Reproductive benefits of no-take marine reserves vary with region for an exploited coral reef fish

A B Carter,A J Tobin,G R Russ,C R Davies,A J Williams,B D Mapstone,M J Emslie

doi:10.1038/s41598-017-10180-w

Abstract

No-take marine reserves (NTMRs) are expected to benefit fisheries via the net export of eggs and larvae (recruitment subsidy) from reserves to adjacent fished areas. Quantifying egg production is the first step in evaluating recruitment subsidy potential. We calculated annual egg production per unit area (EPUA) from 2004 to 2013 for the commercially important common coral trout, Plectropomus leopardus, on fished and NTMR reefs throughout the Great Barrier Reef (GBR), Australia. Geographic region, NTMR status, fish size, and population density were all found to affect EPUA. The interactions among these factors were such that, EPUA on NTMR reefs compared to reefs open to fishing was 21% greater in the southern GBR, 152% greater in the central GBR, but 56% less in the northern GBR. The results show that while NTMRs can potentially provide a substantial recruitment subsidy (central GBR reefs), they may provide a far smaller subsidy (southern GBR), or serve as recruitment sinks (northern GBR) for the same species in nearby locations where demographic rates differ. This study highlights the importance of considering spatial variation in EPUA when assessing locations of NTMRs if recruitment subsidy is expected from them.

Highlights

No-take marine reserves (NTMRs) are expected to benefit fisheries via the net export of eggs and larvae from reserves to adjacent fished areas
This study examines spatial variation in egg production per unit area (EPUA) among NTMRs within a reserve network for an exploited fish, the common coral trout (Plectropomus leopardus, Family Serranidae), using reproductive traits collected from both fished areas and NTMRs spread across 9° of latitude of the Great Barrier Reef (GBR)[9, 10]
Egg production was greatest on central GBR NTMR reefs (682,000 ± 65,200 oocytes 250 m−2 year−1) and lowest on southern fished reefs

Summary

Introduction

No-take marine reserves (NTMRs) are expected to benefit fisheries via the net export of eggs and larvae (recruitment subsidy) from reserves to adjacent fished areas. Geographic region, NTMR status, fish size, and population density were all found to affect EPUA The interactions among these factors were such that, EPUA on NTMR reefs compared to reefs open to fishing was 21% greater in the southern GBR, 152% greater in the central GBR, but 56% less in the northern GBR. No-take marine reserves (NTMRs) theoretically benefit nearby fisheries via the net export of adult fish (spillover) or eggs and larvae (recruitment subsidy), provided that protection from fishing and fish movement across. NTMRs are expected to contribute greater population recruitment compared with fished areas, because egg production per unit area (EPUA) is assumed to be greater inside NTMRs with greater densities of larger and more fecund females[5]. There had been little empirical evidence for recruitment subsidies from

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