Capture for culture: Artificial shelters for grouper collection in SE Asia

This paper addresses a little-discussed relationship between wild capture and mariculture, when the latter involves grow-out of small wild-caught fish or invertebrates in captivity. Seafood generated in this way is typically considered to be a form of aquaculture because it is assumed that, for animals removed from the wild when natural mortality is still very high, the protection conferred by culture operations will improve survivorship and enhance production. This assumption does not necessarily, however, apply when animals are removed well past the time of early high mortality. As one example of the implications of an early life-history phase (ELP) fishery supplying culture operations, a preliminary study was conducted on an ELP fishery supplying live reef fish, especially groupers, in Southeast Asia. Grouper culture depends on both hatchery-produced and wild-caught fish which are then grown out to market size. Following interest to develop grow-out operations in Indonesia, a pilot study was conducted to determine the sizes and capture rates of species of interest to the live fish trade, and to determine the likely environmental footprint of an artificial shelter (gango) type of capture method. From the results of the 15-month study, we drew inferences regarding the sustainability of this fishing method and requirements of space, fish and materials for a viable grow-out operation. The results showed that gangos were unselective for either species or size. Only 1.4% of the total fish catch (by number) were target species, mainly the grouper Epinephelus coioides, and most were large (mean total length was 13.6 cm) enough to have bypassed the early high mortality phase. Moreover, there were large non-target catches that included many food fish species too small to be useful in catches. Given the large number and area of gangos needed for a viable operation, and that many groupers captured could probably have survived to reproduce, the ecological footprint of this approach could be substantial. These results, and literature on other ELP fisheries, suggest that these may often need management, have important links to other capture fishery sectors, and require careful evaluation of potential costs and benefits before introduction or development. © 2006 Blackwell Publishing Ltd.link_to_subscribed_fulltex

Aggregations of Plectropomus areolatus and Epinephelus fuscoguttatus (groupers, Serranidae) in the Komodo National Park, Indonesia: Monitoring and implications for management

We identify fishery management implications from a long-term monitoring program focusing on spawning aggregations of high valued reef fish in Komodo National Park (KNP), Eastern Indonesia. Management objectives of KNP are not only to protect biodiversity, but also to conserve spawning stocks of high-valued commercial species for the replenishment of surrounding fishing grounds. We monitored two sites twice monthly over five years for two species of grouper, Epinephelus fuscoguttatus and Plectropomus areolatus. One site had an aggregation of both E. fuscoguttatus and P. areolatus, whereas the other site contained an aggregation of P. areolatus only. Over the five years monitoring period, aggregations typically formed during each full moon between September and February. Additionally, P. areolatus occasionally aggregated during new moons between April and July. We observed spawning only once, but because formation of aggregations were correlated to a higher incidence of behavior and signs indicative of reproduction and because most fish present were adults, it is likely that the formation of aggregations was associated with spawning. Over the five years monitoring period there was a reduction in mean fish size of up to 8 cm for P. areolatus, and a reduction in numbers of aggregating E. fuscoguttatus. Despite limited protection initiated in 2001, both sites are still heavily fished by local artisanal fishers. Because the observed reductions in size and in numbers could be caused by fishing pressure, managers should follow the precautionary principle by putting additional protective management in place. Since both species are relatively long-lived, at least five years of continued monitoring may be necessary to determine the outcome of management intervention. The variability in timing of aggregation in respect to season and moon phase in P. areolatus indicates that long-term monitoring must cover the entire year and both moon phases. © Springer 2005.link_to_subscribed_fulltex