Accounting for the other 95% : conservation and assessment of data limited marine invertebrates in the Central Philippines

Intense human pressures require that conservation be nimble and action-oriented even in the face of significant data limitations. In the ocean, invertebrates comprise over 95% of animal biodiversity and are a major component of fisheries catch. Yet, exceedingly little effort is dedicated to supporting conservation of these taxa.

The goal of this thesis is to measure how coral reef invertebrates and invertebrate communities respond to conservation action based on limited data and then to suggest how such action can be tailored to maximize invertebrate abundance and reproductive output. I focused on no-fishing zones (marine reserves) and setting limitations on catch of juvenile animals in the Central Philippines—a region of immense ocean biodiversity, but also of enormous human fishing pressures.

In my first data chapter (Chapter 2) I focused on the best timing for sampling invertebrates and I found that surveys at night significantly increased detection, having large impacts on both the number of animals and the number of taxa observed for mobile species.

In Chapters 3 and 4, I examined if marine reserves increase invertebrate abundance and alter their communities. I found that reserves have 1.5 to 2.3 times more invertebrates for taxa important to local fisheries. The best outcomes were found in older reserves with complex habitats. Surprisingly, I found no correlation between abundance of fish and of invertebrates. Invertebrate communities often differed between fished and reserve areas, with the latter showing greater abundances for traits like bearing a shell and filter feeding.

In Chapter 5, I used invertebrate catch data from intertidal fisheries and developed indicators for reproductive output and fishing mortality. For some species, a substantial proportion of catch was either juvenile animals or animals below a body size that would otherwise optimize yield. Introducing a minimum size limit would substantially increase spawning output and yield. Given the significant challenges facing these taxa and the fisheries they support, I urge a combination of marine reserves and size-limits to conserve invertebrates. Such an approach should also support food security in the often marginalized fishers who rely upon them.

Gillespie, K.M. 2021. Accounting for the other 95% : conservation and assessment of data limited marine invertebrates in the Central Philippines. PhD dissertaion. The University of British Columbia.