Extensive genetic population structure in the Indo–West Pacific spot-tail shark, <I>Carcharhinus sorrah</I>

Abstract

Carcharhinus sorrah (Mülle and Henle, 1839) is a coastal pelagic shark of the tropical and subtropical Indo-West Pacific, reaching 1.6 m total length. The species is widely harvested in line, net, and trawl fisheries over tropical continental shelves. We investigated mtDNA genetic differentiation in C. sorrah across the majority of the species' range, and examined the importance of six major historical and contemporary biogeographic features in shaping population genetic structure in this species. The present study includes dense sampling for a shark species across the Indo-West Pacific, with 349 specimens sampled from 21 collection locations from the northwestern Indian Ocean, southeast Asia, New caledonia, and to southerly distribution limits in Australia. based on 469 base pairs of the control region, we found extensive genetic population structure, with allopatric lineages confined to Australia, New caledonia, and the remaining surveyed area. significant genetic subdivisions were observed over stretches of deep water dividing shelf habitat, particularly the Indonesian Throughflow-timor Passage and coral sea, consistent with strong shelf habitat associated dispersal. Male length at maturity was consistent with a larger size throughout southeast Asia and the Arabian sea than known from Australia. Carcharhinus sorrah currently is assessed range-wide on the IUcN red List (Near Threatened) based largely on Australian demographic data, which may under-represent overharvest risk in other parts of the species' range. The present study highlights the need for independent risk assessment and management for C. sorrah in Australia, southeast Asia and the northwestern Indian Ocean, and New caledonia.

Congruent phylogeographic patterns in a young radiation of live‐bearing marine snakes: Pleistocene vicariance and the conservation implications of cryptic genetic diversity

“…This barrier was the strongest taxon filter among the 12 barriers investigated, filtering 72% of taxa in the north–south direction and 93% in the south–north direction (Treml et al., ); however, the Torres Strait was not included among the barriers investigated. These simulations suggest the presence of a generally unappreciated semipermeable barrier between the WAC and TS that may be restricting gene flow in low‐dispersal species (Treml et al., ), but which have not detected by previous genetic studies of some fish species (Giles et al., ; Liggins et al., ; van Herwerden et al., ).…”

Population genetics of four heavily exploited shark species around the Arabian Peninsula

“…; spot‐tail shark: Giles et al. ) or environmental gradients along continuous landmasses extending across different geographic regions (blacktip shark: Keeney and Heist ). In addition, the degree of species‐ and/or location‐specific genetic differentiation is typically reflected by a combination of individual vagility, foraging habits, habitat preferences, reproductive mode, and sensitivity toward natural and anthropogenic influences (Dudgeon et al.…”

Phylogeography, genetic stocks, and conservation implications for an Australian endemic marine turtle

“…Several marine species, in addition to flatback turtles, show evidence of past restrictions to gene flow across Torres Strait, including green turtles (Dethmers et al, ; Jensen et al, ), dugong ( Dugong dugon ) (Blair et al, ), and olive sea snakes ( Aipysurus laevis ) (Lukoschek, Waycott, & Marsh, ), but not hawksbill turtles (Vargas et al, ). Variable patterns have been found in sharks (Giles et al, ), barramundi (Keenan, ), reef fish, and invertebrates (Mirams, Treml, Shields, Liggins, & Riginos, ).…”