Sandy flesh disease found on Western Slope

In April, fishermen in Pueblo caught a walleye trout that had caught something itself, myofibrogranuloma, better known as sandy flesh disease. The angler noticed symptoms of the disease while processing filets off his catch and reported the findings to Colorado Parks and Wildlife (CPW), which identified the sickness.

In a press release from CPW on April 5, aquatic biologist Carrie Tucker of Pueblo was cited: “It’s not a shock that it has reached Colorado since it occurs in so many neighboring states, but it is unfortunate … We don’t expect it to have a big impact, because it typically only shows up in a small number of older walleye.”

The press release urged anglers who come across infected fish not to consume the meat or dispose of infected corpses in the waters, but rather to bury or throw away the remains with other household refuse.

According to officials, the rare disease resembles a type of muscular dystrophy; no infectious agents have been shown to be associated with it. “It is unknown how likely it is to spread amongst other fish. To date, there is no evidence that an infectious agent is responsible for the disease.” explained Dr. John Drennan, CPW state fish pathologist.

The first case recorded in walleye was in North Dakota waters in 1975 and it has primarily been observed in walleye and sometimes trout-perch. It has also been observed in Minnesota, Utah, Idaho, Wyoming and Nebraska.

Drennan elaborated that this suggests the only route of possible spread is during spawning. However, no evidence exists to confirm that the disease is related to genetics. Since so little is known about sandy flesh, CPW advises that fishermen carefully examine any filets from walleye and report any findings to their local CPW office.

“[There is] not any information as to how a person would be affected if they consumed an infected fish,” he explained. “The granulomas and calcium deposition within the affected muscle areas would be very hardened, expanding the entire filet depth.” He said that eating meat from an infected fish would likely be tough, chewy and off in the typical flavor.

“Information is limited, and very little research has been done on this disease. In order to gain more information on the prevalence of this disease in our walleye populations, a creel survey or individuals bringing in affected filets to a CPW area office would benefit our understanding,” Drennan stated. 

For updates, visit cpw.state.co.us or call 970-947-2920.