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<p>Asian sea bass (<i>Lates calcarifer</i>) is a diadromous fish for which limited information is available regarding its demographics and exploitation levels. The length-weight relationships (LWRs) and demographic pattern of the Asian sea bass were investigated monthly from June 2023 to May 2024 in the Vembanad estuary, the largest estuarine system along the southwest coast of India. The fish samples were gathered (gill nets and hook &amp; lines) from the major fish landing centres located near the bar mouth, middle and freshwater zone of the estuary. A total of 351 fish samples were collected, with lengths ranging from 12.2&#xa0;cm to 103.3&#xa0;cm and weights ranging from 52 gm to 13.69&#xa0;kg. The LWRs of the Asian sea bass were described by the equation <i>W</i> = 0.024 TL<sup>2.68</sup> (<i>r</i><sup>2</sup> = 0.98; SE = 0.087), indicating a negative allometric growth pattern. The size composition of commercial catches of <i>L. calcarifer</i> in the estuary revealed that the majority of catch was composed of length groups 31–40&#xa0;cm (31.62%), 41–50&#xa0;cm (18.80%) and 21–30&#xa0;cm (18.23%). The growth parameters <i>L</i><sub><i>α</i></sub> and <i>K</i> were estimated as 105&#xa0;cm and 0.47 yr<sup>− 1</sup>, respectively. Natural (<i>M</i>) and fishing mortality (<i>F</i>) coefficients were 0.41 yr<sup>− 1</sup> and 0.95 yr<sup>− 1</sup> respectively. The length at first capture of <i>L. calcarifer</i> was reported as 18.69&#xa0;cm, which is considerably smaller than its size at first maturity. The exploitation level (<i>E</i>) was calculated to be 0.70, which exceeds the optimal value (<i>E</i><sub><i>50</i></sub>) indicating that the Asian sea bass population in the Vembanad estuary is overexploited. The fishing pressure on the current stocks was found to be excessively high, making it imperative to implement management strategies such as establishing closed fishing seasons, reducing fishing efforts, and enforcing catch quotas for fishers in the estuary and adjoining waters.</p>

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Demographic Characteristics of Asian Sea Bass (Lates calcarifer), A Diadromous Fish from the Vembanad Estuary on the South West Coast of India

  • 期刊论文

  • 发表日期：

    2025年5月13日

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  • Chelapurath Radhakrishnan Renjithkumar,
  • Kuttanelloor Roshni

摘要

Asian sea bass (Lates calcarifer) is a diadromous fish for which limited information is available regarding its demographics and exploitation levels. The length-weight relationships (LWRs) and demographic pattern of the Asian sea bass were investigated monthly from June 2023 to May 2024 in the Vembanad estuary, the largest estuarine system along the southwest coast of India. The fish samples were gathered (gill nets and hook & lines) from the major fish landing centres located near the bar mouth, middle and freshwater zone of the estuary. A total of 351 fish samples were collected, with lengths ranging from 12.2 cm to 103.3 cm and weights ranging from 52 gm to 13.69 kg. The LWRs of the Asian sea bass were described by the equation W = 0.024 TL2.68 (r2 = 0.98; SE = 0.087), indicating a negative allometric growth pattern. The size composition of commercial catches of L. calcarifer in the estuary revealed that the majority of catch was composed of length groups 31–40 cm (31.62%), 41–50 cm (18.80%) and 21–30 cm (18.23%). The growth parameters Lα and K were estimated as 105 cm and 0.47 yr− 1, respectively. Natural (M) and fishing mortality (F) coefficients were 0.41 yr− 1 and 0.95 yr− 1 respectively. The length at first capture of L. calcarifer was reported as 18.69 cm, which is considerably smaller than its size at first maturity. The exploitation level (E) was calculated to be 0.70, which exceeds the optimal value (E50) indicating that the Asian sea bass population in the Vembanad estuary is overexploited. The fishing pressure on the current stocks was found to be excessively high, making it imperative to implement management strategies such as establishing closed fishing seasons, reducing fishing efforts, and enforcing catch quotas for fishers in the estuary and adjoining waters.