Selection responses were compared in 4 lines of channel catfish (lctalurus punctatus) selected for: (1) large 40-week body weight (W+), (2) large spawn weight (S+), (3) sma1l40-week body weight and large spawn weight (W-S+), and (4) large 40-week body weight and small spawn weight (W+S-). Each line comprised 4 spawns hatched into 4 sibling sets. Ten randomly selected fish from each sibling set (40 fish per line) were included in the study and were grown in 2 segments of a recirculating raceway system. Results indicated that single-trait selection for 40-week body weight was most effective in increasing body weight and total length 9 and 28 months after selection was made. Joint selection for body weight and spawn weight (W+S-) was not as effective as selection for body weight alone (W+) on improving growth. Both lines were, however, more effective in growth improvement than S+ and W-S+ lines. Selection for increased spawn weight (S+ or W-S+) reduced subsequent growth severely. An index selection should be constructed to select for both growth and reproduction traits.
