North Carolina State University researchers are studying the movement and mortality of spotted seatrout in North Carolina using advanced tagging and telemetry techniques.
Our objectives are:
1) To estimate movement rates and stock boundaries of spotted seatrout in North Carolina
2) To estimate seasonal and annual rates of fishing mortality for legal-size spotted seatrout in NC estuaries
3) To estimate monthly natural mortality rates of spotted seatrout in North Carolina tributaries during November to April time periods and determine the importance of winter kill
This work began in September 2008 and will conclude in August 2012. Funding for year one came from a NC Sea Grant Fishery Resource Grant and funding for years two through four comes from the NC Marine Resources Fund, which consists of proceeds from the sale of the Coastal Recreational Fishing License.
Principal Investigators are:
Dr. Jeff Buckel, Professor, Dept. of Applied Ecology, NCSU-CMAST
Dr. Joe Hightower, Professor, Dept. of Applied Ecology, NCSU; Asst. Leader of NC Cooperative Fish and Wildlife Research Unit; U.S. Geological Survey
Dr. Ken Pollock, Professor, Depts. of Applied Ecology, Biomathematics, and Statistics, NCSU
Tim Ellis PhD candidate, Dept. of Applied Ecology, NCSU-CMAST
Funding provided by:
What should you look for?
NC speckled trout are being tagged STATEWIDE, from Oregon Inlet to the Cape Fear River and everywhere in between. Tags are being placed in any healthy fish greater than 12 inches in length that we capture, with a goal of tagging 1,500 individuals per year over four years.
We are using an ‘internal anchor tag’ which is placed in the belly of the fish just behind the pelvic fin (see photograph at left). This tag type allows for maximum retention over time (see Preliminary Studies). TWO tag colors are used (see more details below), YELLOW and RED, and all tags are printed with a unique tag number (NCXXXX), telephone number, and a request to ‘CUT TAG’ (see photographs of tags at bottom of page).
We are requesting that all tags be cut (even if fish is released) to ensure accurate reporting of the tag number and IF THE TAG IS RED, IT MUST BE CUT OFF AND SENT IN FOR THE HIGH REWARD. NOTE: ~25% of our yellow-tagged fish have two tags to help us better understand tag retention; please check both sides of the fish for tags (see Conventional Tagging).
Rewards for tagged speckled trout — what should you report?
All tags should be returned to Tim Ellis at 1-800-790-2780. Yellow tags do not have to be sent in but all red tags should be mailed to: Tim Ellis, NCSU-CMAST, 303 College Circle, Morehead City, NC 28557. Please call in all tags prior to mailing them in. When returning a tag, you will be asked to provide information on: Date of capture, Location of capture, Total length of the fish, How you caught the fish, Released or kept, and Overall health of the fish. Also, digital photographs of tagged fish are extremely useful in our assessements of tagging mortality and tag retention. Please email any photographs of tagged speckled trout to Tim Ellis at firstname.lastname@example.org .
Yellow tags are worth $5, a custom NCSU speckled trout tagging HAT, or a custom tagging T-SHIRT. Red tags are worth $100. In addition to the reward, a letter is included that relays the date and location of where the fish was originally caught and tagged. Look for our flyers across the coast of NC!
Historical Tagging in NC
External tags have been used to determine stock boundaries in a variety of fisheries in NC. In 2009, the NC Division of Marine Fisheries chose the northern limit of Virginia and the southern limit of NC as the stock boundaries for its assessment of spotted seatrout.
This stock unit was identified because 15% of all the returns from fish tagged in VA came from NC. Of the spotted seatrout tagged in South Carolina, only 2 out of 350 (0.006%) were recaptured in NC. Unfortunately until now, there has not been an extensive tagging study conducted on spotted seatrout in NC.
Throughout the 1990s, two independent spotted seatrout tagging projects were conducted in NC by recreational fishing organizations. One project had a limited number of tagged fish (n=240) and returns (n=5); of these returns, there were no large range migrations to other states. Extensive efforts have been made to locate data from the other project, however no data have been found. A large scale tagging study that aims to tag a large number of spotted seatrout with methods that reduce tag shedding and tagging mortality is needed to confirm that the combined VA and NC unit stock is valid.
Critical Factors of a Tagging Study
Numerous tagging studies on spotted seatrout have been conducted across the U.S. Gulf and southeast regions, and tag returns have generally been low. Studies using internal anchor tags have had higher returns (6-25%) than studies using t-bar (3%) or dart tags (1-5%).
However, these values are misleading because none have been corrected for any of the three critical factors of a tagging study : reporting rate, tag loss, and tag-induced mortality.
From 2008 to 2009, we conducted preliminary studies to address these factors specifically, and are continuing to collect data on reporting rate and tag loss.
Additionally, and with the help of Dr. Craig Harms of NCSU-CMAST, we developed a surgical procedure for implanting spotted seatrout with sonic transmitters (see Telemetry Tagging)
Long-term Tank Observations
A large number of spotted seatrout ranging from 12-22 inches in total length were held in tanks and observed over a 9-month period. During this time, fish were monitored daily for overall health (e.g., normal smimming and feeding behavior), tag loss of an external anchor tag or transmitter, and mortality. At the termination of these experiments, necropsies were performed on all fish to further examine overall health in relation to the presence of an internal anchor tag or sonic transmitter. More tank and field studies are in the works to continue to refine our estimates of tag loss and tag-induced mortality, but early results fully suggest that long-term spotted seatrout tagging research is feasible.
Conventional Tagging Techniques
Numerous types of tags are available for externally tagging fish. The decision of which type to use depends on many factors, including cost, ease of use, and tag performance. Three commonly used tags that fishermen are familiar with are dart tags, t-bar tags, and internal anchor tags. The first two tag types are placed in the dorsal side of the fish, usually with the help of a tagging stick or gun. These tag types are often preferred by non-scientific tagging programs such as tournament tagging or volunteer angler tagging groups because they are relatively inexpensive and easy to insert.
The downside to these tag types is their poor retention, making them not ideal for use in long-term tagging programs. Dart and t-bar tags are reportedly retained on the scale of weeks to months, where as internal anchor tags, which are placed in the belly of the fish, are retained on a longer scale of months to years. The major drawbacks of internal anchor tags however, are their higher costs, slightly more difficult insertion, and argueably greater invasiveness on the fish. We are using internal anchor tags in this study because of their high retention but we are giving careful consideration to accounting for tag-induced mortality (see Preliminary Studies).
All spotted seatrout that we tag are caught via hook-and-line. Mortality associated with this gear is generally lower for spotted seatrout than other commonly used collection gears such as gill nets, trammel nets, and haul seines. Additionally, we are minimizing capture mortality by only tagging fish that are lipped/mouth-hooked and minimally handled. Tagging a large number of spotted seatrout statewide and by hook-and-line capture is no easy feat, so we have enlisted the help of a select group of regional trout fishing experts to assist with our study. All taggers have undergone one-on-one training and all abide by the same established tagging protocol.
In addition to estimating tag loss rates in controlled tank environments, we are also gathering data on tag loss from fish in the wild. This is done by double-tagging ~25% of our yellow-tagged fish. Tags are located on opposite sides of the body (see photograph below) and we are asking all fishermen to check fish for the presence of two tags or indication that one tag may have been lost. As mentioned earlier (see Return a Tag), photographs of tagged fish are extremely useful in our determinations of tag retention and tag-induced mortality.
Telemetry Tagging Techniques
Tagging fish with conventional external tags (see Conventional Tagging) provide data on movement and mortality of spotted seatrout in NC over large spatial and temporal scales but the resolution of these data are limited. For example, we know where a fish was originally tagged and where it was later re-caught but we don’t know the journey it took between those two points and can only speculate on the route it took and habitat types it used along that route.
Similarly, mortality attributable to natural factors such cold stun or predation may not be easily accounted for with conventional external tags. Sonic tags (i.e., telemetry) can complement conventional tagging by providing valuable information on fish aggregation, fine scale movement, habitat use, and by allowing for direct estimates of natural mortality. The trade-off is that telemetry studies can be temporally (e.g., battery life of transmitter) and spatially (e.g., range of transmitter) limited.
Transmitters are surgically implanted in spotted seatrout, on-vessel at point-of-capture. Only fish greater than or equal to 14 inches in total length are used to carry transmitters which allows for a ~1-2% tag-weight to body-weight ratio.
Our telemetry tagging occurs each year from October to April in the Pungo River. Over this time period, fish are tracked weekly by a manual receiver onboard a vessel and 24/7 by submersible receivers located throughout the region (see illustration below). Our goal with this work is to obtain fine-scale data on fish movement and habitat use during the winter months in NC and in particular, determine what effects temperature has on spotted seatrout movement and mortality in NC (e.g., the nature and importance of cold stun events).
Press and Contacts
In the News!!!
Here are articles published about the NCSU Spotted Seatrout Tagging Study:
- Fisherman’s Post newspaper, March 29, 2012 (linked website)
- The News & Observer, Outdoors section, January 19, 2012 (linked website)
- The Carteret County News-Times, page 10A, April 15, 2011 (PDF download)
- The State Port Pilot, page 5C, April 13, 2011 (PDF download)
- The News & Observer, page 5C, December 23, 2010 (linked website)
- The Fisherman magazine, Mid-Atlantic edition, November 18, 2010 (PDF download)
- Wilmington Star News, Outdoors section, July 24, 2010 (linked website)
- The News & Observer, Outdoors section, January 21, 2010 (linked website)
- Coastwatch magazine, NC Sea Grant, Spring 2009 (linked website)
- The News & Observer, page 10C, March 5, 2009 (PDF download)
- Fisherman’s Post newspaper, Winter 2008 (linked website)