Fishery Statistics and Commercialization of the Mangrove Crab Ucides Cordatus (L.), in Braganca, Para, Brazil

Abstract

This research was part of the scientific MADAM project developed in collaboration between Brazil and Germany. The work focused on fishery statistics and commercialization of the mangrove crab, Ucides cordatus, from the mangrove areas in Braganca District, Para, Brazil. The study area was situated in a continuous mangrove area spanning three districts of the Para State coast: Tracuateua, Braganca and Augusto Correa. This 6.000 km2 area extends between the northeastern coast of Para State and the northwestern coast of the Maranhao State (480 km of real coastline). The total mangrove area available to crab fishermen was approximately 877 km2 divided among: Braganca Peninsula 170 km2, west zone 181 km2 and east zone 526 km2. The main objective of this study was to determine the yearly volume of crab landings (data from January of 2003 to June of 2004) in Braganca District and to identify the channels of and mercantile agents in the crab commercialization. By choosing local communities with the highest landing volume for monitoring, approximately 80% of the total catch in Braganca District could be directly monitored. The communities or points chosen for monitoring were: Caratateua, Tamatateua, Treme and the Braganca-Ajuruteua road (Taici). Results showed that in 2003-2004, there were 1195 crab fishermen in Braganca District. The crab fishermen moved by small boats, canoes and on foot into the mangrove area. The total volume of recorded crab landings in Braganca District was 1859 t in 2003 and 1039 t from January to June of 2004. Due to the impossibility of monitoring all landing points the catch data presented, represent only approximately 80% of the total catch landed in Braganca District. The highest fishing pressure was recorded on the Braganca Peninsula. The mean CPUE in this area was 150 crabs/ man-day, and the carapace widths at capture varied between 5.1 and 9.1 cm. For the study period, the average carapace width of crabs captured on the Braganca peninsula was 7.1 Ã ± 0.5 cm. The best growth parameter combination achieved by ELEFAN I was L = 8.58 cm and K = 0.20 / year. The probability of capture for U. cordatus males calculated with FISAT showed that the size class represented in the actual catch lay between 6.8 and 7.3 cm. The cohort analysis gave estimates of total mortality rate (Z) for this size class varied between 0.40 and 0.80 per year, increasing with increasing size (carapace width, cm). The same tendency was observed for the fishing mortality rate (F), where estimates varied between 0.0 and 0.4 per year. The commercialization analysis showed that the crabs captured and landed in the Braganca District entered the market via the crab fishermen (producers) in two forms: a) in natura - live crab and b) processed - pulp and chelae crabmeat. For live crabs, the most frequently used unit in the landings was the cambada. The commercialization chain's main mercantile agent was the wholesaler/retailer and it ran through three different commercialization channels. The average monthly net income for a producer with a boss was R$ 314.00 and the producer without a boss received R$ 367.00. The total markup (MKT) during the commercialization of live crab raised the end prices by 32% to 67% on the Braganca market and by 58% to 150% on the Belem market. The live crabs that were landed and sold at diverse points in Braganca District, supplied not only the local market, but the state market as well. The processed crab was sold by the kilogram (Kg) and most frequently sold directly to the fisherman's boss (PC). The mercantile agents in the chain were: the middleman, the wholesaler and the retailer. Four processed crabmeat commercialization channels were identified. The average monthly net income of a producer with a boss was R$ 590.00 and R$ 594.00 for a producer without a boss. The total markup (MKT) in the commercialization system of pulp and chelae crabmeat showed that the price paid by the final consumer during the year of 2003 was always more than double the price at first commercialization. The processed crabmeat was commercialized predominantly in Belem.It can be concluded that the crab fishery in Braganca District produces enough financial resources to not only allow the local families to subsist but to maintain a large money flow within the communities that is not easily apparent to the outsider. The Braganca Peninsula still presents a favorable situation for sustainable exploitation because the average size of captured individuals is sufficiently higher than the size at first sexual maturation (L50%=3.51 cm for males and L50%= 4.01 for females). Though the exploitation is presently at sustainable levels, any small fishing effort increase, deforestation or the use of unlawful capture methods could rapidly lead to overfishing of large individuals.