Theme D: Developing optimal release strategies
33. ESTABLISHING RELEASE STRATEGIES FOR STOCK ENHANCEMENT OF HATCHERY-REARED ABALONE HALIOTIS ASININA
Ma. Junemie Hazel Lebata-Ramos1, Ellen Flor Doyola-Solis1, Jeff Bogart Abrogueña1, Hiroshi Ogata2, Joemel Sumbing1, Rema Sibonga1
1 SEAFDEC Aquaculture Department, Tigbauan, Iloilo 5021, Philippines
2 Stock Enhancement Technology Development Center, National Research Institute of Aquaculture, Fisheries Research Agency, Kamiura, Saiki, Oita 879-2602, Japan
jlebata@seafdec.org.ph
The lucrative returns brought by abalone fisheries have caused overexploitation and decline of the wild population. In the Philippines, the Southeast Asian Fisheries Development Center 
Aquaculture Department has successfully developed the hatchery technology and completed the life cycle of the donkey’s ear abalone Haliotis asinina. Success in hatchery production has also led to the development of different grow out techniques. However, production of abalone in aquaculture facilities does not benefit the marginalized fisherfolks who comprise majority of the fisheries sector. This study aimed to enhance abalone population in Carbin Reef Sagay Marine Reserve through release of SEAFDEC/AQD hatchery-reared (HR) juveniles.
Prior to release, a 13-month baseline assessment of the wild population was conducted in 10 50 x 2 m belt transects. Results showed decreasing abalone density from March 2007 to March 2008 (Fig. 1). There is a significantly positive correlation of abalone density with branching corals with epiphytic algae cover (Pearson correlation = 0.73; p < 0.05) showing their preference to this type of substrate. The coral branches provide shelter and the algae are utilized food.
To test the viability of HR abalone in the wild, initial release of 1,010 diet-tagged individuals, 2.1-3.0 cm shell length (SL) was done in July 2008. During the acclimation process, higher mortality was observed in abalone smaller than 3.0 cm SL. Mortality was highest on the day of transport (13.27%) which decreased until day 3 (0.30%). Abalone stayed inside or on the transport pipes until day 7, during which all abalone moved to the corals and other available shelters on the reef. From the recaptures, HR abalone showed higher growth rate (0.27±0.04 cm mo-1) than the wild ones (0.13±0.04 cm mo-1). Hatchery-reared abalone were recaptured until 511 days post release. Results of this preliminary release trial revealed that HR abalone are viable for release in the wild and can survive with their conspecifics. Moreover, a second release was done in August 2010 improving the protocols used in the first release. Results of the second release were more promising than the first with lower acclimation mortality, higher recapture rates and better survival.
Call For Papers