The stone crab Menippe spp. fishery is one of the most unusual fisheries in the world, because only claws are harvested, and animals are released to remain in the fishery via survival and claw regeneration. Florida accounts for the majority of landings, and there both claws can be removed if they are of legal size, but the fishery extends into South Carolina where only one legal-sized claw can be removed from a single crab. One of the major drivers of this fishery is the assumption that stone crabs survive claw harvest and regenerate, but Elizabeth Duermit (South Carolina Department of Natural Resources, Marine Resources Research Institute and Grice Marine Laboratory, College of Charleston) and her colleages found that this may not be the case due to both direct and indirect effects. They used a series of elegant experiments to determine that wound widths greater than 7 mm caused high post-removal mortality, and that wound size was more important than if one or both claws were taken. This suggests that fisher skill with claw removal was an important component underlying short-term survival, but there were also long-term effects in that stone crabs with one claw consumed fewer bivalves, and stone crabs with no claws could consume only fish flesh. Restricted feeding could exacerbate an already-long intermolt claw regeneration interval such that few stone crabs return to the fishery. And by examining stone crab claws for sale in retail environments, they found that 20% of the claws exhibited breakage consistent with high short-term mortality.
We featured this paper because it was elegant and creative, but also because it is a great example of how some long-held beliefs do not hold up when actually tested. And their work suggests that at least a proportion of mortality depends on fisher skill. The Florida Fish and Wildlife Commission (FFWC) has already established video outreach efforts to teach claw removal (youtube.com/ watch?v=YTgXTS8gLjU), but new knowledge of long-term effects may need to be considered to maintain this fishery, as well as outreach directed at providing science education to Youtube commenters.
Duermit, E., P. R. Kingsley-Smith, and D. H. Wilber. 2015. The consequences of claw removal on stone crabs Menippe spp. and the ecological and fishery implications. North American Journal of Fisheries Management 35(5):895-905. dx.doi.org/10.1080/02755947.2015.1064836
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