In two feeding trials conducted with juvenile Atlantic cod Gadus morhua (initial mean weight ¼ 87.9 or 15.92 g), soy protein concentrate (SPC) was used to replace fish meal in isonitrogenous, isocaloric diets. In the first trial, five experimental diets (47% protein, 15% fat; calculated gross energy ¼ 5,059 kcal/kg) were formulated to replace 28, 60, 80, and 100% of dietary fish meal. In the second trial, three diets were formulated with SPC to replace 0, 25, and 50% of the fish meal in a modified commercial diet for marine finfish (50% protein, 15% fat; calculated gross energy ¼ 4,900 kcal/kg; calculated digestible energy ¼ 3,570 kcal/kg). Upon conclusion of the studies, no differences in survival, growth, hepatosomatic index, or viscerosomatic index were found among the treatment groups. The fish attained mean weights of 162.7 and 39.1 g in the first and second trials, respectively, with specific growth rates of 0.76% and 1.12% and feed conversion ratios of 1.28 and 1.29, respectively. No consistent pattern of enteritis was observed in the histological sections taken from fish in either study. These results indicate that SPC can entirely replace fish meal in diets of juvenile Atlantic cod or can be combined with other common feed ingredients to replace up to 50% of dietary fish meal.

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.

Juvenile Atlantic cod Gadus morhua (initial mean weight ¼ 15.6 g) were fed three isonitrogenous, isocaloric diets (55% protein, 16% fat; calculated gross energy ' 20.5 MJ/kg) containing dried laver (nori) Porphyra spp. (red algae) to replace 0, 15, and 30% of the fish meal in a commercially available marine finfish diet. After 84 d, no differences in survival, growth, or hepatosomatic index were found among the treatment groups. The fish attained an average weight of 41.0 g, a specific growth rate (SGR) of 1.19%, and a feed conversion ratio (FCR) of 1.26. The fatty acid composition of the muscle was similar among treatment groups except that arachidonic acid levels were greater in fish given diets with 30% Porphyra replacement. These results indicate that Porphyra spp. at levels up to 30% provide a suitable fish meal replacement in diets for juvenile Atlantic cod.

A feeding trial was conducted with juvenile Atlantic cod Gadus morhua (initial mean weight, 40.7 g) in which a combination of dried Nannochloropsis sp. and Isochrysis sp. replaced fish meal protein in isonitrogenous, isocaloric diets. Three experimental diets (55% protein, 16.5% fat; calculated gross energy = 5,328 kcal/kg) were formulated to replace 0, 15, or 30% of dietary fish meal protein. At the conclusion of the 84‐d study, no differences in survival, feed conversion ratios, viscerosomatic indices, and n‐3 and n‐6 fatty acids in the muscle were found among the treatment groups. Feed intake and growth, which were proportional to the level of algal incorporation, were significantly reduced in the algae‐fed fish and were probably due to palatability problems. Feed intake improved in the fish fed the diet with 15% fish meal protein replacement as the study progressed, but hepatosomatic indices indicate that those fed the diet with 30% replacement were approaching starvation.Received July 13, 2010; accepted September 8, 2010

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.