| The next step is to expand the project beyond the reserve's boundaries to enlarge managers' picture of what is happening beneath the waves. |
New technology is helping New Jersey researchers learn more about natural resources that cannot easily be seen beneath estuarine and ocean waters. The resulting data could help coastal resource and fisheries managers make better decisions, and have the potential to support ecosystem management.
"StriperTracker is an early attempt at using IOOS [Integrated Ocean Observing System] types of approaches to better understand the habitat use, migration, and other behaviors of a variety of finfish at a very local scale," says Mike De Luca, manager of the Jacques Cousteau National Estuarine Research Reserve. "This is a pilot effort demonstrating if we can in fact use acoustic technology to track fish and learn about their behavior."
After four years of tagging and tracking striped bass using acoustic transmitters, the answers appear to be "yes." Scientists from the Rutgers University Marine Field Station have been able to track individual fish movements in detail and have gleaned new information on habitat use. Researchers have expanded the tagging program to include bluefish, summer flounder, horseshoe crabs, and others.
The StriperTracker project and data also have been used to generate public support and promote education through fish "adoptions" and lessons for integration into the kindergarten through 12th-grade curriculum.
The next step, says De Luca, is to expand the project beyond the reserve's boundaries to enlarge managers' picture of what is happening beneath the waves.
Tagging On
The idea for StriperTracker, say Rutgers researchers Thomas Grothues and Ken Able, came out of the Sloan Foundation's Census of Marine Life project, which is a global network of researchers working on a ten-year initiative to assess and explain the diversity, distribution, and abundance of marine life in the oceans.
The foundation issued a challenge to scientists to "come on board at the local level," says Assistant Research Professor Grothues. "We recognized the value of doing something like that, and the technology to do so was maturing."
The scientists chose to look first at striped bass because they are a popular fish with Atlantic coast sport and commercial fishermen, and they feed and live in saltwater but move into freshwater to spawn. With their habitat ranging from Florida to the Gulf of St. Lawrence, Canada, they are able to swim long distances along the coast.
Previous studies, says Grothues, collected fish using nets and provided an aggregate-level assessment of the species. "They missed very important aspects of habitat use and fish dynamics. The idea of being able to look at the behavior and movement of an individual fish—no matter how you did it—is a unique thing."
The researchers determined that by using acoustic tags on fish, they could track individuals by listening to them.
Listen and Learn
The acoustic transmitters are surgically implanted into the fish. Each tag produces a different sound pattern, which becomes an identification code for individual fish.
The transmitters have an external spaghetti tag that alerts any fisherman who catches one of the 106 tagged fish that it is part of the study. If a fisherman sees the tag too late, the internal tag carries an address for its return.
Hydrophones can hear the ultrasonic transmissions from the tags from more than a half mile away under good conditions. A series of hydrophone listening buoys were placed in strategic locations within the Jacques Cousteau Reserve.
Reaching Out
Generating public support and awareness and using the data for educational purposes has been a goal of the program since its inception in 2002.
StriperTracker data and information are part of educational activities for teachers to use with kindergarten through 12th-grade classes. The Web-based programs introduce students to issues associated with fisheries management and enrich basic skills.
"Adopt a Fish" is another means of engaging the public. Individuals or groups can donate $315 to purchase an acoustic tag—thereby adopting the fish that gets that tag. The fish can be named and tracked via the StriperTracker Web site.
"The response has been great," De Luca says. "Fish have been adopted by local fishing clubs, a legislator, classrooms—it's one way of not only engaging the public in the project, but of developing a source of program funding."
Discovery Zone
The acoustic tracking has given the scientists insights into individual fish habitat use, migration, and other behaviors.
For instance, during the fall migration, many striped bass come back to "within yards" of the same spot they inhabited the year before, De Luca says. "That's a pretty astonishing observation. No one knew they were so focused on homing in on their previous residence."
Ken Able, director of the Rutgers Marine Field Station, notes that some fish migrate over great distances, while others don't migrate at all, remaining residents of the estuary year-round.
"Their degree of residency is incredible," Able says. "It's entirely possible that many fish species do this and we don't have that comprehensive understanding. . . This has implications for conservation and management."
Expanding the Range
By shedding new light onto fish habitat use and behavior, StriperTracker has "demonstrated its value to improving the management of coastal resources," De Luca says. "We ought to embrace it."
De Luca and the researchers envision other reserves and research groups starting their own tagging projects. As more hydrophones cover the coast, scientists will be able to share data about fish leaving one study area and entering another. As more species are tagged and tracked, a more ecosystem-scale approach to fisheries management will emerge.
"This is a real opportunity for the reserve system to provide science-based information to a user group that we have traditionally not served and help inform their decision making," he says.
De Luca adds, "This is working, and we need to begin to expand it and start looking at a whole range of critters. Ultimately we will improve the management of our coastal resources."
For more information on StriperTracker, point your browser to www.stripertracker.org. You may contact Mike De Luca at (732) 932-6555, ext. 512, or deluca@marine.rutgers.edu. You may also contact Thomas Grothues at (609) 296-5260, ext. 262, or grothues@marine.rutgers.edu, or Ken Able at (609) 296-5260, ext. 230, or able@marine.rutgers.edu.
