The contribution of macroalgae‐associated fishes to small‐scale tropical reef fisheries

Wilson, Shaun K. and Fulton, Christopher J. and Graham, Nicholas A.J. and A. Abesamis, Rene and Berkström, Charlotte and Coker, Darren J. and Depczynski, Martial and Evans, Richard D. and Fisher, Rebecca and Goetze, Jordan and Hoey, Andrew and Holmes, Thomas H. and Kulbicki, Michel and Noble, Mae and Robinson, James P.W. and Bradley, Michael and Åkerlund, Carolina and Barrett, Luke T. and Bucol, Abner A. and Birt, Matthew J. and Chacin, Dinorah H. and Chong‐Seng, Karen M. and Eggertsen, Linda and Eggertsen, Maria and Ellis, David and Leung, Priscilla T. Y. and Lam, Paul K.S. and van Lier, Joshua and Matis, Paloma A. and Pérez‐Matus, Alejandro and Piggott, Camilla V.H. and Radford, Ben T. and Tano, Stina and Tinkler, Paul (2022) The contribution of macroalgae‐associated fishes to small‐scale tropical reef fisheries. Fish and Fisheries, 23 (4). pp. 847-861. ISSN 1467-2960

Abstract

Macroalgae‐dominated reefs are a prominent habitat in tropical seascapes that support a diversity of fishes, including fishery target species. To what extent, then, do macroalgal habitats contribute to small‐scale tropical reef fisheries? To address this question we: (1) Quantified the macroalgae‐associated fish component in catches from 133 small‐scale fisheries, (2) Compared life‐history traits relevant to fishing (e.g. growth, longevity) in macroalgal and coral‐associated fishes, (3) Examined how macroalgae‐associated species can influence catch diversity, trophic level and vulnerability and (4) Explored how tropical fisheries change with the expansion of macroalgal habitats using a case study of fishery‐independent data for Seychelles. Fish that utilised macroalgal habitats comprise 24% of the catch, but very few fished species relied entirely on macroalgal or coral habitats post‐settlement. Macroalgal and coral‐associated fishes had similar life‐history traits, although vulnerability to fishing declined with increasing contribution of macroalgae association to the catch, whilst mean trophic level and diversity peaked when macroalgal‐associated fish accounted for 20%–30% of catches. The Seychelles case study revealed similar total fish biomass on macroalgal and coral reefs, although the biomass of primary target species increased as macroalgae cover expanded. Our findings reinforce that multiple habitat types are needed to support tropical fishery stability and sustainability. Whilst coral habitats have been the focus of tropical fisheries management, we show the potential for macroalgae‐associated fish to support catch size and diversity in ways that reduce vulnerability to overfishing. This is pertinent to seascapes where repeated disturbances are facilitating the replacement of coral reef with macroalgal habitats.