Genetic markers in marine fisheries: Types, tasks and trends

Thirty years of industrial fishing have led to overexploitation of many species, triggering the urgent need to better assess and manage marine stocks for sustainability. From the very simple definition of stock as “an exploited fishery unit” to its complex delimitation using ecosystem approaches, genetic approaches provide a large number of potential markers to unveil the underlying molecular background of complex biological phenomena in marine species.The present study is a diagnostic assessment of the number of scientific data published in marine fisheries using genetic technologies since the onset of NGS up to 2014. This state of the art approach would allow to derive causalities of real figures and to hypothesize trends in the use and applications of genetic markers. We first briefly overview pros and cons of current technologies used to delineate fish stocks and address intrapopulation knowledge deficits identified under an open population paradigm. Then, in order to assess the advancement of the application of molecular genetic techniques in “fish stock delineation” we review the work published on spatio-temporal structures of fish stocks. Finally, the datamining effort is enlarged across marine fisheries during the period 2004–20014 to decipher the intensity of use of genetic tools per taxa, the main application of each marker type and the trend of use of classic, modern and new generation techniques in fishery research tasks. Although microsatellites and mitochondrial DNA-based markers have being used at a growing pace in fishery research tasks until 2011, a time when application of gene sequencing and NGS-derived markers to fishery research has significantly grown. NGS technologies are underused in fishery science regarding their wide application in other research fields such as agriculture and aquaculture. So a significant increment of new genetic marker types is expected to be implemented in the near future. Conversely, application of classic marker types such as allozymes, AFLPs, whole mitochondrial genomes, RAPDs and RFLPs on mtDNA has been much less used in the period 2004–2014 following the advent of fast and cheap genotypic screening and NGS-derived markers. Power gain afforded from the combination of different genetic markers to address complex processes is lacking in current fishery research since only 21% of the studies over that period employed two genetic marker types and only 3% employed more than two.Combinations of methods would allow addressing management issues such as distribution shifts and population expansion in response to climatic fluctuations and global change, as well as overfishing and fishery collapses