Wels Catfish
National Geographic Fellow Zeb Hogan and a fishing guide hold a 135-pound, 83-inch-long wels catfish (Silurus glanis) in Spain's Ebro River, 2009. Photograph courtesy of Zeb Hogan.
The Virginia blue caught last month weighed in at 143 pounds and measured 57 inches. (The previous record was a 130-pound catfish caught in Missouri last year.)
We asked fish expert and National Geographic Fellow Zeb Hogan—also an assistant research professor at the University of Nevada—to put this giant discovery into perspective:
Can you tell us more about this species — its range, habitat requirements, status, and any threats it may face?
Blue catfish is native to 20 states, primarily within the Mississippi River Basin but also in rivers along the Gulf Coast. It has been introduced in another nine states, including Virginia. It is a big river species; it grows quickly, and it’s popular among anglers for aggressive behavior and good quality meat. It is the largest catfish in North America and the third largest obligate freshwater fish in North America, behind the lake sturgeon and paddlefish.
Blue catfish are the focus of many urban legends, mostly stories of huge catfish below dams. While stories of catfish the size of cars are most likely exaggerations, there are confirmed reports of blue catfish weighing over 200 pounds from the 1800s, and the largest unconfirmed catch, landed in 1866 in Portland, Missouri, weighed in at a whopping 315 pounds. If these reports are true, it gives some perspective on the recent catches and a glimpse into the true potential of the blue catfish if left to grow undisturbed in a healthy environment. Many states, including Virginia, consider blue catfish as an important sportfish and people travel long distances for a chance to catch a trophy fish. Blue catfish populations are considered relatively healthy at the center of its range. On the periphery of its range, populations have declined, primarily due to habitat modification, dam construction, river flow modification, wetland drainage, and pollution.
Do people eat blue catfish?
People definitely eat blues, and have been eating them for a long time. Mark Twain mentions large catfish in his books—those fish were likely blues. Blue catfish were also relatively common in the St. Louis fish market in the 1800s. They have a reputation for firm, tasty meat and lots of it. In some areas catfish harvest is now restricted—either to a set limit per day, a certain size of fish, or in rare cases catch-and-release only. Usually, these rules are in place where fisheries officials hope to develop a trophy fishery (i.e. a recreational fishery for very large fish).
Catfish as a group are an extremely important food fish—in the U.S. alone we consume hundreds of millions of pounds of catfish each year. In Asia, where catfish is an even more important resource, almost one and a half million tons of fish are produced annually. Catfish are also an important food fish in Africa and South America, where they make up most of the catch in many areas.
Incredibly, there are also stories of places where catfish have attacked and even eaten people. Large catfish in North America and Europe have reportedly bitten humans, and one species of very large catfish in Northern India is rumored to stalk and occasionally kill local villagers. These stories are often sensationalized and exaggerated however and there is very little hard evidence of catfish behaving aggressively toward people. To learn more about these stories, and the truth behind them, watch the story of India’s giant catfish on National Geographic Channel.
When were blues introduced to Virginia?
Blue catfish were introduced into Virginia in 1974. Since they can live over 20 years and are capable of growing very quickly, the extremely large fish coming out of Virginia now may have been among the first fish to be introduced there over 30 years ago. It would be interesting to know the age of 143 lb record breaker and since the fish did not survive, I suspect someone is gathering that information now (the easiest way to age a fish is with its ear bone, sacrifice of the fish is required).
How does the blue compare to other catfish? What makes it special or especially interesting?
The blue catfish is North America’s largest catfish species and it is one of the largest freshwater fish in the U.S. If we look outside the U.S., however, there are several larger species of catfish. In fact, globally, catfish are some of the largest and most widespread of any species. There are several that reportedly grow up to 600 pounds and almost 10 feet long. The Mekong giant catfish is the current record holder based on the catch of a 646-pound specimen in 2005.
The recent catch of several record-breaking fish is interesting because it implies that blue catfish may be living longer—and growing larger—than at any time in the last few decades. This may be partially due to management of blue catfish fisheries for trophy-size fish, but it is probably also because blue catfish have been introduced into areas outside their natural range where there is an abundance of food. Introduced species can often undergo a population boom just after introduction. The same phenomenon occurred when wels catfish was introduced into the Ebro River in Spain.
Is fishing for these giant catfish legal?
Recreational fishing for blue catfish is legal in most states—and in fact, blue catfish were introduced outside of their native range to increase angling opportunities for sportfishing. The release of non-native fish is controversial, because big predators like blue catfish almost certainly alter food webs and species diversity in areas where they are introduced. Commercial fishing for blue catfish—and other large species of North American catfish—has been scaled back in recent years due to the perception that large-bodied catfish cannot support intensive harvest. In other parts of the world, catfish support huge fisheries—both wild capture fisheries and aquaculture. Catfish are some of the most popularly cultured fish in the world with millions of tons of fish produced each year. Catfish fishing is only illegal in a small number of places where it has been determined that fishing is unsustainable.
Why should we care about catfish?
While a lot of people think of catfish as ugly, they are actually one of the most diverse and important groups of fish on the planet. And not all catfish are created equal: we tend to think of catfish as slimy bottomfeeders, but that is only true for a small percentage of species. Catfish come in a variety of sizes (some grow to almost 10 feet in length, while others are among the smallest fish on Earth) and they display an impressive array of behaviors and life histories (some make the longest migrations of any freshwater fish, while other live their entire lives in small ponds and creeks).
Throughout their range, catfish are an important component of commercial, subsistence, and recreational fisheries. They can also have an important role in the ecosystem as top predators or as indicators of overfishing. Multiple and combined threats from habitat degradation, dams, water withdrawals, pollution, and overexploitation have led to the decline of many catfish populations.
Despite these challenges, self-sustaining populations of large-bodied catfish still exist. Globally, efforts to protect the ecological integrity of rivers where large-bodied catfish occur will benefit thousands of species of freshwater fish and millions of people who rely on fish for their livelihoods and food security. Plus, they’re cute!
For more on Monster Fish, visit the National Geographic Channel website.
And read more about the monster blue in the Washington Post.
http://newswatch.nationalgeographic.com/2011/07/06/monster-catfish-found-ngs-zeb-hogan-explains/
Posted by Tasha Eichenseher of National Geographic July 6, 2011
