Trophy Largemouth Bass Management at Lake Phelps

The North Carolina Wildlife Resources Commission (NCWRC) often establishes fishing regulations, such as length limits, to enhance sport fisheries in the public waters of North Carolina.  Since July 1, 2002, a special trophy regulation has been in place at Lake Phelps designed to increase the number of largemouth bass greater than 20 inches in the lake.  The minimum length limit of 14 inches protects the bass from harvest until they can spawn at least once and the second part of the regulation establishes a protected “slot limit” for largemouth bass between 16 inches and 20 inches.  In summary, only largemouth bass between 14 and 16 inches in length as well as those greater than 20 inches can be legally possessed.

            Prior to implementation of the regulation, largemouth bass anglers at Lake Phelps voiced concerns that their catch rates of largemouth bass greater than 20 inches were low compared to previous years.  Data from our largemouth bass electrofishing boat sampling collected prior to the trophy regulation revealed an abundance of largemouth bass between 15 inches and 17 inches, but there were indeed few fish greater than 20 inches.  Out of 138 adult largemouth bass collected in our samples during 2001 and 113 collected in 2002 only two were greater than 20 inches in length (see figure below).

In deciding on an appropriate management strategy for Lake Phelps largemouth bass, we also examined largemouth bass body condition to see if forage availability, low lake productivity, or competition for food among themselves was playing a role in the lengths of the fish.  Prior to the trophy regulation, body condition of largemouth bass greater than 16 inches was relatively poor compared to other largemouth bass populations in the Southeast – they were not as plump.  But, we found that the body condition of adult largemouth bass less than 16 inches was better than those greater than 16 inches.  Because lake conditions (low productivity) are the same for all sizes of largemouth bass, relative differences in weight among different size classes of largemouth bass were more likely related to a combination of forage abundance and competition for the forage.  This scenario usually results when there are “too many mouths to feed” with a given level of lake productivity.  In other words, the amount of food available at Lake Phelps may not be able to support multiple size groups of fish.  Therefore, we decided that to increase the number of largemouth bass greater than 20 inches, we may actually have needed a reduction in the number of largemouth bass of smaller sizes.  Thus, a regulation crafted to help influence the sizes of largemouth bass in the lake would need to allow for and maybe even encourage the harvest of largemouth bass in the 14 to 16 inch range.

So, based on the information, we had from our studies, we proposed a regulation which would protect largemouth bass from harvest until they reached spawning size, would also allow harvest of some mid-sized fish, and ultimately would protect the remaining fish from harvest until they grew into the 20 inch “trophy” category.  After a series of public meetings, the trophy regulation was implemented and protocols were developed to annually monitor the fish community at Lake Phelps.

            We are currently evaluating the trophy bass regulation by comparing pre-regulation largemouth bass data to the post-regulation largemouth bass data.  Initial results indicate a general increase in the number of largemouth bass greater than 20 inches at Lake Phelps.  During the past four springtime samples, we have collected at least 15 largemouth bass greater than 20 inches; these large fish made up between 5.7% and 8.0% of our samples (See figure below).  Similarly, anglers have reported catching more largemouth bass greater than 20 inches since the regulation was implemented.  Although catch rates of largemouth bass by both anglers and biologists are relatively higher than pre-regulation catch rates, condition of largemouth bass greater than 20 inches still appears to be less than optimal.  For the current regulation to be effective and condition of largemouth bass to improve, an increase in angler harvest of largemouth bass between 14 inches and 16 inches is necessary, although anglers may not harvest more than 5 largemouth bass per day.  Presently, more largemouth bass anglers are practicing catch and release, and in addition, anglers may not be harvesting largemouth bass because of fish consumption advisories related to mercury contamination across North Carolina.  

Alternately, ongoing management activities to enhance forage fish abundance at Lake Phelps may also boost body condition in Lake Phelps largemouth bass.  We developed a management option to stock bluegill sunfish at Lake Phelps because fish community sampling data revealed that bluegill abundances were much lower than had been seen historically.  Unfortunately, after three years of stocking bluegill fingerlings, abundance of adult bluegill did not change significantly.  Thus, fingerling bluegill stocking to improve forage availability may not be a viable option for the future. 

Another management option being examined is the reintroduction of river herring (blueback herring and alewife) to Lake Phelps.  Historically, during springtime migrations, anadromous river herring swam upstream from the Scuppernong River to Lake Phelps through large drainage canals, including Bee Tree Canal.  In 1984, an experimental fish ladder was installed by NCWRC in Bee Tree Canal in an attempt to enhance herring migration to Lake Phelps.  Although water levels were sufficient to operate the fish ladder in 1984 and part of 1985, use of the fish ladder by river herring was not documented, and adult river herring were not collected in Lake Phelps in those years.  After three consecutive years of drought the fish ladder was removed.  In May 2006, a new fish ladder was installed in Bee Tree Canal by the U.S. Fish and Wildlife Service in another attempt to attract river herring to available spawning habitat in Lake Phelps.  In a concurrent effort, East Carolina University researchers will attempt to jump-start the reintroduction of herring by collecting pre-spawn adult river herring from the Scuppernong River and stocking them into Lake Phelps in spring 2007.  If these programs are successful, juvenile river herring in Lake Phelps could serve as a major boost in the forage fish availability for largemouth bass, and a reestablished spawning run of river herring may also help revitalize severely diminished river herring populations.

The effectiveness of the trophy largemouth bass regulation at Lake Phelps continues to be evaluated.  The numbers of largemouth bass that fall within the slot limit continue to be very abundant in the lake, and provide an outstanding catch-and-release fishing opportunity.  Our initial regulation assessment indicates abundance of largemouth bass greater than 20 inches also appears to be increasing at Lake Phelps.  Condition of these largemouth bass, however, is less than optimal.  Forage fish enhancement projects are underway that may increase the condition of these trophy-size largemouth bass.  Thus, we plan to maintain the current regulation and during the next four years, further evaluate its effectiveness in light of progress in forage fish enhancement. 

chart

Figure 1.  Percent abundance of largemouth bass greater than 20 inches at Lake Phelps from spring electrofishing samples during 2001 (Sample size, n =138), 2002 (n=113), 2003 (n=332), 2004 (n=220), 2005 (n=297) and 2006 (n=199). Note the y-axis is in a logarithmic scale.

 

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