Antifoulants (Copper) (COP)


INDICATOR BACKGROUND AND RATIONAL FOR INCLUSION

The accumulation of fouling organisms on marine aquaculture net pens reduces water flow through the pens and, in turn, decreases the dissolved oxygen concentration inside the pen. These fouling organisms also compromise the buoyancy and durability of the nets (Braithwaite et al. 2007). Antifoulant coating and paint are applied to marine net pens to prevent the colonisation of fouling organisms. Copper is the primary active ingredient in the vast majority of these applications (Burridge et al. 2008). Copper leaches from the nets into the marine environment over time and the on-site cleaning of treated nets can cause spikes of copper to be released into the surrounding water. Copper is highly toxic to a wide range of aquatic organisms, including algae (Franklin et al. 2001), copepods (Bechmann 1994), amphipods (Ahsanullah and Williams 1991), echinoderms (Fernandez and Beiras 2001), and larger microbial communities (Webster et al. 2001). Copper in excess of recommended maximum concentrations has been found at aquaculture facilities (Chou et al. 2002). It also remains biologically active and therefore potentially lethal even when bound in marine sediments (Chou et al. 2002).

INDICATOR FORMULA

Formula

COP = mT Fish Produced x % Production Using Copper-Based Antifoulants

Units: Proportion of production using copper-based antifoulants

Sample Calculation

Sample Normalised Calculation: Gilthead Seabream from Greece, Israel, Italy, Spain, Turkey, 2007

The copper indicator is an estimate of metric tonnes (mT) of the species produced using copper-based antifoulants. Actual data regarding the on-farm usage of copper tend to be unavailable, at either the individual farm level or the aggregated country level. Thus, GAPI uses the next best available data based on the proportion of production that used copper antifoulants.

ADDRESSING DATA GAPS

GAPI employed the following decision rules to treat gaps in antifoulant use data: