Habitat complexity affects habitat preference and predation mortality in postlarval eastern king prawns: Implications for stocking
Ochwada, F., Loneragan, N.R., Gray, C., Suthers, I. and Taylor, M. (2008) Habitat complexity affects habitat preference and predation mortality in postlarval eastern king prawns: Implications for stocking. In: Australian Society for Fish Biology 2008 Workshop and Conference Proceedings, 16 - 18 September, Sydney, Australia.
Attempts to ameliorate declines in Penaeid populations through stock enhancement have been made in several parts of the world and have recently been proposed for the eastern king prawn, Penaeus plebejus. The success of past enhancements has been restricted by limited knowledge on the availability of habitats that best support stocked populations and the mechanisms underlying survival and distribution of stocked species within these habitats.
We examined active habitat selection as a possible mechanism driving the distribution of P. plebejus and evaluated the species’ mortality due to predation in different habitats. The results demonstrated that P. plebejus settle into complex and non‐complex habitats randomly during the night, but actively select complex habitats over non‐complex habitats during the day. We also found that mortality caused by predatory fish was higher in non‐complex habitats than complex habitats. We posit that post‐larvae select complex habitats during the day to lower predation risk, and that reduced predator efficiency at night precludes the need to shelter within complex habitats, which allows the post‐larvae to forage in all habitats.
Based on our findings, we recommend that future releases of P. plebejus be conducted directly into complex macrophyte beds to optimize survival by minimizing predation mortality. Quantitative assessment of the carrying capacity of available macrophyte is also necessary, prior to stocking, to reduce competition for preferred habitat amongst stocked individuals and thereby optimize their growth rates. Such assessment may also ease competition between wild and stocked con‐specifics and thus minimize the risk of significantly affecting the wild population.
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|Murdoch Affiliation:||Centre for Fish and Fisheries Research|
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