Connectivity patterns of anchovy larvae in the Bay of Biscay from a coupled transport-bioenergetic model forced by size-structured zooplankton

Type Proceedings paper
Date 2012
Language English
Author(s) Huret MartinORCID1, Vandromme Pieter2, Petitgas Pierre3, Pecquerie Laure4
Affiliation(s) 1 : IFREMER, Centre de Brest, STH, BP 70, 29280, Plouzané, France
2 : IFREMER, Centre de Brest, DYNECO, BP 70, 29280, Plouzané, France
3 : IFREMER, Centre de Nantes, EMH, BP 21105, 44311 Cedex 03, Nantes, France
4 : Univ. California, Santa Barbara, ERI, Santa Barbara CA, 93106-3060, USA
Meeting ICES-CIEM Annual Science Conference, Bergen
Source ICES CM 2012/E:14
Mot-Clé(s) Connectivity, Larval IBM, bioenergetics, zooplankton, Bay of Biscay, European anchovy
Abstract Connectivity during early life stages of pelagic fish, defined here by survival probability between spawning and early juvenile habitats, depends on a combination of sufficient food availability and low predator encounter along drift trajectories. For anchovy in the Bay of Biscay, larval transport experiments throughout the spawning season suggest accumulation of early juveniles in the offshore area of the southern Bay, as well as retention over the mid-shelf at mid-latitude. However, late summer-early autumn surveys suggest presence of juveniles only in the former region. From this observation, we set up a bioenergetic individual based model to test for the effect of food availability on survival patterns. The model couples a Lagrangian transport module to the hydrodynamic model MARS-3D, as well as a DEB (Dynamic Energy Budget) model for estimation of larval growth and mortality under starvation. Temperature is provided either from CTD casts or the hydrodynamic model, whereas food is provided by observation of size structured zooplankton biomass, from both in-situ LOPC (Laser Optical Plankton Counter) and Zooscan processing of net haul samples from the Pelgas survey in May. Results suggest that for early spawning season, most of the mortality from starvation occurs at early larval stage, mostly for eggs spawned in the deepest on-shelf and off-shelf areas. The southern bay of Biscay is more suitable for growth and survival than the north at that time of the year for both temperature and food limitations reasons. The offshore occurence of late larvae in the south is consistent with observations in the area, but our model is not able to simulate a general drift of the whole distribution, that would be consistent with late larvae mostly found over the slope and off-shelf. Further simulations should investigate whether this comes from interannual and seasonal patterns explanations, or whether our model lacks an important process such as spatially explicit predation.
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Huret Martin, Vandromme Pieter, Petitgas Pierre, Pecquerie Laure (2012). Connectivity patterns of anchovy larvae in the Bay of Biscay from a coupled transport-bioenergetic model forced by size-structured zooplankton. ICES CM 2012/E:14.