Biological observations on the bristly catshark <i>Bythaelurus hispidus</i> from deep waters off the south‐west coast of India

Akhilesh, K; White, William T.; Bineesh, K. K.; Ganga, U; Pillai, N G K

doi:10.1111/jfb.12087

Cited by 11 publications

(17 citation statements)

References 26 publications

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“…During the same period, a targeted gulper shark fishery developed off south‐west India for liver oil production, and Centrophorus spp. were reported as a major by‐catch of the shrimp trawl fishery that expanded to deeper waters (Akhilesh, Bineesh, Ganga, & Pillai, ; Akhilesh, White, Bineesh, Ganga, & Pillai, ; Akhilesh et al., ). Deepsea shark stocks are suspected to have also collapsed in Indian fisheries after a significant increase in landings with an apparent decline in the size of individuals landed between 2002 and 2008 (Akhilesh & Ganga, ; Akhilesh, Bineesh, et al., ; Akhilesh et al., ).…”

Section: Discussionmentioning

confidence: 99%

Troubled waters: Threats and extinction risk of the sharks, rays and chimaeras of the Arabian Sea and adjacent waters

et al. 2018

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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.

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Section: Discussionmentioning

confidence: 99%

Troubled waters: Threats and extinction risk of the sharks, rays and chimaeras of the Arabian Sea and adjacent waters

et al. 2018

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“…In the same genera, Farrugia et al (2011) recorded abundance, habitat use and movement patterns of Rhiobatos productus in a restored southern California estuary and found no evidence of sexual segregation by season based on the sex ratio of the catch. Unequal sex ratios can be the result of sexual segregation by depth or area and/or gear selectivity (Akhilesh et al, 2013).…”

Section: Discussionmentioning

confidence: 99%

Biological observations on the Bengal guitarfish Rhinobatos annandalei Norman, 1926 from the Eastern Arabian Sea, India

Purushottama¹,

Ramasubramanian²,

Akhilesh³

et al. 2020

Indian J. Fish.

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Biological data for the little known Bengal guitarfish Rhinobatos annandalei Norman, 1926 (Rhinopristiformes: Rhinobatidae) are presented based on specimens collected from bycatch of commercial shrimp trawlers, gill netters and bag or dol netters operating in the Arabian Sea at depths of 2-70 m off the north-west coast of India. Five hundred ninety-three specimens measuring 30.0 to 95.0 cm total length (TL) and weighing between 64.0 to 3300 g total weight (TW) were collected for the study. The length-weight relationships (LWR) were significantly different between the sexes (p<0.001) and for the combined sexes was derived as TW= 0.000604 TL3.408256 (r2= 0.997). The co-efficients ‘a’, ‘b’ of the LWR were estimated as 0.000621, 3.410115 (r2= 0.999) for females and 0.000766, 3.333872 (r2= 0.999) for males. The length at maturity (TL50) for females and males was estimated to be 61.0 and 63.3 cm TL, respectively. In a single female, the number of embryos ranged from 2 to 11 and the size at birth was estimated between 25.0 to 30.0 cm TL. The overall sex ratio favoured females at the rate of 1.6:1. An analysis of the stomach contents (%IRI) revealed that R. annandalei mainly fed on Solenocera spp. (18.7% IRI), along with P. sculptilis (0.5% IRI), P. stylifera (0.4% IRI), Loligo spp. (0.4% IRI) and sciaenids (0.3% IRI). Since, the species is poorly studied and assessed as ‘Data Deficient’ in the IUCN red list criterion, it is anticipated that the biological results from the present study, will update information on the species thereby enabling more effective management decisions.

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“…Understanding the life‐history traits and habitat characteristics are highly important in ensuring sustainable fisheries and informing management decisions. The life‐history patterns of chondrichthyans of Indian waters are poorly understood (Akhilesh et al ., ; Kizhakudan et al ., ), but recently there have been concentrated efforts to fill this knowledge gap (Raje et al ., ; Varghese et al ., ) and more regulatory (conservation and trade) implications in the region ( e.g . finning ban and fin attached policy, fin export ban).…”

Section: Stomach‐content Prey Items By Number (%N) Mass (%M) Occurrmentioning

confidence: 96%

Biological observations on the broadfin shark Lamiopsis temminckii (Carcharhiniformes: Carcharhinidae)

Akhilesh

Purushottama

Thakurdas

et al. 2017

Journal of Fish Biology

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Biological information was collected from 214 individuals of the broadfin shark Lamiopsis temminckii measuring 418 to 1782 mm total length, L . Size at maturity (L ) for females and males was estimated at 1430 and 1368 mm L , respectively, while mature and gravid females were observed from 1350 mm L with litter sizes 2-8 and size at birth 418-650 mm L . Analysis of stomach contents revealed a variety of prey, primarily crustaceans (54·0%), teleosts (42·7%) and cephalopods.

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Biological observations on the bristly catshark Bythaelurus hispidus from deep waters off the south‐west coast of India

Cited by 11 publications

References 26 publications

Troubled waters: Threats and extinction risk of the sharks, rays and chimaeras of the Arabian Sea and adjacent waters

Troubled waters: Threats and extinction risk of the sharks, rays and chimaeras of the Arabian Sea and adjacent waters

Biological observations on the Bengal guitarfish Rhinobatos annandalei Norman, 1926 from the Eastern Arabian Sea, India

Biological observations on the broadfin shark Lamiopsis temminckii (Carcharhiniformes: Carcharhinidae)

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