Reproductive biology of the milk shark<i>Rhizoprionodon acutus</i>(Carcharhinidae) off the coast of Senegal

Bâ, Alassane; Bâ, Cheikh Tidiane; Diouf, Khady; Ndiaye, Papa Ibnou; Panfili, Jacques

doi:10.2989/1814232x.2013.796892

Cited by 9 publications

(20 citation statements)

References 25 publications

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“…acutus tended towards W ∞ but grew very little in mass at older ages. According to this study, growth gain of females was greater than that of males, confirming the sexual dimorphism for this species (Capapé et al , ; Ba et al , ). The variation of asymptotic mass between males and females might be related to the sex‐specific preferences in the food‐searching sites.…”

Section: Discussionsupporting

confidence: 85%

“…This study has provided estimates of age and growth for R . acutus , a coastal shark species, which is the most landed shark species along the Senegalese coast and easily accessible to small‐scale fisheries (Capapé et al , ; Ba et al , ). This is the first comprehensive study of age and growth for age estimation in this species in West African waters.…”

Section: Discussionmentioning

confidence: 99%

“…This annual growth band deposition is often seen in other species having a seasonal reproductive cycle similar to R . acutus (Capapé et al , ; Ba et al , ). Despite this result, further validation of the annual periodicity of the ring pattern observed in R .…”

Section: Discussionmentioning

confidence: 99%

“…The milk shark Rhizoprionodon acutus (Rüppell 1837) is the most widely distributed species of this genus, extending all along the West African coast, in the Indo‐Pacific, in the northern part of the Indian Ocean, from the Indonesian to the Philippine archipelagos and from Japan to Australia (Compagno, ; Capap é et al ., ; Harr y et al ., ). The species is common on the West African continental shelf (Capapé et al , , ; Ba et al , , b) in water depths up to 200 m (Compagno, ). It is the most landed shark species on the Senegalese coasts (Ba et al , ) and is also known in many countries, but there are very few available data on their populations status or fisheries (Simpfendorfer, ).…”

Section: Introductionmentioning

confidence: 99%

“…The species is common on the West African continental shelf (Capapé et al , , ; Ba et al , , b) in water depths up to 200 m (Compagno, ). It is the most landed shark species on the Senegalese coasts (Ba et al , ) and is also known in many countries, but there are very few available data on their populations status or fisheries (Simpfendorfer, ).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Slow growth of the overexploited milk sharkRhizoprionodon acutusaffects its sustainability in West Africa

Bâ

Diouf

Guilhaumon

et al. 2015

Journal of Fish Biology

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Age and growth of Rhizoprionodon acutus were estimated from vertebrae age bands. From December 2009 to November 2010, 423 R. acutus between 37 and 112 cm total length (LT ) were sampled along the Senegalese coast. Marginal increment ratio was used to check annual band deposition. Three growth models were adjusted to the length at age and compared using Akaike's information criterion. The Gompertz growth model with estimated size at birth appeared to be the best and resulted in growth parameters of L∞ = 139.55 (LT ) and K = 0.17 year(-1) for females and L∞ = 126.52 (LT ) and K = 0.18 year(-1) for males. The largest female and male examined were 8 and 9 years old, but the majority was between 1 and 3 years old. Ages at maturity estimated were 5.8 and 4.8 years for females and males, respectively. These results suggest that R. acutus is a slow-growing species, which render the species particularly vulnerable to heavy fishery exploitation. The growth parameters estimated in this study are crucial for stock assessments and for demographic analyses to evaluate the sustainability of commercial harvests.

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Section: Discussionsupporting

confidence: 85%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Slow growth of the overexploited milk sharkRhizoprionodon acutusaffects its sustainability in West Africa

Bâ

Diouf

Guilhaumon

et al. 2015

Journal of Fish Biology

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Demographics and length and weight relationships of commercially important sharks along the north‐western coast of India

Barnes¹,

Sutaria

Harry

et al. 2018

Aquatic Conservation

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Biological data including size, sex ratios, male maturity, and length and weight relationships for four commercially important shark species, including the milk shark (Rhizoprionodon acutus Rüppell, 1837), the grey sharpnose shark (Rhizoprionodon oligolinx Springer, 1964), the spadenose shark (Scoliodon laticaudus Muller & Henle, 1838), and the bigeye smoothhound shark (Iago omanensis Norman, 1939), landed in Porbandar, Gujarat, India, are provided. All four species were landed by trawlers and gill‐netters across three defined seasons, with seasonal differences. Higher proportions of mature R. acutus and S. laticaudus were observed in the pre‐monsoon season, with neonates caught throughout the year, whereas higher proportions of mature R. oligolinx and I. omanensis were recorded during the monsoon season, with neonates caught in post‐monsoon and pre‐monsoon, respectively, showing important species‐level differences. These small‐bodied shark species (less than 1 m in total length) showed positive allometry in their length and weight relationships. Unlike the other three species, I. omanensis showed high disparity in total lengths (LT) between the sexes, with females being larger than males, and with males maturing faster, with the smallest mature male of 33.58 cm LT. Females outnumbered males except in R. acutus, and pregnant females of all species were recorded at least once. Of the 971 males recorded across species, 55.1% were mature and 44.9% were immature. Results from this study indicate that there is substantial overlap between the distributions of these species and fishing activities, and show that most, if not all, life stages are susceptible to mortality as a result of fishing. This study provides managers with a better understanding of the life‐history traits of these commercially important species to support future quantitative population assessments, and provides a baseline of trends in fishing‐related mortality.

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Baseline assessment of the coastal elasmobranch fauna of Eastern Cabo Verde, West Africa

Seymour,

Monteiro,

Monteiro

et al. 2024

Aquatic Conservation

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An increasing onus on elasmobranch management by regional bodies has been hindered by a lack of data on abundance, distribution and fisheries, especially in data‐poor areas like the eastern Atlantic Ocean. From 2015 through 2017, 204 baited remote underwater videos (BRUV) were deployed in Cabo Verde around the eastern islands of Sal, Boavista and Maio and the remote offshore reef João Valente to establish a baseline of elasmobranch abundance. Over 200 hours of footage revealed 215 individual elasmobranchs, spanning 14 species from 6 taxonomic families. The abundance of elasmobranchs was highest in Maio, the island with the smallest human population, followed by Boavista and Sal. Smaller‐bodied meso‐predatory species such as the common smoothhound (Mustelus mustelus) and the Atlantic weasel shark (Paragaleus pectoralis) constituted the majority of observations in Maio and Boavista. Inversely, Carcharhinus spp. were observed in considerably greater abundance in Sal, and there was notably lower abundance of small‐bodied sharks at sites with high large‐bodied Carcharhinid abundance. Species richness was consistent with abundance estimates across islands, with Boavista and Sal recording the highest species diversity, followed by Maio. Results suggest that amongst Cabo Verde's eastern islands, there exists a high relative diversity and abundance of coastal elasmobranchs compared to populations in West Africa. Nonetheless, there is evidence of exploitation of higher trophic levels species. This trend is most notable in the decreasing abundance of Carcharhinids with increasing proximity to the capital city Praia, suggesting that fishing efforts from the capital are negatively affecting the abundance of large‐bodied, higher‐trophic predators.

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Reproductive biology of the milk sharkRhizoprionodon acutus(Carcharhinidae) off the coast of Senegal

Cited by 9 publications

References 25 publications

Slow growth of the overexploited milk sharkRhizoprionodon acutusaffects its sustainability in West Africa

Slow growth of the overexploited milk sharkRhizoprionodon acutusaffects its sustainability in West Africa

Demographics and length and weight relationships of commercially important sharks along the north‐western coast of India

Baseline assessment of the coastal elasmobranch fauna of Eastern Cabo Verde, West Africa

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