Differential susceptibility of blue catfish, Ictalurus furcatus (Valenciennes), channel catfish, I. punctatus (Rafinesque), and blue x channel catfish hybrids to channel catfish virus.

摘要

This study was conducted to determine the relative susceptibility of 4 different groups of fish to channel catfish virus (CCV): blue catfish; blue x channel hybrid; a group of channel catfish obtained from 10 farms in the Mississippi Delta (industry pool); and a new strain of catfish produced by the Catfish Genetics Research Unit of USDA. For each fish strain, 9 replicate tanks were stocked with 40 fish/tank. Eight tanks were used for virus challenge, whereas the remaining tank was used as uninfected control. Initial mortalities in all groups occurred within 2 days. Most mortalities occurred before day 6. Thereafter, mortalities were sporadic. The blue catfish were the most resistant fish, experiencing ~11% mortality, followed by the industry pool fish (47% mortality), blue x channel hybrids (63% mortality) and USDA 102 x 103 cross (68% mortality). The hybrids and USDA fish both had the highest daily mortalities on day 3 post-challenge. The industry pool fish and blue catfish had the highest mortalities on days 4 and 5, respectively. The percentage of CCV-positive fish among the mortalities examined varied according to strain. Some of the differences in mortality might be attributable to variation in size between the hybrids and channel catfish.