“The consistent differences we observed in gill damage between resistant and susceptible families after PGD infection suggest a genetic component for PGD resistance,” Bosworth says. “Therefore, it could be possible to improve PGD resistance through genetic selection.”

Selecting superior fish

Scientists routinely evaluate and identify catfish strains with superior performance to help farmers and processors improve traits and increase their profits. In one study, three genetic groups of catfish — NWAC103 line channel catfish, Norris line channel catfish, and a hybrid between the Norris channel catfish and the Dycus Farm line blue catfish — were compared for production, meat yield, and meat quality traits. Juvenile fish were stocked in ponds, fed, and harvested after 200 days.

Fish were weighed, counted, processed, and measured for meat and body component yield. Fresh, frozen-thawed, and baked fillets were measured for quality.

NWAC103 grew faster and had higher production than the other groups. But the hybrid had higher meat yield than either of the channel catfish lines. No difference was found in weight gain, survival, and feed conversion among groups.

In a separate study, Bosworth looked at winter feeding effects on growth, body composition, and processing traits of blue, channel, and hybrid catfish and found that hybrids gained the most weight among fed fish.

Carcass yield was consistently higher for blue catfish and hybrids than for channel catfish, and fillet yield was higher for hybrids than other fish.

Although the catfish industry has taken a blow, further research on hybrids may yield what many farmers need to get back on the road to recovery.

Work continues to determine desirable heritable traits of catfish, improve germplasm for commercial production, and identify water-quality variables that limit production.

“I’m looking at how much better the hybrid fish is now and how much better these production systems have the potential to be, and I really think it is having an impact on the industry,” Bosworth says.