Growing reared spider crabs (Maja squinado) to sexual maturity: The first empirical data and a predictive growth model

In this paper, we report the first successful attempt to grow Maja squinado in captivity from larvae to sexual maturity. Eggs were obtained from wild-caught crabs in the laboratory. The larvae-juveniles were reared together to an age of 150-210 days. Subsequently, up to seven consecutive molts were individually monitored to an age of 490 days maximum. Based on these individually monitored crabs, a growth model was developed to predict the molting probability and molting increment as a function of sex, temperature, and pre-molt size. The predictions of the model show that the females (25-75% percentiles of the 7th monitored molt: 106 to 139 mm and 456 to 654 days) appear to have a lower but less variable growth rate than the males (98 to 152 mm and 378 to 518 days). The size at first maturity for females was estimated to be 103.6 mm. Although the model was parameterized using individuals raised in aquaculture, data and models of this type are very scarce for crustaceans and will be useful for managing the ongoing stocking program for M. squinado in the Balearic Islands. In addition, the full life cycle of the Mediterranean spider crab was completed in captivity. The mating of laboratory-reared crabs was repeatedly observed, and viable eggs and larvae were obtained from laboratory-reared adults.