Milford Lab's GoPro Aquaculture Project
Understanding interactions between shellfish aquaculture gear and the environment
Overview
Project Goal
To determine if oyster cages used in shellfish aquaculture provide habitat similar to that of naturally occurring rock reef environments and if cage densities associated with shellfish farming attract fish differently than single cages in low relief areas.
Project Description
Shellfish aquaculture can increase food production, create economic opportunities in coastal areas and enhance natural harvests. To foster successful, responsible, and sustainable aquaculture for the future, we need to understand how aquaculture gear may interact with the biology, ecology, and habitat of an ecosystem. Off-bottom oyster cages are growing in popularity as a method for culturing large numbers of oysters in a small footprint. These cages create complex 3-dimensional structure that may attract fish and other animals seeking food sources, shelter, and refuge from water currents or protection from predators. Because of the cages' structure, they may function like naturally occurring rock reefs, providing beneficial habitat to ecologically and economically important fish and invertebrates. Understanding if and how oyster cages function like naturally occurring habitats may help with regulatory and permitting processes when siting new shellfish farms.
Naturally occurring rock reefs create habitat complexity in an often otherwise flat and featureless landscape. Rock reefs add vertical height in the water column, crevices and shading for hiding, and surfaces on which epibenthic organisms can colonize and grow. Complex habitats like these often have greater density and diversity of species than a less complex habitat like a flat seafloor. Because of this, oyster cages may be providing benefits similar to those of rock reef habitats. While there is limited scientific data available on aquaculture gear as habitat, extensive anecdotal evidence from commercial shellfish growers suggests that both fish and invertebrates may be using the gear as habitat.
We're conducting a series of field experiments to better understand how fish interact with oyster cages used in shellfish aquaculture farming operations.
This research is being funded by the Northeast Fisheries Science Center and NOAA's Office of Aquaculture.
Study Methods
Study Site Locations
Study sites are located in Long Island Sound near the Charles Island Oyster Farm off Milford, Connecticut. Sites include an inshore commercial oyster farm containing 40+ oyster cages, an inshore naturally occurring rock reef, and an inshore mixed feature habitat of empty shell, live oyster, and featureless seafloor.
Study Methods
To calculate abundance and behavior at naturally occurring rock reef habitat, we constructed four "T-platforms" with dual camera mounts. We then placed the platforms near boulders within the rock reef site. A team of divers scouted and then selected four boulders that we returned to every other week. A buoy attached to cinder blocks was placed at the center of the boulders. Divers swam down the buoy line and followed a series of lines placed along the bottom to relocate the same four boulders during camera deployment and retrieval. Divers then put the cameras on the T-platforms and retrieved the cameras two days later. The T-platform itself stays in place for the entire field season. Each T-platform is outfitted with two cameras that record video for 8 minutes every hour from 7 a.m to 7 p.m over a complete tidal cycle. The two cameras provide a field of view similar to that provided by our oyster cage camera system: one looks across the boulder and one looks down the side of the rock where it meets the sea floor.
To understand if oyster cage density has an effect on fish abundance and behavior we placed four cages about 50 meters apart at the inshore site adjacent the oyster farm, and four cages about 90 meters apart at the inshore mixed-feature habitat. We calculate fish abundance and behavior using a similar approach as that used for the cage/reef comparison: all cages were mounted with two cameras that record 8 minute segments every hour from 7 a.m to 7 p.m over a complete tidal cycle.
Collecting Environmental Data
During camera deployments, we also collected environmental data. To collect water temperature and light intensity data, we used HOBO Pendant® Temperature/Light 64K Data Loggers. Light is important factor affecting visibility and video quality and it may influence fish behavior. Because changing tidal currents may also influence how fish interact with cages and boulders within rock reefs, we used Lowell TCM-1 tilt current meters to collect information on speed and direction of water currents. A current meter and temperature/light data logger was attached to one cage at both the farm and mixed-feature sites and to a spare T-platform at the rock reef. Using YSI probes, we collected additional environmental data (i.e., salinity, dissolved oxygen, water temperature) during deployment and retrieval trips to each site.
Describing Fish Communities using Environmental DNA (eDNA)
When fish and other organisms move around in the water, they leave traces of their DNA behind. Although this DNA is diluted, it can be extracted and analyzed. Each time we retrieve our GoPro cameras, we collect water for environmental DNA (eDNA) analysis. The eDNA method we're using combines DNA-based identification and high throughput next generation sequencing to characterize the fish communities associated with oyster cages and rock reefs. Using eDNA we may detect fish that are in the area surrounding the cages or rock boulders, but that are not seen in video. This may help create a more complete picture of fish community composition than video alone. Compared to capture-based methods, eDNA analysis is a comprehensive, rapid, non-invasive, and cost-effective method.
Collaborators
- Commercial shellfish growers:
- Robert Granfield and Gary Salce, G & B Shellfish Farm
- Chuck Viens, Charles Island Oyster Farm
- Noank Aquaculture Cooperative
- Fisher Island Oysters
- John Pinkowski, Atlantic Clam Farms
- Dave Carey and Kristin DeRosia-Banick, State of Connecticut Aquaculture Division
- Peter Auster, University of Connecticut and the Mystic Aquarium
- Arthur Allen, US Coast Guard Office of Search and Rescue
- Alison Verkade and Kevin Madley, NOAA Greater Atlantic Regional Fisheries Office
- Calandria DeCastro and Keith Golden, Dive support from NOAA Corps officers
- The Nature Conservancy and Northeastern University
- Daphne Munroe, Rutgers University
- NOAA Northwest Fisheries Science Center
Preliminary Results
To date, we've observed 19 species of fish associating and interacting with oyster cages, including: black sea bass, tautog, cunner, scup, summer flounder, conger eel, hake, goby, oyster toadfish, and rock gunnel. Identifying fish to species level and counting fish are only the first steps in our video analysis.
We'e partnered with fish ecologist Dr. Pete Auster from the University of Connecticut and the Mystic Aquarium to identify and quantify the different ways that fish are using oyster cages. So far we've seen fish feeding on the epibenthic fouling organisms growing on the cages, little fish escaping from bigger fish by darting inside the cage itself, and even female fish retreating inside the cage to escape male fish of the same species.
Multimedia
GoPro footage captures a double-crested cormorant searching for fish prey around an aquaculture research cage. Video credit: NOAA Fisheries/Milford Laboratory
GoPro footage captures a double-crested cormorant searching for fish prey around an aquaculture research cage as a tautog looks on. Video credit: NOAA Fisheries/Milford Laboratory
GoPro footage captures a double-crested cormorant searching for fish prey around an aquaculture research cage. Video credit: NOAA Fisheries/Milford Laboratory
GoPro footage captures a double-crested cormorant searching for fish prey around an aquaculture research cage. Video credit: NOAA Fisheries/Milford Laboratory
Citizen Science
We've created a citizen science guide to help growers capture high quality underwater footage of their aquaculture gear to monitor the ecosystem interactions:Contact Information
Project/Principal Investigators:
Project Team:
Paul Clark, Erick Estela, Peter Hudson, Yuan Liu, Renee Mercaldo-Allen, Lisa Milke, Gillian Phillips, Matthew Poach, Dylan Redman, and Julie Rose. Dive team includes Barry Smith, Mark Dixon, and Jerry Prezioso.
