Optimizing Conch Shell Pot Efficiency for Sandbird Octopus, Amphioctopus Aegina (Gray, 1849)

Veeramani, Marimuthu and Kalaiarasan, Muthupandi and Neethiselvan, Neethirajan and Jayakumar, Natarajan and Kavitha, Josephine and Radhakrishnan, Kalidoss and Emiema, Soosaiantony and Gayathre, Lakshme and Dineshkumar, Esakkimuthu and Sulaiman, Jiyavudeen Musraf (2025) Optimizing Conch Shell Pot Efficiency for Sandbird Octopus, Amphioctopus Aegina (Gray, 1849). Thalassas: An International Journal of Marine Sciences, 41. ISSN 2366-1674

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Abstract

The study evaluated the efficiency of conch shell pots for harvesting the sandbird octopus (Amphioctopus aegina) along the Palk Bay coast of India. From December 2023 to August 2024, 165 samples were collected using a randomized protocol from local fisheries deploying five conch species: Chicoreus ramosus, Tonna dolium, Rapana rapiformis, Phalium glagum, and Volegalea cochlidium. Catch data were analyzed with two-way analysis of variance (ANOVA; P < 0.05) to assess variation in efficiency among conch species and across months. The C. ramosus yielded the highest catches, accounting for 44.9% of individuals and 44.9% of total biomass (301.4 tonnes), followed by T. dolium (29.9%, 30.6%), R. rapiformis (21.9%, 21.1%), P. glagum (2.1%, 2.1%), and V. cochlidium (1.2%, 1.3%). Absolute catch was greatest with C. ramosus pots (10,046,520 individuals) and lowest with V. cochlidium (272,140 individuals). Reduced yields from V. cochlidium and the frequent capture of sub-adults (< 15 g) in P. glagum pots were identified as limiting factors. Catch efficiency, expressed as octopus per 100 shells, increased with conch weight, with values highest for C. ramosus (27.2), followed by T. dolium (25.7), R. rapiformis (24.3), P. glagum (22.2), and V. cochlidium (14.1). On the basis of total biomass and efficiency, C. ramosus is identified as the most effective conch species for sustainable harvesting of A. aegina in Palk Bay. However, limited availability of natural conch shells, the development of artificial conch shell pots is essential to ensure the long-term sustainability of octopus fisheries in Palk Bay.

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