Distribution and Reproductive Biology of the Spinner Shark, Carcharhinus Brevipinna (Müller and Henle, 1841) (Chondrichthyes: Carcharhinidae)

Capapé, Christian; Hemida, Farid; Seck, Amadou Abdoulaye; Diatta, Youssouph; Guélorget, O.; Zaouali, J.

doi:10.1560/dhhm-a68m-vkqh-cy9f

Cited by 19 publications

(11 citation statements)

References 25 publications

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“…Based on the total number of hooks deployed, and number of individuals caught of each species, the catch per unit effort (CPUE) was calculated as the number of individuals caught per 1000 hooks (Ind/1000H), and data are presented as mean ± 95% confidence interval (C.I). In order to investigate the impact of pelagic longline of each life stage, specimens were classified as neonate, juvenile or adult based on the available reproductive information from the area (Capapé et al, 2003;Saidi et al, 2005Saidi et al, , 2008Enajjar et al, 2012).…”

Section: Discussionmentioning

confidence: 99%

Shark pelagic longline fishery in the Gulf of Gabes: Inter-decadal inspection reveals management needs

et al. 2019

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This study explores the status of exploited shark populations in the Gulf of Gabes in relation to fishing pressure, based on data pertaining to shark longline fishery, collected during two periods. Catch data from 48 and 96 pelagic longline sets collected, respectively, during 2007/2008 and 2016/2017, were used to compare species composition and catch rates between periods. Four species were recorded during 2007/2008, while 11 additional species of pelagic and demersal elasmobranchs along with teleosts were fished during 2016/2017. Elasmobranch species dominated the catches with 94% and 99.3% in terms of specimens number, respectively, during 2016/2017 and 2007/2008. The sandbar shark, Carcharhinus plumbeus, was the predominant species in catch (>84% of all fishes) during both periods. Two other species of sharks, Carcharhinus brevipinna and Isurus oxyrinchus, were relatively common, while the other species were a minor component. Despite the increase in terms of diversity pertaining to species captured during 2016/2017, the nominal catch rates of elasmobranch and C. plumbeus decreased by 39.17% and 42.21%, respectively, suggesting populations’ declines. In addition, size distribution analyses revealed that this fishery may opportunistically operate on breeding and nursery areas, which affect main species over most of their life stages. The mortality and hooking location proportions were species-specific, with some species having significant percentages of live specimens at the time of haulback, providing an opportunity to release the sensitive life stages. Given the described state of shark exploitations in the Gulf of Gabes, urgent and efficient fishery regulation measures and conservation strategies, together with further investigations, are required to allow changing the unregulated shark longline fishery to a sustainable one.

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Section: Discussionmentioning

confidence: 99%

Shark pelagic longline fishery in the Gulf of Gabes: Inter-decadal inspection reveals management needs

et al. 2019

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“…This indicates that where data are available, ~ 2 in 10 gravid females across a subset of species showed capture-induced parturition. The rate of parturition is, however, quite variable amoung species (Table 2); it ranged from 2% of embryos being induced in Carcharhinus brevipinna (Capapé et al, 2003) and Galeocerdo cuvier (Jaquemet et al, 2013) to 85% of females releasing embryos on capture for Pteroplatytrygon violacea (Mollet, 2002). Given this variability, the induced parturition rate is likely to be highly species specific; however there are currently insufficient data to support reliable conclusions given the variation in fishing methods used across these studies.…”

Section: The Frequency Of Capture-induced Parturition Eventsmentioning

confidence: 99%

“…The frequency of capture-induced parturition calculated for 26 species from a variety of fishing methods. Capapé et al, 2003 An important consideration in estimating the frequency of capture-induced parturition is the time of year when captured. For example, we have observed two species experiencing capture-induced parturition in the same trawl; one species released near-term pups (premature birth) and the other species released mid-term embryos (abortion) (authors', pers.…”

Section: Tablementioning

confidence: 99%

Sharks, rays and abortion: The prevalence of capture-induced parturition in elasmobranchs

Adams¹,

Fetterplace²,

Davis³

et al. 2018

Preprint

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The direct impacts of fishing on chondrichthyans (sharks, rays and chimeras) are well established. Here we review a largely unreported, often misinterpreted and poorly understood indirect impact of fishing on these animals — capture-induced parturition (either premature birth or abortion). Although direct mortality of discarded sharks and rays has been estimated, the prevalence of abortion/premature birth and subsequent generational mortality remains largely unstudied. We synthesize a diffuse body of literature to reveal that a conservative estimate of > 12% of live bearing elasmobranchs (n = 88 species) show capture-induced parturition. For those species with adequate data, we estimate capture-induced parturition events ranging from 2 to 85% of pregnant females (average 24%). To date, capture-induced parturition has only been observed in live-bearing species. We compile data on threat-levels, method of capture, reproductive mode and gestation extent of premature/aborted embryos. We also utilise social media to identify 41 social-media links depicting a capture-induced parturition event which provide supplementary visual evidence for the phenomenon. The mortality of embryos will have implications for elasmobranch populations, and there are limited options to deal with this problem. This review is the first to synthesize available data on capture-induced parturition in sharks and rays, and highlights an important ethical and management issue for fishers and managers deserving of much greater attention.

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“… N: number of individuals; M: males; F: females; percentage of each life stage in brackets; Sizes are total length for sharks, T. torpedo and disc width for Dasyatis sp. ; (a) Saidi et al., ; (b) Saidi et al., ; (c) Saidi et al., ; (d) Capapé et al., ; (e) Enajjar et al., ; (f) Enajjar et al., . …”

Section: Resultsmentioning

confidence: 99%

Elasmobranch captures in shrimps trammel net fishery off the Gulf of Gabès (Southern Tunisia, Mediterranean Sea)

2016

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Summary Small‐scale fisheries are generally promoted as a sustainable alternative to large‐scale industrial fisheries. However, there is recent growing evidence that small‐scale fisheries may be the largest threat to marine species of conservation concern. The objective of this study was to evaluate the potential impact of the trammel net fishery on elasmobranchs in the Gulf of Gabès, Southern Tunisia. Data are based on 191 shrimp trammel net set (40 mm stretched mesh size) surveys conducted aboard commercial fishing vessels from May to July 2009. Five species of the small coastal elasmobranchs (Mustelus mustelus (Linnaeus, 1758), Mustelus punctulatus Risso 1827, Dasyatis pastinaca (Linnaeus, 1758), Dasyatis marmorata (Steindachner, 1892) and Torpedo torpedo (Linnaeus, 1758)) and two species from the large coastal shark (Carcharhinus plumbeus (Nardo, 1827) and Carcharhinus brevipinna (Müller & Henle, 1839)) were recognized as by‐catch in this fishery. Elasmobranch by‐catch was dominated by sharks (90.3%), smoothhound sharks Mustelus sp. being by far the most important (88.9%) and reflecting their abundance in the area; 58% of the sets caught at least one specimen, with 4.8 ± 1.3 caught per set. Captures were composed essentially of neonate and juvenile sharks, while the batoids were dominated by mature individuals. This study shows that shrimp trammel nets represent a considerable source of mortality for early life stages of elasmobranch species in the Gulf of Gabès. Additionally, there was a high density of neonates and small juvenile M. mustelus in the Sfax zone, suggesting that these nearshore waters are a nursery grounds for smoothhound sharks. Further research should focus on the incidents of by‐catch and evaluate the potential solutions to allow trammel net fisheries to coexist alongside the elasmobranch species.

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Distribution and Reproductive Biology of the Spinner Shark, Carcharhinus Brevipinna (Müller and Henle, 1841) (Chondrichthyes: Carcharhinidae)

Cited by 19 publications

References 25 publications

Shark pelagic longline fishery in the Gulf of Gabes: Inter-decadal inspection reveals management needs

Shark pelagic longline fishery in the Gulf of Gabes: Inter-decadal inspection reveals management needs

Sharks, rays and abortion: The prevalence of capture-induced parturition in elasmobranchs

Elasmobranch captures in shrimps trammel net fishery off the Gulf of Gabès (Southern Tunisia, Mediterranean Sea)

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