Artificial Beats Natural in Fish Attractor Study
8/8/2013 3:09 PM
Results from a three-year fish attractor study are in and confirm what fisheries biologists with the N.C. Wildlife Resources Commission have long suspected but never knew for certain until now — artificial structures constructed from synthetic materials are much better at attracting and holding fish over a long period of time than structures made of natural materials.
Brian McRae, Piedmont Region Fisheries Supervisor, answers a few questions about the study and what it means for fisheries management in Piedmont reservoirs.
What was the purpose of the study?
The study and data analysis, which began in June 2008 and ended in August 2012, evaluated the effectiveness of four different types of fish attractors, in terms of how well they concentrated fish and how well they held up over a three-year duration. The Commission worked with cities of Greensboro and Burlington to complete the fish attractor study, which was funded through the Sport Fish Restoration Program.
Where did biologists evaluate the fish attractors?
We deployed four different types of fish attractors — three that were constructed from synthetic materials and one from natural materials — into Lake Townsend in Greensboro and Lake Cammack in Burlington. We selected these lakes because of their abundance of sport fish,similarity in size, and lack of underwater structures.
Using GPS coordinates, we dropped two porcupine attractors, two attractors constructed of PVC pipe and corrugated plastic pipe, two attractors constructed of PVC pipes and halved plastic barrels, and two attractors constructed out of Christmas tree bundles into each lake. We also marked two “control” sites in each lake that were devoid of structure.
How did biologists evaluate the effectiveness of each attractor?
We evaluated each attractor site every fall, winter, spring and summer for three years, using a high definition imagery sonar unit called the DIDSON(Duel-Frequency Identification Sonar). The use of the DIDSON was important because it allowed us to evaluate these structures visually in low-clarity water without disturbing the fish that were using structures.
The DIDSON imagery was clear enough for us to identify larger sport fish and schools of small bait fish swimming through the attractors. However, it wasn’t clear enough for us to identify specific species, except for large catfish. We also used traditional sampling methods to supplement the DIDSON images and verify the species utilizing the attractors.
How well did each fish attractor work during the study period?
During the first two years, all four types of structures were holding more fish than the control sites, and all were holding about the same amount of fish. However, by the third year, all three artificial structures held more fish than the Christmas trees, which by this time, had lost all of their needles and were nothing more than trunks and a few major branches. We also found that by the third year of the study, the “Georgia” attractor, a structure composed of PVC pipes and corrugated plastic pipes, was holding more fish than any of the other three structures.
Artificial structures attracted a wide variety of fish species — from bait fish, such as shad, to game fishes like large mouth bass, bluegill and crappie. The PVC pipe barrel structures held the largest fish — mostly catfish — and the three attractors made of synthetic materials had higher odds of having schools of bait fish present.
We are not sure why the “Georgia” attractor held more fish than the other artificial structures in the third year, but we were not surprised by the Christmas trees’ decrease in performance over time because they decompose so quickly.
Now that the fish attractor study results are in, what happens next?
Because the fish attractor study yielded the results we expected, we have begun using artificial structure constructed from synthetic materials for many bodies of water in the Piedmont. In 2012, we deployed 19 fish reefs made of Moss Back Fish Attractors™ in Hyco and Mayo lakes near Roxboro (Person and Caswell counties). In 2013, we deployed nine fish reefs in Lake Thom-a-lex, four fish reefs in Shearon Harris Reservoir, and two fish reefs in Tar River Reservoir. We plan to deploy similar fish reefs in Lake Reidsville early next year.
Using artificial structures made from synthetic material, we believe we are being more efficient because once the artificial structure is deployed, we know that it will be there attracting fish for years to come.
Are the fish attractors marked so I know where to find them?
Yes.Fish attractors are marked by white and orange buoys with black lettering and the green N.C. Wildlife Resources Commission diamond logo. The agency also posted a new searchable online map this spring featuring GPS coordinates o fnearly 550 fish attractors across the state.
You can access the map and download GPS coordinates from the Where to Fish section on the Commission’s website. You can import way points (longitude/latitude) using a text file, anExcel file or a GPX (GPS Exchange Format) file, and you can use the map to find the approximate locations and types of fish attractors found in each body of water.
For rmore information on fishing in public, inland waters, visit www.ncwildlife.org/fishing.