Preliminary studies on environmental impact of cage aquaculture in Canary Islands

摘要

More than 50percent of the present marine finfish aquaculture production in the Canary Islands (800 Mt for 1999) is carried out in off-shore cage farms, being the predominant technology involved in all new commercial projects in the Archipelago. This economical sector has experienced a significant growth in recent years at a Regional level, with excellent prospects for expansion due to different geographic and climatic advantages. However, this is giving rise to an increasing social concern about environmental implications, being frequently used as an argument to restrain this activity. The present work aimed to develop a protocol for environmental impact assessment of these farms, by identifying those physical, chemical, and biological parameters more sensitive to the operation of this type of facilities. A comprehensive sampling program was carried out since 1994 at a cage farm producing 500 metric tons per year of gilthead seabream (Sparus aurata) and seabass (Dicentrarchus labrax), located at the East Coast of Gran Canaria Island. The studies included water quality, retention and discharge of nitrogen and phosphorus by cultured fish, sediments, hydrology, fouling, and biological phosphorus by cultured fish, sediments, hydrology, fouling, and biological assessment of benthic reosystems.