Genome-wide analysis reveals striking lack of genetic differentiation over long distances for the Antarctic Toothfish Dissostichus mawsoni: High genetic connectivity or shared spawning grounds?

CEBALLOS, SANTIAGO G.; CHIARA PAPETTI; MASSIMILIANO BABBUCCI; DANIEL ALFREDO FERNANDEZ; LUCA SCHIAVON; CHRISTINA CHENG

FISHERIES RESEARCH

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2021

0165-7836

The giant Antarctic toothfish Dissostichus mawsoni is one of the most economicallyvalued fishery resources from the Southern Ocean. However, the distinctive biologicalcharacteristics and life history of this species, including large body sizes, long life span,late sexual maturity, and specialization to freezing polar waters, make it particularlyvulnerable to overfishing and global climate change. It is therefore of fundamentalimportance to administer sound management and conservation actions to avoiddepletion of this unique species. The crucial issue of whether the species consists ofdistinct biological units or stocks, needed to inform appropriate management andconservation is currently unresolved. We report here the first RAD-seq analysis ofAntarctic toothfish populations, a powerful approach of genome-wide discovery of SNPloci, to assess genetic differentiation between the geographically distant individualsbetween CCAMLAR Subarea 48.1 locations (South Shetland Islands and WestAntarctic Peninsula coasts) and Subarea 88.1 (Ross Sea and McMurdo Sound). Werecovered 19,611 SNPs belonging to 13,251 widely shared loci. Comprehensivepopulation structure analyses unambiguously indicated absence of any significant levelof population differentiation, thus the null hypothesis of panmixia cannot be rejected.Together with currently known life history traits of D. mawsoni, we suggest thisstriking lack of genomic differentiation likely reflects high degrees of contemporaryand/or historical gene flow rather than shared spawning grounds. Complementaryanalyses particularly otolith microchemistry would contribute useful inference of natalorigins.