Sexual maturity of the edible crab (Cancer pagurus) in the Skagerrak and the Kattegat, based on reproductive and morphometric characters

Abstract

Abstract Ungfors, A. 2007. Sexual maturity of the edible crab (Cancer pagurus) in the Skagerrak and the Kattegat, based on reproductive and morphometric characters. – ICES Journal of Marine Science, 64: 318–327. The size at the onset of sexual maturity of female and male edible crab (Cancer pagurus) from the Skagerrak and the Kattegat and the fecundity of females were estimated. Physiological maturity of females, i.e. ovary development, was at a larger size than behavioural maturity (indications of successful copulation). The carapace width (CW) at which 50% of females were mature (CW50), based on development of the gonads, was 132 mm, sperm presence gave a CW50 of 107 mm, and the presence of sperm plugs a CW50 of 118 mm. Changes in relative abdominal width were found at approximately 100 and 130 mm, and CW50 was 104 mm. A smaller fraction (25%) of the females is functionally mature at sizes <140 mm. However, male physiological and functional maturity was more synchronized: CW50s based on advanced sperm production and allometric changes in the chelae were within 5 mm (117–122 mm). Size-specific fecundity increases with CW (0.5–2.5 million eggs). Recommendations for a minimum landing size (MLS) of 140 mm and a change of escape gap size to 90 mm are given. Legislation of a MLS of 140 mm CW for females and males will reduce future potential landings more in the Skagerrak than in the Kattegat.