Topshells play a pivotal role in intertidal rocky ecosystems and are adapted to harsh thermal and hydric stress. Phorcus sauciatus, a common grazer in the Macaronesian region (Madeira and the Canaries), has rarely been studied due to its restricted geographic distribution compared with Phorcus lineatus. Monthly samples were taken throughout 2017 to analyse biological parameters and evaluate the harvesting effect on the stocks of this species in Madeira. Individuals of the first age classes (<4 years) were dominant (~89%), while immature individuals were more abundant during the summer season. The spawning season occurs between March and August, especially from March to June. The size at first maturity was 12.95 mm long (1.68 years), with a continuous recruitment pattern throughout the year. Yield-per-recruit analysis (Y/R) showed that maximum production is achieved at a fishing mortality of 1.7 year−1, corresponding to a Y/R of 0.023 g. Currently, Phorcus sauciatus seems to be moderately exploited in Madeira, but urgent conservation measures, such as a landing obligation, the establishment of a minimum catch size of 15 mm length, and a closed season (February–May), are warranted to preserve stocks of this species in the medium to long term.

Madagascar's endemic freshwater crayfish (Parastacidae: Astacoides) are harvested by local people for both subsistence use and small-scale trade. There has been concern that populations, and even species, are threatened by overexploitation but little is known about the harvest or its economic importance. We studied crayfish exploitation in eastern Madagascar over 3 years. The existence of local taboos (fady) preventing commercial crayfish harvesting, as well as access to markets and forest, influenced involvement in the harvest. All four crayfish species found in the region were harvested, but A. granulimanus provided the majority of the catch. In one harvesting village more than 50% of the 47 households were directly involved in the harvest, which contributed USD 2,382 to the village economy in 2003/2004, an important sum in the context of local incomes. Subsistence use was widespread, particularly by children to whom it may provide an important protein source. Community-based conservation (through transfer of harvesting rights and responsibilities for forest management to local communities) is central to a new conservation paradigm in Madagascar. This recognizes communities' long term interest in their natural resources and offers an ideal opportunity for those concerned with the sustainability of the harvest to implement management tools (such as avoiding reproductive females, size limits and no-take zones). We discuss each tool with respect to biological implications and practical constraints. We note that community-based approaches may not be sufficient to conserve rarer species, which make up a small proportion of the value of the harvest.