Pan-Atlantic distribution patterns and reproductive biology of the bigeye thresher, Alopias superciliosus

Fernandez‐Carvalho, Joana; Coelho, Rui; Mejuto, J.; Cortés, Enric; Domingo, Andrés; Yokawa, Kotaro; Liu, Kwang‐Ming; García-Cortés, B.; Forselledo, Rodrigo; Ohshimo, Seiji; Ramos-Cartelle, A.; Tsai, Wen‐Pei; Santos, Miguel N.

doi:10.1007/s11160-015-9389-7

Cited by 16 publications

(15 citation statements)

References 35 publications

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“…In terms of the spatial distribution of CPUE, records of catches ranging from 45°N to 35°S were observed, confirming the wide latitudinal range of this species in the Atlantic Ocean (Compagno, 1984;Cortés et al, 2015). Higher CPUE was found closer inshore in both the Tropical North and Equatorial regions.…”

Section: Discussionsupporting

confidence: 60%

Distribution patterns and indicators of the smooth hammerhead shark (Sphyrna zygaena) in the Atlantic Ocean

Santos

Coelho

2019

Fisheries Research

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The smooth hammerhead shark, Sphyrna zygaena, is a pelagic shark occasionally captured as bycatch by industrial pelagic longline fleets in the Atlantic Ocean. Data for this study were collected by fishery observers, between 2003 and 2016. Datasets analyzed included information on catches per unit effort (CPUE), size and sex of smooth hammerhead sharks bycaught by the Portuguese pelagic longline fishery in the Atlantic Ocean. A total effort of 2 523 288 hooks yielded 638 sharks, ranging in size from 123-275 cm fork length. Larger sharks tended to occur in open ocean habitats and smaller specimens in coastal areas. Results confirmed the wide latitudinal range of the species (45°N-35°S), although CPUE was higher closer inshore within the Tropical North and Equatorial regions. An overall sex ratio of 1.4 males for each female was observed, with more males in both inshore and offshore waters. Significant differences in CPUE and size distribution were found between regions, years and quarters of the year. Mean CPUE increased and mean specimen size decreased in the Equatorial region from 2012 onwards. In order to remove fishery-dependent effects from CPUE data, a Tweedie Generalized Linear Model (GLM) was used to create a relative index of abundance (standardized CPUE). The index showed some oscillations in the initial years (2008-2010), followed by a decreasing trend until 2013 and then an increasing trend in more recent years, until 2016. The distributional patterns and indicators presented in this study provide a better understanding of the smooth hammerhead shark's spatiotemporal dynamics and population structure in the Atlantic Ocean and can be used to improve management and conservation measures for this species.

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Section: Discussionsupporting

confidence: 60%

Distribution patterns and indicators of the smooth hammerhead shark (Sphyrna zygaena) in the Atlantic Ocean

Santos

Coelho

2019

Fisheries Research

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“…A 1999 study on shark bycatch from pelagic longline fisheries mentions the presence of this species based on the author's personal observations (Simões, 1999). The occurrence of this species in the region has since been confirmed by experimental pelagic longlines (Martins, 2013), and observer logbook data from commercial longlines operating in the region (Fernandez-Carvalho et al, 2015).…”

Section: Alopiidaementioning

confidence: 82%

Review of the Diversity, Ecology, and Conservation of Elasmobranchs in the Azores Region, Mid-North Atlantic

Das

Afonso

2017

Front. Mar. Sci.

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A vulnerable species group, such as, the elasmobranchs, in a data-deficient context presents a complicated management problem. Evidence suggests that the Azores islands, a remote archipelago on the Mid-Atlantic Ridge, serve essential functions in the life-history of species across taxa. The diversity of marine resources within its EEZ are exploited by local to international fleets, and the full extent of fishing pressure can often be underestimated. Although sharks and rays appear to be of minor importance in the fishery, the possibilities of illegal, unreported, and unregulated fishing raises concerns about these threatened species. However, this group has failed to attract management attention, visible in the lack of regional studies focused on biodiversity, ecology, or threats of elasmobranchs. Our work attempts to review and update the information on elasmobranchs of the Azores and identify potential threats, mainly by the local fisheries. We aim to highlight knowledge gaps that require further research and conservation actions. We (1) update the annotated checklist of elasmobranch species, (2) compare species distribution across a biogeographically similar section of the North Atlantic, and (3) analyze the interaction of elasmobranch species with local fisheries. We confirm 61 chondrichthyan species for the Azores (39 sharks, 17 rays, and 5 chimaeras), adding 19 species to the previous annotated checklist of 1997. The Azores elasmobranch species assemblage most resembles Madeira, the neighboring Macaronesian archipelago. Biogeographic affinities between the chosen regions of the North Atlantic are reflected in the taxonomic structure of families. Although underestimated in the local fisheries, elasmobranchs constitute a regular but highly variable portion of total landings. Misreporting and misidentification is perhaps the greatest concern in the local fisheries records, further aggravated by few existing catch regulations for elasmobranchs. Local knowledge indicates that the Azores serves as essential habitat for at least a few species in coastal areas and shallow seamounts, and potentially so for a number of deep-sea elasmobranchs. The intersection of fishery threats and local essential habitat functions around the archipelago warrants greater research effort and studies.

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“…It is crucial that these sharks, which can give birth up to 2-4 juvenile sharks at a time (Carvalho et al, 2015), are taken under protection in order not to be extinct. According to the information received from fishers and scuba divers, in the region around the place where Göksu Delta flows into the sea, juvenile sharks are frequently seen.…”

Section: Discussionmentioning

confidence: 99%

“…The number of juvenile sharks is usually 2, rarely 4. A. superciliosus species mature more slowly than other thresher sharks (Carvalho et al, 2015). During the birth, individuals are around 100-140 cm.…”

Section: Introductionmentioning

confidence: 98%

Occurrence of the Young Thresher Shark Alopias superciliosus Lowe, 1841 (Lamniformes: Alopiidae) in the Northeastern Mediterranean Sea

Ayas¹,

Akbora²,

Çiçek³

2020

Commagene Journal of Biology

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The Bigeye Thresher Shark Alopias superciliosus Lowe, 1841 is one of the largest shark species found in the Pacific, Atlantic, and Indian oceans. They also have started to be seen in the Mediterranean Sea since the 1980s. The presence of two different species of Thresher sharks in Turkish waters is known, which are A. vulpinus and A. superciliosus. Thresher sharks can easily be distinguished from other shark species with their big tails. A juvenile female specimen of A. superciliosus with a total length of 240 cm was caught incidentally in Mersin Bay in January 2020. Essential measurements of the fish were fulfilled and the specimen was deposited in the Museum of the Systematic, Faculty of Fisheries, Mersin University (catalog number: MEUFC-20-11-127). This study is the first record of A. superciliosus in Mersin Bay.

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Pan-Atlantic distribution patterns and reproductive biology of the bigeye thresher, Alopias superciliosus

Cited by 16 publications

References 35 publications

Distribution patterns and indicators of the smooth hammerhead shark (Sphyrna zygaena) in the Atlantic Ocean

Distribution patterns and indicators of the smooth hammerhead shark (Sphyrna zygaena) in the Atlantic Ocean

Review of the Diversity, Ecology, and Conservation of Elasmobranchs in the Azores Region, Mid-North Atlantic

Occurrence of the Young Thresher Shark Alopias superciliosus Lowe, 1841 (Lamniformes: Alopiidae) in the Northeastern Mediterranean Sea

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