MEPS 528:161-172 (2015)  -  DOI: https://doi.org/10.3354/meps11271

ABSTRACT: Spatial closures are an important component of regulations to protect cold-water corals and sponges from potential damage by bottom trawling. However, designing spatial closures can be challenging because the distribution of most cold-water coral and sponge habitat is unknown, and closures that overlap with fishing areas may reduce fishing opportunities and landings. In this paper, we examined trade-off relationships between bottom trawl fishery landings and the proportion of coral and sponge habitat protected by alternative spatial closure designs within Hecate Strait, British Columbia, Canada. We selected closures using a spatial optimization procedure involving 3 steps: (1) maximum entropy species distribution modelling to predict habitat suitability for Hexactinellida sponges and Alcyonacea and Pennatulacea corals, (2) matching habitat suitability predictions with spatially explicit estimates of bottom trawl landings value from at-sea observer data, and (3) Marxan spatial optimization to select closures that protect the most suitable coral and sponge habitat while minimizing losses in landings value. Our results suggest that the majority of coral and sponge habitat within Hecate Strait could be protected while maintaining existing fisheries value; spatial closures protecting up to 70% of the most suitable coral and sponge habitat resulted in negligible losses in trawl fishery landings. Protecting 99% of suitable coral and sponge habitats decreased landings value to 63% of its former total. Landings for rockfishes Sebastes and Sebastolobus spp. were the most sensitive to spatial closures, decreasing twice as much as average landings value for all groundfish species. By explicitly revealing potential trade-offs between fisheries and conservation objectives, our analysis provides a concrete starting point towards implementing spatial closures with increased transparency, credibility, and acceptability from stakeholders.

KEY WORDS: Bottom trawling · Cold-water corals and sponges · Conservation planning · Marxan · Maximum entropy · Species distribution modelling · Trade-offs