Cold Tolerance and Fatty Acid Composition of Striped Bass, White Bass, and Their Hybrids

Cold tolerance of striped bass Morone saxatilis , white bass M. chrysops , palmetto bass (female striped bass × male white bass), and sunshine bass (female white bass × male striped bass) were compared under controlled laboratory conditions. Two groups of each taxon were acclimated at 20°C in a recirculating‐water system housed in an environmental chamber and were fed either a natural or prepared diet for 84 d. The fatty acid composition of the natural diet was 13% more unsaturated than that of the prepared diet. Fish fed the natural diet subsequently had unsaturated: Saturated fatty acid ratios 10‐25% higher than fish fed the prepared diet. After being subjected to identical simulated cold fronts (10°C drop in surface water temperature, as if the fish were confined in cages or pens), all groups of fish fed the prepared diet suffered high mortality (50‐90%) whereas there was zero mortality among the groups receiving the natural diet. White bass and sunshine bass fed the prepared diet had higher survival rates (50% and 40%, respectively) compared with their striped bass and palmetto bass counterparts (10% and 20%, respectively). The lower incipient lethal temperature was higher for fish fed the prepared diet (5.9, 4.8, 2.5, and 1.9°C for striped bass, palmetto bass, sunshine bass and white bass, respectively) than for those fed the natural diet (near 0.0°C, but 1.8°C for sunshine bass). Both studies reflect a maternal affect on cold tolerance, with white bass being most tolerant. We demonstrated that diet‐induced muscle fatty acid composition directly affects cold tolerance of striped bass, white bass, and their hybrids.