August 15, 2018


Julie Rose and Renee Mercaldo-Allen, NOAA Fisheries Northeast Fisheries Science Center, Milford Laboratory

Scientists at the National Oceanic and Atmospheric Administration (NOAA) Fisheries Northeast Fisheries Science Center laboratory in Milford have been working for the last two summers in Long Island Sound to document environmental benefits provided by Connecticut’s oyster aquaculture industry.

Off-bottom oyster cages are growing in popularity as a method for culturing large numbers of oysters on a small footprint. These cages create complex three-dimensional structures that may attract fish and other animals.

Fish may utilize oyster cages as a food source, for shelter, refuge from current flow, or protection from predation. Shellfish farms with many cages add habitat and structure to the seafloor and may act as an artificial reef, attracting greater numbers of fish than would normally be found in areas without natural structure.

Considerable anecdotal evidence from shellfish growers suggests that fish of a variety of life stages frequently interact with aquaculture gear.  But there is limited scientific data available that documents which fish species use oyster cages, how many fish interact with cages on a daily basis, and how those fish are using the cages.

Point-of-view video cameras provide a new opportunity to document and quantify the interactions between fish and oyster aquaculture gear.  The relatively low cost of individual cameras has increased the feasibility of collecting scientifically rigorous data underwater, on aquaculture operations at leased sites. 

These data demonstrating habitat services provided to fish are valuable to regulators and fishery managers who make decisions about siting shellfish farms and protecting habitat for recreationally and commercially important fish species.  Videos of fish using oyster cages can also serve as compelling outreach tools to demonstrate environmental benefits provided by the shellfish aquaculture industry to the public.

Milford Lab scientists have been working on Connecticut oyster aquaculture leases, using cages typical of the style used in Connecticut, stocked with local oyster seed. They have attached two GoPro cameras to each of a series of oyster cages. 

One camera looks across the top of the cage like a periscope and the second camera hangs off one corner so that it looks down two sides of the cage and can also view the interface between the cage and the seafloor. 

The team also uses Blink timers to delay the onset of video recording for approximately 24 hours in order to let any seafloor disturbance associated with cage deployment to dissipate.  Cameras record video for eight minutes every hour, for 12 hours, so that they can collect video over the course of nearly all daylight hours as well as a full tidal cycle.

So far, the team has observed black sea bass, tautog, cunner, scup, conger eel, hake, goby, oyster toadfish, and rock gunnel associated with the oyster cages.

Identifying the fish species and counting the numbers of fish using the cages is only the first step in the video analysis.  The team has also partnered with University of Connecticut professor and fish ecologist Pete Auster to identify and quantify the many different ways that fish are using the oyster cages. 

The scientists have seen fish feeding on the fouling community that has grown on the cages, little fish escaping from bigger fish by darting inside the cage itself, and even female fish escaping male attention by retreating inside the cage.

The team plans to continue collecting video throughout the summer, and has only just begun to analyze the many hours of video they already have on hand.