CONICET | Buscador de Institutos y Recursos Humanos

The fishery of Lithodes santolla is the second most productive lithodid crab fishery in the world and in southernmost South America is considered a mixed fishery due to its co-occurrence with Paralomis granulosa. Fishing takes place in Argentina and Chile, where regulations restrict to land only males larger than a legal size, but with variable fishing seasons. All females and small males must be returned to water. Both species have long periods of embryogenesis. Individual fishers operate on a small geographic scale, following lithodid crabs which are typically confined to channels, fjords or straits. Therefore females can be fished and discarded on multiple occasions throughout egg-bearing period. We studied the effect of the fishing practices on the fecundity of L. santolla and P. granulosa. First, we experimentally evaluated the effect of seven repeated return-to-water simulations in different conditions: aerial exposition or aerial exposition followed by a free fall (FF) or ramp. Secondly and only in L. santolla, we tested the effect on the egg-loss of different stocking densities followed by a FF return-to-water. Finally, we estimated the fecundity at the beginning and at the end of the egg-bearing period in females of L. santolla. The FF produced a high egg-loss and did not increase with the trial repetitions in L. santolla. Female P. granulosa showed a similar egg-loss pattern for all treatments, and overall lost fewer eggs than female L. santolla. In P. granulosa except for the FF, the trial repetition produced an increase in the egg-loss. In L. santolla there was no effect on the egg-loss due to stocking densities. Based on the field studies, fecundity of L. santolla decreased during the egg-bearing period. This study demonstrated the effects of repetitive fishing events on the fecundity in two lithodid species of commercial interest.