Growth at moulth, intermoult period and moulting seasonality of the spider crab "Maja brachydactyla" : combining information from mark-recapture and experimental studies

Abstract

[Abstract] An analysis of growth at moult (for both the prepubertal and terminal moults), moulting seasonality and the intermoult period in the spider crab Maja squinado in the Ría de A Coruña (NW Spain) was carried out based on a mark-recapture experiment. Crabs between 70 and 130 mm carapace length (CL) undergo a mean increase at moult of 32.4% from their pre-moult size. Generalised Linear Models (GLMs) were used to construct growth models, employing a combination of information from the mark-recapture study and other previous studies performed in both laboratory and extensive culture, to estimate the effects of the biological variables and the study method. No differences were found in the growth rate between males and females. However, the effects of the study method, the premoult CL and the interaction between them were significant. The smallest-sized crabs undergo a greater increase in size in the laboratory and culture studies, while the largest individuals undergo greater growth in the field. The mean intermoult period estimated for prepubertal moults in the field ranged from 50 to 86 days, which Corgos et al., GROWTH AT MOULT OF MAJA BRACHYDACTYLA is similar to the 84.7 days observed in the laboratory study. The prepubertal moults occurred primarily in spring and autumn in the field, while under culture conditions, the crabs moulted mainly in the spring. The intermoult period for terminal moults was estimated to be around 90 days, slightly lower than the value of 104 days obtained in the laboratory. The terminal moult took place generally in summer (June-September) both at sea as well as in culture experiments. The intermoult period of juveniles at sea was highly variable, and some of the specimens did not moult for more than 5 months.