Regional differentiation in fleet characteristics and economic efficiency, as well as the total elasticity of scale in the commercial fishing fleets of the Brazilian Amazon were analysed. Data were collected in 893 interviews with boat operators in four major ports on the River Amazon. Boats operating from the largest cities (Bele´m and Manaus) are mostly operated by hired skippers and non-permanent crews, while boats from smaller cities (Santare´m and Tefe´) are mostly owner-operated and use permanent crews. In the lower Amazon, a large proportion of fishermen (89% in Santare´m and 53% in Bele´m) are based in rural areas, while in the upper Amazon commercial fishermen are predominantly urban-based. A production function analysis identified boat length, gear type used (gill net/purse seine), number of fishermen employed, quantities of fuel and ice used, and education level of the skipper as significant factors determining the catch. The analysis provided no evidence of regional differences in stock levels. The use of purse seines was associated with significantly higher catches (by 32%), all other factors being equal. Purse seines are banned in the lower Amazon (Santarem and Belem), and this results in overall lower levels of technical efficiency in this region. No significant total scale effect on efficiency was detected. These results are discussed with respect to the institutional sustainability of current fisheries co-management initiatives.
Starch and lipid storage strategies in tropical trees relate to growth and mortality
Starch and lipid storage strategies in tropical trees relate to growth and mortality
Non-structural carbon (NSC) storage (i.e. starch, soluble sugras and lipids) in tree stems play important roles in metabolism and growth. Their spatial distribution in wood may explain species-specific differences in carbon storage dynamics, growth and survival....