Monitoring the Influence of Marine Aquaculture on Wild Fish Communities: Benefits and 2 Limitations of Fatty Acid Profiles 3 4

1 Monitoring the influence of marine aquaculture on wild fish communities: benefits and 2 limitations of fatty acid profiles 3 4 Authors: Damian Fernandez-Jover, Pablo Arechavala-Lopez, Laura Martinez-Rubio, Douglas 5 R. Tocher, Just T. Bayle-Sempere, Jose Angel Lopez Jimenez, Francisco Javier Martinez López, 6 Pablo Sanchez-Jerez. 7 8 9 Department of Marine Sciences and Applied Biology, University of Alicante, P.O. Box 99, E10 03080-Alicante, Spain 11 12 Institute of Aquaculture, University of Stirling, Stirling FK9 4LA, Scotland, UK 13 14 Department of Physiology, Faculty of Biology, University of Murcia, Campus of Espinardo, P.O. 15 Box 30100, Murcia, Spain 16 17 *e-mail address: [email protected] 18 19 Abstract: Fatty acids (FA) have been applied as indicators of the influence of coastal sea-cage fish 20 farming on wild fish communities in several recent scientific publications. Due to the relatively 21 high conservation of FA composition throughout the food web, they are useful for characterizing 22 trophic relationships. The increasing utilization of vegetable or alternative animal oils in the 23 production of aquafeeds results in cultivated fish exhibiting higher levels of terrestrial FA in their 24 tissues. As previously reported, wild fish ubiquitously aggregate around fish farms as a 25 consequence of the introduction of new habitat and the easy availability of food fish farms act as 26 enhanced Fish Attraction Devices (FADs). The influence of food pellets on the composition of wild 27 fish has been detected in recent studies on salmon, sea bass and sea bream aquaculture, showing 28 increased levels of linoleic acid (18:2n-6) and low n-3/n-6 ratio as clear indicators of the 29 consumption of food pellets from the farms. The potential ecological and physiological effects on 30 wild fish are presently unknown. In this article, guidelines are proposed for the investigation and 31 use of terrestrial FAs to track the effects of coastal aquaculture on wild fish communities and local 32 fisheries as well as the benefits or limitations of this technique. 33 34