Genetic population structure of marine fish: mismatch between biological and fisheries management units

Abstract

Introduction 362Determination of populations and management units 363 Mismatch between management and biological units in the NE Atlantic 371Fisheries management and management units in the NE Atlantic 371Population structure of demersal fish species 372Cod 372Haddock 378Other demersal roundfish species 378Plaice 379Sole 379Other flatfish species 380 AbstractAn essential prerequisite of a sustainable fisheries management is the matching of biologically relevant processes and management action. In fisheries management and assessment, fish stocks are the fundamental biological unit, but the reasoning for the operational management unit is often indistinct and mismatches between the biology and the management action frequently occur. Despite the plethora of population genetic data on marine fishes, to date little or no use is made of the information, despite the fact that the detection of genetic differentiation may indicate reproductively distinct populations. Here, we discuss key aspects of genetic population differentiation in the context of their importance for fisheries management. Furthermore, we evaluate the population structure of all 32 managed marine fish species in the north-east Atlantic and relate this structure to current management units and practice. Although a large number of studies on genetic population structure have been published in the last decades, data are still rare for most exploited species. The mismatch between genetic population structure and the current management units found for six species (Gadus morhua, Melanogrammus aeglefinus, Merlangius merlangus, Micromesistius poutassou, Merluccius merluccius and Clupea harengus), emphasizes the need for a revision of these units and questions the appropriateness of current management measures. The implementation of complex and dynamic population structures into novel and less static management procedures should be a primary task for future fisheries management approaches.

Fine-scale spatial and temporal genetic structure of Atlantic cod off the Atlantic coast of the USA

“…Our findings are in accordance with a recent awareness of a mismatch between biological and management units for a number of commercially important marine fishes (Reiss et al 2009). Our results also add to the growing body of knowledge that marine fish populations do not conform to the classical panmictic population view, but rather are characterized by population structure on a much finer scale than expected from their dispersal and migratory abilities (Hauser & Carvalho 2008).…”

“…Our results suggest, therefore, that Atlantic cod are broadly structured into 3 complexes: (1) a northern spring-spawning coastal complex in the GOM, (2) a southern complex consisting of winterspawning inshore GOM, offshore GOM and sites south of Cape Cod, and (3) a Georges Bank complex. This population structure is temporally stable and the magnitude of genetic differentiation, while not large, is sufficient to assign juveniles to their complex of origin via mixture modeling.Our findings are in accordance with a recent awareness of a mismatch between biological and management units for a number of commercially important marine fishes (Reiss et al 2009). Our results also add to the growing body of knowledge that marine fish populations do not conform to the classical panmictic population view, but rather are characterized by population structure on a much finer scale than expected from their dispersal and migratory abilities (Hauser & Carvalho 2008).…”

“…The implications of such fine-scale population structure are important for effective management (Palumbi 2003, Bradbury et al 2008, Reiss et al 2009). …”

“…Our results also add to the growing body of knowledge that marine fish populations do not conform to the classical panmictic population view, but rather are characterized by population structure on a much finer scale than expected from their dispersal and migratory abilities (Hauser & Carvalho 2008). It may be warranted to re-evaluate current management units and tailor management plans toward this finer scale in light of the importance of managing for biologically meaningful units, based on concepts of ecological exchangeability and maintaining biodiversity and biocomplexity (Crandall et al 2000, Bradbury et al 2008, ICES 2009, Reiss et al 2009). …”

“…A growing body of literature points to the importance of processes that limit dispersal and promote self-replenishment of local populations, such as sedentary adult life history strategies (Robichaud & Rose 2004, Howell et al 2008, spawning site fidelity (Taggart 1997), natal homing (Thorrold et al 2001, Svedäng et al 2007), egg and larval retention (Jones et al 1999, 2005, Bradbury et al 2008) and local adaptation (McIntyre & Hutchings 2003, Conover et al 2006, Hutchings et al 2007). The implications of such fine-scale population structure are important for effective management (Palumbi 2003, Bradbury et al 2008, Reiss et al 2009). …”