Dynamic models applied to giant barnacle culture

Abstract

In this study, a dynamic model is applied to giant barnacle (Austromegabalanus psittacus) spat collection from artificial substrates located in the wild. Semi-industrial culture of the giant barnacle, A. psittacus “picoroco” in southern Chile is an interesting option for aquaculture diversification. The model establishes relationships between variables and carries out simulations to determine their effects on spat provision. The dynamic hypothesis proposes that the number of giant barnacle spat obtained from the wild is influenced by competent larval abundance (cyprids) over time, substrate availability and mortality after larval settlement. In the conceptual model, 15 variables were selected and related, establishing the polarities of each causal relationship and of each feedback loop. The Stock & Flow diagram was undertaken using STELLA 9.0 simulation software. Simulation tests were carried out to establish the consistency of the model using the empirical background obtained from semi-industrial cultures in southern Chile. The model establishes relative quantity of competent larvae, substrate area and the number of spat, as key variables. Synchrony between level of cyprid abundance and location of artificial substrates in the water is critical to achieve maximum collector efficiency. A difference of less than 1 week out of synchronization produces significant losses (60–70%) in spat production. When the deployment of collectors and maximum quantity of competent larvae are synchronized, sensitivity analysis establishes an increase of up to 49.4% in the number of spat, as a result of the collector area released by spat early mortality. The application of dynamic models in aquaculture constitutes a useful tool for optimizing the process. The model proposed enables us to understand the processes associated with obtaining seed from the environment and can be applied to other similar processes, such as mytilid cultures.