Population Genetic Structure of Tunas Inferred from Molecular Markers: A Review

Abstract

In this study, we have reviewed the population genetic structure of eleven tuna species (albacore, bigeye, yellowfin, Pacific bluefin, Atlantic bluefin, southern bluefin, blackfin, longtail, skipjack, frigate, and little tuna) with a global perspective. Based on the studies using molecular markers, there are 50 genetically distinct populations of tuna species worldwide (12 albacore, 4 bigeye, 9 yellowfin, 4 bluefin, 2 blackfin, 2 longtail, 12 skipjack, 2 little tuna, and 3 frigate tuna). It is evident that some tunas (albacore, bigeye, yellowfin, bluefin, and skipjack) have got more attention of researchers than the others (longtail tuna, blackfin tuna, little tuna, and frigate tuna), possibly because of their higher commercial importance. So, the larger number of studies on some species of tuna might be the reason for the higher number of population structure observed. Also, relying on the results of a single molecular marker, which were used in some studies, may produce misleading conclusions. Therefore, complementary sets of markers should be used in assessing population structure. Still, the number of to date revealed genetically distinct populations in some tunas species (albacore, yellowfin, and skipjack) is higher than number of stocks managed by authorities grouped in tuna regional fisheries management organizations. It might be a signal for reevaluation of fishery management of such tunas.

Large‐scale genetic panmixia in the blue shark (Prionace glauca): A single worldwide population, or a genetic lag‐time effect of the “grey zone” of differentiation?

“…For example, Ely et al. () study found no genetic differentiation between nor within oceanic basins for skipjack tuna ( Katsuwonus pelamis ) while Kumar and Kocour review () reports several stocks/populations revealed by more recent studies with different mtDNA regions. Finally, the apparent panmixia between Atlantic and Indian Ocean populations of albacore ( Thunnus alalunga ) recorded with microsatellites (Montes et al., ) was recently demonstrated with SNP as hiding substructuration (Laconcha et al., ).…”

The population genomics of yellowfin tuna (Thunnus albacares) at global geographic scale challenges current stock delineation

“…The misspecification of genetically different populations may lead to management that negatively affects productivity and long-term stability of tuna populations, as well as the capacity of populations to respond to the variability of oceanic conditions and fishing pressures 5 , 6 . Designing stock-specific management plans and conservation policies tailored to life history traits, genetic structure and ecological dynamics would mitigate the risk of stock decline and irreversible collapse 1 , 7 , 8 .…”

“…high fecundity and large population size) that make it difficult to detect fine-scale genetic differentiation among populations by analysing only a few individuals and a small number of neutral loci (i.e. microsatellites, mitochondrial DNA) representative of a limited portion of the whole genetic variability 5 , 7 , 11 , 12 . The recent introduction of genome-wide Single Nucleotide Polymorphism (SNP) genotyping has increased the accuracy and speed of population genetic analyses at relatively low costs.…”

Genetic diversity of Atlantic Bluefin tuna in the Mediterranean Sea: insights from genome-wide SNPs and microsatellites

“…When investigating the population structure of a particular species, the limitations of the given study should always be considered. Furthermore, identification of the population structure is not always straightforward and there are cases where detection of genetic heterogeneity fails, despite its presence [ 58 ].…”