As do many who enjoy fishing, we feel a connection to nature. Whether it is fighting a 10 pound largemouth bass or landing a trophy brown trout, there is something that draws us to the water. But, fishing also gives us a glimpse of the ecology and complicated species interactions in nature that makes our trips even more worthwhile.
Consider the food web: Nutrients provide energy for microscopic plankton, which get eaten by fish that ultimately serve as food for larger game fish (like the 10 pound largemouth). Nature comprises many of these interactions, which teeter in a very delicate balance. Unfortunately, if we are not careful, this balance can be easily disrupted, and the consequences can be severe and long-lasting. It takes only one introduction of fish from a bait bucket or livewell to upset ecological stability and harm fishing.
We all have heard stories of how someone caught a fish at one lake and released it at another in an attempt to improve the fishing. Regrettably, we also hear such stories on an even grander scale: tens to hundreds of fish transported to a new home with the intent of helping anglers catch more and bigger fish. Regardless of the number of fish or whether they are game or forage fishes, these stockings are illegal in North Carolina and can be disastrous to the fisheries. Once introduced, these fish frequently thrive in their new environment, where they can quickly take over, altering the ecology and impacting the established fisheries that everyone enjoys.
For example, well-intentioned anglers are spreading white perch (a native to the coastal waters of the Atlantic Ocean) across the inland waters of North Carolina. White perch feed on the eggs of bass, crappie, striped bass, sunfish, walleye and white bass, just to name a few. In addition, white perch compete for available food with other young fishes—including sport fish. As a result, the introduction of white perch often leads to the decline of several resident sport fish species.
Another fish expanding its range in North Carolina is the spotted bass (or Kentucky bass). Spotted bass are often a favorite of anglers due to their aggressive nature. Unfortunately, it is that aggressiveness that has encouraged illegal stockings and caused harm. Anglers often notice a brief improvement in the bass fishery after spotted bass are established due to an increase in the diversity and number of bass. In reality, the honeymoon period is not likely to last very long. Given time, spotted bass have the ability to out-compete resident largemouth and smallmouth bass and hybridize with smallmouth bass. Consequently, spotted bass populations can become stunted (concentrated at small sizes). These threats are greater in nutrient-poor reservoirs located in the Mountain region of the state, where spotted bass often interbreed with smallmouth bass and directly compete with them for food. While illegal stocking of spotted bass may seem to diversify a fishery initially, the long-term negative impacts of fewer smallmouth bass and small spotted bass far outweigh the perceived short-term benefits.
Introduced game fish are not the only fish that shift the balance of fish communities; forage fish introductions can severely impact ecosystems as well. Blueback herring are a common bait fish for striped bass and hybrid striped bass, but their introduction has wreaked havoc on numerous white bass and walleye fisheries in North Carolina. Anglers using blueback herring for bait established them in Chatuge and Nottely reservoirs in Georgia, where they were first noticed in the late 1990s. Despite their small size and delicate appearance, blueback herring were able to move downstream through hydropower turbines, and by 1998, they were established in Hiwassee Reservoir in North Carolina. Research has shown that blueback herring eat larval fish and fish eggs. As a result, walleye and white bass reproduction in Hiwassee Reservoir was virtually nonexistent by 2000. Similar research has shown the alewife, a cousin of the blueback, is equally destructive to sportfish communities.
In addition to adding unwanted fish species to new environments, stockings can spread fish diseases (diseases that are specific to fish and not humans). Fish often carry disease without showing any symptoms and without examination from a fish disease specialist, it is impossible to know if a fish is disease free.
Recently, the Largemouth Bass Virus, commonly referred to as LMBV, has been linked to die offs of largemouth bass across the United States. So far it appears that LMBV is fatal only to largemouth bass, but it can be carried by many members of the sunfish family, even healthy-looking bluegill.
Trout fisheries are also at risk to disease; the parasite that causes Whirling disease has devastated rainbow trout fisheries in the western and northern United States. This parasite was brought to the United States via fish stockings and is easily spread by the continued introduction of infected fish into new waters.
Introduced fish can alter resident fish communities by competing with them, eating their young, altering their genetics and transmitting disease. The next time you hear people say they are going to “add more bait” or “stock more fish” by emptying their live wells into another body of water, think about the lessons learned over time and remind them of the possible consequences. They may think they are doing something positive, but let them know the truth: Illegal stockings can ultimately ruin your favorite fishing spot.
Anglers and agencies devote a lot of energy into the conservation and wise use of North Carolina’s natural resources. It takes only one misinformed individual to undo all of the management efforts and permanently alter fishing waters. Illegal introductions help create unstable and unpredictable environments that are difficult to manage and unwanted by all. Do your part to help prevent the illegal introduction of fishes into your favorite waters by reporting wildlife violations in North Carolina to 1-800-662-7137. By acting responsibly and working together, anglers and the N.C. Wildlife Resources Commission can help maintain our fishery resources for future generations of anglers.