Food consumption pattern in the snow crab Chionoecetes opilio (Fabricius, 1788) (Decapoda, Majoidea) megalopae under laboratory conditions

Abstract

The food consumption pattern in megalopae of the snow crab Chionoecetes opilio (Fabricius, 1788) was investigated in the laboratory. Ten megalopae were individually cultured and given an excess of Artemia nauplii each day. All megalopae moulted into first-instar crabs 28-34 days after metamorphosis. The mean total number and total weight of Artemia consumed during the megalopal stage were 1920 individuals and 5.2 mg, respectively. Hence, the food requirement of snow crab megalopae was estimated as ∼190% of the dry body weight of the first-instar crab. Initially, the number of Artemia consumed was nearly constant or decreased only slightly but, later, Artemia consumption decreased with development days. Two-segmented regressions provided good fits to the relationship between the number of days after metamorphosis and the cumulative number of Artemia consumed by individual megalopae. The mean value of the time after metamorphosis of the breakpoint in the rate of food consumption was estimated as 69% of the stage duration, which corresponds to the intermediate of late premoult. Crab sizes (carapace width, wet and dry body weight) were not significantly dependent on the number of Artemia consumed during the entire megalopal period although a positive correlation between these variables was observed. These results provide useful information on the appropriate feeding schedule and management practice for culturing snow crab megalopae and contribute to the understanding of megalopal growth efficiency to the first-instar crab in their natural habitat.