Black abalone status in Baja California. Are there recovery signals for a sustainable harvest?

Resumo

The black abalone (Haliotis cracherodii) is an important fishery species in Baja California, México; however, in the 1980s, fishing pressure and drastic mortalities due to the wasting syndrome caused the populations to become apparently extinct. Because of population decline, in 1996, the fishing cooperatives agreed to cease the catch. Recently, signs of recovery of the species were observed in some sites, hence, some cooperatives and fishing permit holders obtained catch quotas, which were based on the evaluation of the abalone stock from which extraction permission was requested. Given the risk of the reopening of the fishery, it is vitally important to assess the status of the black abalone populations in Baja California and identify priority sites for the conservation and recovery of the species. In this study, black abalone populations were studied at 22 sites from Tijuana to El Faro San José. Although the observed densities were low (0.0009 to 0.23 abalones/m²), some sites showed moderate densities of juveniles, suggesting recent recruitment. At other sites, we found adults distributed in clusters forming groups of 5 individuals on average, suggesting some probabilities of reproductive success in these populations. We found that juvenile and subadult abalone were associated with moderate habitats, and adults with good habitat. Some sites showed that five or more adults per group were common, suggesting that at these sites successful reproduction might be possible. Our results indicate a high relationship between human disturbance and density, suggesting that this is the main threat to the species in this region. It is imperative that the government, academia, NGO’s and stakeholders work together to propose a recovery plan that assures that enough numbers of individuals are surviving to contribute to healthy and stable populations.