Elasmo Project

The bowmouth guitarfish ( Rhina ancylostomus ) is a unique and understudied species of wedgefish with a distribution spanning the Indo-Pacific Oceans. Due to targeted and bycatch fisheries, this species is experiencing serious declines across its range. It is now considered among the most threatened species of elasmobranch. Despite this, species-specific management is limited, particularly around primary fishing hotspots. This is in part due to knowing very little about fundamental population processes. Here, we combine mitochondrial and single nucleotide polymorphism (SNP) data to carry out the first genetic assessment of R. ancylostomus across the Northwest Indian Ocean. We detect genetic differentiation across the northwest range, shaped by both oceanographic barriers and intrinsic dispersal constraints, and uncover a cline in genetic variation from east to west. These findings emphasise the importance of maintaining habitat connectivity while also identifying regions that may require heightened protection. In doing so, our study provides a critical baseline for conservation planning of R. ancylostomus and highlights the value of genomic data in elasmobranch conservation.

Abstract Small‐scale fisheries ensure food security and employment in Angolan coastal communities. These dynamic, widespread fisheries remain mostly unregulated, with limited data available despite their likely significant impact on marine megafauna. We used an interview‐based survey to investigate local fisher interactions with elasmobranchs (sharks and rays) and gather information on utilization, trade and perceptions. All fishers (n = 83) landed elasmobranchs. Most fishers considered sharks as bycatch (74.7%, n = 62), while 100% targeted rays (Order Myliobatiformes), and 62.8% (n = 52) targeted guitarfishes (Order Rhinopristiformes). Over 80% of fishers reported declining catches and sizes of elasmobranchs over the last 30 years, raising concerns about the sustainability of these fisheries. Utilization and trade routes varied depending on elasmobranch products, with exports to China (fins) and local market sales (meat). Specifically, 8.4% (n = 5) of fishers confirmed meat and fin exports to China (4.8%, n = 3). The protection of sharks was considered by 32.5% (n = 30) of respondents, while 21.7% (n = 18) believed only certain shark species should be protected. Most respondents reported that rays (80.5%, n = 67) and guitarfishes (61%, n = 51) should not be protected. Regarding the ban on fishing, none considered it for ray species, with only 6.1% (n = 5) supporting this idea for guitarfishes. We highlight the lack of elasmobranch‐specific conservation measures and the need for a multi‐pronged approach to inform policy. Considering the scale of these fisheries, management actions need to be urgently developed and implemented to ensure the sustainability of elasmobranch fisheries while securing the livelihoods of coastal communities.

This guide forms part of a three-volume series of identification guides: Volume I - Full Carcas ID [this guide], Volume II - Processed Carcass ID, and Volume III - Dried Product ID. Each of these guides has been designed to follow a similar simple structure to guide users with no previous knowledge of sharks and rays with identification of whole carcasses or different derivative products. This Full Carcass ID guide is intended for field use to assist the fishing industry, fisheries observers, enforcement bodies, researchers, policy makers, and non-specialists. It was created to enable visual identification of all shark and ray species listed in Appendix I and II of CITES that might be captured and/or landed and eventually enter the trade. It has been designed to meet the need expressed by inspectors for an identification tool that is quick and easy to use when faced with the identification of carcasses present at landing sites. Technical terms are kept to a minimum and identification features are mostly those that can be readily observed on freshly caught animals without the need for dissection or further examination.

Abstract All five species of sawfishes (family Pristidae) are amongst the most threatened marine fishes in the world, with steep population declines and local extinctions documented across their ranges. Sawfishes have featured in Sri Lankan species checklists since 1889. However, landing records are extremely rare and little information is available on their status, diversity, and recent occurrences. Interviews were conducted with 300 fishers and 10 fish traders. Only 39% of fishers (n = 118) could identify sawfishes, 37% had seen sawfishes (although half not since 1992), and only 10.7% had ever caught one. No respondents under 30 years could identify sawfishes. Older respondents (>50 years) were more likely to have caught sawfishes and reported seeing them frequently until 30 years ago, while younger respondents had only seen them at landing sites and, at most, once or twice in their life. Only 10 respondents had seen a sawfish in the last decade, suggesting that sawfishes were relatively abundant in the past but that populations have drastically declined. Of the 32 respondents who had caught sawfishes, 30 reported declining numbers and attributed it to fishing pressure. These steep declines coincide with the time of increased fishing effort, the development of the aquaculture industry, and resulting degradation of coastal habitats in the 1980–1990s. Overall, sawfishes had little cultural significance although fishers had specific names for the different species occurring here and rostra were sometimes donated to Catholic churches for ‘good luck’. Landed sawfishes were primarily sold for meat and traders appeared unaware of the high value of fins. It is likely that sawfishes are now functionally extinct as a component of coastal ecosystems in Sri Lanka. Immediate action including species‐specific legislation and critical habitat protection is urgently needed to provide remaining sawfishes and other sharks and rays with a fighting chance.

<p>Data used in the Living Planet Index analysis in Pacoureau et al. 2020 - Half a century of global decline in oceanic sharks and rays.</p> <p>Available at <a href="http://www.sharkipedia.org">www.sharkipedia.org</a>.</p>

Abstract Practical biodiversity conservation relies on delineation of biologically meaningful units, particularly with respect to global conventions and regulatory frameworks. Traditional approaches have typically relied on morphological observation, resulting in artificially broad delineations and non-optimal species units for conservation. More recently, species delimitation methods have been revolutionised with High-Throughput Sequencing approaches, allowing study of diversity within species radiations using genome-wide data. The highly mobile elasmobranchs, manta and devil rays (Mobulaspp.), are threatened globally by targeted and bycatch fishing pressures resulting in recent protection under several global conventions. However, a lack of global data, morphological similarities, a succession of recent taxonomic changes and ineffectual traceability measures combine to impede development and implementation of a coherent and enforceable conservation strategy. Here, we generate genome-wide Single Nucleotide Polymorphism (SNP) data from among the most globally and taxonomically representative set of mobulid tissues. The resulting phylogeny and delimitation of species units represents the most comprehensive assessment of mobulid diversity with molecular data to date. We find a mismatch between current species classifications, and optimal species units for effective conservation. Specifically, we find robust evidence for an undescribed species of manta ray in the Gulf of Mexico and show that species recently synonymised are reproductively isolated. Further resolution is achieved at the population level, where cryptic diversity is detected in geographically distinct populations, and indicates potential for future traceability work determining regional location of catch. We estimate the optimal species tree and uncover substantial incomplete lineage sorting, where standing variation in extinct ancestral populations is identified as a driver of phylogenetic uncertainty, with further conservation implications. Our study provides a framework for molecular genetic species delimitation that is relevant to wide-ranging taxa of conservation concern, and highlights the potential for genomic data to support effective management, conservation and law enforcement strategies.

Abstract The extinction risk of sharks, rays and chimaeras is higher than that for most other vertebrates due to low intrinsic population growth rates of many species and the fishing intensity they face. The Arabian Sea and adjacent waters border some of the most important chondrichthyan fishing and trading nations globally, yet there has been no previous attempt to assess the conservation status of species occurring here. Using IUCN Red List of Threatened Species Categories and Criteria and their guidelines for application at the regional level, we present the first assessment of extinction risk for 153 species of sharks, rays and chimaeras. Results indicate that this region, home to 15% of described chondrichthyans including 30 endemic species, has some of the most threatened chondrichthyan populations in the world. Seventy‐eight species (50.9%) were assessed as threatened (Critically Endangered, Endangered or Vulnerable), and 27 species (17.6%) as Near Threatened. Twenty‐nine species (19%) were Data Deficient with insufficient information to assess their status. Chondrichthyan populations have significantly declined due to largely uncontrolled and unregulated fisheries combined with habitat degradation. Further, there is limited political will and national and regional capacities to assess, manage, conserve or rebuild stocks. Outside the few deepsea locations that are lightly exploited, the prognosis for the recovery of most species is poor in the near‐absence of management. Concerted national and regional management measures are urgently needed to ensure extinctions are avoided, the sustainability of more productive species is secured, and to avoid the continued thinning of the regional food security portfolio.

Data on the occurrence of whale sharks, Rhincodon typus, in the Arabian Gulf and Gulf of Oman were collected by dedicated boat surveys and via a public-sightings scheme during the period from 2011 to 2014. A total of 422 individual whale sharks were photo-identified from the Arabian Gulf and the northern Gulf of Oman during that period. The majority of sharks (81%, n = 341) were encountered at the Al Shaheen area of Qatar, 90 km off the coast, with the Musandam region of Oman a secondary area of interest. At Al Shaheen, there were significantly more male sharks (n = 171) than females (n = 78; X2 = 17.52, P < 0.05). Mean estimated total length (TL) for sharks was 6.90 m ± 1.24 (median = 7 m; n = 296). Males (7.25 m ± 1.34; median = 8 m, n = 171) were larger than females (6.44 m ±1.09; median = 7 m, n = 78; Mann-Whitney U test, p < 0.01). Of the male sharks assessed for maturity 63% were mature (n = 81), with 50% attaining maturity by 7.29 m and 100% by 9.00 m. Two female sharks of >9 m individuals were visually assessed as pregnant. Connectivity among sharks sighted in Qatari, Omani and UAE waters was confirmed by individual spot pattern matches. A total of 13 identified sharks were re-sighted at locations other than that at which they were first sighted, including movements into and out of the Arabian Gulf through the Strait of Hormuz. Maximum likelihood techniques were used to model an estimated combined population for the Arabian Gulf and Gulf of Oman of 2837 sharks ± 1243.91 S.E. (95% C.I. 1720–6295). The Al Shaheen aggregation is thus the first site described as being dominated by mature males while the free-swimming pregnant females are the first reported from the Indian Ocean.

Abstract Devil rays (genus Mobula) are pelagic elasmobranchs widely distributed throughout tropical, subtropical and warm‐temperate waters. Their occurrence and distribution remains poorly documented in the Arabian Seas region. A review is provided of species occurrence in these water bodies along with a synthesis of regional information on their biology and ecology. Based on the available evidence, five Mobula species occur in the region (M. eregoodootenkee, M. japanica, M. kuhlii, M. tarapacana, and M. thurstoni). Of these, three (M. eregoodootenkee, M. tarapacana and M. thurstoni) were found to occur in the Red Sea, and three (M. eregoodootenkee, M. japanica, and M. kuhlii) were found to occur in the Arabian/Persian Gulf. Mobula japanica and M. kuhlii are reported here for the first time in Gulf waters. All five species were found in the Indian Ocean waters between the Gulf of Aden and Pakistan. To address the still uncertain taxonomy of M. kuhlii, a redescription of this species is provided based on a sample of fresh specimen material. Mobula diabolus is a nomen ambiguum, never used to unambiguously designate any newly described species, and its use should be avoided. Considering the life‐history traits that make these species particularly vulnerable to fishing pressure, current levels of exploitation in by‐catch fisheries are unlikely to be sustainable, despite the fact that the trade in gill plates does not seem to be prevalent in this region. Critical knowledge gaps unfortunately still exist, crippling effective management and conservation actions. Copyright © 2016 John Wiley &amp; Sons, Ltd.