Growth, feeding, and mortality of larval and early postlarval stages of the oceanic shrimp Sergestes similis Hansen

Abstract

Sergestes similis Hansen released from 670 to 1,140 eggs under laboratory conditions and was, for the first time, successfully reared from the egg to the 8th postlarval stage. Hatching viability, growth, mortality, and feeding during various developmental stages were investigated at four temperatures. Four phytoplankton and three zooplankton species were used as food. The optimum temperature range for larval development was 10°–15°C. The protozoeal stages, particularly the first and third, were the most critical in the development of S. similis. Growth rates were higher in the protozoeal and zocal than in the naupliar and postlarval stages. Average coefficients of daily exponential growth ranged from 0.021 to 0.098 during the larval and early postlarval stages. Filtering, clearance, and ingestion rates increased with increasing body weight and with particle size. Filtering rates changed with concentration of algal cells, suggesting the existence of a threshold value at lower algal density. However, the clearance rates were affected not by the density but only by the size of prey. When animals began predation, at the 2nd protozoeal stage, the size range of food particles and the volume over which the animals searched for food increased abruptly. The maximum daily ration ranged from 24 to 110% of body weight; it was highest in the protozoeal stages and gradually decreased afterward. The gross growth efficiency was 10–50% (average 32%) in the larval and postlarval stages.