Growth, productivity and relative extinction risk of a data-sparse devil ray

Sebastián A Pardo,Oscar Sosa-Nishizaki,Holly K Kindsvater,Nicholas K Dulvy,Elizabeth Cuevas-Zimbrón,Juan Carlos Pérez-Jiménez

doi:10.1038/srep33745

Abstract

Devil rays (Mobula spp.) face intensifying fishing pressure to meet the ongoing international demand for gill plates. The paucity of information on growth, mortality, and fishing effort for devil rays make quantifying population growth rates and extinction risk challenging. Furthermore, unlike manta rays (Manta spp.), devil rays have not been listed on CITES. Here, we use a published size-at-age dataset for the Spinetail Devil Ray (Mobula japanica), to estimate somatic growth rates, age at maturity, maximum age, and natural and fishing mortality. We then estimate a plausible distribution of the maximum intrinsic population growth rate (rmax) and compare it to 95 other chondrichthyans. We find evidence that larger devil ray species have low somatic growth rate, low annual reproductive output, and low maximum population growth rates, suggesting they have low productivity. Fishing rates of a small-scale artisanal Mexican fishery were comparable to our estimate of rmax, and therefore probably unsustainable. Devil ray rmax is very similar to that of manta rays, indicating devil rays can potentially be driven to local extinction at low levels of fishing mortality and that a similar degree of protection for both groups is warranted.

Highlights

Devil rays (Mobula spp.) face intensifying fishing pressure to meet the ongoing international demand for gill plates
The degree to which devil ray populations can withstand current patterns and levels of fishing mortality depends on their intrinsic productivity, which determines their capacity to replace individuals removed by fishing
We examined multiple lines of evidence that suggest devil rays have relatively low productivity, and high risk of extinction compared to other chondrichthyans

Summary

Introduction

Devil rays (Mobula spp.) face intensifying fishing pressure to meet the ongoing international demand for gill plates. Understanding the sustainability and extinction risk of data-sparse species is a pressing problem for policy-makers and managers This challenge can be compounded by economic, social and environmental actions, as in the case of the mobulid rays (family Mobulidae). Slow somatic growth and large body size are associated with low productivity and elevated threat status and extinction risk in marine fishes, including elasmobranchs[9,10,11]. Based on these correlations, the American Fisheries

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