SEAFDEC PROGRAMS OF ACTIVITIES IN 2019
1. Strategy I: Securing the sustainability of fisheries to contribute to food security, poverty alleviation and livelihood of people in the region
2.5 Development of responsible and sustainable aquaculture technologies Maintaining Environmental Integrity through Responsible Aquaculture
2.5 Development of responsible and sustainable aquaculture technologies
Oyster. Aquaculture expansion in the 1980s led to the immediate boom in shrimp production especially in the Philippines and Southeast Asia as a whole. However, the advent of diseases starting from the late 1990s has left many of these brackishwater ponds to be unproductive until today. To make use of these abandoned ponds, field tests and studies are being conducted to explore the potential of diversifying the commodities that could be cultured in these ponds. A potential commodity with high demand and economic value would be oysters. Traditionally, in the Philippines, oysters had been cultured in brackish rivers and estuaries. A current study at AQD, which aims to assess the growth and survival of oyster Crassostrea iredalei cultured in brackishwater pond by comparing production with those cultured in a nearby river, is a follow-up to the recently concluded study funded by the Department of Science and Technology-Philippine Council for Agriculture, Aquatic, and Natural Resources Research and Development (DOST-PCAARRD) which identified the ‘pouch method’ as the best strategy in producing single oysters with fast growth and homogenous sizes. The experiment using rafts and pouches commenced using a total of 3,000 oyster spats. After three months, higher survival was observed in the river set-up (86%) compared with those inside the ponds (32%) which might have been caused by mortality inside the ponds due to predation of crabs. Growth was also higher for oysters from the river (8 cm) than from the pond (7 cm) after 5 months which could be associated with water conditions since higher temperature, salinity, sulfide and nitrite where recorded in the ponds than in the river, although the river also registered higher nitrate, phosphate and ammonia.
Pouch method for oyster culture
Rafts set-up in brackishwater pond in Brgy. Pawa,
Oyster Crassostrea iredalei harvested from the experimental sites
Rafts set-up in Arellano River
Abalone. While refining its aquaculture technology and making it more environment- friendly, AQD is developing an alternative culture method using PVC pipes as culture container and natural food (seaweeds (Gracilariopsis heteroclada)) as feeds for abalone culture. A collaborative effort with Ayala Corporation, as part of the industry collaboration initiative which targets local island-based communities as beneficiaries, the alternative culture system makes use of perforated PVC pipes which has previously shown to promote good growth and survival in abalone culture, while being practical and easy to deploy. In AQD’s earlier culture trials, stocking of about 6,000 abalone juveniles at Sicogon Island in northern Iloilo, Philippines led to successful harvests of abalone after 3 months of culture.
By October 2019, a total partial harvest of about 1,500 was recorded. This project would be turned over to the private partner and local communities as part of AQD’s commitment in disseminating its developed aquaculture technologies.
Abalone in PVC pipes stocked in Sicogon Island, Philippines
Abalone harvested in Sicogon Island, Philippines
Sea cucumber. AQD has been in the forefront of developing technologies in the culture of emerging species, particularly of the tropical sea cucumber Holothuria scabra or sandfish.
The culture of this tropical species is gaining more popularity in the recent years, and is mainly aimed to augment the drastic decline of sea cucumber populations in the wild caused by overfishing. Starting with streamlining the sea cucumbers production methods by optimizing culture technologies from hatchery, nursery and grow-out in sea ranch sites, this project was carried out in collaboration with the Australian Centre for International Agricultural Research (ACIAR) and various universities in the Philippines. Also conducted in Viet Nam, the project is intended for five years, where the first year is focused on optimizing hatchery production by utilizing micro-algal concentrates in order to minimize dependence on live feed, which is often the bottleneck in small-scale hatcheries. Initial trials showed
promising results using ISO1800 and Shellfish1800 (commercial Instant Algae® products from Reed Mariculture Inc., USA), although further assessments would be conducted.
Nursery rearing trials focuses on sea-based floating nets because this is one of the most practical method based on results of previous studies. Secondary nursery in pens at AQD’s Igang Marine Station (IMS) are also being assessed, although initial challenges revealed that predation is a major risk in the culture of sandfish in the field. Further studies on predation mitigation measures would also be explored.
Floating primary nursery cage for sandfish at AQD’s Igang Station in Guimaras, Philippines
Fast-growing sandfish at AQD’s Igang Station nursery pens
Polychaete. Marine worms or polychaetes, which are used as an additive in maturation feeds to enhance the reproductive performance of crustacean and fish broodstock, are also known to be good potential bioremediators of muddy sediments. Thus, enhancement of the culture methods for polychaetes is being explored considering its potential as feed ingredient. Since polychaete needs to be disease-free, this requires that it should be produced in controlled environments like in land-based raceways using hapa nets. Results of a stocking density experiment showed that as high as 2,000 polychaetes could be stocked per one square meter. In a culture duration of only four months, the yield could give a biomass of >100 g/m2, while the soil organic matter content could be reduced from
>5% to 3.8% after four months, confirming the bioremediation potential of this species.
Raceway culture experiment system for polychaetes using hapa nets Achievements: Off-season spawning of milkfish breeders achieved
The Philippines could now avail of the technology being promoted by AQD related to the environmental manipulation on milkfish breeders that successfully facilitated two spawning events even during the cold season that began December 2019. December until February is commonly known as off-season for milkfish spawning because of low temperatures. With environmental manipulation, AQD was able to achieve year- round spawning to boost the production of milkfish fry which are in short supply in the Philippines.
2.6 Compilation of scientific data and information to support policy on