Mud crab pen culture: replacement of fish feed requirement and impacts on mangrove community structure

Abstract

Brackishwater pond culture has been a major factor in mangrove loss in Southeast Asia, hence, the need to develop environment‐friendly technologies such as mud crab Scylla (Portunidae) culture in mangrove pens exists. This study evaluated the effects of mud crab netpen systems in central Philippines on mangrove macroflora, and the replacement of dietary fish with low‐cost pellets. Wild or hatchery‐sourced Scylla olivacea and Scylla serrata were stocked at 0.5–0.8 m−2 in 167–200 m2 nylon netpens (2.3 cm stretched mesh) in Avicennia‐dominated mangrove habitats. The feeding treatments were: (A) Zarraga: (1) no feeding (natural productivity), (2) no feeding for 1 month+supplementary feeding, (3) fish biomass and (4) low‐cost pellets, and (B) Batan: (1) fish biomass and (2) pellets+fish biomass. Feeds were given ad libitum twice daily. Growth and survival rates of S. olivacea in Zarraga pens were not significantly different among treatments, although crabs fed fish biomass had the highest survival, body weight and production. Similarly, growth and survival of S. serrata were not significantly different between the Batan treatments. Economic analysis of the latter gave a 38.5% return on investment (ROI) and 2.6 years payback period (PP) for pellets+fish biomass treatment compared with 27.5% ROI and 3.6 years PP for fish alone. Sensitivity analysis showed an improved economic performance of the pellets+fish biomass treatment by increasing the survival rate. Evaluation of mangrove community structure showed that crab culture reduced species diversity, numbers and biomass of seedlings and saplings, but not of mangrove trees. Therefore, mud crab pen culture is recommended for mangrove sites with mature trees, but not seedlings and saplings, and low‐cost pellets can reduce dependence on fish biomass.

Community-Based Technology Transfer in Rural Aquaculture: The Case of Mudcrab Scylla serrata Nursery in Ponds in Northern Samar, Central Philippines

“…Nonetheless, the high survival (68 %) of crablets in a mangrove pond compared to a non-mangrove area (50 %) suggests that mangroves played a role in mudcrabs' endurance. This confirms that mangroves are part of portunid crabs habitat in its life cycle (Walton et al 2006;Ellison 2008;Primavera et al 2010). Mangrove habitat provides essential nursery beds, feeding areas, and shelter for a large variety of marine and estuarine biota (Ellison 2008).…”

“…However, cooperativism may work well in sourcing common supplies and marketing their products. But it needs good leadership and social preparation (e.g., value formation) of members to make it successful (Gutiérrez et al 2010;Primavera et al 2010;Petersen et al 2011). Own labor is the main asset and source of power of the poor households and the key determinant of household output, income, and food security when access to resources is a limiting factor for them (Smith et al 2005).…”

Systems and techniques used in the culture of soft‐shell swimming crabs

“…; Mwaluma ; Shelley ; Primavera et al . ; Paterson & Mann ; Shelley & Lovatelli ). However, in recent years, industrial scale swimming crab production has focused on closed production systems (Kennedy & Cronin ; Gaudé & Anderson ).…”

A model for the future: Ecosystem services provided by the aquaculture activities of Veta la Palma, Southern Spain

“…While in Europe the use of aquaculture as either a driver of wetland construction or wetland conservation is relatively unknown and has not entered mainstream thinking or policy, in tropical climates the integration of aquaculture into sensitive habitats such as mangroves have long been practiced with numerous examples from Africa, South East Asia and China (Binh, et al, 1997;Folke and Kautsky, 1992;Huang, et al, 1997;Primavera, et al, 2010). The VLP example presented here, provides one method of how this can be achieved in a more temperate setting.…”