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Filling biological information gaps of the marine topshell Phorcus sauciatus (Gastropoda: Trochidae) to ensure its sustainable exploitation
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Advisor(s)
Abstract(s)
Topshells play a pivotal role in intertidal rocky ecosystems and are adapted to harsh thermal
and hydric stress. Phorcus sauciatus, a common grazer in the Macaronesian region (Madeira
and the Canaries), has rarely been studied due to its restricted geographic distribution com pared with Phorcus lineatus. Monthly samples were taken throughout 2017 to analyse biological
parameters and evaluate the harvesting effect on the stocks of this species in Madeira.
Individuals of the first age classes (<4 years) were dominant (∼89%), while immature indivi duals were more abundant during the summer season. The spawning season occurs between
March and August, especially from March to June. The size at first maturity was 12.95 mm
long (1.68 years), with a continuous recruitment pattern throughout the year. Yield-per-recruit
analysis (Y/R) showed that maximum production is achieved at a fishing mortality of
1.7 year−1
, corresponding to a Y/R of 0.023 g. Currently, Phorcus sauciatus seems to be mod erately exploited in Madeira, but urgent conservation measures, such as a landing obligation,
the establishment of a minimum catch size of 15 mm length, and a closed season
(February–May), are warranted to preserve stocks of this species in the medium to long term.
Description
Keywords
Life history North-eastern Atlantic Phorcus sauciatus Sustainable exploitation Yield-per-recruit . Faculdade de Ciências da Vida
Citation
Sousa, R., Vasconcelos, J., Delgado, J., Riera, R., González, J. A., Freitas, M., & Henriques, P. (2019). Filling biological information gaps of the marine topshell Phorcus sauciatus (Gastropoda: Trochidae) to ensure its sustainable exploitation. Journal of the Marine Biological Association of the United Kingdom, 99(4), 841-849. https://doi.org/10.1017/S0025315418001054
Publisher
Cambridge University Press