Fishing ground and seasonal availability of diamondback squid (Thysanoteuthis rhombus) along southern Tañon Strait: Local fishermen’s insights

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Research Paper 16/07/2025
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Fishing ground and seasonal availability of diamondback squid (Thysanoteuthis rhombus) along southern Tañon Strait: Local fishermen’s insights

Robinson S. Amihan Jr., Hannah Abigail R. Daita
J. Biodiv. & Environ. Sci. 27(1), 61-70, July 2025.
Copyright Statement: Copyright 2025; The Author(s).
License: CC BY-NC 4.0

Abstract

This study documented the fishing grounds and seasonal availability of the diamondback squid (DBS) (Thysanoteuthis rhombus) along the southern Tañon Strait region of southwestern Cebu, Philippines, using purposive sampling of 105 fishermen across seven municipalities. All respondents had prior experience in capturing T. rhombus using a gear specifically designed for the species. Findings revealed that DBS fishing grounds spanned from the Municipality of Barili to Santander, with Barili emerging as the most prominent site. DBS fishing was also noted in Carcar, marking the first fisher-reported records of DBS in Cebu Strait. Respondents commonly used motorized boats (0.3–0.39 GT) with 6–10 HP gasoline engines, consuming 1–2L of fuel per trip. Fishing lasted 7–11 hours, typically conducted solo during daylight hours. The peak DBS season was observed from March to early August, with May yielding the highest catches—typically 1–10 pieces per trip, each weighing 1–10 kg. A lean season occurred from late August to February, with October having the lowest catch rates and most operations reporting no catch. Respondents noted a general decline in DBS catches from 2021 to 2022, coinciding with the COVID-19 pandemic. However, some fishermen linked the decline from 2011 to 2020 to excessive fishing effort and the use of the “multiple jigs in a line” method. While various causes were proposed, most attributed the decline to the species’ natural seasonal behavior. The findings offer baseline data for resource assessment and highlight the need for adaptive, season-based management to ensure sustainable catches.

Alejo-Plata MC, Urbano-Alonso B. 2018. The finding of diamond squid Thysanoteuthis rhombus in the Gulf of Tehuantepec, Northeastern Tropical Pacific. Hidrobiologica 28(1), 147–150. http://dx.doi.org/10.24275/uam/izt/dcbs/hidro/201 8v28n1/Alejo

Amihan RS Jr., Daita HAR. 2025. Squid jig types, composition and CPUEs, utilized in diamondback squid (Thysanoteuthis rhombus) fishing along southern Tañon Strait, Philippines. Journal of Biodiversity and Environmental Sciences 26(4), 17-26.

Arkhipkin AI, Rodhouse PK, Pierce GJ, Sauer W, Sakai M, Allcock L, Arguelles J, Bower JR, Castillo G, Ceriola L, Chen CS, Chen X, Diaz Santana M, Downey N, González AF, Amores JG, Green CP, Guerra A, Hendrickson LC, Ibáñez C, Ito K, Jereb P, Kato P, Katugin ON, Kawano M, Kidokoro H, Kulik VV, Laptikhovsky VV, Lipinski MR, Liu B, Mariátegui L, Marin W, Medina A, Miki K, Miyahara K, Moltschaniwskyj N, Moustahfid H, Nabhitabhata J, Nanjo N, Nigmatullin CM, Ohtani T, Perez GA, Piatkowski U, Saikliang P, Salinas-Zavala CA, Steer M, Tian Y, Ueta Y, Vijai D, Wakabayashi T, Yamaguchi T, Yamashiro C, Yamashita N, Zeidberg LD. 2015. World squid fisheries. Reviews in Fisheries Science & Aquaculture 23(2), 92-252. http://dx.doi.org/10.1080/23308249.2015.1026226 

Batcha H, Thangavelu R, Poovannan P, Srinivasan G. 2009. Rare occurrence of diamond back squid Thysanoteuthis rhombus (Troschel, 1867) off Chennai coast. Central Marine Fisheries Information Service T&E Ser. 201, 15.

Bello G. 1999. New records of Thysanoteuthis rhombus (Cephalopoda: Thysanoteuthidae) in the Mediterranean Sea. Bolletino Malacologico 34, 125–128.

Billings VC, Sullivan M, Vine H. 2000. Sighting of Thysanoteuthis rhombus egg mass in Indonesian waters and observations of embryonic development. Journal of the Marine Biological Association of the United Kingdom 80, 1139–1140.

Bower JR, Miyahara K. 2005. The diamond squid (Thysanoteuthis rhombus): A review of the fishery and recent research in Japan. Fisheries Research Journal 73(1–2), 1–11. https://doi.org/10.1016/j.fishres.2005.01.020

Brown TW, Izaguirre A, De Silva-Dávila R. 2022. Planktonic Egg Masses of the Diamondback Squid Thysanoteuthis rhombus in the Western Caribbean, Honduras; a Comprehensive Review of Global Observations. Caribbean Journal of Science 52, 34-49.

Cunha CM, Oliveira LE. 2014. Geographic distribution of Thysanoteuthis rhombus (Cephalopoda, Thysanoteuthidae) on the Brazilian coast. Check List 10(4), 939-942. http://dx.doi.org/10.15560/10.4.939

De Chavez P, Calderon GA, Santos SB, Cruz EMV, Santos MD. 2021. Vulnerability to climate change of “giant squid” (Thysanoteuthis rhombus) fishery in Marinduque, Philippines. The Philippine Journal of Fisheries 28(2), 171–180. http://dx.doi.org/10.31398/tpjf/28.2.2021-0002

Dickson JO, Ramiscal RV, Magno B. 2000. Diamondback squid (Thysanoteuthis rhombus) exploration in the South China Sea, Area III: Western Philippines. In: Proceedings of the Third Technical Seminar on Marine Fishery Resources Survey in the South China Sea, Area III: Western Philippines, 13–15 July 1999. Bangkok, Thailand, Secretariat, Southeast Asian Fisheries Development Center, 32-38.

Hernando AM, Flores EC. 1981. The Philippines squid fishery: A review. Marine Fisheries Review 43(1), 13–20.

Lamayo RC, Cunado VD, Delan GG, Rica RV, Ilano AS, Lamayo MHA. 2008. Catch distribution and biological characteristics of diamondback squid off Northeast Cebu Island, Philippines. Tropical Technology Journal 11(1-2).

Marčić Z, Ćaleta M, Buj I, Mrakovčić M, Mustafić P, Zanella D, Dulčić J. 2009. First record of Thysanoteuthis rhombus (Cephalopoda: Thysanoteuthidae) in the Adriatic Sea. 2009. Marine Biodiversity Records 2, 1-3. https://doi.org/10.1017/S1755267208000146

Nigmatullin CM, Arkhipkin AI, Sabirov RM. 1995. Age, growth and reproductive biology of diamond-shaped squid Thysanoteuthis rhombus (Oegopsida: Thysanoteuthidae). Marine Ecology Progress Series 124, 73-87.

Nigmatullin CM, Arkhipkin AI. 1998. A review of the biology of the diamondback squid, Thysanoteuthis rhombus (Oegopsida: Thysanoteuthidae). In: Okutani, T. Ed. International Symposium on Large Pelagic Squids. Japan Marine Fishery Resources Research Center, Tokio. p. 155-181.

Pulido-López P, López-Pinto Y. 2002. First record of the diamond squid Thysanoteuthis rhombus Troschel, 1857 (Cephalopoda: Teuthida: Oegopsina) in the Colombian Caribbean Sea. Boletín de Investigaciones Marinas y Costeras- INVEMAR 31, 239–241.

Rajikumar M, Midun M, Thirumalaiselvan S, Rajkumar R, Saravanan R. 2022. A unique occurrence of large-sized diamondback squid Thysanoteuthis rhombus (Troschel, 1857) in the Gulf of Mannar. Indian Journal of Geo Marine Sciences 51(07), 650-653. https://doi.org/10.56042/ijms.v51i07.48858

Roper CFE, Sweeney MJ, Nauen CE. 1984. FAO Species Catalogue: Vol. 3 Cephalopods of the World. FAO Fisheries Synopsis 3(125), 187-188.

Salvat-Torres HM, Avila LC, Bermejo MG. 2009. A new record for the marine molluscs of Cuba: the diamond squid Thysanoteuthis rhombus (Mollusca: Cephalopoda). Revista de Investigaciones Marinas 30, 227–239.

Yano K, Ochi Y, Shimizu H, Kosuge T. 2000. Diurnal swimming patterns of the diamondback squid as observed by ultrasonic telemetry. In Eiler JH, Alcorn DJ, Neuman ME Eds. Biotelemetry 15: Proceedings of the 15th International Symposium on Biotelemetry. Juneau, Alaska USA: International Society on Biotelemetry. p. 108–116.

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