Biological characteristics of a newly established green crab (Carcinus maenas) population in the southern Gulf of St. Lawrence, Canada

摘要

Various biological characteristics of the exotic green crab (Carcinus maenas) were studied in 2000 and 2001 to describe its population structure and reproductive strategy off the coast of Prince Edward Island (PEI), Canada. This particular population is found at the northern limit of the green crab distribution off the east American coast. Results showed that the number of female crabs was higher during springtime compared with the rest of the year. Male crabs were found in higher numbers from August to December. Ovigerous females were observed from early July to mid-September, their numbers peaking in early July. This was confirmed by a gonadosomatic analysis, which showed that the relative gonadal wet weight dropped from late July to mid-September 2001. Fecundity was estimated at 140,000-200,000 embryos per mass. Mating occurred after larval release, which occurred from late August to December with a peak in September. Mature males were molting from June to December, but mainly in July. This was observed a few weeks before mating. Size at maturity was estimated at a carapace width of 21.30-34.49 mm for males. Size at maturity for females was estimated at 28.66-41.43 mm. Overall, our results showed that most reproductive characteristics of the green crab's life cycle tend to occur about a month later in PEI in contrast to what is usually observed in Maine (USA).