Diet and sexual maturity of yellowfin and skipjack tuna taken by hand lines from fish-aggregating 'payaw' off northwestern Luzon
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Skipjack tuna Katsuwonus pelamis and yellowfin or albacore tuna Thunnus albacares taken by hand lines from the 'payaw' off La Union and Ilocos Sur were sampled from April 1994 until August 1995. Skipjack ranged from 28 cm to 59 cm in fork length and from 0.35 to 4.2 kg in weight. Yellowfin ranged 24–67 cm and 0.25–6.4 kg. The common size landed was about 40 cm for both species. Size at first maturity of skipjack was about 41 cm in males and 42 cm in females. The yellowfin tuna taken by hand lines were almost all immature except two mature males about 60 cm long. About 18 prey species were identified in the stomachs of skipjack, and about 25 prey species in yellowfin. The preferred prey were mantis shrimps and squids. Small fishes and other invertebrates were also eaten. Mesopelagic lanternfish were eaten by yellowfin and epipelagic jellyfish were eaten by skipjack.
Mamhot, J. R., & Verceles, E. R. (2007). Diet and sexual maturity of yellowfin and skipjack tuna taken by hand lines from fish-aggregating 'payaw' off northwestern Luzon. In T. U. Bagarinao (Ed.), Research Output of the Fisheries Sector Program (Vol. 2. Reports on Fisheries and Aquaculture, pp. 25-27). Quezon City, Philippines: Bureau of Agricultural Research, Department of Agriculture.
PublisherBureau of Agricultural Research, Department of Agriculture
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Book chapterVR Panay & NL Ledda - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of AgricultureA study of tuna fishers in northwestern Luzon (Region I) was done by means of a questionnaire. The 511 respondents included 178 from Ilocos Sur, 200 from La Union, and 133 from Pangasinan. Most of them were younger than 50 years, had basic education, married with large families of 3-9 children, owned the houses they lived in, and had low annual incomes of about P35,000. Fishing was their sole means of livelihood for almost all the respondents, except some for whom farming supplemented the income from fishing. Majority worked every night or day, 36% went fishing every other night or day, and 13% went fishing five times a week. Most fishers went out to sea at night. Fully 52% of the fishers worked within 50 km from shore; 38% fished within 51–100 km, and the others went out farther than 100 km and even 200 km. La Union fishers worked closest to shore (average 38 km) and Pangasinan fishers the farthest (average 92 km). More than 90% of all fishers used motorized bancas, which made it possible for them to fish farther out to sea. Only 36% of the fishers owned the boats and fishing gears they used, and most did not. In all three provinces, the capital for the fishing enterprise came mainly from savings. The average cost of motorized boats was P31,200; non-motorized boats, P1,200. Longlining was the most preferred fishing method in the region. Hand lining was the second most preferred in Ilocos Sur and Pangasinan. Gillnetting and other methods (rabuk, kawil, pana, and bira-bira) were ranked third and fourth, and trawling was the least preferred. Drift gill nets used for tunas cost on average P680; tuna long lines, about P600; tuna hand lines, P345; and troll lines, P750. The main species caught by the fishers were skipjack tuna, yellowfin tuna, frigate tuna, Spanish mackerel, rainbow runner, dolphinfish, sailfish, blue marlin, and threadfins. In Ilocos Sur, most fishers reported catches of 11-20 kg in one trip, and a few fishers caught 50 kg. Spanish mackerel and sailfish gave the fishers better incomes than the other species. Fish catches and prices and fisher incomes in La Union were lower than in Ilocos Sur. Threadfins were more abundant in La Union. Fishers in Pangasinan did not catch sailfin, marlin, or threadfins, but caught higher volumes (20–60 kg/trip) of the other species.
The tuna fishery off northwestern Luzon: catch of purse seines and hand lines operating around fish-aggregating 'payaw' VV Prado - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of AgricultureThe tuna fishery along northwestern Luzon was studied from March 1994 to April 1995. About 120 units of fish aggregating ‘payaw’ were set 20–100 km offshore and fished by about 350 handline boats and 6 purse seines. The handline landing areas were in Apatot, San Esteban, Ilocos Sur and in Darigayos Cove, La Union. The resident purse seine was based at Poro Point in San Fernando, La Union; the others were occasional operators. Skipjack tuna Katsuwonus pelamis was the primary species landed by the purse seine and yellowfin tuna Thunnus albacares was mostly landed by the hand lines. These species occurred year-round with peaks during the dry season. The purse seine was operated about 9 sets per month, and landed an average of 51 mt fish monthly (catch rate 5.7 mt/set), highest in November, December and March. Handline fishing was carried out an average of 17 days a month (catch rate about 19 kg/boat-day). The tuna fishery was adversely affected by strong monsoon winds and typhoons. The rough seas inhibit fishing and give the tuna populations much needed respite from the intense fishing pressure.
Book chapterEEM Santos-Yap - In T Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of AgricultureThe recommended steps in new product development were followed to utilize bullet tuna maximally. New products were generated, evaluated, and refined. Three product concepts were initially advanced to the product optimization stage; both product and positioning blueprints were created. The products were optimized in terms of the levels and combinations of additives and spices, and the organoleptic properties were evaluated. The new products—bullet tuna loaf, seasoned dried bullet tuna, canned spicy bullet tuna, and canned pet foods—were tested for shelf-life. Tuna loaf treated with potassium sorbate remained acceptable for 29 days at 0°C, whereas untreated samples remained acceptable for 26 d at 0°C, 16 d at 14°C, and 3 d at 35°C. Seasoned dried tuna was still acceptable until 15 d in storage at 0°C and until 6 d at 35°C. Canned spicy tuna remained acceptable after more than a year of storage at 35°C. Cost analysis based on the current retail prices of bullet tuna (P30/kg), additives, spices and other raw materials showed that the production costs were: P19 for 100 g of bullet tuna loaf; P2 for a piece of seasoned dried tuna; and P 12.5 for a can of spicy bullet tuna. Traditional processing methodologies were applied to bullet tuna as raw material. Smoking and dry-salting yield bullet tuna products that can be offered to the consumers at prices much lower than those of the newly developed value-added products.