​Lake Havasu's giant redears attributed to invasive quagga mussels

It’s no secret that Lake Havasu’s redear sunfish are big, and the Arizona Game and Fish Department has seemingly confirmed a longstanding theory that the reason may be because of invasive quagga mussels in Havasu’s waters.
A report by the Arizona Game and Fish Department last week has attributed quagga mussels to the Havasu redear’s unusual size. The invasive mussels were first detected in Havasu in 2007, and according to the report, the growth of Havasu’s redears saw its most dramatic increases from 2009 to 2014. For locals, it seemed an unlikely coincidence.
Lake Havasu’s redears have gotten big enough for a few fish stories – including that of Hector Brito, who reeled a world record 17-inch, 5.78-pound redear from Havasu’s waters in February 2014. While the report said Game and Fish officials couldn’t completely attribute the growth of Havasu’s redears entirely to quagga mussel populations, the connection was undeniable.
“Havasu is home to some of the biggest (shellcrackers) on the globe,” the report said. “The U.S. Bureau of Reclamation did a study about the effects of redear and bluegill on quagga populations and found these sunfish do consume quaggas. Even more, the redear reduced quagga numbers by as much as 25 percent. The experiments of the study were conducted in field enclosures of Lake Havasu, as well as in (the Bureau of Reclamation)’s Boulder City, Nev. Fish Lab.”
The 2015 study indicated that while redear sunfish were unlikely to ever completely eradicate quagga mussels in an ecosystem, they could put a dent in quagga infestations with enough numbers.
“It’s absolutely true,” said former Lake Havasu Marine Association President Jim Salscheider. “We have the largest redears in the state, which is largely attributed to mussels. Utah may start stocking redears at Lake Powell … it seems like a prudent thing to do.”
According to Salscheider, there have been few scientific studies about how mussels are impacting Havasu’s ecosystem. Each mussel can spawn as many as one million more mussels within a year, and are known to clog manmade drainage pipes and boat pumps. Their vast numbers can also deplete an ecosystem of its minerals, robbing aquatic plant life and native animal species of food and oxygen as they continue to spread. The Arizona Game and Fish Department has worked with multiple state and federal agencies in attempting to mitigate their spread.
“I’m hoping Arizona Game and Fish gets a grant to further study the lake,” Salscheider said. “But when people catch these redears, their stomachs are full of these mussels. The fishing is very good in Havasu … people fly here because they want to catch the next world record. The larger redears are good for business, and good for fishing.”
Brook Knotts, of Utah-based Sunfish Fish Farm, specializes in breeding sunfish like the redear and bluegill. He last visited Lake Havasu City last spring.
“Havasu’s sunfish are super-sized,” Knotts said. “They’re doing very well. The fisheries are good, the water quality is good, the docks are in good shape … the sunfish seem to be keeping quaggas in check. The fisheries in Lake Mead (by contrast) have crashed. There are so many quaggas in Lake Mead that they’re starting to wash up on the beaches. The shells are like glass, they’re so paper-thin. They’re destroying lakes and ecosystems, and naturally-reproducing fish in Lake Mead are starving.”
According to Knotts, redear sunfish are more effective at controlling quagga mussels than their cousins, the bluegill sunfish, which are stocked at Lake Mead.
“Bluegills have smaller mouths than redears do,” Knotts said. “Bluegills will eat quaggas too, but they can’t eat quaggas larger than the tip of your thumbnail. Redears have larger mouths, with longer teeth, and bones that allow them to crush the shells. When sunfish get into a place that has a lot of mussels, they’ll explode in size, because they’re getting all of the nutrients they need.”
According to Knotts, introducing redear sunfish to Lake Mead and Lake Powell wouldn’t be an immediate solution to the proliferation of quagga mussels, however.
“It would take one million redear sunfish per year, for the next five years, to reduce the number of quagga mussels in Lake Powell,” Knotts said. “In Lake Mead, it would take twice that many. Utah has been fighting a battle with quagga mussels for the past 12 years, and they’re losing. Every time they try to get proactive about stopping quagga mussels, they get a lawsuit from environmental groups. In ten years, 90 percent of Utah’s waters will have mussels in them.”
According to Knotts, Havasu’s preference for producing redears has been a positive step in mitigating quagga populations. While the proof may be in the size of Havasu’s legendary redears, however, Knotts says consideration should be given to vulnerable redears.
Redear sunfish spawn when water temperatures are 65 to 89 degrees. According to U.S. Climate Data records, average February high water temperatures in Lake Havasu is 53 degrees. Redears will be spawning most heavily during Havasu’s peak boating season, the agency says. Havasu’s waters often reach 70 degrees by May, and peak at about 87 degrees in August.
“Redear sunfish are at their most vulnerable when they’re on their spawn bed, and they’re really easy to catch. I’ve seen people catch them out of their spawning beds, and drive home with them. There needs to be a catch-and-release rule while they’re spawning, because if redear fisheries crash, the rest of the fisheries will crash because of quagga mussel infestations.”