Evidence of Genetic Segregation among Meagre (Argyrosomus regius) Atlantic Spawning Areas

Abstract

The meagre Argyrosomus regius, one of the largest sciaenidae in the world, is a valuable resource for fisheries and aquaculture. Despite its socioeconomic relevance, knowledge about population dynamics and wild stocks is still scarce, and conservation risks are associated with overexploitation. Two genetic distinct groups, one in the North Atlantic Ocean and one in the eastern Mediterranean Sea, were identified by previous studies. However, little is known about the genetic structure of the Atlantic group, where four important spawning areas have been identified. To assess if each spawning area is an independent breeding unit, the genetic diversity, populational structure, and demographic history of A. regius along the North–East and Eastern Central Atlantic coast were analyzed, using 15 microsatellite loci. Results corroborate the hypothesis tested, suggesting four genetic groups: a first group encompassing individuals from the Gironde spawning area, a second group encompassing individuals from the Tagus spawning area, a third group corresponding to individuals captured in the Algarve region, and a forth group gathering individuals from Morocco and Mauritania. This study reveals the need for specific fisheries management plans considering genetic structure information, and highlights the need for international cooperation.

Long-distance migrations and seasonal movements of meagre (Argyrosomus regius), a large coastal predator, along the Iberian Peninsula coast

“…Until recently, information on meagre population structure and stock connectivity remained scarce and mostly based on indirect sources such as fisheries landings [ 24 ] and otolith geochemical signatures [ 46 ]. To date, only three studies have conducted DNA analyses to infer its population structure: Haffray et al [ 28 ] using 11 microsatellites and, more recently, Almeida et al [ 29 ] relying on 15 microsatellite loci and Abecasis et al [ 30 ] using a more powerful set of genome-wide SNP-genotyping and mitochondrial DNA. Although all three studies have reported an unexpectedly high degree of genetic differentiation between meagre populations (not only between the Atlantic and Mediterranean populations, but also within the Atlantic), our large movement and low residency data provide strong evidence against the hypothesis of restricted adult dispersal/movement as a mechanism for genetic isolation, as previously speculated [ 28 ].…”

“…Previous genetic studies have unveiled an unexpectedly high degree of population differentiation not only between the Atlantic and Mediterranean, but also between the West and South coasts of the Iberian Peninsula [ 28 , 29 ]. More recently, Abecasis et al [ 30 ] confirmed this populational subdivision through a multi-disciplinary approach, combining DArT sequencing and mitochondrial DNA analysis with biotelemetry and biophysical models.…”