Commercial relationships between intermediaries and harvesters of the mangrove crab Ucides cordatus (Linnaeus, 1763) in the Mamanguape River estuary, Brazil, and their socio-ecological implications

The large mangrove crab Ucides cordatus (“caranguejo-uçá”) is a key fisheries resource in Brazil, critical for the sustenance of livelihoods of thousands of people in coastal rural areas. Today's crab populations suffer from habitat degradation, disease, and increasing fishing pressure. Crabs are sold alive on local and regional markets, or traded as processed meat and the market chains typically involve intermediaries (i.e. traders). The present study examined the relationship between crab harvesters and the intermediaries, and the socio-ecological implications thereof. The research was performed between September 2013 and October 2014 in the Mamanguape River estuary, northeastern Brazil. Socioeconomic information and data regarding the catch (sex and carapace width of the crabs), the processing of U. cordatus meat and the commercial relationship between harvesters and intermediaries were obtained through structured (questionnaires) and semi-structured interviews and direct observations. The crab harvesters exist under precarious socioeconomic conditions that place them at the edge of society and therefore often seek loans offered by the intermediaries, generating loyalty and dependence that guarantees the intermediaries a stable supply of crabs needed to supply an avid market. Within this relationship, the intermediaries create pressure on natural crab populations by stimulating non-selective captures, as they buy specimens below the legal size limit (6cm wide carapace) for meat processing. During crab meat processing, the intermediaries themselves report that the meat is often mixed with cooked and shredded of other marine vertebrates, such as spotted eagle ray (Aetobatus narinari) and nurse shark (Ginglymostoma cirratum), to increase the weight of the final product. As with the crab harvesters, the women involved in processing the crabmeat often accept loans, resulting in the same type of dependence and loyalty to the intermediaries. The intermediaries, with their strong influence on the crab harvesting, are directly linked to the commercial, social and ecological implications of these harvesting activities, together with the crab harvesters themselves. Hence, to ensure sustainability of the U. cordatus fishery and maintain (better improve) dependant livelihoods, all actors involved in the production chain of U. cordatus must be considered when developing management strategies, rather than the current approach of considering the crab harvesters only. We advise the development and implementation of fisheries associations to give the crab harvesters (and regulating bodies) greater control over and capital gains from their catches.