Aquaculture contributes a significant portion of the global aquatic biomass destined for human consumption. Bivalve and marine finfish aquaculture operations require sea‐based farm sites that result in considerable interactions with the natural environment. The addition of feed waste and physical structures (e.g., net pens and longline mussel culture) can provide an attractive artificial reef for many species and studies have shown both positive and negative effects on the surrounding ecosystem due to wild species interactions with aquaculture sites. Assessing these interactions can be complex, depending on the local ecosystem, and several monitoring techniques have been used to accurately determine associations of wild finfish and decapods to marine farms. In this review, we assessed the main methods used to monitor aquaculture‐ecosystem interactions. The advantages and disadvantages of each technique are discussed and suggestions to mitigate shortfalls for future studies are outlined. It was evident that combining methodologies should be prioritised to lessen the impact of identified weaknesses of any given approach. Designing studies with complementary approaches may help attain robust data that can be used to further understand aquaculture‐ecosystem interactions and the underlying proximate mechanisms.

Many Atlantic salmon ( Salmo salar) populations have experienced significant declines for decades throughout North America and Europe. Mortality due to marine mammal predation during their early marine life could be an important factor contributing to these declines and limiting their population recoveries. However, quantifying predation events, and particularly the extent of marine mammal predation on Atlantic salmon, remains a challenge. In this study, we estimated the contribution of mesothermic and endothermic species predation to the mortality of Atlantic salmon post-smolts during their early marine life using acoustic telemetry. Predation events were inferred from changes in temperatures and depths experienced by acoustically tagged hatchery-reared Atlantic salmon smolts. No salmon were consumed by mesothermic predators, with most endothermic predation events being classified as marine mammals. Post-smolt mortality during the study period was low overall in both years (13.1%–16.7%), with endothermic predation accounting for 33.1%–42.9% of all marine mortality events (5.2%–5.6% mortality). Our results suggest that the current low return of adult Atlantic salmon observed in this area in recent years was not heavily influenced by endothermic predation on post-smolts in the first weeks at sea.

Atlantic salmon ( Salmo salar) are reared in marine net-pens and may escape due to operational errors and structural failures. The fate of these fish is poorly understood. This study sought to identify spatial patterns and the fate of Atlantic salmon post-smolts following a simulated escape event from an aquaculture site in the Bay of Fundy, Canada. Farm-raised salmon ( N = 99) were implanted with an acoustic tag and released from a commercial aquaculture facility with their movement patterns and mortality tracked over a 4-month period. Fish took ∼5 h to leave the release site and initially opted to either move inshore ( N = 8) or out to sea ( N = 73). Although, many fish returned to the release site. Most fish (72.7%) succumbed to predation shortly after release (64% by 48 h). Together, site fidelity and early stage predation could substantially reduce the ecological risks associated with farm-raised salmon that escape from commercial aquaculture facilities.