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Genetic analyses reveal complex dynamics within a marine fish management area

Authors :: Thorsten B. H. Reusch
Henrik Mosegaard
Jan Dierking
Hans-Harald Hinrichsen
Holger Haslob
Marie Storr-Paulsen
Henrik Baktoft
Margit Eero
Karin Hüssy
Andres Velasco
Einar Eg Nielsen
Uwe Krumme
Jens-Peter Herrmann
Bastian Huwer
Dorte Bekkevold
Jakob Hemmer-Hansen
Burkhard von Dewitz
Source :: Evolutionary Applications, Evolutionary Applications, 12 (4). pp. 830-844., Hansen, J H, Hüssy, K, Baktoft, H, Huwer, B, Bekkevold, D, Haslob, H, Herrmann, J-P, Hinrichsen, H-H, Krumme, U, Mosegaard, H, Eg Nielsen, E, Reusch, T B H, Storr-Paulsen, M, Velasco, A, von Dewitz, B, Dierking, J & Eero, M 2018, ' Genetic analyses reveal complex dynamics within a marine fish management area ', Evolutionary Applications, vol. 12, pp. 830-844 . https://doi.org/10.1111/eva.12760, Evolutionary Applications, Vol 12, Iss 4, Pp 830-844 (2019)
Publication Year :: 2019
Publisher :: Wiley, 2019.
Abstract: Genetic data have great potential for improving fisheries management by identifying the fundamental management units—that is, the biological populations—and their mixing. However, so far, the number of practical cases of marine fisheries management using genetics has been limited. Here, we used Atlantic cod in the Baltic Sea to demonstrate the applicability of genetics to a complex management scenario involving mixing of two genetically divergent populations. Specifically, we addressed several assumptions used in the current assessment of the two populations. Through analysis of 483 single nucleotide polymorphisms (SNPs) distributed across the Atlantic cod genome, we confirmed that a model of mechanical mixing, rather than hybridization and introgression, best explained the pattern of genetic differentiation. Thus, the fishery is best monitored as a mixed‐stock fishery. Next, we developed a targeted panel of 39 SNPs with high statistical power for identifying population of origin and analyzed more than 2,000 tissue samples collected between 2011 and 2015 as well as 260 otoliths collected in 2003/2004. These data provided high spatial resolution and allowed us to investigate geographical trends in mixing, to compare patterns for different life stages and to investigate temporal trends in mixing. We found similar geographical trends for the two time points represented by tissue and otolith samples and that a recently implemented geographical management separation of the two populations provided a relatively close match to their distributions. In contrast to the current assumption, we found that patterns of mixing differed between juveniles and adults, a signal likely linked to the different reproductive dynamics of the two populations. Collectively, our data confirm that genetics is an operational tool for complex fisheries management applications. We recommend focussing on developing population assessment models and fisheries management frameworks to capitalize fully on the additional information offered by genetically assisted fisheries monitoring.