Stock Enhancement of Threatened Species in Southeast Asia

Abstract

Natural populations of global inshore fisheries are coming under heavy pressure, primarily due to overexploitation and habitat degradation. Stock enhancement of hatchery-reared seeds is perceived as an alternative strategy to enhance the regeneration process. The Aquaculture Department of the Southeast Asian Fisheries Development Center in the Philippines has been implementing activities related to stock enhancement of donkey's ear abalone (Haliotis asinina), mud crabs (Scylla spp.), giant clam (Tridacna gigas), and seahorses (Hippocampus spp.). Seed production techniques for abalone including a diet tagging method were established, and juvenile abalone were released and monitored in a marine protected area. Mud crabs conditioned before release had higher recapture rates compared to the non-conditioned crabs, which can be translated to higher survivorship. Giant clams stocked at 8-10 cm shell length have high survival 4 mo after stocking (90%), with initial mortalities occurring within the first few days due to transportation stress. Seed production trials for seahorse have begun.

Rearing cuttings of the soft coral Sarcophyton glaucum (Octocorallia, Alcyonacea): towards mass production in a closed seawater system

“…The advantage of these systems lies in their ability to control abiotic and biotic parameters (Wheeler 1996; Borneman & Lowrie 2001; Abramovitch‐Gottlib, Katoshevski & Vago 2002). Such systems have been proposed as a source by which to obtain corals and other invertebrates with commercial value (e.g., Wabnitz et al 2003; Sipkema et al 2005), as well as for restoration and conservation purposes (Becker & Mueller 1999; Petersen, Laterveer, Van Bergen, Hatta, Hebbinghaus, Janse, Jones, Richter, Ziegler, Visser & Schuhmacher 2006; Okuzawa, Maliao, Quinitio, Buen‐ursua, Lebata, Gallardo, Garcia & Primavera 2008).…”

Restocking, Stock Enhancement, and Sea Ranching: Arenas of Progress

“…The proposal to use marine protected areas and no-take zones to safeguard hatchery-reared individuals as part of larger conservation and rehabilitation programs is encouraging (Okuzawa et al, 2006). Programs in Asia-Pacific are developing methods for restoring a range of endangered or severely overfished invertebrates (Bell et al, 2005;Nair, 2005;Okuzawa et al, 2006), and Purcell and Kirby (2006) have modeled the sizes of no-take zones needed to protect aggregations of released sea cucumbers.…”

“…Programs in Asia-Pacific are developing methods for restoring a range of endangered or severely overfished invertebrates (Bell et al, 2005;Nair, 2005;Okuzawa et al, 2006), and Purcell and Kirby (2006) have modeled the sizes of no-take zones needed to protect aggregations of released sea cucumbers. Similar approaches can be used for other species, but a key question concerns the need to determine the average "footprint" of larval dispersal around no-take zones.…”

Evaluation of Post-Release Behavior, Recapture, and Growth Rates of Hatchery-Reared AbaloneHaliotis asininaReleased in Sagay Marine Reserve, Philippines

“…The study site, Sagay Marine Reserve (SMR) in Sagay City, Negros Occidental, Philippines, has been described in earlier studies of Maliao et al (2004) and Okuzawa et al (2008). The reserve has been protected since 1983 by a local ordinance and the National Fisheries Law and is vigilantly monitored and patrolled by the bantay dagat (literally means "sea watchers").…”