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Marine Ecology Progress Series

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MEPS 710:71-83 (2023)  -  DOI:

Growth and population structure of bloody cockles Senilia senilis at Banc d’Arguin and Bijagós with different environmental conditions and harvesting regimes

El-Hacen M. El-Hacen1,2,3,*, Sidi Yahya Cheikhna Lemrabott1,4, Kasper J. Meijer1, Theunis Piersma1,2,5, Laura L. Govers1,5, Jan A. van Gils1,5, Han Olff1

1Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, PO Box 11103, 9700 CC Groningen, The Netherlands
2BirdEyes, Centre for Global Ecological Change at the Faculties of Science & Engineering and Campus Fryslân, University of Groningen, Zaailand 110, 8911 BN Leeuwarden, The Netherlands
3Parc National du Banc d’Arguin (PNBA), Rue Gleiguime Ould Habiboullah, B Nord No 100, BP 5355, Nouakchott, Mauritania
4Institut Mauritanien de Recherches Océanographiques et des Pêches (IMROP), BP 22, Nouadhibou, Mauritania
5NIOZ Royal Netherlands Institute for Sea Research, Department of Coastal Systems, PO Box 59, 1790 AB Den Burg, Texel, The Netherlands
*Corresponding author:

ABSTRACT: In addition to density-dependent (i.e. food availability) and independent (i.e. abiotic gradients) forces, size-selective harvests of organisms often induce changes to their life history, demography, and reproduction. Shellfish are increasingly overexploited worldwide, and the effect of size-selective harvest on their populations is unclear. The African bloody cockle Senilia senilis is a dominant bivalve in most West African coastal systems, where it is an important source of protein. Here, we studied its population structure (abundance, biomass, and size) and life history traits (age, annual growth rate, and size for age) under contrasting harvesting conditions at the 2 largest intertidal systems in the region: the Bijagós archipelago in Guinea-Bissau (harvested) and Banc d’Arguin in Mauritania (unexploited). To account for local ecological context, we assessed environmental variables that could also affect the abundance and size of S. senilis at these sites. We found that the S. senilis population at Bijagós is significantly denser and older, with lower standing biomass and smaller-sized shells than the population from Banc d’Arguin. In Bijagós, the annual growth is 3-fold lower, and the size-for-age is half of that at Banc d’Arguin. At both sites, S. senilis densities and sizes were correlated with habitat quality indicators: mangrove and mudflat productivity at Bijagós and seagrass and sediment characteristics at Banc d’Arguin. The smaller-sized mature individuals, denser populations, and lower standing biomass at Bijagós compared to Banc d’Arguin are indications of considerable size-selection pressure at Bijagós.

KEY WORDS: Banc d’Arguin (Mauritania) · Bijagós archipelago · Exploitation · Shellfish · Size-selective harvesting

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Cite this article as: El-Hacen EM, Lemrabott SYC, Meijer KJ, Piersma T, Govers LL, van Gils JA, Olff H (2023) Growth and population structure of bloody cockles Senilia senilis at Banc d’Arguin and Bijagós with different environmental conditions and harvesting regimes. Mar Ecol Prog Ser 710:71-83.

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