Fishing catch shares in the face of global change: A framework for integrating cumulative impacts and single species management

Background/Question/Methods

Catch shares, or individual fishing quotas (IFQs), are a promising fisheries management method that allocates individual fishers a set portion of the total catch, and may reduce overcapitalization and promote sustainable fishing practices. Any management scheme, including catch shares, should be robust to potential shifts in the biophysical system.  Here we couple possible catch scenarios under an IFQ scheme with ocean acidification impacts on shelled benthos and plankton, using an Atlantis ecosystem model for the US West Coast.
Results/Conclusions

IFQ harvest scenarios alone in most cases did not have strong impacts on the food web, beyond the direct effects on harvested species. However, when we added impacts of ocean acidification, the abundance of commercially important groundfish such as English sole (Pleuronectes vetulus), arrowtooth flounder (Atheresthes stomias), and yellowtail rockfish (Sebastes flavidus) declined up to 20-80% due to the loss of shelled prey items from their diet. English sole exhibited a tenfold decline in potential catch and economic yield when confronted with strong acidification impacts on shelled benthos.  Therefore, it seems prudent to complement catch shares with careful consideration of potential climate change effects such as acidification. Our analysis provides an example of how new ecosystem modeling tools that evaluate cumulative impacts can be integrated with established management reference points and decision mechanisms.