MEPS prepress abstract   -  DOI: https://doi.org/10.3354/meps14395

ABSTRACT: Wild fish have been shown to associate with sea cage aquaculture and consume waste feed; however, little is known about the effects of waste feed consumption on wild fish. We used Atlantic cod Gadus morhua collected in the direct vicinity of sea cages and reference divisions, either outside the direct vicinity (‘local division’) or completely removed from aquaculture (‘outside divisions’), to compare length, weight, and condition for G. morhua ages 2 to 4. Concentrations of vegetable oil-based fatty acids (linoleic acid and α-linolenic acid) were then used as biomarkers for waste feed consumption to determine their role in explaining differences in length, weight, and condition (Fulton’s condition index) among cage-associated G. morhua. Age 2 cage-associated G. morhua were in lower condition than age 2 G. morhua from the local division and lighter than age 2 G. morhua from all outside divisions. Age 3 cage-associated G. morhua were comparable to age 3 G. morhua from the local division but in lower condition than age 3 G. morhua from all outside divisions. However, age 4 cage-associated G. morhua were longer and heavier than age 4 G. morhua from the local division, but in lower condition than age 4 G. morhua from two of three outside divisions. Additionally, there were positive relationships between fatty acid concentrations and length and weight for age 2 cage-associated G. morhua, but no such relationships for age 3 or 4 cage-associated G. morhua. Results suggest the effects of waste feed consumption are contradictory but not consistent enough to disrupt established growth and condition patterns among divisions.