An approach to the economic value of diving sites: artificial versus natural reefs off Sal Island, Cape Verde

Abstract

Summary In the present paper there was a twofold hypothesis, i.e. that the deployment of artificial reefs adds value to natural features by diversifying diving sites and thus be a certain propensity concerning the type of added value (either of non-extractive direct or indirect use). Two vessels were used as artificial reefs off Sal Island (Cape Verde) in 2006 and 2008, with the aim of bolstering the local economy through ecotourism. The additional economic value anticipated was to: (i) enhance fish aggregation as well as other marine organisms, and (ii) mitigate human pressure on natural reefs by diverting divers. The supply-side view of diving trips was tested and analysed over a 4-year period (2008–2011) in the choice of divers between natural and artificial reefs, as well as such reef attributes as reef depth, reef distance from the main pier in Santa Maria Bay, and the year-season as well as combinations thereof. Data were also analysed to determine if the deployed reefs off Sal Island had a complementary or a substitute function. It was observed that the presence of artificial reefs created more dive users, but that divers who used these reefs were not deterred from diving at natural reefs. This resulted in a low-diversion effect (low substitutability). Thus, dive operators can offer additional options to divers (moderate to highly complementary). The distance to diving sites was the most influential factor in diving decisions (linear model results indicated 15 more divers at distances closer to Santa Maria Bay than elsewhere). From the log-linear model the number of divers would be expected to change, the distance being the most influential factor (11.7 times higher at closer sites); reef type and depth were less influential (0.2 times fewer divers at artificial reefs; 2.3 times more divers in shallower waters). Also apparent was that the depth of the reef was fundamental in the diver niche allocation throughout the seasons.