virginia Tech, the University of Florida, and Reed Mariculture Inc. of Campbell, California, on the two-year project to figure out just what’s needed at each stage.

Then there’s the copepod diet of live algae. “Producing large volumes of algae is also a problem,” Blaylock said. He said Reed is providing its algae concentrate as a possible copepod diet supplement.

Researchers at the universities and Reed all have been studying copepod culture for some time, “so we’re not having to start from scratch,” Blaylock said.

The $994,955 grant was among 11 for “integrated projects to increase aquaculture production” announced Tuesday by the National Oceanic and Atmospheric Administration Sea Grant . The agency said the grants total $6.6 million and were chosen from 80 proposals.

The Mississippi-Alabama Sea Grant’s center at Auburn, Alabama, got $100,000 to help pay travel costs for oyster farmers and business owners who want to attend the annual Oyster South Symposium and other business meetings and workshops.

In a separate category, NOAA announced $2.6 million in 21 grants for “addressing impediments to aquaculture opportunities.”

Louisiana Sea Grant received nearly $88,000 in that category for its program to breed Gulf of Mexico oysters with extra chromosomes so their spawn will grow faster than normal oysters and stay fatter year-round. Such work is common in the plant world, Supan noted — seedless watermelons are triploid.

Although triploid oysters make up one-third to one-half of all seed oysters along the West Coast, Louisiana State University biologist John Supan “guesstimates” that they may make up about 1 percent of Louisiana’s harvest.

His team has identified two strains of native oysters to work with. One prefers higher salinity than most oysters do and is resistant to a parasitic disease called Dermo , and the other can thrive in waters with lower salinity than most oysters like.

They’ll use those to develop oysters with four sets of chromosomes. When bred with normal oysters, their spawn have three copies of each chromosome set. The triploid oysters are sterile. That means they don’t spend energy spawning, unlike regular oysters, which lose up to half their body weight each summer to reproduction.

The researchers hope the triploids will show the same characteristics as their normal ancestors.

“We hope to get to the point where the grower calls the hatchery and says, ‘I’m growing oysters and my salinity is this’ — and we have a salinity to fit,” Supan said.


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