LIPID CONDITION AND SURVIVAL IN SHRIMP (PANDALUS-BOREALIS) LARVAE

Groups of shrimp (Pandalus borealis) larvae were reared under different food concentrations and types to assess changes in condition and survival during development. As expected, rate of growth (wet weight) was higher for larvae fed on 300 Artemia nauplii.L-1 (San Francisco strain: 0.0528 mg.d-1; Canada strain: 0.0355 mg.d-1) compared with those reared at 150 nauplii.L-1 (San Francisco strain: 0.0211 mg.d-1), larvae fed Isochrysis cells only, and no food. Shrimp larvae reared without food and larvae fed on Isochrysis cells showed a decreasing trend in wet weight during development and did not survive beyond stage II. The triacylglycerol (TAG) content of larvae accumulated rapidly during the initial phase of intermoult followed by a decline to a minimum coincident with ecdysis. High mortality (average 2.2%.d-1) occurred during the first phases of development (first 25 d) for all rations. Differences among experiments in the magnitude of the mortality (from 0.86 to 4.66%.d-1) at the first moult were related to the proportion of larvae in poor TAG condition. The results are consistent with the concept that the TAG condition index can be used to forecast, on a relative basis, differential survival among larval groups.