Dispersal of wild and escapee farmed Atlantic cod (Gadus morhua) in Newfoundland

Abstract

Inherent trait differences and changes that arise through domestication could be maladaptive and lead to negative ecological consequences when non-native individuals escape from aquaculture cages and interact with wild populations. We used acoustic telemetry to map the spatiotemporal distribution of local wild (n = 29) and “escapee” farmed Atlantic cod (Gadus morhua) (n = 52) through experimental releases off eastern Newfoundland to determine the potential for interaction. Dispersal from the cage (>600 m) was rapid (50% dispersal: 12 h for farmed; 5 h for wild) and nonrandom. Most cod (85% farmed, 55% wild) moved northward, remaining close to shore. Although recaptures of escapees during small-scale recreational and commercial fisheries was high (11% farmed; 10% wild), our results suggest that directed efforts to recapture escapees would be logistically challenging. Cod migrated a considerable distance (maximum 256 km for wild; 157 km for farmed), and some returned to the bay the following year. The similarity of the distribution of escapee farmed and wild cod suggests the potential for interactions between farmed and wild fish, highlighting the importance of minimizing escapes.