RECENT STUDIES ON THE CRAWFISH PALINURUS-ELEPHAS IN SOUTH WALES AND CORNWALL

From May 1993 until January 1994, 788 male and 1604 female crawfish, P alinurus elephas in total, were examined from the South Wales and Corn ish fisheries. Mean carapace length (CL) of Cornish crawfish was 125.6 mm for males, 132.4 mm for females and 135.0 mm for berried females, while mean CL for Welsh crawfish was 155.8 mm for males, 138.7 mm for females and 138.6 mm for berried females. The overall size distributio n of male Welsh crawfish differed significantly from that observed in the Cornish population. An analysis of variance gave significant (P<0. 05) differences for the factors; Site, Sex and the Sex/Site and Month/ Sex interactions. Male crawfish reached greater overall size than fema le crawfish, but for specimens of equal CL, total lengths (TL) of fema les were longer than those of males. Males were heavier than females o f equal CL or TL. Females bearing spermatophores were retrieved betwee n August and October. The first freshly berried females were observed in August, with 90% of Cornish females in berry by January. Incubation time was 8-9 months. The smallest berried female measured 90 mm CL. D issection of 40 females measuring 79-137 mm revealed ovaries typical o f those of other palinurids. Only two immature specimens were observed , both measuring 79 mm CL. Six stages of ovarian development were dist inguished. Dissection of 20 male crawfish measuring 89-169 mm CL also revealed testes similar to those of other palinurids, and no immature specimens were observed. Peak moulting was recorded in September for b oth male and female crawfish from both fisheries. Moult condition was recorded in conjunction with fouling level. Female crawfish outnumbere d males in both Cornish and Welsh landings throughout the season at a ratio of similar to 2:1. A record was also maintained of the occurrenc e of three distinct colour morphs, normal, sandy and brown. In the lab oratory, brittlestars and mussels were eaten more readily than fish. T hese results are discussed in relation to previous findings and relati ve to changes in fishing methods employed in the crawfish fishery over the past 30 years.