High-density production of Southern King Crab (Lithodes santolla) juveniles in the field for stock enhancement

Abstract

The Southern King Crab -SKC- (Lithodes santolla) is a highly demanded gastronomic resource in South America, specially from tourism. As many others crab fisheries, the current state of L. santolla's population in the Beagle Channel is compromised, since the production of new recruits is below its potential. In this sense and in order to overcome this limitation, late efforts have been directed towards the development of efficient larvae and juvenile culture, either in hatcheries or in the field for future stock enhancement. With some progress in culturing larvae in hatcheries and some novel results on the feasibility of culturing juveniles in the field, the present study takes a step forward and addressed field culture at high density and for a mid-term period of 5 months. Field culture was performed in prefouled meshed-bags enclosures suspended in the water column. Thus, 2500 stage 1 SKC juveniles were massively cultured for 5 months and no external food provided. Over 62% of the juveniles survived and less than 10% were injured (i.e. lost appendages). The smallest and biggest crabs recovered were 2.20 and 7.05 mm of carapace length respectively. A total of 6 modal groups explained the size frequency distributions of the recovered crabs and over 70% of the survivors ranged between 3.75 and 4.75 mm of carapace length. In comparison with a previous work, our results also show that the longer the culture period, the grater the size disparity among crabs. The effectiveness of SKC juvenile massive culture in the field in terms of survival and growth is encouraging specially since the meshed-bags enclosure system stands as a low cost and low maintenance system to produce large numbers of bigger crabs. This knowledge is crucial in the context of the implementation of a stock enhancement program, which may help to L. santolla's population recovery in the Beagle Channel.