Many fishing shows and wildlife documentaries over the last decade have focused on angling experiences for river monsters. There are lots of ways to define a fish as a river monster but the simplest may be those that can obtain a weight of over 100 pounds.
In the United States there are at least seven species that meet that criteria: Blue Catfish (angler caught record: 143 pounds); Flathead Catfish (123 pounds); Alligator Gar (279 pounds, 320 with a bow); Paddlefish (144 pounds, 198 with a spear); White Sturgeon (468 pounds, estimates of fish up to 1,100 pounds caught and released); Green Sturgeon (320 pounds); and Lake Sturgeon (168 pounds).
Many of these species have been around since the dinosaurs. Sturgeon and Gars have been roaming rivers for 200 million years while the first catfish appeared 140 million years ago Paddlefish have been around for 75 million years. The ancient lineage of these species is why so many of these fish look unique. Most are capable of producing millions of small eggs each year. Not only does this make the eggs of some of these fish prized for caviar, it means in good years a lot of offspring can be produced.
One of the primary requirements for getting big is time. Many of these river monsters live over 100 years and even catfish take 20 years to grow to gargantuan sizes. Given the potential length of a White Sturgeon’s life, it is likely there are fish swimming the Columbia River that have been around since before the Bonneville Dam near Portland Oregon was completed in 1937.
Most salmon and trout species don’t even come close to reaching the century mark in weight. The world record Chinook Salmon is almost 100 pounds (97 pounds to be exact), but Brown, Cutthroat and Rainbow Trout records all hover closer to 40 pounds. The biggest fish likely ever caught in Utah was a Colorado Pikeminnow (a native minnow species). There are reports that the biggest of these fish may have exceeded 100 pounds with the largest ever caught on rod-and-reel likely tipping the scales at around 80 pounds.
Television shows about these large fish do a good job of talking about how humans have put these species at risk. In many other countries, the primary reason these fish rarely make it to large sizes is the strong economic incentive to keep and sell all fish that are caught. In the U.S., there is much better management and few commercial freshwater fisheries. As a result, the biggest threat in this country to these fish are dams. While damming rivers can benefits a portion of these fish’s lives, this is generally outweighed by the negative effects. For example, Sturgeon grow faster in reservoirs but without fast flowing stream sections to spawn in, their eggs will not successfully hatch. Also, as more recreational anglers seek these fish, even if they practice catch-and-release, it is likely a fews more fish will die. This is especially true given the increasing number of people bow hunting species such as Gar. It shouldn’t be a surprise that research has shown any added fishing mortality can greatly reduce the average size of these fish.
The best baits for most of these river monsters are very large pieces of fish or other big slices of protein. Paddlefish, in contrast, feed primarily on zooplankton. Because of their foraging behavior, these fish are caught by snagging them at the base of riffles during their spawning migration.
If you are going to pursue these fish, the sturgeon of the Columbia and Snake Rivers are likely the nearest destination to catch a 100 pound fish. Next are the Paddlefish in the Yellowstone and Missouri Rivers of eastern Montana. If you’re after Alligator Gar, you’ll likely have to travel to Texas. While it is possible to catch nonnative Blue Catfish in Idaho’s Snake River, if you want to catch a 100 pound fish, you’ll need to travel to the Mississippi River Basin. The same is true if you’re after large Flathead Catfish.
Even if you never get a chance to try to catch these fish, it is nice to know and amazing to think that fish this large can be found in the nation’s rivers. Given I have been lucky enough to see several of these fish emerge out from the Snake River and try to take jump, I can easily say there really is no other kind of fishing experience to which this can be compared.