Population dynamics of a poorly known serranid, the duskytail grouper <i>Epinephelus bleekeri</i> in the Arabian Sea

Richu, Avinipully; Dahanukar, Neelesh; Ali, Angrej; Ranjeet, Kutty; Raghavan, Rajeev

doi:10.1111/jfb.13762

Cited by 3 publications

(2 citation statements)

References 7 publications

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“…However, the observed natural mortality (0.88 year − 1 ) in P. khavalchor was found to be higher as compared to the other catfish species such as Clarotes laticeps (0.87) (Abowei & Davies, 2009), Schilbe intermedius (0.81) (Etim et al, 1999) and Schilbe mystus (0.28) (Kolding et al, 1992). Such high natural mortality could be attributed to various factors such as predation, diseases, or different environmental stressors acting independently or synergistically (Caveriviere & Toure, 1996;Raghavan et al, 2018a;Richu, Dahanukar, Ali, Ranjeet, & Raghavan, 2018). However, the exact information on the factor/s causing higher natural mortality at the small size of P. khavalchor is not known and thus need further investigation.…”

Section: Discussionmentioning

confidence: 99%

Assessing the sustainability of lepidophagous catfish, Pachypterus khavalchor (Kulkarni, 1952), from a tropical river Panchaganga, Maharashtra, India

Gosavi¹,

Kharat²,

Kumkar³

et al. 2019

JoBAZ

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Background: The Western Ghats of India, one of the global biodiversity hotspots and freshwater eco-regions, harbors several fish species which not just form the important part of the world's freshwater biodiversity yet in addition are the vital segment of livelihood of the neighborhood population. The rate of fish decline in the Western Ghats is alarming. The absence of organized study and data scarcity on basic biology and life history traits of several species could be one reason behind the decline, and thus it is difficult to execute conservation action/s. This is especially true, particularly for data-deficient species for which definite data related to distribution, population size, and trend is not available. The present study deals with the detailed investigation of population dynamics of catfish species, Pachypterus khavalchor, which is data-deficient species inhabiting the Western Ghats of India and forms an important component of freshwater inland fishery, providing nutritional and financial security to the local community. Methods: Specimens for the present study were collected monthly for a period of 1 year from the River Panchaganga and length-frequency data were analyzed using FiSAT II software. Results: Length-weight analysis of pooled (male + female) data suggested the fish exhibited higher exponent than expected under isometry, indicating the positive allometric growth of P. khavalchor in the Panchaganga River. The asymptotic length (L∞) and the growth rate (K) were estimated as 149.63 mm and 0.71 year −1 respectively. Potential longevity (t max ) and length at first capture (Lc) were estimated as 4.22 years and 73 mm respectively. The total (Z), natural (M), and fishing mortality (F) were estimated as 2.23 year −1 , 0.88 year −1 , and 1.35 year −1 respectively. The current exploitation rate (E cur = 0.60) was found to be almost 90% that gives the maximum relative yield per recruit (E max = 0.67). Recruitment pattern revealed two peaks, suggesting the fish have two spawning bouts each year. Conclusions: The stock of P. khavalchor in the Panchaganga River may be in near full exploitation under the current harvesting strategy, with a high chance of recruitment failure in the future. Additional studies on the reproductive biology of P. khavalchor would be particularly welcome for the imposition of the seasonal closure for effective conservation of stock.

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Section: Discussionmentioning

confidence: 99%

Assessing the sustainability of lepidophagous catfish, Pachypterus khavalchor (Kulkarni, 1952), from a tropical river Panchaganga, Maharashtra, India

Gosavi¹,

Kharat²,

Kumkar³

et al. 2019

JoBAZ

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“…In Indian waters, stock estimates and studies on different grouper species were done by several authors (Premalatha, 1989;Ameer and Kasim, 1992;Chakraborty, 1994;Rangaswamy et al, 1999;Manojkumar, 2005;Sivakami and Seetha, 2006;Jayasankar et al, 2007;Sujatha et al, 2010;Kirubasankar et al, 2013). Studies on population dynamics and stock characteristics of genus Epinephelus were done by very few authors (Manojkumar, 2005;Mehanna et al, 2013;Richu et al, 2018). However, information on the stock assessment more specifically on E. malabaricus from Indian waters is scanty with an exception of a publication by Kirubasankar et al (2013) from the Andaman Islands.…”

Section: Introductionmentioning

confidence: 99%

Fishery and population dynamics of Epinephelus malabaricus (Bloch & Schneider, 1801) off Tuticorin, southeast coast of India

Manojkumar¹,

Ranjith²,

Karuppasamy³

et al. 2019

J. Mar.Biol.Ass.India

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Fishery, population characteristics and stock estimates of grouper with special reference to Epinephelus malabaricus from Tuticorin were carried out during 2015-2017. Among the groupers, E. malabaricus was the dominant resource contributing 42.2%, with an annual average production of 420t along this region. The asymptotic length (L ∞), growth coefficient (K) and arbitrary origin of growth (t 0) were estimated at 99.75 cm, 0.53 y-1 and 0.18 respectively. The mortality parameters, the instantaneous total mortality rate (Z), fishing mortality (F) and natural mortality rates (M) were estimated at 1.14 y-1 , 0.62 y-1 and 0.52 y-1 respectively. The recruitment season was during April to August. The length structured virtual population (VPA) analysis revealed a heavy fishing pressure on length group between 40 and 55cm and there is no sign of recruitment over-fishing in this region. The estimated maximum sustainable yield (MSY) and annual catch were 384 t and 420 t respectively. E. malabaricus was optimally exploited as the exploitation ratio (E) was 0.54 but the study infers that further increase in effort may have a detrimental effect on the stock of this species. The results of this study will serve as baseline information for formulating future management measures for the resource along the coast.

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By-catch-associated demographics of two threatened seahorses from the south-east coast of India

Shalu

Dahanukar

Raghavan

et al. 2021

Mar. Freshwater Res.

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Seahorses comprise a charismatic, high-value and high conservation-concern group of fishes, whose demographics, including the dynamics of populations, are poorly studied. In this paper, we fill this key knowledge gap by determining the population dynamics of two threatened species, Hippocampus kuda and H. trimaculatus, from the south-east coast of India using samples encountered in trawl by-catch. Hippocampus kuda showed a comparatively greater asymptotic length, whereas H. trimaculatus had a greater growth coefficient and growth performance index. Further, H. trimaculatus showed two recruitment peaks (March/April and December) in a year, against a single peak (February) for H. kuda. An assessment of mortality rates (instantaneous total, natural and fishing) indicated a high vulnerability of the local population of both species to fishing pressure. Hippocampus kuda had a greater mean length at first capture than H. trimaculatus. Biomass-per-recruit analysis showed that the exploitation of H. kuda is closer to the exploitation rates under which stock will be reduced to half the unexploited biomass, suggesting their extreme vulnerability to overexploitation, even as ‘by-catch’. Demographic parameters of the two threatened seahorses indicated that even as ‘incidental catch’, these species are vulnerable to overfishing, and species-specific conservation guidelines need to be developed and their on-ground implementation and enforcement ensured.

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Population dynamics of a poorly known serranid, the duskytail grouper Epinephelus bleekeri in the Arabian Sea

Cited by 3 publications

References 7 publications

Assessing the sustainability of lepidophagous catfish, Pachypterus khavalchor (Kulkarni, 1952), from a tropical river Panchaganga, Maharashtra, India

Assessing the sustainability of lepidophagous catfish, Pachypterus khavalchor (Kulkarni, 1952), from a tropical river Panchaganga, Maharashtra, India

Fishery and population dynamics of Epinephelus malabaricus (Bloch & Schneider, 1801) off Tuticorin, southeast coast of India

By-catch-associated demographics of two threatened seahorses from the south-east coast of India

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