Management of fish health in broodstock and larvae of milkfish, sea bass and grouper
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Historically, reports on the occurrence of disease problems in milkfish, seabass and grouper were mainly on the isolation and identification of etiological agents. Studies on the tolereance of fish to chemotherapeutants were also conducted. Various species of vibrios and gill-infesting parasites have been associated with diseases in all life stages of these fish. Presently, mortalities due to diseases of unknown etiology, environmental failure and nutritional or husbandry shortfalls affect successful fry production in the hatchery. Morphological deformities in hatchery-produced milkfish fry is a major problem to be solved. In seabass fry production, swim-bladder stress syndrome occasionally occurs and results in mass mortalities. In larval grouper culture, the problem of low survival is being addressed through improved husbandry and nutrition. For cage-held broodstock that naturally spawn in captivity, such as milkfish and grouper, the main problem is fouling of net enclosures in the cages. However, for fish that need hormonal manipulation to spawn, such as seabass and snapper, stressful handling procedures during sampling and hormone injection may lead to injuries and scale loss. The damaged areas become focal points for secondary bacterial infection. Future fish health management strategies in these fish should incorporate a holistic approach to include environmental monitoring, nutritional manipulation, immunostimulants and vaccine use, and biological control in addition to pathogen exclusion in the rearing system and the fish.
Emata, A. C., Lavilla-Pitogo, C. R., Duray, M. N., & Toledo, J. D. (1996). Management of fish health in broodstock and larvae of milkfish, sea bass and grouper. In K. L. Main & C. Rosenfeld (Eds.), Aquaculture health management strategies for marine fishes?: proceedings of a workshop in Honolulu, Hawaii, October 9- 13, 1995 (pp. 47-56). Walmanalo, Hawaii: The Oceanic Institute.
PublisherThe Oceanic Institute
- Conference Proceedings 
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Larval and early juvenile development of silver therapon, Leiopotherapon plumbeus (Actinopterygii: Perciformes: Terapontidae), reared in mesocosms FA Aya, MNC Corpuz, MA Laron & LMB Garcia -
Acta Ichthyologica et Piscatoria, 2017 - Szczecińskie Towarzystwo NaukoweThe silver therapon, Leiopotherapon plumbeus (Kner, 1864), is an endemic and economically important freshwater food fish in the Philippines. The natural populations of this species have been declining during the past years, mainly due to intense fishing pressure, habitat degradation, and introduction of invasive alien species. At present, it is considered a target species for domestication and conservation efforts. Despite several attempts of artificial reproduction and larval rearing, little is known on larval and early juvenile development of silver therapon. The presently reported study was therefore intended to fill this gap in the knowledge by determining the growth and describing body proportions, pigmentation, and fin formation of this fish. Newly hatched larvae were reared in mesocosm tanks at a mean temperature of 29.5°C. Larvae up to 30 days after hatching were sampled at irregular intervals and preserved in 5% buffered formalin. Early development stages for 245 preserved specimens were described in detail with reference to changes in morphology, growth and body proportions, pigmentation, and fin formation. Five developmental stages of silver therapon were identified: yolk sac larva (1.88 mm TL), preflexion (2.51 mm TL), notochord flexion (4.50-8.27 mm TL), postflexion larva (6.90-12.21 mm TL), and early juvenile (>13.40 mm TL). Growth was isometric for eye diameter and gape size whereas positive allometry was observed for body depth, head length, and preanal length. Some body proportions showed abrupt changes from preflexion to postflexion larvae before it stabilized during the early juvenile stage. Pigmentation in the form of stellate and punctate melanophores increased with developmental stage, with larvae becoming heavily pigmented from postflexion to early juvenile stage. These morphological changes, together with the full complement of fin rays and squamation observed in specimens larger than 13.4 mm TL, suggest the attainment of the juvenile stage of this species. These morphological changes may explain the food and feeding habits during the early life stages of silver therapon which is critical to their survival and recruitment in the wild and in a mesocosm hatchery environment.
Conference paperK Fukusho - In TU Bagarinao & EEC Flores (Eds.), Towards sustainable aquaculture in Southeast Asia and Japan: Proceedings of the Seminar-Workshop on Aquaculture Development in Southeast Asia, Iloilo City, Philippines, 26-28 July, 1994, 1995 - Aquaculture Department, Southeast Asian Fisheries Development CenterAquaculture production in Japan in 1993 was 1,351,000 tons, 15.6% of the total fisheries production. About 93.6% came from mariculture and 6.4% from freshwater aquaculture. The per cent contribution of aquaculture to total production has increased in recent years but partly because marine fisheries,especially of sardine and pollack, have decreased. Aquaculture has reached a plateau, and decreased slightly between 1992 and 1993. Diverse marine and freshwater species are cultured in Japan — various fishes, crustaceans, mollusks, seaweeds, sea squirt, sea urchin, and others. Research and development in mariculture focus on finding substitutes for animal protein in feeds, improvement of fish quality, protection of the culture environment, use of offshore floating culture systems, and protection from diseases. Research in freshwater aquaculture has expanded to include recreational fishing, the propagation and preservation of endangered species, and the construction of fish ladders for salmonids and other migratory species.
Fish catch and fisher incomes before and after installation of artificial reefs in Panguil Bay, northern Mindanao HP Moncay & LP Cablo - In TU Bagarinao (Ed.), Research Output of the Fisheries Sector Program, 2007 - Bureau of Agricultural Research, Department of AgricultureTwo artificial reef complexes (10 modules) were deployed in Panguil Bay in 1990. The effect of the ARs on the fish catch and fisher incomes was studied from March 1993 to April 1994 in Purok 3, 4, 6, and 7 in San Antonio, Ozamis City and in Poblacion 1 and 4 in Clarin, Misamis Occidental. Clarin‘s 40 full-time fisher respondents had 50 outrigger boats, all without engines, and used 181 fishing gears, 93% of them simple or multiple hand lines. San Antonio‘s 80 full-time fisher respondents had 87 non-motor boats and 44 motor boats and used 489 fishing gears, 86% of them bottom-set gill nets. The fishers worked an average of 19 days a month and four hours a day. The fishing grounds were mostly between 3 and 3.5 km from shore, and the gears were operated in waters about 50 m deep. Of about 17,000 kg of fish harvested in Clarin and San Antonio over one year, 33% came from bottom-set gill nets, 32% from bottom-set long lines, and 28% from multiple hand lines. The catch included a great variety of fishes, plus shrimps and cuttlefish; threadfins made up 13% of the total volume by weight, slipmouths 10%, and sardines 7%. The catch ranged from 2,382 kg valued at P75,862 in Purok 3 to 3,212 kg worth P97,303 in Poblacion 1, but in Purok 7, the catch was 2,965 kg worth P123,195. The average annual revenues of fishers was P24,191 in San Antonio and P11,472 in Clarin, corresponding to monthly earnings of P2,016 and P956, respectively. The revenues and net incomes were low, but the returns on investment were high (78–300%). The fishing boat, with or without engine and gas, was the major expense incurred by the fishers. Between 1989 and 1993–94, the volume of fish catch increased two-fold in San Antonio and four-fold in Clarin. The average annual income of fishers in the six villages increased by 10–60% after the ARs, and the average annual expenses also increased by 5–30%. In 1993-94, the computed return on investment was 105% in San Antonio and 274% in Clarin, higher than in 1989.