Multiple-scale processes shape the population genetics of Tehuelche scallop, Aequipecten tehuelchus, in Northern Patagonia

Shell shape as an indicator of phenotypic stocks of Tehuelche scallop (Aequipecten tehuelchus) in Northern Patagonia, Argentina

“…While the tehuelchus morphotype is found in the warm-temperate waters from the Argentine Biogeographic province, the madrynensis morphotype inhabits the cold-temperate Magellanic province (Real et al, 2004;Trovant et al, 2019). The presence of the Peninsula Valdés tidal front in this region (Pisoni et al, 2015) seems to act as a physical barrier that partially constrains larval dispersal (Alfaya et al, 2020;Getino Mamet et al, 2021). The isolation resulting from such barrier might be strong enough to produce both the morphologic and genetic differentiation between morphotypes (Getino Mamet et al, 2021).…”

“…Tehuelche scallop, Aequipecten tehuelchus (d'Orbigny, 1846) is one of the main coastal shellfish resources that sustain a small-scale fishery in Northern Patagonia, Argentina (Elías et al, 2009;Getino Mamet et al, 2021). The species is found in shallow waters of the Southwestern Atlantic Ocean, between 23° to 45° latitude S, along the Argentine and Magellanic biogeographic provinces (Fig.…”

“…The fishery management in each provincial jurisdiction differs in the fishing method, the access regime, stock assessment, and quota allocation (Orensanz et al, 2007;Orensanz andSeijo, 2013, Getino et al, 2021). However, these scallop demes, belong to a single genetic stock being part of the tehuelchus morphotype (Getino Mamet et al, 2021). Combining captures from San José and San Matías gulfs, reported landings in 2020 were less than a thousand tons (Getino Mamet et al, 2021).…”

“…Genetic studies using allozymes (Real et al, 2004) and mitochondrial markers (Trovant et al, 2019) indicated an absence of differentiation among morphotypes at the species level. On the other hand, employing more variable microsatellites markers, genetic differentiation at the population level was detected between tehuelchus and madrynensis morphotypes following the biogeographical distribution of the morphotypes (Getino Mamet et al, 2021). Within the tehuelchus morphotype, scallops also present allometric variations (Ciocco, 1992;Márquez et al, 2010a).…”

“…However, these scallop demes, belong to a single genetic stock being part of the tehuelchus morphotype (Getino Mamet et al, 2021). Combining captures from San José and San Matías gulfs, reported landings in 2020 were less than a thousand tons (Getino Mamet et al, 2021). On the other hand, northerly and outside of this regular fishing region, a Tehuelche scallop bed was incidentally detected and exploited in a single fishing pulse near Buenos Aires Province in 2002 by the industrial Patagonian scallop fleet (Lasta and Campodónico, 2003;Soria et al, 2016) without fishing records afterward.…”