1
|
Jackson TK, Rhode C. Comparative genomics of dusky kob (Argyrosomus japonicus, Sciaenidae) conspecifics: Evidence for speciation and the genetic mechanisms underlying traits. JOURNAL OF FISH BIOLOGY 2024. [PMID: 38885946 DOI: 10.1111/jfb.15844] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 04/17/2024] [Accepted: 05/28/2024] [Indexed: 06/20/2024]
Abstract
Dusky kob (Argyrosomus japonicus) is a commercially important finfish, indigenous to South Africa, Australia, and China. Previous studies highlighted differences in genetic composition, life history, and morphology of the species across geographic regions. A draft genome sequence of 0.742 Gb (N50 = 5.49 Mb; BUSCO completeness = 97.8%) and 22,438 predicted protein-coding genes was generated for the South African (SA) conspecific. A comparison with the Chinese (CN) conspecific revealed a core set of 32,068 orthologous protein clusters across both genomes. The SA genome exhibited 440 unique clusters compared to 1928 unique clusters in the CN genome. Transportation and immune response processes were overrepresented among the SA accessory genome, whereas the CN accessory genome was enriched for immune response, DNA transposition, and sensory detection (FDR-adjusted p < 0.01). These unique clusters may represent an adaptive component of the species' pangenome that could explain population divergence due to differential environmental specialisation. Furthermore, 700 single-copy orthologues (SCOs) displayed evidence of positive selection between the SA and CN genomes, and globally these genomes shared only 92% similarity, suggesting they might be distinct species. These genes primarily play roles in metabolism and digestion, illustrating the evolutionary pathways that differentiate the species. Understanding these genomic mechanisms underlying adaptation and evolution within and between species provides valuable insights into growth and maturation of kob, traits that are particularly relevant to commercial aquaculture.
Collapse
Affiliation(s)
- Tassin Kim Jackson
- Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| | - Clint Rhode
- Department of Genetics, Stellenbosch University, Stellenbosch, South Africa
| |
Collapse
|
2
|
Shen Y, Hussey NE, David M, Wu F, Li Y. Vertebral microchemistry as an indicator of habitat use of the oceanic whitetip shark Carcharhinus longimanus in the central and eastern Pacific Ocean. JOURNAL OF FISH BIOLOGY 2024; 104:1732-1742. [PMID: 38445757 DOI: 10.1111/jfb.15705] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2024] [Accepted: 02/13/2024] [Indexed: 03/07/2024]
Abstract
The oceanic whitetip shark, Carcharhinus longimanus, is a highly migratory, epipelagic top predator that is classified as critically endangered. Although this species is widely distributed throughout the world's tropical oceans, its assumed mobility and pelagic behavior limit studies to derive required lifetime data for management. To address this data deficiency, we assessed variation in the habitat use of C. longimanus by oceanic region and over ontogeny through time series trace element and stable isotope values conserved along the vertebral centra (within translucent annulus bands) of 13 individuals sampled from the central and eastern Pacific Ocean. Elemental ratios of Mg:Ca, Mn:Ca, Fe:Ca, Zn:Ca, and Ba:Ca varied significantly among individuals from both sampling regions while principal component analysis of combined standardized elements revealed minimal overlap between the two areas. The limited overlap was also in agreement with stable isotope niches. These findings indicate that C. longimanus exhibit a degree of fidelity to sampling regions but also connectivity in a proportion of the population. The relatively stable Sr:Ca ratio supports its occurrence in oceanic environments. The decreasing trends in Ba:Ca, Mn:Ca, and Zn:Ca ratios, as well as in carbon and nitrogen isotope values along vertebral transects, indicate that C. longimanus undergo a directional habitat shift with age. Combined elemental and stable isotope values in vertebral centra provide a promising tool for elucidating lifetime data for complex pelagic species. For C. longimanus, management will need to consider subpopulation movement behavior in the Pacific to minimize the potential for localized depletions. Further work is now required to sample individuals across the entire Pacific and to link these findings with genetic and movement data to define population structure.
Collapse
Affiliation(s)
- Yongfu Shen
- College of Marine Living Resources and Management, Shanghai Ocean University, Shanghai, China
| | - Nigel E Hussey
- Department of Integrative Biology, University of Windsor, Windsor, Ontario, Canada
| | - Mboglen David
- College of Marine Living Resources and Management, Shanghai Ocean University, Shanghai, China
| | - Feng Wu
- College of Marine Living Resources and Management, Shanghai Ocean University, Shanghai, China
- The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, Shanghai, China
- National Engineering Research Centre for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| | - Yunkai Li
- College of Marine Living Resources and Management, Shanghai Ocean University, Shanghai, China
- The Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, Shanghai, China
- National Engineering Research Centre for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China
| |
Collapse
|
3
|
Harned SP, Bernard AM, Salinas‐de‐León P, Mehlrose MR, Suarez J, Robles Y, Bessudo S, Ladino F, López Garo A, Zanella I, Feldheim KA, Shivji MS. Genetic population dynamics of the critically endangered scalloped hammerhead shark ( Sphyrna lewini) in the Eastern Tropical Pacific. Ecol Evol 2022; 12:e9642. [PMID: 36619714 PMCID: PMC9797937 DOI: 10.1002/ece3.9642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Revised: 11/17/2022] [Accepted: 11/30/2022] [Indexed: 12/30/2022] Open
Abstract
The scalloped hammerhead shark, Sphyrna lewini, is a Critically Endangered, migratory species known for its tendency to form iconic and visually spectacular large aggregations. Herein, we investigated the population genetic dynamics of the scalloped hammerhead across much of its distribution in the Eastern Tropical Pacific (ETP), ranging from Costa Rica to Ecuador, focusing on young-of-year animals from putative coastal nursery areas and adult females from seasonal aggregations that form in the northern Galápagos Islands. Nuclear microsatellites and partial mitochondrial control region sequences showed little evidence of population structure suggesting that scalloped hammerheads in this ETP region comprise a single genetic stock. Galápagos aggregations of adults were not comprised of related individuals, suggesting that kinship does not play a role in the formation of the repeated, annual gatherings at these remote offshore locations. Despite high levels of fisheries exploitation of this species in the ETP, the adult scalloped hammerheads here showed greater genetic diversity compared with adult conspecifics from other parts of the species' global distribution. A phylogeographic analysis of available, globally sourced, mitochondrial control region sequence data (n = 1818 sequences) revealed that scalloped hammerheads comprise three distinct matrilines corresponding to the three major world ocean basins, highlighting the need for conservation of these evolutionarily unique lineages. This study provides the first view of the genetic properties of a scalloped hammerhead aggregation, and the largest sample size-based investigation of population structure and phylogeography of this species in the ETP to date.
Collapse
Affiliation(s)
- Sydney P. Harned
- Save Our Seas Foundation Shark Research Center and Guy Harvey Research InstituteNova Southeastern UniversityDania BeachFloridaUSA
| | - Andrea M. Bernard
- Save Our Seas Foundation Shark Research Center and Guy Harvey Research InstituteNova Southeastern UniversityDania BeachFloridaUSA
| | - Pelayo Salinas‐de‐León
- Save Our Seas Foundation Shark Research Center and Guy Harvey Research InstituteNova Southeastern UniversityDania BeachFloridaUSA,Charles Darwin Research StationCharles Darwin FoundationGalápagos IslandsEcuador
| | - Marissa R. Mehlrose
- Save Our Seas Foundation Shark Research Center and Guy Harvey Research InstituteNova Southeastern UniversityDania BeachFloridaUSA
| | - Jenifer Suarez
- Direccion Parque Nacional GalápagosDepartamento de Ecosistemas MarinosIslas GalápagosEcuador
| | - Yolani Robles
- Universidad de Panamá, Centro Regional Universitario de VeraguasSan Martín de PorresPanama
| | - Sandra Bessudo
- Fundacion Malpelo y Otros Ecosistemas MarinosBogotáColombia
| | - Felipe Ladino
- Fundacion Malpelo y Otros Ecosistemas MarinosBogotáColombia
| | - Andrés López Garo
- Asociación Conservacionista Misión Tiburon, Playas del CocoCarrilloGuanacasteCosta Rica
| | - Ilena Zanella
- Asociación Conservacionista Misión Tiburon, Playas del CocoCarrilloGuanacasteCosta Rica
| | - Kevin A. Feldheim
- Pritzker Laboratory for Molecular Systematics and EvolutionField Museum of Natural HistoryChicagoIllinoisUSA
| | - Mahmood S. Shivji
- Save Our Seas Foundation Shark Research Center and Guy Harvey Research InstituteNova Southeastern UniversityDania BeachFloridaUSA
| |
Collapse
|
4
|
Population structure and genetic connectivity of the scalloped hammerhead shark (Sphyrna lewini) across nursery grounds from the Eastern Tropical Pacific: Implications for management and conservation. PLoS One 2022; 17:e0264879. [PMID: 36525407 PMCID: PMC9757582 DOI: 10.1371/journal.pone.0264879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Accepted: 08/18/2022] [Indexed: 12/23/2022] Open
Abstract
Defining demographically independent units and understanding patterns of gene flow between them is essential for managing and conserving exploited populations. The critically endangered scalloped hammerhead shark, Sphyrna lewini, is a coastal semi-oceanic species found worldwide in tropical and subtropical waters. Pregnant females give birth in shallow coastal estuarine habitats that serve as nursery grounds for neonates and small juveniles, whereas adults move offshore and become highly migratory. We evaluated the population structure and connectivity of S. lewini in coastal areas and one oceanic island (Cocos Island) across the Eastern Tropical Pacific (ETP) using both sequences of the mitochondrial DNA control region (mtCR) and 9 nuclear-encoded microsatellite loci. The mtCR defined two genetically discrete groups: one in the Mexican Pacific and another one in the central-southern Eastern Tropical Pacific (Guatemala, Costa Rica, Panama, and Colombia). Overall, the mtCR data showed low levels of haplotype diversity ranging from 0.000 to 0.608, while nucleotide diversity ranged from 0.000 to 0.0015. More fine-grade population structure was detected using microsatellite loci where Guatemala, Costa Rica, and Panama differed significantly. Relatedness analysis revealed that individuals within nursery areas were more closely related than expected by chance, suggesting that S. lewini may exhibit reproductive philopatric behaviour within the ETP. Findings of at least two different management units, and evidence of philopatric behaviour call for intensive conservation actions for this highly threatened species in the ETP.
Collapse
|
5
|
Rodriguez-Arana Favela JP, Hernández S, González-Armas R, Galván-Magaña F, Tripp-Valdez A, Hoyos-Padilla M, Ketchum JT. A priority nursery area for the conservation of the scalloped hammerhead shark Sphyrna lewini in Mexico. JOURNAL OF FISH BIOLOGY 2022; 101:1623-1627. [PMID: 36208114 DOI: 10.1111/jfb.15227] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Accepted: 09/15/2022] [Indexed: 06/16/2023]
Abstract
This study describes the genetic diversity and level of genetic differentiation of the scalloped hammerhead shark Sphyrna lewini from eight putative nursery areas in the Mexican Pacific Ocean, using the mtDNA control region. Genetic analyses revealed a particular spatial divergence between La Reforma and all the remaining sites, with five exclusive haplotypes and the highest genetic diversity. This pattern may be interpreted as the signature of regional female philopatry, relatively to a particular female-mediated gene flow for La Reforma, which shows a strong subdivision in the Gulf of California.
Collapse
Affiliation(s)
- Juan P Rodriguez-Arana Favela
- Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, La Paz, Mexico
- Pelagios Kakunja A.C., La Paz, Mexico
| | - Sebastián Hernández
- Biomolecular Laboratory, Center for International Programs and Sustainability Studies, Universidad Veritas, San José, Costa Rica
- Sala de Colecciones, Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chile
| | - Rogelio González-Armas
- Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, La Paz, Mexico
| | - Felipe Galván-Magaña
- Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, La Paz, Mexico
| | - Arturo Tripp-Valdez
- Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, La Paz, Mexico
| | | | - James T Ketchum
- Pelagios Kakunja A.C., La Paz, Mexico
- MigraMar, Bodega Bay, California, USA
- Centro de Investigaciones Biológicas Noroeste (CIBNOR), La Paz, Mexico
| |
Collapse
|
6
|
Villate-Moreno M, Cubillos-M JC, Stibor H, Crawford AJ, Straube N. Molecular identification and first demographic insights of sharks based on artisanal fisheries bycatch in the Pacific Coast of Colombia: implications for conservation. PeerJ 2022; 10:e13478. [PMID: 35945934 PMCID: PMC9357375 DOI: 10.7717/peerj.13478] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Accepted: 05/01/2022] [Indexed: 01/17/2023] Open
Abstract
The Pacific coast of Colombia is characterized by mangrove ecosystems which play a crucial role as possible nurseries for juvenile sharks. However, trophic food webs from coastal ecosystems are heavily disturbed by increased fishing pressure, which affects numerous shark species. In this region of the Eastern Tropical Pacific (ETP), fisheries' data from coastal areas are scarce and unspecific, as most sharks from artisanal fisheries are landed decapitated and finless, making their morphological identification difficult. For the establishment and implementation of effective regional conservation and management policies, information on the diversity and population dynamics of shark species is crucial. We therefore sequenced the mitochondrial NADH2 gene of 696 samples taken from fishermen's landings of shark's bycatch along the Colombian north Pacific coast. We were able to identify 14 species of sharks, two of the most abundant species were Sphyrna lewini and Carcharhinus falciformis, both evaluated on IUCN the Red List of Threatened species (Critically Endangered and Vulnerable) and CITES regulated. We found low genetic diversity in the sampled area increasing the concern for both species in the region, even more considering that the majority of individuals were juveniles. Our results showed the importance of genetic markers for first population genetic insights as a complementary tool during the decision-making process in management plans. For this specific region, strategies such as the delimitation of conservation priority areas or the regulation of fishing gears could help improve the sustainability of shark populations in the Colombian Pacific.
Collapse
Affiliation(s)
- Melany Villate-Moreno
- Fundación MarAdentro, Bahía Solano, Colombia,Aquatic Ecology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany,SNSB- Bavarian State Collection of Zoology, Munich, Germany
| | - Juan Camilo Cubillos-M
- Ecological Genomics Group, Institute of Biology and Environmental Sciences, University of Oldenburg, Oldenburg, Germany
| | - Herwig Stibor
- Aquatic Ecology, Department Biology II, Ludwig-Maximilians-Universität München, Planegg-Martinsried, Germany
| | - Andrew J. Crawford
- Department of Biological Sciences, Universidad de Los Andes, Bogotá, Colombia
| | - Nicolas Straube
- SNSB- Bavarian State Collection of Zoology, Munich, Germany,Department of Natural History, University Museum of Bergen, Bergen, Norway
| |
Collapse
|
7
|
Cerutti-Pereyra F, Salinas-De-León P, Arnés-Urgellés C, Suarez-Moncada J, Espinoza E, Vaca L, Páez-Rosas D. Using stable isotopes analysis to understand ontogenetic trophic variations of the scalloped hammerhead shark at the Galapagos Marine Reserve. PLoS One 2022; 17:e0268736. [PMID: 35687546 PMCID: PMC9187089 DOI: 10.1371/journal.pone.0268736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 05/02/2022] [Indexed: 11/25/2022] Open
Abstract
Changes in life-history requirements drive trophic variations, particularly in large marine predators. The life history of many shark species is still poorly known and understanding their dietary ontogeny is a challenging task, especially for highly migratory species. Stable isotope analysis has proven as a useful method for examining the foraging strategies of sharks and other marine predators. We assessed the foraging strategies and ontogenetic changes of scalloped hammerhead sharks, Sphyrna lewini, at Galapagos Marine Reserve (GMR), by analysing δ13C and δ15N signatures in different maturity stages. Our isotopic results suggest ontogenetic shifts in resource use between sub-adult and adult stages, but not between adult and juvenile stages. Carbon isotopic signatures found in the juvenile stage were enriched in contrast to sub-adults (~0.73‰) suggesting a combination of the maternal input and the use of coastal resources around the Galapagos Islands. Adult female sharks also showed enrichment in δ13C (~0.53‰) in comparison to sub-adult stages that suggest feeding in high primary productivity areas, such as the GMR. This study improves the understanding of the trophic ecology and ontogenetic changes of a highly migratory shark that moves across the protected and unprotected waters of the Eastern Tropical Pacific.
Collapse
Affiliation(s)
- Florencia Cerutti-Pereyra
- Charles Darwin Research Station, Charles Darwin Foundation, Puerto Ayora, Galapagos Islands, Ecuador
- * E-mail:
| | - Pelayo Salinas-De-León
- Charles Darwin Research Station, Charles Darwin Foundation, Puerto Ayora, Galapagos Islands, Ecuador
- Save Our Seas Foundation Shark Research Center and Guy Harvey Research Institute, Nova Southeastern University, Dania Beach, Florida, United States of America
| | - Camila Arnés-Urgellés
- Charles Darwin Research Station, Charles Darwin Foundation, Puerto Ayora, Galapagos Islands, Ecuador
| | | | - Eduardo Espinoza
- Galápagos National Park Directorate, Puerto Ayora, Galápagos, Ecuador
- Migramar Marine Research and Conservation Network, Olema, California, United States of America
| | - Leandro Vaca
- Galapagos Science Center, Universidad San Francisco de Quito, Puerto Baquerizo Moreno, Galápagos, Ecuador
| | - Diego Páez-Rosas
- Galapagos Science Center, Universidad San Francisco de Quito, Puerto Baquerizo Moreno, Galápagos, Ecuador
| |
Collapse
|
8
|
Canfield SJ, Galván-Magaña F, Bowen BW. Little Sharks in a Big World: Mitochondrial DNA Reveals Small-scale Population Structure in the California Horn Shark (Heterodontus francisci). J Hered 2022; 113:298-310. [PMID: 35438775 DOI: 10.1093/jhered/esac008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Accepted: 02/22/2022] [Indexed: 11/13/2022] Open
Abstract
The California horn shark (Heterodontus francisci) is a small demersal species distributed from southern California and the Channel Islands to Baja California and the Gulf of California. These nocturnal reef predators maintain small home-ranges as adults, and lay auger-shaped egg cases that become wedged into the substrate. While population trends are not well documented, this species is subject to fishing pressure through portions of its range and has been identified as vulnerable to overexploitation. Here we present a survey of 318 specimens from across the range, using mtDNA control region sequences to provide the first genetic assessment of H. francisci. Overall population structure (ΦST = 0.266, P < 0.001) is consistent with limited dispersal as indicated by life history, with two distinct features. Population structure along the continuous coastline is low, with no discernable breaks from Santa Barbara, CA to Bahia Tortugas (Baja California Sur, Mexico); however, there is a notable partition at Punta Eugenia (BCS), a well-known biogeographic break between tropical and subtropical marine faunas. In contrast, population structure is much higher (max ΦST = 0.601, P < 0.05) between the coast and adjacent Channel Islands, a minimum distance of 19 km, indicating that horn sharks rarely disperse across deep habitat and open water. Population structure in most elasmobranchs is measured on a scale of hundreds to thousands of kilometers, but the California Horn Shark has population partitions on an unprecedented small scale, indicating a need for localized management strategies which ensure adequate protection of distinct stocks.
Collapse
Affiliation(s)
- Sean J Canfield
- School of Life Sciences, University of Hawai'i at Mānoa, Honolulu, HI, USA.,Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kaneohe, HI, USA
| | - Felipe Galván-Magaña
- Instituto Politécnico Nacional, Centro Interdisciplinario de Ciencias Marinas, La Paz, Baja California Sur, México
| | - Brian W Bowen
- Hawai'i Institute of Marine Biology, University of Hawai'i at Mānoa, Kaneohe, HI, USA
| |
Collapse
|
9
|
Brown banded bamboo shark (Chiloscyllium punctatum) shows high genetic diversity and differentiation in Malaysian waters. Sci Rep 2021; 11:14874. [PMID: 34290296 PMCID: PMC8295251 DOI: 10.1038/s41598-021-94257-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2020] [Accepted: 07/07/2021] [Indexed: 02/06/2023] Open
Abstract
The demersal brown banded bamboo shark Chiloscyllium punctatum is a major component of sharks landed in Malaysia. However, little is known about their population structure and the effect of high fishing pressure on these weak swimming sharks. Both mitochondrial DNA control region (1072 bp) and NADH dehydrogenase subunit 2 (1044 bp) were used to elucidate the genetic structure and connectivity of C. punctatum among five major areas within the Sundaland region. Our findings revealed (i) strong genetic structure with little present day mixing between the major areas, (ii) high intra-population genetic diversity with unique haplotypes, (iii) significant correlation between genetic differentiation and geographical distance coupled with detectable presence of fine scale geographical barriers (i.e. the South China Sea), (iv) historical directional gene flow from the east coast of Peninsular Malaysia towards the west coast and Borneo, and (v) no detectable genetic differentiation along the coastline of east Peninsular Malaysia. Genetic patterns inferred from the mitochondrial DNA loci were consistent with the strong coastal shelf association in this species, the presence of contemporary barriers shaped by benthic features, and limited current-driven egg dispersal. Fine scale population structure of C. punctatum highlights the need to improve genetic understanding for fishery management and conservation of other small-sized sharks.
Collapse
|
10
|
Bergés-Tiznado ME, Vélez D, Devesa V, Márquez-Farías JF, Páez-Osuna F. Arsenic in Tissues and Prey Species of the Scalloped Hammerhead (Sphyrna lewini) from the SE Gulf of California. ARCHIVES OF ENVIRONMENTAL CONTAMINATION AND TOXICOLOGY 2021; 80:624-633. [PMID: 33740087 DOI: 10.1007/s00244-021-00830-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2020] [Accepted: 02/27/2021] [Indexed: 06/12/2023]
Abstract
The bioaccumulation of arsenic (As) in the muscle, liver, kidneys, and brain of the shark Sphyrna lewini was measured in 40 juvenile specimens from southeast Gulf of California. Additionally, the biomagnification factor was calculated through prey items from stomach contents of the analyzed specimens. The concentrations of As (mg kg-1, wet weight) were higher in the muscle (10.1 ± 0.3) and liver (9.4 ± 0.5) than in the brain (4.5 ± 0.3) and kidneys (4.2 ± 0.2), which may be attributed to the biological functions of each tissue. Positive correlations were found between the levels of As in muscle and liver with the biological parameters of S. lewini. Hammerhead sharks feed mainly of teleost fishes with low As values (Clupeidae fishes, 1.1 ± 0.5; Sciaenidae fishes, 1.0 ± 0.6; Scomber japonicus, 1.2 ± 0.6; and Etropus crossotus 2.1 ± 0.4) compared with the predator, indicating biomagnification. Inorganic arsenic (Asi) in muscle was estimated as 3% of the total As, although muscle consumption is unlikely to represent a risk (HQ < 1) in humans. Moreover, the probabilities of developing cancer were estimated as low (3.99 × 10-5 to 3.32 × 10-6). To avoid health risks related to As, a weekly ration must not exceed 69.3 and 484.8 g in children and adults, respectively.
Collapse
Affiliation(s)
- Magdalena E Bergés-Tiznado
- Posgrado en Ciencias de Mar y Limnología, Unidad Académica Mazatlán, Universidad Nacional Autónoma de México, P.O. Box 811, C.P. 82000, Mazatlán, Sinaloa, Mexico.
- Unidad Académica de Ingeniería en Tecnología Ambiental, Universidad Politécnica de Sinaloa, Carretera Municipal Libre Mazatlán-Higueras km. 3, C.P. 82199, Mazatlán, Sinaloa, Mexico.
| | - Dinoraz Vélez
- Instituto de Agroquímica Y Tecnología de Alimentos, Calle Catedrático Agustín Escardino Benlloch, 7, 46980, Paterna, Valencia, Spain
| | - Vicenta Devesa
- Instituto de Agroquímica Y Tecnología de Alimentos, Calle Catedrático Agustín Escardino Benlloch, 7, 46980, Paterna, Valencia, Spain
| | - J Fernando Márquez-Farías
- Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa, Paseo Claussen S/N Col. Centro, C.P. 82000, Mazatlán, Sinaloa, Mexico
| | - Federico Páez-Osuna
- Instituto de Ciencias del Mar y Limnología, Unidad Académica Mazatlán, Universidad Nacional Autónoma de México, P.O. Box 811, C.P. 82000, Mazatlán, Sinaloa, Mexico
- El Colegio de Sinaloa, Antonio Rosales 435 Pte. Culiacán, Sinaloa, Mexico
| |
Collapse
|
11
|
Sort M, Manuzzi A, Jiménez-Mena B, Ovenden JR, Holmes BJ, Bernard AM, Shivji MS, Meldrup D, Bennett MB, Nielsen EE. Come together: calibration of tiger shark (Galeocerdo cuvier) microsatellite databases for investigating global population structure and assignment of historical specimens. CONSERV GENET RESOUR 2021. [DOI: 10.1007/s12686-021-01197-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
|
12
|
Klein JD, der Merwe AEBV, Dicken ML, Emami-Khoyi A, Mmonwa KL, Teske PR. A globally threatened shark, Carcharias taurus, shows no population decline in South Africa. Sci Rep 2020; 10:17959. [PMID: 33087802 PMCID: PMC7578018 DOI: 10.1038/s41598-020-75044-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 10/09/2020] [Indexed: 12/03/2022] Open
Abstract
Knowledge about the demographic histories of natural populations helps to evaluate their conservation status, and potential impacts of natural and anthropogenic pressures. In particular, estimates of effective population size obtained through molecular data can provide useful information to guide management decisions for vulnerable populations. The spotted ragged-tooth shark, Carcharias taurus (also known as the sandtiger or grey nurse shark), is widely distributed in warm-temperate and subtropical waters, but has suffered severe population declines across much of its range as a result of overexploitation. Here, we used multilocus genotype data to investigate the demographic history of the South African C. taurus population. Using approximate Bayesian computation and likelihood-based importance sampling, we found that the population underwent a historical range expansion that may have been linked to climatic changes during the late Pleistocene. There was no evidence for a recent anthropogenic decline. Together with census data suggesting a stable population, these results support the idea that fishing pressure and other threats have so far not been detrimental to the local C. taurus population. The results reported here indicate that South Africa could possibly harbour the last remaining, relatively pristine population of this widespread but vulnerable top predator.
Collapse
Affiliation(s)
- Juliana D Klein
- Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Stellenbosch, 7600, South Africa
- Centre for Ecological Genomics and Wildlife Conservation, Department of Zoology, University of Johannesburg, Auckland Park, 2006, South Africa
| | - Aletta E Bester-van der Merwe
- Molecular Breeding and Biodiversity Group, Department of Genetics, Stellenbosch University, Stellenbosch, 7600, South Africa
| | - Matthew L Dicken
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, 4320, South Africa
- Department of Development Studies, School of Economics, Development and Tourism, Nelson Mandela University, Port Elizabeth, 6031, South Africa
| | - Arsalan Emami-Khoyi
- Centre for Ecological Genomics and Wildlife Conservation, Department of Zoology, University of Johannesburg, Auckland Park, 2006, South Africa
| | - Kolobe L Mmonwa
- KwaZulu-Natal Sharks Board, Umhlanga Rocks, 4320, South Africa
| | - Peter R Teske
- Centre for Ecological Genomics and Wildlife Conservation, Department of Zoology, University of Johannesburg, Auckland Park, 2006, South Africa.
| |
Collapse
|
13
|
Fields AT, Fischer GA, Shea SKH, Zhang H, Feldheim KA, Chapman DD. DNA Zip‐coding: identifying the source populations supplying the international trade of a critically endangered coastal shark. Anim Conserv 2020. [DOI: 10.1111/acv.12585] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
| | | | | | - H. Zhang
- Kadoorie Farm and Botanic Garden Tai Po Hong Kong
| | - K. A. Feldheim
- Pritzker Laboratory for Molecular Systematics and Evolution The Field Museum Chicago IL USA
| | - D. D. Chapman
- Stony Brook University Stony Brook NY USA
- Department of Biological Sciences Florida International University Miami FL USA
| |
Collapse
|
14
|
Sandoval-Castillo J. Conservation genetics of elasmobranchs of the Mexican Pacific Coast, trends and perspectives. ADVANCES IN MARINE BIOLOGY 2019; 83:115-157. [PMID: 31606069 DOI: 10.1016/bs.amb.2019.08.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
One of the most critical threats to biodiversity is the high extinction rate driven by human activities. Reducing extinction rates requires the implementation of conservation programmes based on robust scientific data. Elasmobranchs are important ecological components of the ocean, and several species sustain substantial economic activities. Unfortunately, elasmobranchs are one of the most threatened and understudied animal taxa. The Mexican Pacific Coast (MPC) is a region with high elasmobranch diversity and is the seat of major elasmobranch fisheries. But it is also a developing region with several conservation and management challenges which require national and international attention. Here, we review the conservation genetics literature of elasmobranchs from the MPC. We present a synthesis of the works using samples from the region and emphasize the main gaps and biases in these data. In addition, we discuss the benefits and challenges of generating genomic information to improve the management and conservation of an elasmobranch biodiversity hotspot in a developing country. We found 47 elasmobranch genetic articles that cover <30% of the elasmobranch diversity in the region. These studies mainly used mitochondrial DNA sequences to analyse the genetic structure of commercially important and abundant species of the order Carcharhiniformes. Some of these papers also assessed mating systems, demographic parameters, and taxonomic uncertainties, all of which are important topics for efficient management decisions. In terms of conservation genetics, elasmobranchs from the MPC remain understudied. However, high-throughput sequencing technologies have increased the power and accessibility of genomic tools, even in developing countries such as Mexico. The tools described here provide information relevant for biodiversity conservation. Therefore, we strongly suggest that investment in genomic research will assist implementation of efficient management strategies. In time, this will reduce the extinction risk of the unique elasmobranch biodiversity from the MPC.
Collapse
Affiliation(s)
- Jonathan Sandoval-Castillo
- Molecular Ecology Lab, College of Science and Engineering, Flinders University, Adelaide, SA, Australia.
| |
Collapse
|
15
|
Pirog A, Jaquemet S, Ravigné V, Cliff G, Clua E, Holmes BJ, Hussey NE, Nevill JEG, Temple AJ, Berggren P, Vigliola L, Magalon H. Genetic population structure and demography of an apex predator, the tiger shark Galeocerdo cuvier. Ecol Evol 2019; 9:5551-5571. [PMID: 31160982 PMCID: PMC6540675 DOI: 10.1002/ece3.5111] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Revised: 01/20/2019] [Accepted: 02/26/2019] [Indexed: 12/16/2022] Open
Abstract
Population genetics has been increasingly applied to study large sharks over the last decade. Whilst large shark species are often difficult to study with direct methods, improved knowledge is needed for both population management and conservation, especially for species vulnerable to anthropogenic and climatic impacts. The tiger shark, Galeocerdo cuvier, is an apex predator known to play important direct and indirect roles in tropical and subtropical marine ecosystems. While the global and Indo-West Pacific population genetic structure of this species has recently been investigated, questions remain over population structure and demographic history within the western Indian (WIO) and within the western Pacific Oceans (WPO). To address the knowledge gap in tiger shark regional population structures, the genetic diversity of 286 individuals sampled in seven localities was investigated using 27 microsatellite loci and three mitochondrial genes (CR,COI, and cytb). A weak genetic differentiation was observed between the WIO and the WPO, suggesting high genetic connectivity. This result agrees with previous studies and highlights the importance of the pelagic behavior of this species to ensure gene flow. Using approximate Bayesian computation to couple information from both nuclear and mitochondrial markers, evidence of a recent bottleneck in the Holocene (2,000-3,000 years ago) was found, which is the most probable cause for the low genetic diversity observed. A contemporary effective population size as low as 111 [43,369] was estimated during the bottleneck. Together, these results indicate low genetic diversity that may reflect a vulnerable population sensitive to regional pressures. Conservation measures are thus needed to protect a species that is classified as Near Threatened.
Collapse
Affiliation(s)
- Agathe Pirog
- UMR ENTROPIE (Université de La Réunion/IRD/CNRS)Université de La RéunionSaint Denis, La RéunionFrance
| | - Sébastien Jaquemet
- UMR ENTROPIE (Université de La Réunion/IRD/CNRS)Université de La RéunionSaint Denis, La RéunionFrance
| | | | - Geremy Cliff
- KwaZulu‐Natal Sharks BoardUmhlanga RocksSouth Africa
- School of Life SciencesUniversity of KwaZulu‐NatalDurbanSouth Africa
| | - Eric Clua
- EPHE‐CNRS‐UPVDCNRS UPVDUSR 3278 CRIOBEPSL Research UniversityPerpignanFrance
- Laboratoire d'Excellence CORAILPerpignanFrance
| | - Bonnie J. Holmes
- School of Biological SciencesUniversity of Queensland, St LuciaBrisbaneQueenslandAustralia
| | - Nigel E. Hussey
- Biological SciencesUniversity of WindsorWindsorOntarioCanada
| | | | - Andrew J. Temple
- School of Natural and Environmental SciencesNewcastle UniversityNewcastle‐upon‐TyneUK
| | - Per Berggren
- School of Natural and Environmental SciencesNewcastle UniversityNewcastle‐upon‐TyneUK
| | - Laurent Vigliola
- Laboratoire d'Excellence CORAILPerpignanFrance
- UMR ENTROPIE (Université de La Réunion/IRD/CNRS)Institut de Recherche pour le DéveloppementNouméaNouvelle CalédonieFrance
| | - Hélène Magalon
- UMR ENTROPIE (Université de La Réunion/IRD/CNRS)Université de La RéunionSaint Denis, La RéunionFrance
- Laboratoire d'Excellence CORAILPerpignanFrance
| |
Collapse
|
16
|
Félix-López DG, Bolaño-Martinez N, Díaz-Jaimes P, Oñate-González EC, Ramírez-Pérez JS, García-Rodríguez E, Corro-Espinosa D, Osuna-Soto JE, Saavedra-Sotelo NC. Possible female philopatry of the smooth hammerhead shark Sphyrna zygaena revealed by genetic structure patterns. JOURNAL OF FISH BIOLOGY 2019; 94:671-679. [PMID: 30847921 DOI: 10.1111/jfb.13949] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2018] [Accepted: 03/07/2019] [Indexed: 06/09/2023]
Abstract
We assessed the spatial pattern of genetic structure of smooth hammerhead shark Sphyrna zygaena in 10 localities from the Northern Mexican Pacific. A total of 35 haplotypes were identified in 129 sequences of the mtDNA control region. The results showed slight but significant genetic structure among localities (ΦST = 0.044, P < 0.001). In addition, the localities with highest number of juveniles were genetically different (ΦST = 0.058, P < 0.024), which may be representative of nursery areas. The genetic differentiation pattern can be associated to female philopatry and preference for particular birthing sites. Finally, historical demography shows that S. zygaena populations present a recent demographic expansion that occurred during glacial events in the late Pleistocene to early Holocene.
Collapse
Affiliation(s)
- Daniela G Félix-López
- Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa, Mazatlán, Sinaloa, Mexico
- Departamento de Oceanografía Biológica, Centro de Investigación Científica y Educación Superior de Ensenada Baja California, Ensenada, Baja California, Mexico
| | - Nataly Bolaño-Martinez
- Instituto de Ciencias del Mar y Limnología, Unidad CDMX, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
| | - Pindaro Díaz-Jaimes
- Instituto de Ciencias del Mar y Limnología, Unidad CDMX, Universidad Nacional Autónoma de México, Ciudad de Mexico, Mexico
| | - Erick C Oñate-González
- Facultad de Ciencias Biológicas, Universidad Autónoma de Nuevo León, San Nicolas de los Garza, Nuevo León, Mexico
| | - Jorge S Ramírez-Pérez
- Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa, Mazatlán, Sinaloa, Mexico
| | - Emiliano García-Rodríguez
- Departamento de Oceanografía Biológica, Centro de Investigación Científica y Educación Superior de Ensenada Baja California, Ensenada, Baja California, Mexico
| | - David Corro-Espinosa
- Centro Regional de Investigación Pesquera, Instituto Nacional de Pesca, Mazatlán, Sinaloa, Mexico
| | - Jesus E Osuna-Soto
- Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa, Mazatlán, Sinaloa, Mexico
| | - Nancy C Saavedra-Sotelo
- Facultad de Ciencias del Mar, Universidad Autónoma de Sinaloa, Mazatlán, Sinaloa, Mexico
- Cátedras CONACYT, Consejo Nacional de Ciencia y Tecnología, Ciudad de Mexico, Mexico
| |
Collapse
|
17
|
Population genetics of the endangered Maugean skate (Zearaja maugeana) in Macquarie Harbour, Tasmania. CONSERV GENET 2018. [DOI: 10.1007/s10592-018-1117-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
|
18
|
Wang Y, Jiang W, Ye W, Fu C, Gitzendanner MA, Soltis PS, Soltis DE, Qiu Y. Evolutionary insights from comparative transcriptome and transcriptome-wide coalescence analyses in Tetrastigma hemsleyanum. BMC PLANT BIOLOGY 2018; 18:208. [PMID: 30249188 PMCID: PMC6154912 DOI: 10.1186/s12870-018-1429-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 09/17/2018] [Indexed: 05/22/2023]
Abstract
BACKGROUND Tetrastigma hemsleyanum is of great medicinal importance and used as a model system to address the evolutionary history of warm-temperate evergreen (WTE) forest biomes in East Asia over Neogene time scales. However, further studies on the neutral and adaptive divergence processes of T. hemsleyanum are currently impeded by a lack of genomic resources. In this study, we de novo assembled and annotated a reference transcriptome for two cpDNA lineages (Central-South-East vs. Southwest) of T. hemsleyanum. We further used comparative genomic and multilocus coalescent approaches to investigate the tempo and mode of lineage diversification in T. hemsleyanum. RESULTS A total of 52,838 and 65,197 unigenes with an N50 of 1,667 and 1,841 bp for Central-South-East (CSE) and Southwest (SW) lineages, respectively, were recovered, and 6,692 putative orthologs were identified between the two lineages. Estimation of Ka/Ks ratios for these orthologs revealed that ten genes had Ka/Ks values significantly greater than 0.5 (P < 0.05), whereas 2,099 (Ka/Ks < 0.5, P < 0.05) were inferred to be under purifying selection. Based on three bioinformatic strategies, we identified a total of 1,018 single-copy nuclear genes (SCNGs) from the orthologs. We successfully designed eight nuclear gene primer pairs with high intraspecific variation (e.g. hT = 0.923, πT = 1.68×10-3), when surveyed across a subset of T. hemsleyanum individuals. Concordant with the previous cpDNA data, the haplotype networks constructed for most nuclear gene loci clearly identified the two lineages. A multilocus coalescence analysis suggested that the separation between the two lineages appears to have occurred during the mid-Pliocene. Despite their ancient divergence, both lineages experienced expansion at rather localized scales and have continued to exchange genes at a low rate. CONCLUSIONS This study demonstrated the utility of transcriptome sequencing as a basis for SCNG development in non-model species and the advantages of integrating multiple nuclear loci for phylogeographic and phylogenetic studies.
Collapse
Affiliation(s)
- Yihan Wang
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
- College of Life Sciences, Henan Agricultural University, Zhengzhou, 450002 China
| | - Weimei Jiang
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Wenqing Ye
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | - Chengxin Fu
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| | | | - Pamela S Soltis
- Florida Museum of Natural History, University of Florida, Gainesville, FL 32611 USA
| | - Douglas E Soltis
- Department of Biology, University of Florida, Gainesville, FL 32611 USA
- Florida Museum of Natural History, University of Florida, Gainesville, FL 32611 USA
| | - Yingxiong Qiu
- Key Laboratory of Conservation Biology for Endangered Wildlife of the Ministry of Education, and College of Life Sciences, Zhejiang University, Hangzhou, 310058 China
| |
Collapse
|
19
|
Almojil D, Cliff G, Spaet JLY. Weak population structure of the Spot-tail shark Carcharhinus sorrah and the Blacktip shark C. limbatus along the coasts of the Arabian Peninsula, Pakistan, and South Africa. Ecol Evol 2018; 8:9536-9549. [PMID: 30377521 PMCID: PMC6194305 DOI: 10.1002/ece3.4468] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Revised: 07/22/2018] [Accepted: 07/23/2018] [Indexed: 11/24/2022] Open
Abstract
The increase in demand for shark meat and fins has placed shark populations worldwide under high fishing pressure. In the Arabian region, the spot-tail shark Carcharhinus sorrah and the Blacktip shark Carcharhinus limbatus are among the most exploited species. In this study, we investigated the population genetic structure of C. sorrah (n = 327) along the coasts of the Arabian Peninsula and of C. limbatus (n = 525) along the Arabian coasts, Pakistan, and KwaZulu-Natal, South Africa, using microsatellite markers (15 and 11 loci, respectively). Our findings support weak population structure in both species. Carcharhinus sorrah exhibited a fine structure, subdividing the area into three groups. The first group comprises all samples from Bahrain, the second from the UAE and Yemen, and the third from Oman. Similarly, C. limbatus exhibited population subdivision into three groups. The first group, comprising samples from Bahrain and Kuwait, was highly differentiated from the second and third groups, comprising samples from Oman, Pakistan, the UAE, and Yemen; and South Africa and the Saudi Arabian Red Sea, respectively. Population divisions were supported by pairwise F ST values and discriminant analysis of principal components (DAPC), but not by STRUCTURE. We suggest that the mostly low but significant pairwise F ST values in our study are suggestive of fine population structure, which is possibly attributable to behavioral traits such as residency in C. sorrah and site fidelity and philopatry in C. limbatus. However, for all samples obtained from the northern parts of the Gulf (Bahrain and/or Kuwait) in both species, the higher but significant pairwise F ST values could possibly be a result of founder effects during the Tethys Sea closure. Based on DAPC and F ST results, we suggest each population to be treated as independent management unit, as conservation concerns emerge.
Collapse
Affiliation(s)
| | - Geremy Cliff
- KwaZulu‐Natal Shark BoardUmhlanga, South Africa and School of Life SciencesUniversity of KwaZulu‐NatalDurbanSouth Africa
| | - Julia L. Y. Spaet
- Department of ZoologyUniversity of CambridgeCambridgeUK
- Red Sea Research CenterDivision of Biological and Environmental Science and EngineeringKing Abdullah University of Science and TechnologyThuwalSaudi Arabia
| |
Collapse
|
20
|
|
21
|
Vella N, Vella A. Population genetics of the deep-sea bluntnose sixgill shark, Hexanchus griseus, revealing spatial genetic heterogeneity. Mar Genomics 2017; 36:25-32. [PMID: 28602510 DOI: 10.1016/j.margen.2017.05.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2017] [Revised: 05/23/2017] [Accepted: 05/29/2017] [Indexed: 01/30/2023]
Abstract
Hexanchus griseus is a globally distributed deep-water shark species. It inhabits tropical and temperate waters throughout the world, including the Mediterranean Sea where it is by-caught by small-scale fisheries in the region. In this study, we analysed the genetic variation of H. griseus specimens collected from different areas within and outside the Mediterranean region, to assess its genetic connectivity. The mitochondrial DNA (mtDNA) sequence analysed in this study ranged from cytochrome b to 16S rRNA genes including the control region, the 12S rRNA gene and the interspersed tRNA genes in the region, covering a total of 3731 to 3914 nucleotides. Results have shown that this species exhibits geographically distinct maternal lineages, indicating population structure along geographical ranges. These findings reveal population subdivisions not only between the Pacific Ocean and the Atlantic Ocean, but also within the oceans and on a smaller scale within the Mediterranean Sea. This highlights the need to consider each population subdivision separately when designing management plans for the conservation of this species.
Collapse
Affiliation(s)
- Noel Vella
- Conservation Biology Research Group, Department of Biology, University of Malta, Msida MSD2080, Malta.
| | - Adriana Vella
- Conservation Biology Research Group, Department of Biology, University of Malta, Msida MSD2080, Malta.
| |
Collapse
|
22
|
Phillips NM, Fearing A, Morgan DL. Genetic bottlenecks in Pristis sawfishes in northern Australian waters. ENDANGER SPECIES RES 2017. [DOI: 10.3354/esr00815] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
23
|
Crossing lines: a multidisciplinary framework for assessing connectivity of hammerhead sharks across jurisdictional boundaries. Sci Rep 2017; 7:46061. [PMID: 28429742 PMCID: PMC5399444 DOI: 10.1038/srep46061] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 03/07/2017] [Indexed: 11/21/2022] Open
Abstract
Conservation and management of migratory species can be complex and challenging. International agreements such as the Convention on Migratory Species (CMS) provide policy frameworks, but assessments and management can be hampered by lack of data and tractable mechanisms to integrate disparate datasets. An assessment of scalloped (Sphyrna lewini) and great (Sphyrna mokarran) hammerhead population structure and connectivity across northern Australia, Indonesia and Papua New Guinea (PNG) was conducted to inform management responses to CMS and Convention on International Trade in Endangered Species listings of these species. An Integrated Assessment Framework (IAF) was devised to systematically incorporate data across jurisdictions and create a regional synopsis, and amalgamated a suite of data from the Australasian region. Scalloped hammerhead populations are segregated by sex and size, with Australian populations dominated by juveniles and small adult males, while Indonesian and PNG populations included large adult females. The IAF process introduced genetic and tagging data to produce conceptual models of stock structure and movement. Several hypotheses were produced to explain stock structure and movement patterns, but more data are needed to identify the most likely hypothesis. This study demonstrates a process for assessing migratory species connectivity and highlights priority areas for hammerhead management and research.
Collapse
|
24
|
Momigliano P, Harcourt R, Robbins WD, Jaiteh V, Mahardika GN, Sembiring A, Stow A. Genetic structure and signatures of selection in grey reef sharks (Carcharhinus amblyrhynchos). Heredity (Edinb) 2017; 119:142-153. [PMID: 28422134 DOI: 10.1038/hdy.2017.21] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 02/17/2017] [Accepted: 03/02/2017] [Indexed: 01/01/2023] Open
Abstract
With overfishing reducing the abundance of marine predators in multiple marine ecosystems, knowledge of genetic structure and local adaptation may provide valuable information to assist sustainable management. Despite recent technological advances, most studies on sharks have used small sets of neutral markers to describe their genetic structure. We used 5517 nuclear single-nucleotide polymorphisms (SNPs) and a mitochondrial DNA (mtDNA) gene to characterize patterns of genetic structure and detect signatures of selection in grey reef sharks (Carcharhinus amblyrhynchos). Using samples from Australia, Indonesia and oceanic reefs in the Indian Ocean, we established that large oceanic distances represent barriers to gene flow, whereas genetic differentiation on continental shelves follows an isolation by distance model. In Australia and Indonesia differentiation at nuclear SNPs was weak, with coral reefs acting as stepping stones maintaining connectivity across large distances. Differentiation of mtDNA was stronger, and more pronounced in females, suggesting sex-biased dispersal. Four independent tests identified a set of loci putatively under selection, indicating that grey reef sharks in eastern Australia are likely under different selective pressures to those in western Australia and Indonesia. Genetic distances averaged across all loci were uncorrelated with genetic distances calculated from outlier loci, supporting the conclusion that different processes underpin genetic divergence in these two data sets. This pattern of heterogeneous genomic differentiation, suggestive of local adaptation, has implications for the conservation of grey reef sharks; furthermore, it highlights that marine species showing little genetic differentiation at neutral loci may exhibit patterns of cryptic genetic structure driven by local selection.
Collapse
Affiliation(s)
- P Momigliano
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia.,Sydney Institute of Marine Science, Mosman, New South Wales, Australia.,Ecological Genetics Research Unit, Department of Biosciences, University of Helsinki, Helsinki, Finland
| | - R Harcourt
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - W D Robbins
- College of Marine and Environmental Science, James Cook University, Townsville, Queensland, Australia.,Wildlife Marine, Perth, Western Australia, Australia
| | - V Jaiteh
- Centre for Fish and Fisheries Research, Murdoch University, Murdoch, Western Australia, Australia
| | - G N Mahardika
- The Indonesian Biodiversity Research Centre, Udayana University, Denpasar, Bali, Indonesia
| | - A Sembiring
- The Indonesian Biodiversity Research Centre, Udayana University, Denpasar, Bali, Indonesia
| | - A Stow
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales, Australia
| |
Collapse
|
25
|
Human Influences On Eastern Tropical Pacific Coral Communities and Coral Reefs. CORAL REEFS OF THE EASTERN TROPICAL PACIFIC 2017. [DOI: 10.1007/978-94-017-7499-4_20] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
|
26
|
Rougemont Q, Roux C, Neuenschwander S, Goudet J, Launey S, Evanno G. Reconstructing the demographic history of divergence between European river and brook lampreys using approximate Bayesian computations. PeerJ 2016; 4:e1910. [PMID: 27077007 PMCID: PMC4830234 DOI: 10.7717/peerj.1910] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 03/17/2016] [Indexed: 12/19/2022] Open
Abstract
Inferring the history of isolation and gene flow during species divergence is a central question in evolutionary biology. The European river lamprey (Lampetra fluviatilis) and brook lamprey (L. planeri) show a low reproductive isolation but have highly distinct life histories, the former being parasitic-anadromous and the latter non-parasitic and freshwater resident. Here we used microsatellite data from six replicated population pairs to reconstruct their history of divergence using an approximate Bayesian computation framework combined with a random forest model. In most population pairs, scenarios of divergence with recent isolation were outcompeted by scenarios proposing ongoing gene flow, namely the Secondary Contact (SC) and Isolation with Migration (IM) models. The estimation of demographic parameters under the SC model indicated a time of secondary contact close to the time of speciation, explaining why SC and IM models could not be discriminated. In case of an ancient secondary contact, the historical signal of divergence is lost and neutral markers converge to the same equilibrium as under the less parameterized model allowing ongoing gene flow. Our results imply that models of secondary contacts should be systematically compared to models of divergence with gene flow; given the difficulty to discriminate among these models, we suggest that genome-wide data are needed to adequately reconstruct divergence history.
Collapse
Affiliation(s)
- Quentin Rougemont
- UMR 985 Ecologie et Santé des Ecosystèmes, Institut National de la Recherche Agronomique, Rennes, France
- UMR 985 Ecologie et Santé des Ecosystèmes, Agrocampus Ouest, Rennes, France
| | - Camille Roux
- Department of Ecology and Evolution, Université de Lausanne, Lausanne, Switzerland
| | - Samuel Neuenschwander
- Department of Ecology and Evolution, Université de Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Vital-IT, Lausanne, Switzerland
| | - Jérôme Goudet
- Department of Ecology and Evolution, Université de Lausanne, Lausanne, Switzerland
| | - Sophie Launey
- UMR 985 Ecologie et Santé des Ecosystèmes, Institut National de la Recherche Agronomique, Rennes, France
- UMR 985 Ecologie et Santé des Ecosystèmes, Agrocampus Ouest, Rennes, France
| | - Guillaume Evanno
- UMR 985 Ecologie et Santé des Ecosystèmes, Institut National de la Recherche Agronomique, Rennes, France
- UMR 985 Ecologie et Santé des Ecosystèmes, Agrocampus Ouest, Rennes, France
| |
Collapse
|
27
|
Bester-van der Merwe AE, Gledhill KS. Molecular species identification and population genetics of chondrichthyans in South Africa: current challenges, priorities and progress. AFRICAN ZOOLOGY 2015. [DOI: 10.1080/15627020.2015.1063408] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
|
28
|
Quintanilla S, Gómez A, Mariño-Ramírez C, Sorzano C, Bessudo S, Soler G, Bernal JE, Caballero S. Conservation Genetics of the Scalloped Hammerhead Shark in the Pacific Coast of Colombia. J Hered 2015; 106 Suppl 1:448-58. [DOI: 10.1093/jhered/esv050] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
|
29
|
Population Genetic Structure of the Bonnethead Shark,Sphyrna tiburo, from the Western North Atlantic Ocean Based on mtDNA Sequences. J Hered 2015; 106:355-65. [DOI: 10.1093/jhered/esv030] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
|
30
|
Spaet JLY, Jabado RW, Henderson AC, Moore ABM, Berumen ML. Population genetics of four heavily exploited shark species around the Arabian Peninsula. Ecol Evol 2015; 5:2317-32. [PMID: 26120422 PMCID: PMC4475365 DOI: 10.1002/ece3.1515] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Revised: 04/22/2015] [Accepted: 04/23/2015] [Indexed: 01/31/2023] Open
Abstract
The northwestern Indian Ocean harbors a number of larger marine vertebrate taxa that warrant the investigation of genetic population structure given remarkable spatial heterogeneity in biological characteristics such as distribution, behavior, and morphology. Here, we investigate the genetic population structure of four commercially exploited shark species with different biological characteristics (Carcharhinus limbatus, Carcharhinus sorrah, Rhizoprionodon acutus, and Sphyrna lewini) between the Red Sea and all other water bodies surrounding the Arabian Peninsula. To assess intraspecific patterns of connectivity, we constructed statistical parsimony networks among haplotypes and estimated (1) population structure; and (2) time of most recent population expansion, based on mitochondrial control region DNA and a total of 20 microsatellites. Our analysis indicates that, even in smaller, less vagile shark species, there are no contemporary barriers to gene flow across the study region, while historical events, for example, Pleistocene glacial cycles, may have affected connectivity in C. sorrah and R. acutus. A parsimony network analysis provided evidence that Arabian S. lewini may represent a population segment that is distinct from other known stocks in the Indian Ocean, raising a new layer of conservation concern. Our results call for urgent regional cooperation to ensure the sustainable exploitation of sharks in the Arabian region.
Collapse
Affiliation(s)
- Julia L Y Spaet
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology23955-6900, Thuwal, Saudi Arabia
| | - Rima W Jabado
- Gulf Elasmo ProjectP.O. Box 29588, Dubai, United Arab Emirates
| | - Aaron C Henderson
- Department of Marine Science & Fisheries, College of Agricultural & Marine Sciences, Sultan Qaboos UniversityMuscat, Oman
| | - Alec B M Moore
- RSK Environment Ltd, Spring LodgeHelsby, Cheshire, WA6 0AR, UK
| | - Michael L Berumen
- Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology23955-6900, Thuwal, Saudi Arabia
| |
Collapse
|
31
|
Vignaud TM, Mourier J, Maynard JA, Leblois R, Spaet J, Clua E, Neglia V, Planes S. Blacktip reef sharks, Carcharhinus melanopterus, have high genetic structure and varying demographic histories in their Indo-Pacific range. Mol Ecol 2014; 23:5193-207. [PMID: 25251515 DOI: 10.1111/mec.12936] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2014] [Accepted: 09/19/2014] [Indexed: 12/20/2022]
Abstract
For free-swimming marine species like sharks, only population genetics and demographic history analyses can be used to assess population health/status as baseline population numbers are usually unknown. We investigated the population genetics of blacktip reef sharks, Carcharhinus melanopterus; one of the most abundant reef-associated sharks and the apex predator of many shallow water reefs of the Indian and Pacific Oceans. Our sampling includes 4 widely separated locations in the Indo-Pacific and 11 islands in French Polynesia with different levels of coastal development. Four-teen microsatellite loci were analysed for samples from all locations and two mitochondrial DNA fragments, the control region and cytochrome b, were examined for 10 locations. For microsatellites, genetic diversity is higher for the locations in the large open systems of the Red Sea and Australia than for the fragmented habitat of the smaller islands of French Polynesia. Strong significant structure was found for distant locations with FST values as high as ~0.3, and a smaller but still significant structure is found within French Polynesia. Both mitochondrial genes show only a few mutations across the sequences with a dominant shared haplotype in French Polynesia and New Caledonia suggesting a common lineage different to that of East Australia. Demographic history analyses indicate population expansions in the Red Sea and Australia that may coincide with sea level changes after climatic events. Expansions and flat signals are indicated for French Polynesia as well as a significant recent bottleneck for Moorea, the most human-impacted lagoon of the locations in French Polynesia.
Collapse
Affiliation(s)
- Thomas M Vignaud
- Laboratoire d'Excellence "CORAIL", USR 3278 CNRS - EPHE, CRIOBE, BP 1013 - 98 729 Papetoai, Moorea, Polynésie, Française
| | | | | | | | | | | | | | | |
Collapse
|
32
|
Teske PR, Sandoval-Castillo J, Waters JM, Beheregaray LB. Can novel genetic analyses help to identify low-dispersal marine invasive species? Ecol Evol 2014; 4:2848-66. [PMID: 25165524 PMCID: PMC4130444 DOI: 10.1002/ece3.1129] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 05/04/2014] [Accepted: 05/06/2014] [Indexed: 01/18/2023] Open
Abstract
Genetic methods can be a powerful tool to resolve the native versus introduced status of populations whose taxonomy and biogeography are poorly understood. The genetic study of introduced species is presently dominated by analyses that identify signatures of recent colonization by means of summary statistics. Unfortunately, such approaches cannot be used in low-dispersal species, in which recently established populations originating from elsewhere in the species' native range also experience periods of low population size because they are founded by few individuals. We tested whether coalescent-based molecular analyses that provide detailed information about demographic history supported the hypothesis that a sea squirt whose distribution is centered on Tasmania was recently introduced to mainland Australia and New Zealand through human activities. Methods comparing trends in population size (Bayesian Skyline Plots and Approximate Bayesian Computation) were no more informative than summary statistics, likely because of recent intra-Tasmanian dispersal. However, IMa2 estimates of divergence between putatively native and introduced populations provided information at a temporal scale suitable to differentiate between recent (potentially anthropogenic) introductions and ancient divergence, and indicated that all three non-Tasmanian populations were founded during the period of European settlement. While this approach can be affected by inaccurate molecular dating, it has considerable (albeit largely unexplored) potential to corroborate nongenetic information in species with limited dispersal capabilities.
Collapse
Affiliation(s)
- Peter R Teske
- Molecular Ecology Laboratory, School of Biological Sciences, Flinders University Adelaide, South Australia, 5001, Australia ; Department of Zoology, University of Johannesburg Auckland Park, 2006, Johannesburg, South Africa
| | - Jonathan Sandoval-Castillo
- Molecular Ecology Laboratory, School of Biological Sciences, Flinders University Adelaide, South Australia, 5001, Australia
| | - Jonathan M Waters
- Department of Zoology, University of Otago PO Box 56, Dunedin, New Zealand
| | - Luciano B Beheregaray
- Molecular Ecology Laboratory, School of Biological Sciences, Flinders University Adelaide, South Australia, 5001, Australia
| |
Collapse
|
33
|
Elasmobranchs of the Galapagos Marine Reserve. SOCIAL AND ECOLOGICAL INTERACTIONS IN THE GALAPAGOS ISLANDS 2014. [DOI: 10.1007/978-3-319-02769-2_2] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
|
34
|
Molfetti É, Torres Vilaça S, Georges JY, Plot V, Delcroix E, Le Scao R, Lavergne A, Barrioz S, dos Santos FR, de Thoisy B. Recent demographic history and present fine-scale structure in the Northwest Atlantic leatherback (Dermochelys coriacea) turtle population. PLoS One 2013; 8:e58061. [PMID: 23516429 PMCID: PMC3596356 DOI: 10.1371/journal.pone.0058061] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2012] [Accepted: 02/01/2013] [Indexed: 11/18/2022] Open
Abstract
The leatherback turtle Dermochelys coriacea is the most widely distributed sea turtle species in the world. It exhibits complex life traits: female homing and migration, migrations of juveniles and males that remain poorly known, and a strong climatic influence on resources, breeding success and sex-ratio. It is consequently challenging to understand population dynamics. Leatherbacks are critically endangered, yet the group from the Northwest Atlantic is currently considered to be under lower risk than other populations while hosting some of the largest rookeries. Here, we investigated the genetic diversity and the demographic history of contrasted rookeries from this group, namely two large nesting populations in French Guiana, and a smaller one in the French West Indies. We used 10 microsatellite loci, of which four are newly isolated, and mitochondrial DNA sequences of the control region and cytochrome b. Both mitochondrial and nuclear markers revealed that the Northwest Atlantic stock of leatherbacks derives from a single ancestral origin, but show current genetic structuration at the scale of nesting sites, with the maintenance of migrants amongst rookeries. Low nuclear genetic diversities are related to founder effects that followed consequent bottlenecks during the late Pleistocene/Holocene. Most probably in response to climatic oscillations, with a possible influence of early human hunting, female effective population sizes collapsed from 2 million to 200. Evidence of founder effects and high numbers of migrants make it possible to reconsider the population dynamics of the species, formerly considered as a metapopulation model: we propose a more relaxed island model, which we expect to be a key element in the currently observed recovering of populations. Although these Northwest Atlantic rookeries should be considered as a single evolutionary unit, we stress that local conservation efforts remain necessary since each nesting site hosts part of the genetic diversity and species history.
Collapse
Affiliation(s)
- Érica Molfetti
- Departamento de Biologia Geral, ICB, Universidade Federal de Minas Gerais, 31270-010, Belo Horizonte, Minas Gerais, Brazil
| | - Sibelle Torres Vilaça
- Dipartimento di Biologia ed Evoluzione, Sezione di Biologia Evolutiva, Università di Ferrara, Ferrara, Italy
| | - Jean-Yves Georges
- Université de Strasbourg, IPHC (Institut Pluridisciplinaire Hubert Curien), 67087, Strasbourg, France
- CNRS,UMR 7178, 67087, Strasbourg, France
| | - Virginie Plot
- Université de Strasbourg, IPHC (Institut Pluridisciplinaire Hubert Curien), 67087, Strasbourg, France
- CNRS,UMR 7178, 67087, Strasbourg, France
| | - Eric Delcroix
- Office National de la Chasse et de la Faune Sauvage Guadeloupe, 97129, Lamentin, Guadeloupe, French West Indies
| | - Rozen Le Scao
- Office National de la Chasse et de la Faune Sauvage, Martinique, 97200, Martinique, French West Indies
| | - Anne Lavergne
- Institut Pasteur de la Guyane, 97300, Cayenne, French Guiana
| | | | - Fabrício Rodrigues dos Santos
- Departamento de Biologia Geral, ICB, Universidade Federal de Minas Gerais, 31270-010, Belo Horizonte, Minas Gerais, Brazil
| | - Benoît de Thoisy
- Institut Pasteur de la Guyane, 97300, Cayenne, French Guiana
- Kwata NGO, 97300 Cayenne, French Guiana
- * E-mail:
| |
Collapse
|
35
|
Effects of species biology on the historical demography of sharks and their implications for likely consequences of contemporary climate change. CONSERV GENET 2012. [DOI: 10.1007/s10592-012-0437-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
|
36
|
Ward-Paige CA, Keith DM, Worm B, Lotze HK. Recovery potential and conservation options for elasmobranchs. JOURNAL OF FISH BIOLOGY 2012; 80:1844-69. [PMID: 22497409 DOI: 10.1111/j.1095-8649.2012.03246.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Many elasmobranchs have experienced strong population declines, which have been largely attributed to the direct and indirect effects of exploitation. Recently, however, live elasmobranchs are being increasingly valued for their role in marine ecosystems, dive tourism and intrinsic worth. Thus, management plans have been implemented to slow and ultimately reverse negative trends, including shark-specific (e.g. anti-finning laws) to ecosystem-based (e.g. no-take marine reserves) strategies. Yet it is unclear how successful these measures are, or will be, given the degree of depletion and slow recovery potential of most elasmobranchs. Here, current understanding of elasmobranch population recoveries is reviewed. The potential and realized extent of population increases, including rates of increase, timelines and drivers are evaluated. Across 40 increasing populations, only 25% were attributed to decreased anthropogenic mortality, while the majority was attributed to predation release. It is also shown that even low exploitation rates (2-6% per year) can halt or reverse positive population trends in six populations currently managed under recovery plans. Management measures that help restore elasmobranch populations include enforcement or near-zero fishing mortality, protection of critical habitats, monitoring and education. These measures are highlighted in a case study from the south-eastern U.S.A., where some evidence of recovery is seen in Pristis pectinata, Galeocerdo cuvier and Sphyrna lewini populations. It is concluded that recovery of elasmobranchs is certainly possible but requires time and a combination of strong and dedicated management actions to be successful.
Collapse
Affiliation(s)
- C A Ward-Paige
- Department of Biology, Dalhousie University, Halifax NS, B3H 4R2, Canada.
| | | | | | | |
Collapse
|