Blue Swimming Crab

(Portunus pelagicus and Portunus trituberculatus)

1. What is it?

Blue swimming crab (Portunus pelagicus & Portunus trituberculatus) are fast growing species that spawn several times in a season indicating they have a low vulnerability to fishing pressure. Fishing mortality is unknown but thought to be high.

2. How was it caught or farmed?

Blue swimming crabs are caught using demersal otter trawl nets. This type of trawling is known to damage the seabed; however the extent and impact of damage remains unknown. Trawling is not a very selective fishing method and a number of other species are often caught in the nets including endangered, threatened or protected species of sharks, rays and turtles. Detailed information on discards and bycatch are not available and the effect of removing significant amounts of crabs from the ecosystem cannot be determined.

3. Where is it from?

Blue swimming crabs are caught by a number of countries within FAO 51 and FAO 57 before being imported into South Africa. Management is largely uncertain as each country has its own individual management system. Only a few measurements are implemented but the effectiveness is unknown and enforcement weak.