Complex small pelagic fish population patterns arising from individual behavioral responses to their environment

Type Article
Date 2018-05
Language English
Author(s) Brochier Timothee1, 2, Auger Pierre-Amael3, 12, Pecquerie Laure4, Machu Eric3, 5, Capet Xavier6, Thiaw Modou7, Mbaye Baye Cheikh5, Braham Cheikh-Baye8, Ettahiri Omar9, Charouki Najib9, Sene Ousseynou Ndaw10, Werner Francisco11, Brehmer Patrice2, 4
Affiliation(s) 1 : Sorbonne Univ, IRD, Unite Modelisat Math & Informat Syst Complexes UM, Bondy, France.
2 : ISRA CRODT, UMR 195, IRD, Lab Sci Environm MARin Lemar, BP 1386, Dakar, Senegal.
3 : Univ Brest, CNRS, IRD, Ifremer,LOPS,IUEM, Brest, France.
4 : IRD, IUEM, Lab Sci Environm MARin LEMAR, Plouzane, France.
5 : UCAD, Ecole Super Polytech, LPAO SF, BP 5085, Dakar, Senegal.
6 : Univ Paris 06, CNRS, LOCEAN, Paris, France.
7 : CRODT, ISRA Pole Rech Hann, Dakar, Senegal.
8 : IMROP, BP 22, Nouadhibou, Mauritania.
9 : INRH, Bd Sidi Abderrahmane 2, Casablanca 20180, Morocco.
10 : UCAD, Fac Sci & Technol Educ Format FASTEF, GIRES, Ave Habib Bourguiba BP 5036, Dakar, Senegal.
11 : NOAH Fisheries, 1315 East West Highway, Silver Spring, MD 20910 USA.
12 : Pontificia Univ Catolica Valpara Iso, Escuela Ciencias Mar, IMO, Ave Altamirano 1480, Valpara Iso, Chile.
Source Progress In Oceanography (0079-6611) (Pergamon-elsevier Science Ltd), 2018-05 , Vol. 164 , P. 12-27
DOI 10.1016/j.pocean.2018.03.011
WOS© Times Cited 9
Keyword(s) Small pelagic fish, Sardinella aurita, Fish migration, Eastern boundary upwelling system, Individual based biophysical models, Dynamic energy budget
Abstract

Small pelagic fish (SPF) species are heavily exploited in eastern boundary upwelling systems (EBUS) as their transformation products are increasingly used in the world food chain. Management relies on regular monitoring, but there is a lack of robust theories for the emergence of the populations’ traits and their evolution in highly variable environments. This work aims to address existing knowledge gaps by combining physical and biogeochemical modelling with an individual life-cycle based model applied to round sardinella (Sardinella aurita) off northwest Africa, a key species for regional food security. Our approach focused on the processes responsible for seasonal migrations, spatio-temporal size-structure, and interannual biomass fluctuations. Emergence of preferred habitat resulted from interactions between natal homing behavior and environmental variability that impacts early life stages. Exploration of the environment by the fishes was determined by swimming capabilities, mesoscale to regional habitat structure, and horizontal currents. Fish spatio-temporal abundance variability emerged from a complex combination of distinct life-history traits. An alongshore gradient in fish size distributions is reported and validated by in situ measurements. New insights into population structure are provided, within an area where the species is abundant year-round (Mauritania) and with latitudinal migrations of variable (300 to 1200 km) amplitude. Interannual biomass fluctuations were linked to modulations of fish recruitment over the Sahara Bank driven by variability in alongshore current intensity. The identified processes constitute an analytical framework that can be implemented in other EBUS and used to explore impacts of regional climate change on SPF.

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Brochier Timothee, Auger Pierre-Amael, Pecquerie Laure, Machu Eric, Capet Xavier, Thiaw Modou, Mbaye Baye Cheikh, Braham Cheikh-Baye, Ettahiri Omar, Charouki Najib, Sene Ousseynou Ndaw, Werner Francisco, Brehmer Patrice (2018). Complex small pelagic fish population patterns arising from individual behavioral responses to their environment. Progress In Oceanography, 164, 12-27. Publisher's official version : https://doi.org/10.1016/j.pocean.2018.03.011 , Open Access version : https://archimer.ifremer.fr/doc/00433/54433/