Abstract. We describe the basic ecology of two key‐hole limpets, Fissurella crassa and Fissurella limbata, which are heavily harvested by coastal shellfishermen (mariscadores) at the rocky intertidal of central Chile. The ecological role of human predation on these species was assessed. Anthropic exclusion from a stretch of the rocky intertidal at Las Cruces (non‐harvested area) for about two and a half years resulted in changes of the densities and size distributions of these fissurelid species as compared to populations in control zones (harvested area). Differential human predation generates, on key‐hole limpets, responses of different intensities related to the accessibility of man to the mesohabitats (sheltered platforms, exposed platforms and vertical walls) and fringes of the intertidal (mid‐low intertidal and Lessonia nigrescens fringe). Thus, size distributions and mean densities of both fissurelids differ widely between the harvested and non‐harvested areas on both platform habitats but not on vertical walls. In the mid‐low intertidal fringe, differences are greater than in the less accessible L. nigrescens intertidal fringe. Moreover, we discuss the way in which other species, directly harvested by mariscadores (i. e., the mollusc Concholepas concholepas) can affect the keyhole limpet populations of central Chile rocky shores. Finally, we highlight the ecological role of these limpets on the dynamics of intertidal ecosystems and how they can modify community landscape.

By means of surveys in 48 salmon farms in Chile, and the analysis of ¢sh mortality in 23, the results showed that attacks by the South American sea lion, Otaria £avescens, were periodical at a daily and seasonal scale, and because of their natural nocturnal feeding behaviour, were more frequent at night and in fall^winter seasons. The attacks varied markedly between the farms studied. No relation was found between the intensity of attacks, the distance to the nearest colony of sea lions and the population in the colony. Di¡erences found between farms could be because of the di¡erent protective devices used, namely anti-predator nets, acoustic harassment devices (AHDs) and ¢breglass models of killer whales, and the way in which they were used. Of these devices, only the anti-predator net achieved a permanent reduction in sea lion attacks. Both AHDs and ¢breglass killer whales were ine⁄cient in the short term.

Vilata, J., Oliva, D., and Sepúlveda, M. 2010. The predation of farmed salmon by South American sea lions (Otaria flavescens) in southern Chile. – ICES Journal of Marine Science, 67: 475–482. The South American sea lion Otaria flavescens is abundant off southern Chile. Because Chilean salmon farming has experienced an explosive growth in the past two decades, interactions between O. flavescens and this industry have increased. Fieldwork, including in situ behavioural observations, was carried out at three salmon farms off southern Chile from May to July 2008. The aim was to analyse possible patterns in the interactions and to evaluate whether they were influenced by the endogenous circa-rhythms of the species, prey size, tidal flux, and the use of an acoustic harassment device (AHD). The results showed that the attacks by O. flavescens followed seasonal patterns, with salmon predated more in autumn and winter, and daily patterns, with more interactions at night. In addition, attacks were more frequent on larger salmon, suggesting the existence of a prey-size preference. More sea lions were sighted at the ebb and flow tide peaks, when currents are stronger, suggesting that currents linked to tidal flux might facilitate the access of the sea lions to the farmed salmon. Although the use of AHDs appeared positive at one site, there is a strong suspicion that their efficacy may be site-specific.

The rocky shore of central Chile is heavily harvested by mariscadores de orilla and skin-divers, but their catches are not considered in the fishery statistics. The aim of the present paper is to estimate the intensity of human predation and annual catch of each of the species taken at Las Cruces, Central Chile. The activity pattern of both categories of collectors demonstrate a temporal grouping. The observation of mariscadores de orilla and skin-divers in 3 sectors of fringe totalling 1,500 m of rocky shore during 12 months allowed us to estimate the annual catch per species caught (kg per year).

No abstract