Match/mismatch between biological and management units Two types of spatial units BIOLOGY MANAGEMENT Populations Stocks The historical demarcation of the ICES distribution areas is a measure of convenience. It implies gross simplifications and assumptions on the biology of the fish. The spatial organisation of the true population structure, connectivity and life-history traits are not taken into account in the ICES areas. In addition, the associated overexploitation leads to loss of genetic diversity and potential to adapt. Key Questions: 1. What levels of genetic differentiation between populations justify treatment as stocks that are managed separately? 2. How are these populations interrelated? Genetics to unravel population processes Connectivity of turbot and brill populations in European waters as a basis for sustainable management Sara Vandamme 1,2 , Kelle Moreau 1 , Gregory Maes 2 , Daan Delbare 1 , Stefan Hoffman 1 and Filip Volckaert² 1 Institute for Agricultural and Fisheries Research, Animal Sciences – Fisheries, Ankerstraat 1, 8400 Oostende, Belgium ² Katholieke Universiteit Leuven, Laboratory of Animal Diversity and Systematics, Ch. Deberiotstraat 32, 3000 Leuven, Belgium Similarities in biology, fishery and current management Habitat: sandy and stony bottoms down to 70 m, both salt and brackish waters Juvenile diet: benthivorous; adult diet: mainly piscivorous Spawning: April - August, pelagic eggs By-catch species in fisheries targeting demersal fish (sole, plaice, dab, cod, …) Fishing methods: bottom trawls (beam and otter), gillnets, trammel nets, long lines High commercial value No analytical assessment, only advice in Baltic based on historical trends EC requests analytical advice for all areas Measure Biological info Application Genetic Variation - Allelic diversity, A - Genetic consequences of demographic - Biodiversity conservation - Heterozygosity, H processes: population fluctuations, - Genetic effect of MPAs - Inbreeding, FIS reductions & bottlenecks - Genetic imprinting of fishing Abundance - Effective population size, Ne - Population dynamics - Stock assessment & management - Reproductive succes - Recruitement prediction Structure and - Spatial genetic differentiation - Population structure - Management units definition connectivity FST, RST, GST, D - Gene and migration flow - Delineation of MPAs - Temporal genetic divergence - Mixed fisheries assessment FST-Temporal ABOVE Distribution and density of turbot in Europe (fishbase.org). Brill has a similar distribution with much lower densities in the Baltic and Black Seas. Turbot Psetta maxima (© Luc Viatour) Institute for Agricultural and Fisheries Research, Animal Sciences – Fisheries Corresponding author : Sara .Vandamme @ ilvo.vlaanderen.be , +32(0)59/569896 OTX COD PLE SOL SRX INV TUR BLL COD PLE SOL SRX INV BLL TUR RIGHT Relative importance of turbot and brill in A) Belgian landings (all harbours) and B) Total Value of these landings, summed over the period 2000-2008. Note that both species show a significantly larger share in the value, illustrating their high commercial values. OTX Landings Value COD = Cod Gadus morhua PLE = Plaice Pleuronectes platessa SOL = Sole Solea solea SRX = Skates and Rays (Rajidae) TUR = Turbot Psetta maxima BLL = Brill Scophthalmus rhombus INV = invertebrates (crustaceans, shellfish and squid) OTX = all other fish Areas for stock assessments defined by the International Council for the Exploration of the Sea (ICES; www.ices.dk) Belgian Beam trawler (© Kelle Moreau) Future work: Delineation of biological populations based on genetics Characterisation and quantification of connectivity between populations Development of an appropriate assessment method taking these results into account