Fishery benefits from exploiting spawning aggregations not solely dependent on enhanced fish density

Robinson, Jan and Graham, Nicholas Anthony James and Gruss, A and Gerry, C and Bijoux, J (2017) Fishery benefits from exploiting spawning aggregations not solely dependent on enhanced fish density. African Journal of Marine Science, 39 (3). pp. 269-278. ISSN 1814-2338

PDF (Robinson et al_manuscript_v2)
Robinson_et_al_manuscript_v2.pdf - Accepted Version
Available under License Creative Commons Attribution-NonCommercial.

Download (156kB)


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.

Item Type:
Journal Article
Journal or Publication Title:
African Journal of Marine Science
Additional Information:
This is an Accepted Manuscript of an article published by Taylor & Francis in African Journal of Marine Science on 15/11/2017, available online:
Uncontrolled Keywords:
ID Code:
Deposited By:
Deposited On:
06 Dec 2017 14:30
Last Modified:
09 Dec 2022 00:32