Why Smallmouth Bass Is One Of The Most Dangerous Fish In The Country


The smallmouth bass is at the top of the list of the most popular fish species in America. Although below the range of largemouth bass, America more popular game fish – they are still available to millions of anglers. From the Great Lakes in the north to the deep reservoirs of south-central creeks, from the northeast to the mighty rivers of the Pacific Northwest, “bronzebacks” have become standouts in many regional fishing cultures. Because of this, it’s easy to forget that they don’t belong in most places we catch them.

Of course, the same can be said for our beloved largemouth, walleye, and brown and rainbow trout. These brown trout came from Europe and would never have occurred here naturally. Rainbows were only native to the Pacific Northwest; Bigmouth is only native to the Southeast and Midwest (Florida to southern Minnesota). As for the smallmouth, it was originally native to the Great Lakes and Ohio River watershed in the United States, but has spread naturally throughout the entire Mississippi basin. Everywhere else they are found, someone put them there at some point in history – or at least put them somewhere nearby and they spread and expanded their range on their own.

Original smallmouth native range, in orange. USGS

Small Mouth in the Grand Canyon

That’s not to say that fish transplantation is a bad thing, as it has created huge fisheries across the country, which in turn have boosted everything from tackle sales to motel room rentals to the paychecks of biologists working in hatcheries. For the most part, restocking and transplanting fish are well-calculated efforts, but problems arise when transplants end up in waters where they are not supposed to be. And despite our general love for the smallmouth bass, the reality is that they are one of the most destructive and disruptive fish in the country, causing more concern in many areas than even the dreaded invasives. such as snakeheads and Asian carps.

More recently, smallmouth bass is creating a major concern in Arizona. According to this story on Azcentral.com, the smallmouths, along with several other non-native species, were stored decades ago in Lake Powell, which is an impoundment of the Colorado River. The transplants took place to stimulate recreational angling on the lake and have been very successful in doing so. For years all was well, but a combination of recent droughts and overuse of the Colorado as a commercial water source created problems. As the story goes, “The Southwest’s thirst for the drying river is pushing a difficult aquatic environment out of whack.”

Lake Powell is held back by the famous Glen Canyon Dam, and every day the water level behind it drops lower and lower. Biologists worry that the reduced flows will make it more likely that small vents will pass through the turbines, and if that happens, it will introduce small vents into the Grand Canyon. Biologists fishing the lower end of Powell regularly catch small mouths near the dam. A handful of bass caught in the riparian swamps below the dam suggest it may already be too late.

What’s at stake?

If the Smallmouths take up residence in the Colorado River below Glen Canyon, it could spell the end of many native species that biologists are already scrambling to protect — they’re trying to preserve the legacy of the Grand Canyon ecosystem. In particular, fisheries managers fear that the small species could completely wipe out the native population of humpback chub, a species that has only recently moved from endangered to threatened.

Arizona has already put a bounty on brown trout below the dam for the same reason, but the trout won’t venture too far below the dam and the cold water it discharges. Small mouths are a kind of hot water that can and wants to settle where it wants.

Part of the reason anglers love smallmouths so much is their voracity, and it might be easy to say, “who cares about some chub?” The reality is that transplanting has disrupted native species like the humpback chub across the country. It’s just that we tend to treat fish we can’t or can’t target with a rod and reel as expendables. What if smallmouths threaten one of the most famous trout fisheries in the world? That’s what happened in February when cubs were captured in Montana’s Gardner River, a tributary of the Yellowstone at the gates of Yellowstone National Park.

Then there’s Maine, which has spent countless time, money and resources trying to eradicate stray bass from systems that support wild trout breeding. Eradication efforts are also underway in Manitoba, Oregon, ponds in Montana…I could go on.

The lesson here is that just because a fish is deeply embedded in our national fishing culture doesn’t mean more is always better. Likewise, the popularity of a fish should not allow us to ignore the problems it can cause. Most of us wouldn’t mind catching a nice little mouth in a stream or river where you’ve never caught one before, but it might actually be cause for concern.


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