The American Dream: How Invasive Species Have Created New Fisheries

Foreign influences in America extend into our hunting and fishing cultures as well. Across the country alien animal species from other parts of the world have been introduced to the US. Some like the feral hog, have spread and populated so rapidly that they’ve forced hunters to take action against them. However, there are other non-native species that have actually been embraced by the outdoor community. A great example of this would be the Ring-Necked Pheasant, which was introduced to the US in 1881 from China. Since its introduction, the pheasant has become the official state bird of South Dakota and created an obsessive group of gamebird hunters who specifically train dogs, buy shotguns, and come up with hunting strategies to pursue them.

This idea of non-native species having their own unique sporting cultures around them is even more prevalent in the world of fishing. Across the country, there are a variety of foreign and displaced fish species reshaping and even creating their own fisheries with some opening up a whole new world of angling adventures.

Happy Accidents

One of the greatest examples of a foreign fish species being entirely welcomed by anglers is the brown trout. Browns were first brought to the US from Scotland and Germany in the 1860s, with the salmonid’s eggs incubated in barrels which were then stacked on ships and shipped across the Atlantic. The fish were first stocked in New York, where the aggressive nature and beautiful colors of the non-native fish were quickly embraced by the angling community. Soon brown trout were being shipped across the country where they were stocked in rivers lakes and streams from Maine to Montana, becoming one of the country's most iconic and sought-after species, especially by the fly fishing community.

“I think I love catching browns more than any other trout,” fly fishing guide David Force of Emigrant, Montana, said. “They’re just so big and strong and beautiful. They’re more predatory than other trout and love to smash big streamers. In fact, I think the entire culture of big streamer fishing has been built around catching big brown trout. Every year I have clients who come out to fish with me who only want to chase big browns. The fish are just a quintessential part of fly fishing, and I don’t think fly fishing in Montana would be where it is today without them.”

Other introduced species may have not only been welcomed by US anglers but have still created entirely new fishing methods and specific techniques designed to catch them. There’s no better example of this than the common carp. Introduced to the US in the 1860s by Asian and European immigrants who could not believe that this vast and fruitful land had no carp swimming in its waters, carp were brought to America to serve primarily as a food fish for growing migrant populations in California. However, the popularity of the fish and its ability to live and reproduce in a variety of water conditions soon had the US Commission of Fish and Wildlife stocking carp around the country. Carp were looked at as a replacement for declining native fish stocks with the thought being that they could fill in the voids created by the loss of salmon and other standard food fishes which were being severely over-fished in the US at that time. With carp being such a hardy and adaptable species though, they quickly spread to other waters outside of the F&W’s control, and very soon carp became categorized as a nuisance species in many parts of the country.

Despite all this, or perhaps because of it, carp have subsequently formed their own fishing cultures around their pursuit. The fish are a favorite among bow fishermen. A sport where anglers armed with bows hit the water to shoot fish with arrows attached to fishing line. Most bow fisherman target “trash fish” like gar and paddlefish, but the sport probably wouldn’t be nearly as popular as it is today without the carp’s introduction as an archery target. Whether they’re after the common carp or the recently invasive bighead carp, the bulk of a bow anglers catch is usually made up of these invasive species.

Carp have also found their own niche in the fly fishing community, where their large size and fighting ability has triggered a wave of fly anglers to start pursuing the fish on the fly rod.

“The appeal of catching carp on the fly is first and foremost their size,” carp fishing guide Beau Thebault told MeatEater. “The fish can be larger than 20 pounds on average and can you name another freshwater fish out there that has the power a carp has?”

Thebault pursues carp from a paddleboard on lakes and large rivers around his home in Wilmington, North Carolina. He targets the fish on open sand and mud flats believing that pursuing carp in these environments is the freshwater equivalent to saltwater flats fishing for bonefish and permit in more exotic locations.

“Where else can you sight cast for big fish in freshwater in North America?” Thebault said. “You can put a chunk of cut bait into some deep channel and catch a bonefish or permit down in the Florida Keys, but the true appeal of pursuing them is chasing them around on the fly under bluebird skies on the open flats. It’s the same thing with carp. You can catch them easily on some stinky piece of bait in a dirty pond, but when you’re fishing for them in gin clear water where the fish are spooky, and your casts have to be put in the exact right place at the exact right time to get them to take your fly, carp fishing truly shines.”

Foreign Aid

While having an invasive species infiltrate a body of water is rarely a good thing, on occasion, it’s actually done on purpose because certain non-native species' feeding habits can help to counterbalance the damaging effects other invasives are having on an environment. A great example of this can be found on the Great Lakes where Pacific salmon were introduced to prey on alewives, an invasive species of herring that were wreaking havoc on the ecology of the lakes in the early 20^th century. The alewives infiltrated Lake Ontario and later Lake Huron through a series of canals constructed in the 1870s, where they quickly began out-competing many native species for food, causing massive population declines.

These freshwater herring also dined on the eggs of native species like walleye and lake trout, dropping the numbers of large predators in the Great Lakes which in turn allowed the alewives population to become completely uncontrollable. That is until the 1960s when Pacific salmon were introduced to the lake systems. The salmon fed heavily on the alewives, dropping the alewives population to manageable levels and subsequently making the Great Lakes one of the premier salmon fisheries in the world with thousands of anglers making the pilgrimage every year to try and catch the salmon which have become alewive-fueled behemoths.

The salmon’s introduction to the Great Lakes and its ensuing success in controlling out-of-control populations of invasive species has led Fish and Wildlife Departments in other parts of the country to try similar ventures. In the American West, tiger muskie have been introduced to lakes and reservoirs in states like Montana, Idaho, Colorado, Oregon, and Washington, to help mitigate invasive species having a negative effect on other fish populations.

“We primarily stock tiger muskie in reservoirs to help control populations of invasive species,” Northeast Colorado Senior Aquatic Biologist, Jeff Spohn said. “Primarily we use the fish as predators for white suckers, which can breed rapidly in reservoirs and can outcompete both stocked and native trout dropping the population of the species.”

According to Spohn, white suckers can begin to drop trout populations in reservoirs within 5 to 6 years of trout being stocked so that eventually 75 to 80 percent of the fish population in said reservoirs are made up of the suckers. That’s where the tiger muskie comes into play. A hybrid of a muskie and a northern pike, tiger muskie are sterile super predators that can’t spawn, so once they’re introduced to a system, the fish will gorge themselves on the most prolific prey item and then eventually die off.

“While they don’t completely solve the problem, the introduction of tiger muskies to a reservoir slows down the takeover of white suckers,” Spohn said. “This in turn helps out our stocked trout populations by allowing them to grow in size and numbers.”

The tiger muskie’s introduction means that trout populations in lakes and reservoirs will last longer and grow larger, giving anglers more opportunities to catch the trout. Additionally, having tiger muskies in a system means anglers with the patience and the desire needed to catch muskies have the chance to land one of the giant predators as well, an opportunity that most western anglers wouldn’t have otherwise.

The Darkside

Despite the apparent benefits of having an aquatic invasive species present in a waterbody, it should be made clear that no matter how good they seem to be for an environment, having invasive species in any waterway is never a good thing. Most invasives that infiltrate and infest an ecosystem would have never found their way there naturally, and only did so through human intervention. In many cases, the introduction of foreign species to new environments has completely wiped out native fish and caused irreversible damage to the aquatic environment, and in many cases, the survival of these environments as viable fisheries simply comes down to luck. A great example of this serendipity can be found with the introduction of the round goby to the Great Lakes.

Round goby are invasive species of marine and freshwater fish found in the waters of Eurasia, with the bulk of their populations being found in the Black and Caspian seas. The fish were accidentally introduced to the Great Lakes when ballast water from ships traveling from Eurasia was dumped into North American waters, allowing the fish to invade the Great Lakes system and their populations to explode. Normally this would have a devastating impact on the native fish of the lakes because the gobies are an aggressive species that can displace native fish and completely take over a habitat. While they have done that, there have also been some benefits to the round goby invasion.

“The goby situation on the Great Lakes is interesting,” Ph.D. Fisheries Biologist Dimitry Gorsky, who works for the Native Species Program of US Fish and Wildlife in the Lower Great Lakes office said. “Our native fish on the Great Lakes are a real mess thanks to invasive species, and while this includes the goby, their introduction has at least benefited the lakes in a couple ways.”

Years ago, the introduction of zebra mussels to the Great Lakes created a devastating effect on the ecosystem. The filter-feeding mollusks wiped out the algae and zooplankton that many of the native species of the Great Lakes used as food, completely degrading the environment. One of the native species that was lost was the slimy sculpin, a vital prey item for many Great Lakes predators such as bass, walleye, and lake trout. Gobies arrived around the same time as the zebra mussel, and as the mussels are one of the round goby’s primary food sources, the population of the small fish exploded. This displaced the slimy sculpin even further as the two species shared similar habitats and environments. However, this goby population boom had a rather interesting effect on many of the other native species of the Great Lakes.

“My job is to restore native fish species, but in a lot of cases you can’t end up restoring the ecosystem because the prey items simply aren’t there,” Gorsky told MeatEater. “Then you get these weird situations like with the round goby that comes in and fills a void. The slimy sculpin was lost, but at the same time, they had incredibly similar habits to the goby which has doubled or even tripled the population of the sculpin. So, in their own little way the goby are providing their own all-you-can-eat buffet for the lake's native predators.”

One of Gorsky’s main projects is to help restore populations of native lake sturgeon to the Great Lakes, a task that is being made easier by the round goby as the small fish are now making up a huge amount of the lake sturgeon’s diet. Additionally, gamefish like smallmouth and walleye in the Great Lakes have been growing much larger much more quickly because of the goby’s booming population providing an endless amount of protein for them. This means that anglers who pursue said species within the Great Lakes can reap the rewards, with more trophy-sized fish in the water for them to catch.

Other native species such as the lake trout may also be reaping the benefits of the goby’s presence in the lakes. For years the bulk of lake trout’s diet in the Great Lakes was made up of alewives, which actually had a negative effect on the trout’s growth and survival due to the alewives containing an enzyme called thiaminase which causes a thiamine deficiency (lack of Vitamin B1) in the predatory fish who eat them. It is believed that the increase in lake trout populations in the Great Lakes may be due to their increased predation on goby’s helping with their thiamine issues though no clear data has been collected on the subject.

“We're not happy to have our food web filled with invasive species,” said Gorsky. “Yet at the same time, some are at least playing a big role in the restoration and health of many of our native species. I think it’s important to let the animals figure out how best to adapt to the changes that come with invasive species though honestly most of the time it doesn’t work out this way, but when it does, it’s a gift. While overall invasive species are a terrible thing, there are occasional lucky benefits.

Making Lemonade

The fact is that in many cases, the presence of invasive species in our watersheds has moved beyond much of our control. Though we need to continue to try and prevent and combat their introduction and spread into our lakes, rivers, and oceans, often it’s already too late to stop them. It’s a terrifying issue to think about, our waters being taken over and destroyed by some alien species.

But one of the truly magnificent benefits of being an angler is that we have the ability to adapt. Whether we’re changing flies to better match the hatch, slowing down our presentation because of cold water conditions, or even buying a cheaper brand of beer because the store is out of our favorite, we anglers have the ability to overcome any situation we’re faced with, and we can do the same with invasive species. We’ll adjust our expectations, blend our tactics, and do whatever is necessary to find a more harmonious outcome to make our fisheries work for us. Because in the end, that’s just the American way.