State of Fish Populations and Influence on the Trammel Net Fishery at Three Balearic Island (Western Mediterranean) Artificial Reefs a Decade After their Deployment

Aggregation/production artificial reefs (ARs) were first deployed in the Balearic Islands in the early 1990s. Early studies concluded that these ARs concentrated medium- and large-sized commercial fish, a fact that could lead to a risk of overfishing in the area. A decade after their deployment, the same ARs were re-examined using experimental fishing and visual censuses. Results from our study demonstrated that the Balearic ARs have not increased the risk of overfishing because fishing effort on them is moderate, trammel net efficiency on ARs is low, there are high immigration rates to the ARs, and there are natural areas with a medium-high seabed relief that hold reserve stocks that are larger than those found on the ARs. Likewise, we found that the overall condition of the ecosystem is more important for the characterization of the composition and yield of AR catches than are the eutrophic-oligotrophic conditions of the surrounding water masses. We note that the function of the aggregation/production ARs is only analogous to that of marine protected areas (MPAs) and that ARs therefore should always be managed to ensure the correct use of marine resources. Combining both intervention measures (ARs and MPAs) in the environment may synergistically reinforce their respective effects.