Advancing fishery-independent stock assessments for the Norway lobster (Nephrops norvegicus) with new monitoring techn

The Norway lobster, Nephrops norvegicus, supports a key European fishery. Stock assessments for this species are mostly based on trawling and UnderWater TeleVision (UWTV) surveys. However, N. norvegicus are burrowing organisms and these survey methods are unable to sample or observe individuals in their burrows. To account for this, UWTV surveys generally assume that “1 burrow system = 1 animal”, due to the territorial behavior of N. norvegicus. Nevertheless, this assumption still requires in-situ validation. Here, we outline how to improve the accuracy of current stock assessments for N. norvegicus with novel ecological monitoring technologies, including: robotic fixed and mobile camera-platforms, telemetry, environmental DNA (eDNA), and Artificial Intelligence (AI). First, we outline the present status and threat for overexploitation in N. norvegicus stocks. Then, we discuss how the burrowing behavior of N. norvegicus biases current stock assessment methods. We propose that state-of-the-art stationary and mobile robotic platforms endowed with innovative sensors and complemented with AI tools could be used to count both animals and burrows systems in-situ, as well as to provide key insights into burrowing behavior. Next, we illustrate how multiparametric monitoring can be incorporated into assessments of physiology and burrowing behavior. Finally, we develop a flowchart for the appropriate treatment of multiparametric biological and environmental data required to improve current stock assessment methods

Les recherches françaises en évaluation quantitative et modélisation des ressources et des systèmes halieutiques : actes du colloque

La stratégie de pêche de la coquille Saint-Jacques (#Pecten maximus$, L.) en baie de Saint-Brieuc (Manche Ouest, France) a été développée au fil des années en franchissant plusieurs étapes caractérisées par des modifications de l'engin de pêche (adoption de la drague à volet, l'introduction de la lame renforcée au carbure), par la mise au point d'un système de gestion de la ressource par quota global pondéral et par l'accroissement de la puissance motrice par navire de pêche. La caractéristique principale de cette stratégie est la recherche de maximisation des rendements de pêche par concentration ou dispersion des bateaux de pêche selon l'état annuel de deux groupes d'âge-cibles. Ces principes ont été pris en compte pour bâtir des modèles de capturabilité pour les groupes d'âges 2 et 3 qui tiennent la place dominante dans la pêcherie. Les modèles utilisent comme variables explicatives l'abondance et la puissance motrice moyenne des navires de pêche. La validité des modèles devra être testée dans l'avenir. Dans la mesure où ces modèles seront jugés valables, ils garderont leur intérêt d'un point de vue prévisionnel car ils fourniront des réponses sur l'état du stock plus rapidement que l'analyse des cohortes. (Résumé d'auteur

Estimating MSY and MEY in multi-species and multi-fleet fisheries, consequences and limits: an application to the Bay of Biscay mixed fishery

Full text : http://archimer.ifremer.fr/doc/00129/24000/22053.pdf (Version "auteur", 0.50 Mo)International audienc

Distribution of Pecten maximus (L.) and its main potential competitors and predators in the Bay of Brest

International audienceThe distributions of Pecten maximus and its potential benthic competitors and predators in the Bay of Brest were studied from dredge samples to define best areas for seeding of scallop juveniles produced in hatcheries. Negative associations would occur between scallops and their main competitors (segregated distributions), reflecting negative density-dependent relationships between major epifaunal suspension feeders. Highest scallop densities at Roscanvel were not associated with high predator densities, in contrast to the ''Chenal de l'Aulne'' and Caro; this result could signify higher scallop survival in the former zone. Results would indicate a decrease of the area colonized by scallops in the Bay, when comparing to data from 1954/1955. This would be explained by increased sediment silting in several parts of the Bay and/or the proliferation of scallop competitors (large-sized epifaunal suspension feeders) or predators due to benthic community degradation

A stochastic viability approach to ecosystem-based fisheries management

International audienceAcademia and management agencies show a growing interest for ecosystem-based fishery management (EBFM). However, the way to operationalize this approach remains challenging. The present paper illustrates how the concepts of stochastic co-viability, which accounts for dynamic complexities, uncertainties, risk and sustainability constraints, can be useful for the implementation of EBFM. In the present case, this concept is used to identify fishing strategies that satisfy both ecological conservation and economic sustainability in a multi-species, multi-fleet context. Economic Viability Analysis (EVA) and the broader Co-Viability Analysis (CVA), are proposed to expand the usual Population Viability Analysis (PVA) and precautionary approach. An illustration is proposed, using data on the fisheries of Bay of Biscay (France) exploiting the stocks of nephrops and hake. Stochastic simulations show how CVA can guarantee both ecological (stock) and economic (profit) sustainability. Using 2008 as a baseline, the model is used to identify fishing efforts that ensure such co-viability. (C) 2012 Elsevier B.V. All rights reserved