Inland Fisheries Division’s Project "Establishing & Monitoring Hybrid Striped Bass in Lake Norman" Wins National Award

Author: NCWRC blogger/Friday, August 28, 2020/Categories: Blog, Fishing

Inland Fisheries Division’s Project "Establishing & Monitoring Hybrid Striped Bass in Lake Norman" Wins National Award

The Wildlife Commission's Inland Fisheries Division recently won the 2019 Federal Aid in Sport Fish Restoration Award in the category of Sport Fishery Development and Management for creating a successful hybrid striped bass fishery in Lake Norman. The project, “Establishing and Monitoring a New Hybrid Striped Bass Fishery in Lake Norman,” was initiated in 2013 as an alternative to managing for striped bass. NCWRC biologists explored various options to sustain a viable fishery and met with anglers to discuss scenarios. To address angler demands for a fishery that centered on a fish like striped bass, the NCWRC began stocking hybrid striped bass in June 2013. Since 2014, the hybrid striped bass fishery has become increasingly popular among bank and boat anglers.

 

More information on the project is below.

The North Carolina Wildlife Resources Commission (NCWRC) had traditionally managed Lake Norman for a Striped Bass Morone saxatilis fishery. Striped Bass were stocked annually from 1969 through 2012.  Due to the lake’s low productivity, the Striped Bass routinely exhibited poor growth and condition.  However, anglers continued to insist the reservoir be managed for Striped Bass and often questioned why NCWRC biologists could not manage the reservoir for trophy Striped Bass.  In the late 1990’s, anglers asked NCWRC biologists to stock Alewife Alosa pseudoharengus in the reservoir as forage for Striped Bass.  When the NCWRC biologists recommended against introducing Alewife, anglers took it upon themselves to stock them.

 

Despite the poor growth and condition, the only Striped Bass mortality event prior to 2004 occurred in 1983.  In 2004 and again in 2009, 2010, 2011, and 2012, substantial mortality was observed in the deeper portion of the reservoir near the dam.  NCWRC biologists monitored conditions each summer to determine the cause of these kills.  Efforts included monitoring water quality, tracking fish congregations with hydroacoustics, and counting and evaluating mortalities.  After several years of data collection, NCWRC biologists determined the kills were a result of Striped Bass being trapped in an “oxygen bubble” deep within the hypolimnion.

 

NCWRC biologists demonstrated that during the summer, Striped Bass followed Alewife, a preferred food, into the hypolimnion to feed.  However, as the summer progressed the hypolimnion eventually turned into an “oxygen bubble” created when dissolved oxygen levels in the metalimnion decreased faster than those in the hypolimnion.  This process can occur naturally during the summer in deep reservoirs (greater than 100 feet).  The hypolimnion eventually becomes anoxic and any trapped Striped Bass die.

 

With the increased frequency of Striped Bass fish kills, NCWRC biologists explored alternatives to sustain a viable fishery.  Biologists met with the anglers to discuss potential scenarios and in 2012 the annual stocking of Striped Bass was ended at Lake Norman.  But to address angler demands for a fishery that centered on a fish like Striped Bass, the NCWRC began stocking hybrid Striped Bass Morone saxatilis X Morone chrysops in June 2013.  Since 2014, the hybrid Striped Bass fishery has become increasingly popular among both bank and boat anglers across the reservoir.

 

In 2015, the hybrid Striped Bass reached a size large enough to be caught and harvested.  Hybrid Striped Bass behavior in Lake Norman, schooling at the reservoir’s two warmwater effluents during winter months and riverine spawning in the spring, makes the fishery potentially more susceptible to harvest.  So NCWRC biologists implemented a 5-year tagging study (2015-2020) to understand exploitation rates of the fishery.  Specific objectives of this research were to 1) understand the exploitation rates of anglers on a new hybrid Striped Bass fishery, 2) compare the harvest rates between bank and boat anglers, 3) understand the effect anglers have on the population when fishing in warmwater effluents and spawning ground locations, and, 4) evaluate the efficacy of stocking rates and minimum size limits on the population.

 

At the end of the study, exploitation rates will be determined through a high reward tag-return model. Individual fish were tagged using a Floy FM-84 tag with a unique number. Each tag is valued at $100 to ensure a 100% tag reporting rate. Tagging began in December 2015 with a goal of tagging 20-30 fish per month for three years (completion November 2018). Tags were returned starting in January 2016 and will be accepted through November 2020. An angler who captures a tagged fish calls NCWRC staff to report the tag and receive the reward. The staff member interviews the angler seeking information on 1) the tag number, 2) the date of capture, 3) whether the angler was boat or bank fishing, 4) if the angler harvested or released the fish, 5) the type of bait used by the angler, and 6) lake location where the fish was captured.

 

From December 2015 to November 2018, over 3,000 hybrid Striped Bass were collected, of which 1,462 fish were tagged.  A pilot effort to collect and tag harvestable hybrid Striped Bass demonstrated that angling was the most efficient way to collect hybrid Striped Bass in Lake Norman due to their habitat use.  Collections were accomplished through both staff effort and project volunteers. Volunteers helped during each tagging period, catching and transferring fish to staff for tagging. Volunteers could also “deposit” fish into live cars stationed throughout the lake and contact staff for tagging. An outreach campaign including various media outlets, boating access area signage, personal communication and an involved constituency resulted in over fifty volunteers participating in the tagging portion of the project.

 

To date, 832 tagged fish have been returned equating to 56.9% return rate thus far. Preliminary analysis indicates that return rates for this tagging project are much higher than average for tagging projects. These high return rates can be attributed to increased fishing pressure and the susceptibility of capture of hybrid Striped Bass at Lake Norman during certain seasons.  Of the returned tags, 289 fish were captured by bank anglers with 544 fish captured by boat anglers. Preliminary data indicates that overall 67.9% of fish captured were harvested. Bank anglers harvested 88.2% of fish they caught while 65.4% of fish captured by boat anglers were harvested. Tag location data also indicate that fish can be found throughout the reservoir, but most fish were captured in the upper portion of the reservoir which is more productive and contains higher amounts of forage for hybrid Striped Bass. 

 

The hybrid Striped Bass fishery at Lake Norman has been a tremendous success by all accounts, and its popularity of continues to increase.  Anglers now have an established and viable hybrid Striped Bass fishery in the largest reservoir in North Carolina.  Hybrid Striped Bass grow well and to date no summer mortality events have occurred.  Involving anglers in the tagging study has increased interest in the hybrid Striped Bass fishery and increased the overall interest in NCWRC fisheries management activities at Lake Norman.

 

One of the major accomplishments of this project is the improved communication between anglers and NCWRC biologists. The one-on-one communication and high visibility of NCWRC biologists has resulted in an improved relationship with constituents that was once often contentious and volatile.  The tagging effort has increased staff interactions with anglers which has contributed substantially to the management of the hybrid Striped Bass as well as other fisheries at Lake Norman.  Communication has also increased with Hispanic and Asian anglers.

 

At the completion of the reward portion of the project in November 2020, data will be analyzed to study the annual, seasonal, and monthly mortality rates of the hybrid Striped Bass population. This information will help determine appropriate stocking rates and size and creel limits for the Lake Norman fishery.  Based harvest rate initially observed, biologists have already requested to double stocking rates beginning in 2017.  Study results will likely demonstrate the need to increase the minimum size limit which is currently 16 inches. The increased stocking rate and minimum size limit should help retain fish in the lake longer and help sustain the high harvest rates.

 

The new information collected through the tagging effort has spurned further interest by NCWRC biologists and anglers.  Additional research projects are being planned to begin in spring 2020.  The popularity of hybrid Striped Bass at Lake Norman has led to anglers wanting hybrid Striped Bass fisheries in other areas of North Carolina. In 2019, hybrid Striped Bass were stocked in Hyco Lake to develop another angling opportunity.

 

Biological staff have presented preliminary data to fisheries professionals at both the state and regional level. Also, staff continue to present to local fishing clubs, civic organizations, and wildlife societies around Lake Norman.  After final data analysis, manuscripts will be submitted to fisheries journals, communication will continue with constituency both locally and statewide, and information will be updated on the NCWRC’s website and social media.

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1 comments on article "Inland Fisheries Division's Project "Establishing & Monitoring Hybrid Striped Bass in Lake Norman" Wins National Award"

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Danny Hocutt

8/31/2020 8:47 AM

2 important things more minnow varieties put in lakes and rivers down East —. Put F-1 type Bass I the lakes -rivers in our state

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