Juvenile Atlantic cod Gadus morhua (initial weight = 24.1 ± 1.4 g [mean ± SE) were fed diets in which fish meal (FM) was replaced with soy protein concentrate (SPC) and soybean meal (SBM) in isonitrogenous, isocaloric diets for 84 d. A standard marine finfish diet (3 mm, 54% protein, 14% fat) was modified to produce four experimental diets in which 50% of FM was replaced with soy at 0:1, 1:1, or 1:2 ratios of SPC:SBM and 100% FM replacement with a 1:1 ratio of SPC:SBM. No differences in mortality or feed intake were detected among treatments, and fish fed the 50% FM replacement diets, in any combination, grew as well or better than the control for all variables investigated. Cod fed the 100% FM replacement diet exhibited the lowest growth and differed from the control with respect to final body weight, growth, specific growth rate, and thermal‐unit growth coefficient. No enteritis was observed in histological sections. These results indicate that 100% fish meal replacement is not recommended, but 50% replacement can be used without significant reductions in growth or condition indices.

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Interest in cobia, Rachycentron canadum, culture has shown significant growth in recent years, but few hatcheries are available to support this developing industry. To facilitate the transport of cobia between facilities, four 24‐h experiments were conducted to examine the effects of density, temperature, and actual versus simulated transport on juvenile cobia (1.5–3.0 g) survival. Mortality during actual transport at fish densities of 5, 10, and 15 kg/m3 (2.9 ± 0.6, 2.9 ± 1.8, and 6.3 ± 0.8%, respectively) did not differ by treatment but was significantly higher than that during simulated transport at each density (0%). No differences in mortality were found following simulated shipping at 19, 21, and 25 C at 15 kg/m3. Significantly greater mortality occurred when juveniles were packed at 25 kg/m3 (10.4 ± 0.7%) than at 20 kg/m3 (1.9 ± 1.6%) and 15 kg/m3 (0.1 ± 0.1%). Recovery following simulated and actual shipping was high in all treatment groups. Under the conditions examined, results indicate that transport density should not exceed 20 kg/m3.

The rainbow smelt Osmerus mordax is a small anadromous fish that has potential as an aquaculture species because of its value as a premium baitfish. Three studies were conducted to establish a weaning protocol for larval rainbow smelt and to define the temperature and salinity ranges that support growth during their juvenile stages. In the first study, larvae were randomly assigned to one of two five‐phase weaning protocols that lasted for 2 or 3 d per phase (designated P2 and P3, respectively) and a control group that was fed Artemia metanauplii throughout the study (n = 3 tanks per treatment). In the second study, weaned juveniles (approximately 67 d posthatch) were cultured in triplicate tanks at 16, 20, and 24°C and 15 g/L salinity. In the third study, weaned juveniles (approximately 180 d posthatch) were cultured in triplicate tanks at 0, 5, and 15 g/L salinity and at 17°C. Survival in the P2 (20.3%) and P3 (28.4%) treatment groups did not differ, but survival in the P2 group was lower than that in controls (46%). Survival did not differ in weaned juveniles raised at different salinities or temperatures, but growth declined at temperatures higher than 16°C. A high degree of cannibalism was noted in the postmetamorphosed juveniles, and procedures must be developed to minimize this problem in commercial operations.