Differential gene flow patterns for two commercially exploited shark species, tope (Galeorhinus galeus) and common smoothhound (Mustelus mustelus) along the south–west coast of South Africa

Bitalo, Daphne Nyachaki; Maduna, Simo N.; Silva, Charlene da; Roodt‐Wilding, Rouvay; Merwe, Aletta E. Bester‐van der

doi:10.1016/j.fishres.2015.07.003

Cited by 14 publications

(15 citation statements)

References 39 publications

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“…In line with previous studies by Bitalo et al. () and Maduna et al. (), we detected interoceanic genetic structure in the common smooth‐hound across the Atlantic/Indian Ocean boundary.…”

Section: Discussionsupporting

confidence: 93%

“…Results from previous research indicated that levels of gene flow across the Atlantic/Indian Ocean boundary for the tope shark were relatively high (Bitalo et al, 2015), yet we found significant interoceanic genetic structure with two genetic clusters characterized by lower levels of admixture (SEAO and SWIO). The Bitalo et al (2015) study, however, included only one Indian Ocean population (Struis Bay) in close proximity to the proposed boundary and noted significant population differentiation between this SWIO sampling site and a SEAO sampling site, Robben Island. In addition, Bitalo et al (2015) did note that overall samples collected west of the Atlantic/Indian…”

Section: Discussioncontrasting

confidence: 55%

“…Results from previous research indicated that levels of gene flow across the Atlantic/Indian Ocean boundary for the tope shark were relatively high (Bitalo et al., ), yet we found significant interoceanic genetic structure with two genetic clusters characterized by lower levels of admixture (SEAO and SWIO). The Bitalo et al.…”

Section: Discussioncontrasting

confidence: 53%

“…The Bitalo et al (2015) study, however, included only one Indian Ocean population (Struis Bay) in close proximity to the proposed boundary and noted significant population differentiation between this SWIO sampling site and a SEAO sampling site, Robben Island. In addition, Bitalo et al (2015) did note that overall samples collected west of the Atlantic/Indian…”

Section: Discussionmentioning

confidence: 96%

“…In addition, Bitalo et al. () did note that overall samples collected west of the Atlantic/Indian Ocean boundary exhibited a more significant level of admixture than those collected east of the boundary. We conclude that the genetic structure observed in our study is in agreement with that of the previous study given our sampling locations for the species.…”

Section: Discussionmentioning

confidence: 99%

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Species identification and comparative population genetics of four coastal houndsharks based on novel NGS‐mined microsatellites

Maduna

Rossouw

Silva³

et al. 2017

Ecology and Evolution

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The common smooth-hound (Mustelus mustelus) is the topmost bio-economically and recreationally important shark species in southern Africa, western Africa, and Mediterranean Sea. Here, we used the Illumina HiSeq™ 2000 next-generation sequencing (NGS) technology to develop novel microsatellite markers for Mustelus mustelus. Two microsatellite multiplex panels were constructed from 11 polymorphic loci and characterized in two populations of Mustelus mustelus representative of its South African distribution. The markers were then tested for cross-species utility in Galeorhinus galeus, Mustelus palumbes, and Triakis megalopterus, three other demersal coastal sharks also subjected to recreational and/or commercial fishery pressures in South Africa. We assessed genetic diversity (N A , A R , H O , H E, and PIC) and differentiation (F ST and D est ) for each species and also examined the potential use of these markers in species assignment. In each of the four species, all 11 microsatellites were variable with up to a mean N A of 8, A R up to 7.5, H E and PIC as high as 0.842. We were able to reject genetic homogeneity for all species investigated here except for T. megalopterus. We found that the panel of the microsatellite markers developed in this study could discriminate between the study species, particularly for those that are morphologically very similar. Our study provides molecular tools to address ecological and evolutionary questions vital to the conservation and management of these locally and globally exploited shark species. K E Y W O R D Scross-amplification, Galeorhinus galeus, Illumina sequencing, microsatellites, Mustelus mustelus, Mustelus palumbes, Triakis megalopterus | INTRODUCTIONSharks play a crucial role in maintaining the ecological balance in marine ecosystems as keystone species, yet these animals are gradually declining worldwide in seascapes heavily impacted by humans (Dulvy et al., 2014). Such declines in wild populations not only will have negative ecological impacts on lower trophic species (Price, O'Bryhim, Jones, & Lance, 2015) but can also alter the levels and distribution of | 1463genetic diversity among populations (Dudgeon et al., 2012). It is likely that sharks may not respond well to population declines compared to other marine fishes owing to their K-selected life-history traits, i.e., slow growth, late maturity, and low reproductive outputs (Compagno, 1984;Ebert, Fowler, Compagno, & Dando, 2013). This highlights the need for conservation and management measures to ensure the sustainable utilization of these fishery resources. Implementing such measures often requires information on fishery dynamics, biological and baseline ecological data which in most cases are not yet available (Velez-Zuazo, Alfaro-Shigueto, Mangel, Papa, & Agnarsson, 2015).Molecular approaches have been very useful in providing insight into historical and contemporary demography of various commercially important shark species, especially with respect to population connectivity, stock structure, and m...

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“…In line with previous studies by Bitalo et al. () and Maduna et al. (), we detected interoceanic genetic structure in the common smooth‐hound across the Atlantic/Indian Ocean boundary.…”

Section: Discussionsupporting

confidence: 93%

Section: Discussioncontrasting

confidence: 55%

Section: Discussioncontrasting

confidence: 53%

Section: Discussionmentioning

confidence: 96%

Section: Discussionmentioning

confidence: 99%

See 3 more Smart Citations

Species identification and comparative population genetics of four coastal houndsharks based on novel NGS‐mined microsatellites

Maduna

Rossouw

Silva³

et al. 2017

Ecology and Evolution

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Distribution and population structure of the smooth‐hound shark, Mustelus mustelus (Linnaeus, 1758), across an oceanic archipelago: Combining several data sources to promote conservation

Espino

González

Bosch

et al. 2022

Ecology and Evolution

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Sharks play a key role in the structure and functioning of marine ecosystems. More ecological information is essential to implement responsible management and conservation actions on this fauna, particularly at a regional level for threatened species. Mustelus mustelus is widely found in the eastern Atlantic Ocean and catalogued as “Vulnerable” by the IUCN European assessment. In this study, data on the distribution and population structure of this species across the islands of the Canarian archipelago, located along an east to west gradient in the north‐eastern Atlantic, were collected by taking advantage of “Local Ecological Knowledge,” in terms of sightings in coastal waters and long‐term imprints on the local gastronomic heritage, and decadal fisheries landings. Both sources of quantitative data (sightings and fisheries landings) demonstrated that adults of M. mustelus has a significantly larger presence in the eastern and central, than in the western islands of the archipelago. This is also reflected on local gastronomic legacies, with a larger number of recipes in the eastern and central islands. Adult smooth‐hound sharks were significantly more observed in sandy and sandy‐rocky bottoms, with individuals seen throughout the entire year, whereas juveniles aggregate on very shallow waters in spring and summer. Such aggregations require a special management strategy, as they play a key role in critical life stages; these sites should be protected from human perturbations. We also suggest a temporal fishing ban between April and October, when individuals tend to concentrate on nearshore waters. Because of the large differences in presence of this shark among the Canary Islands, management of the species should be adapted to the specific peculiarities of each island, rather than adopting a management policy at the entire archipelago‐scale. Overall, this study sets the basis for further investigation to promote conservation of this vulnerable shark in the study region.

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The importance of considering genetic diversity in shark and ray conservation policies

2017

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Many populations of elasmobranchs (sharks and rays) are experiencing severe declines due to the high demand for shark fins in Asia, the activities of unregulated fisheries, and increases in shark and ray catches. Recently, the effects of the decline in the populations of marine fish species on genetic diversity have drawn increasing attention; however, only a few studies have addressed the genetic diversity of shark and ray populations. Here, we report the results of a quantitative analysis of the genetic diversity of shark and ray species over the past 20 years and discuss the importance and utility of this genetic information for fisheries management and conservation policies. Furthermore, we suggest future actions important for minimizing the gaps in our current knowledge of the genetic diversity of shark and ray species and to minimize the information gap between genetic scientists and policymakers. We suggest that shark and ray fisheries management and conservation policies consider genetic diversity information, such as the management unit, effective population size (Ne), haplotype and nucleotide diversity, observed heterozygosity, and allelic richness, because the long-term survival of a species is strongly dependent on the levels of genetic diversity within and between populations. In addition, sharks and rays are a group of particular interest for genetic conservation due to their remarkable life histories.

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Differential gene flow patterns for two commercially exploited shark species, tope (Galeorhinus galeus) and common smoothhound (Mustelus mustelus) along the south–west coast of South Africa

Cited by 14 publications

References 39 publications

Species identification and comparative population genetics of four coastal houndsharks based on novel NGS‐mined microsatellites

Species identification and comparative population genetics of four coastal houndsharks based on novel NGS‐mined microsatellites

Distribution and population structure of the smooth‐hound shark, Mustelus mustelus (Linnaeus, 1758), across an oceanic archipelago: Combining several data sources to promote conservation

The importance of considering genetic diversity in shark and ray conservation policies

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