THE BIOLOGY AND POPULATION ECOLOGY OF DEEP-SEA RED CRABS, CHACEON SPP. IN THE NORTH ATLANTIC OCEAN

Abstract

Red crab (Chaceon spp.) fishery resources exist on both sides on the North Atlantic, and the fisheries that harvest these resources seek to maintain their sustainability. To be able to conduct fishery assessments with less uncertainty, resource managers need a better understanding of the life history characteristics of the species, more recent information on the abundance and distribution of the resource, and finally reliable estimates of the levels of exploitation and the effects of harvesting of the resources. This study contributes to the body of knowledge of the resource in the western Atlantic resource and red crab fishery off the Northeast US coast, and of the resource in the eastern Atlantic and emerging red crab fishery in the Cape Verde Islands off West Africa. One aspect of this study assessed the characteristics of sea-sampled catches in the western and eastern Atlantic as indicators of population characteristics. In the western Atlantic, I investigated the past and current status of the population, changes in the size distribution of the red crab population due to fishing and the effects of discarding. I used data from a tagging study initiated in 2010 and 2004-2005 trawl survey by Dr. Richard Wahle of the University of Maine. I have supplemented these data with National Marine Fisheries Service trawl-survey data from 1974, and data that I collected in the summer of 2012 and 2013 aboard red crab commercial fishing vessels. In the eastern Atlantic, I used data collected during four exploratory fishing trips on a virgin resource located in the Cape Verde Islands. In general, the life history characteristics of red crab resources are similar in the western and eastern Atlantic in terms of carapace width and size-frequency iii distribution. Males are always larger than females. In the western Atlantic I found that there has been a size increase in the harvested male population between 2010 and 2012, and I hypothesize that this could be due to a decrease in fishing effort overall, or is a response to an effort to return the smaller males to the sea. I also documented that there is a discard mortality of male and female red crabs, but the level of this mortality is small, and interestingly, corresponds to a level reported by a previous researcher based on “hotel experiments.” The fishery in the western Atlantic, although certified sustainable by the Marine Stewardship Council, experiences the effects of moderate fishing intensity