Rights statement: This is an Accepted Manuscript of an article published by Taylor & Francis in African Journal of Marine Science on 15/11/2017, available online: http://www.tandfonline.com/10.2989/1814232X.2017.1364665
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Final published version
Research output: Contribution to Journal/Magazine › Journal article › peer-review
Research output: Contribution to Journal/Magazine › Journal article › peer-review
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TY - JOUR
T1 - Fishery benefits from exploiting spawning aggregations not solely dependent on enhanced fish density
AU - Robinson, Jan
AU - Graham, Nicholas Anthony James
AU - Gruss, A
AU - Gerry, C
AU - Bijoux, J
N1 - This is an Accepted Manuscript of an article published by Taylor & Francis in African Journal of Marine Science on 15/11/2017, available online: http://www.tandfonline.com/10.2989/1814232X.2017.1364665
PY - 2017
Y1 - 2017
N2 - The vulnerability of spawning aggregations to exploitation varies among fisheries as a result of differences in the population-density changes associated with this behaviour. However, vulnerability to fishing is also influenced by technology, environmental factors, and fish and fisher behaviours. Focusing on a fishery for the rabbitfish Siganus sutor at Praslin Island, Seychelles, we examined how catch rate varied across spawning and non-spawning habitats in relation to in situ population-density changes and other factors known to influence catchability. Catch rates in spawning habitat were disproportionate to density changes, being only fourfold greater than catch rates in non-spawning habitat, despite the fact that spawning-aggregation formation involved nine- to thirteen-fold increases in population density. Catch rates in spawning habitat were also highly variable across the spawning season (0–23.4 fish trap-hour−1). Current strength was of similar importance to density as a catch-rate predictor, with the highest catch rates in spawning habitats confined to months with the strongest currents. Therefore, in addition to density-dependent catchability, other factors that influence catch rates must be examined to avoid overestimation of the vulnerability of populations to aggregation fishing. The dynamics of catchability at spawning sites can limit the ability of fishers to predict and maximise returns based on increases in fish density.
AB - The vulnerability of spawning aggregations to exploitation varies among fisheries as a result of differences in the population-density changes associated with this behaviour. However, vulnerability to fishing is also influenced by technology, environmental factors, and fish and fisher behaviours. Focusing on a fishery for the rabbitfish Siganus sutor at Praslin Island, Seychelles, we examined how catch rate varied across spawning and non-spawning habitats in relation to in situ population-density changes and other factors known to influence catchability. Catch rates in spawning habitat were disproportionate to density changes, being only fourfold greater than catch rates in non-spawning habitat, despite the fact that spawning-aggregation formation involved nine- to thirteen-fold increases in population density. Catch rates in spawning habitat were also highly variable across the spawning season (0–23.4 fish trap-hour−1). Current strength was of similar importance to density as a catch-rate predictor, with the highest catch rates in spawning habitats confined to months with the strongest currents. Therefore, in addition to density-dependent catchability, other factors that influence catch rates must be examined to avoid overestimation of the vulnerability of populations to aggregation fishing. The dynamics of catchability at spawning sites can limit the ability of fishers to predict and maximise returns based on increases in fish density.
KW - catchability
KW - catch rates
KW - density dependence
KW - fishing effects
KW - reef fish
KW - Seychelles
KW - Siganidae
KW - trap fishery
KW - video survey
U2 - 10.2989/1814232X.2017.1364665
DO - 10.2989/1814232X.2017.1364665
M3 - Journal article
VL - 39
SP - 269
EP - 278
JO - African Journal of Marine Science
JF - African Journal of Marine Science
SN - 1814-2338
IS - 3
ER -