Re-stocking practices and illegal fishing in northern Chile (SE Pacific coast): a study case

We constructed eco-social models with different levels of complexity in order to represent the activities that fishermen operating under two different regimes, Chilean Territorial Use Rights in Fisheries (TURFs) and Open Access Areas (OAAs). We used Levins's loop analysis as a theoretical framework for assessing the local stability or sustainability of the models and management strategies represented by the scenarios. Our results suggest that the current harvest dynamics (scenario 1 of all models) cannot be locally stable or sustainable unless they meet the following conditions: (1) the abundance of Concholepas concholepas adults fluctuates close to its carrying capacity (K); and (2) the demand (market) presents some type of control (i.e. taxes). Likewise, simultaneous re-stocking of C. concholepas adults and juveniles in TURFs seems to be sustainable only if the demand is controlled, thus, under current conditions it is not recommended as a management strategy. Alternatively, the simultaneously exploiting C. concholepas and re-stocking juveniles can lead to stability, but again if the demand is controlled. The sustainability of illegal fishing of C. concholepas from OAAs (for re-stocking into TURFs and for the local market) is not reached independent of the self-dynamics of demand and the abundance of wild meta-populations. Moreover, habitat destruction caused during the search for C. concholepas individuals in OAAs causes instability in the system and, therefore, educational efforts should be aimed at the fishermen as a way to avoid these practices. Given the results obtained, we find it difficult to consider TURFs - as a whole - to be a conservationist administrative measure. On the contrary, we believe that, as currently practiced, TURFs better resemble a simple program of C. concholepas mariculture, in which case they are comparable to traditional intensive agriculture, which is itself far from conservationist. The approach developed here is proposed as a general strategy for examining the consequences of natural changes and human interventions in marine coastal ecosystems.