Demographic Patterns of Two Poorly known Glassy Perchlets in Small-Scale Fisheries of Vembanad Estuary, a Ramsar Site in Southwest India

• Chelapurath Radhakrishnan Renjithkumar ^[2] ; Kuttanelloor Roshni ^[1]
  1. [1] Cochin University of Science and Technology

     Cochin University of Science and Technology

     India

     
  2. [2] Research Department of Fisheries and Aquaculture, St. Albert’s College (Autonomous), Ernakulam, Kochi, Kerala
• Localización: Thalassas: An international journal of marine sciences, ISSN 0212-5919, Vol. 42, Nº. 1, 2026
• Idioma: inglés
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• Resumen

  • Parambassis dayi and P. thomassi are endemic glassy perchlets exploited by small-scale fisheries in the Western Ghats (WG) biodiversity hotspot of India. Unregulated exploitation of these small-sized fishes has led to significant population declines. A comprehensive understanding of their demographic traits is essential for sustainable fishery management. The present study examined the length-weight relationships (LWRs) and demographic patterns of these two poorly known species based on monthly samples collected from April 2019 to March 2020 in the Vembanad estuary-a Ramsar wetland of international significance on the southwest coast of India. Fish samples were obtained using cast nets, seine nets, and gill nets from major fish landing centres in the middle stretch of the estuary. A total of 646 specimens were analyzed, comprising 263 individuals of P. dayi and 383 individuals of P. thomassi. P. dayi exhibits a negative allometric growth, while P. thomassi shows positive allometric growth. P. dayi exhibited a higher asymptotic length (L∞=189 mm vs. 147 mm), but a lower growth constant (K) (0.630 year− 1 vs. 1.100 year− 1) than P. thomassi, indicating faster growth rate for the latter species in the estuarine system. The fishing mortality rate (F) for P. thomassi was higher compared to P. dayi, suggesting greater fishing pressure and exploitation on P. thomassi. The exploitation rate (E) of P. thomassi was calculated as 0.63 exceeding the optimal value (E50) indicating overexploitation, while P. dayi is approaching this critical level. This study provides a comprehensive estimate of demographic parameters for P. dayi and P. thomassi and offer valuable insights for the management and conservation of glassy perchlets fisheries in Vembanad estuary and other regions of India facing similar exploitation pressure