Behaviour of Temperate Reef Fish Species Around Oyster Aquaculture Farms and Natural Rock Reefs

ABSTRACT Cultivation of eastern oysters using aquaculture gear increases habitat for temperate reef fish. Cunner ( Tautogolabrus adspersus ), scup ( Stenotomus chrysops ) and tautog ( Tautoga onitis ) inhabit a variety of complex natural and manmade habitats, including oyster aquaculture cage farms. Underwater video was recorded on two cage farms and a rock reef during May–September 2018 to quantify fish behavioural interactions and to assess ecological services provided by aquaculture gear, relative to natural structured seafloor. To collect video, action cameras were mounted on four study cages at a high‐density farm of 40–100 commercial cages (dense farm), on four single cages interspersed on low relief seafloor (sparse farm) and adjacent to four boulders on a rock reef (rock reef), within an embayment off Milford, Connecticut in Long Island Sound (NW Atlantic). Video was recorded hourly in 8‐min segments from 7 AM to 7 PM. Behaviours associated with habitat provisioning (e.g., courtship/reproduction, escape from predators, foraging, sheltering, schooling/grouping, territoriality) were observed for all three fish species on cages and boulders. Foraging and sheltering activity in cunner was significantly higher on cages than boulders while territorial behaviour occurred more frequently on boulders. Instances of escape from predators, foraging and sheltering behaviours in scup and tautog were significantly higher on cages than on boulders. Courtship/reproduction, grouping and territoriality were also higher on cages than boulders in tautog. Our results suggest that oyster cages confer ecological services that fulfil the basic biological and functional requirements of reef‐oriented fish, and provide habitat attributes afforded by natural rock reefs.