Pen culture of mud crab Scylla serrata in tidal flats reforested with mangrove trees

Abstract

Growth and survival of mixed sex mud crabs <i>Scylla serrata</i> (Forskal), held in 200 m² pens located in reforested mangrove tidal flats, were evaluated. The effects of stocking density (0.5 or 1.5 m⁻²) and feed (salted fish bycatch or a mixed diet of 75% salted brown mussel flesh and 25% salted fish bycatch) were determined in a replicated factorial experiment. Duration of the experiment was 160 days. There were no significant differences (<i>P</i>&gt;0.05) in growth, apparent feed conversion ratio (FCR), survival, and production among the two types of feed. Regardless of feed, the mean±SE FCR of 5.30±0.34 and survival of 56.00±1.90% at 0.5 m⁻² stocking density were significantly better (<i>P&lt;</i>0.05) than at 1.5 m⁻² stocking density (7.6±0.63 FCR and 33.00±3.61% survival). However, growth was not significantly affected by stocking density. Cost–return analysis on a per crop per 200 m² basis showed that the use of either of the two stocking densities with either diet was economically viable with a return on capital investment of 49–68%. However, crabs stocked at 1.5 m⁻² and fed a mixed diet of 75% salted brown mussel flesh and 25% salted fish bycatch is more profitable. The integration of crab aquaculture within natural mangroves is therefore feasible in the Philippines, providing both immediate and long-term commercial and environmental benefits.