1-25-12 — Parasites found on Lake Cumberland striped bass; fish still safe to eat

    Fisheries biologists at Lake Cumberland found a parasitic copepod is  

the cause of unusual sores on the tongue and mouth of striped bass in  

the lake.

    "When we sampled the lake's striped bass fishery in mid-December,  

every fish we handled was infested," said John Williams, southeastern  

district fishery biologist for the Kentucky Department of Fish and  

Wildlife Resources.

    The copepod, genus Achtheres, has been found in recent years in  

mountain lakes in Arkansas, North Carolina, Tennessee and Virginia.

    "The parasites infest the fish's oral cavity and do not affect the  

fish's flesh. The fish are okay to eat," said Williams.

    The external parasites are visible to the naked eye. Young copepods  

attach to the fish's gill filaments and migrate to its mouth as  

adults to reproduce. The parasites can impact the gills and hamper  

respiration in larger fish.

    It's uncertain at this time if the parasite is native to the region  

or has somehow been introduced. Angler transfer of fish through  

livewells and the introductions of infected fish may have enabled the  

parasite to spread so quickly from lake to lake in the region.

    Williams said the parasites have also been found on a small  

percentage of largemouth bass in three reservoirs in south central  

Kentucky: Wood Creek Lake, Laurel River Lake and Cedar Creek Lake.

    "Fish get a variety of parasites. They are an annoyance," said  

Williams. "They would not be the primary cause of a die-off of  

stripers in Lake Cumberland."

    Another mystery is why the parasite spread so rapidly through the  

population. "We suspect the lowering of body condition has made  

striped bass more susceptible to the parasites," said Williams.

    Lake Cumberland, a 50,250-acre major reservoir near Jamestown, Ky.,  

is the state's premier striped bass fishery and has supported a  

quality population of stripers since the 1980s.

    In 2007, Lake Cumberland was drawn down about 40 feet below summer  

pool to make repairs to Wolf Creek Dam. Since that time, the body  

condition of striped bass in the lake has been impacted due to the  

loss of cool water habitat in the fall.

    "Growth rates have declined considerably. In the past, it took  

striped bass in Lake Cumberland three years to reach the keeper size  

of 24 inches. Now, we have a majority of fish stockpiling below that  

length," said Williams. "We believe all this is due to conditions  

that are stressing fish. They're not eating and are not growing as  

fast."

    However, Williams said the stomachs of striped bass recently sampled  

were full. "In December, the stripers were up in the creeks gorging  

on small shad. By all indications, there was a good shad spawn last  

spring," he said.

    An ecological study funded by Virginia's Department of Game and  

Inland Fisheries found that a number of lakes in the region with  

populations of striped bass have been affected as early as 2000.

    The parasites were first identified on striped bass in the Potomac  

River in 1915. A study in the 1950s in Louisiana found the parasite  

on black bass, bullheads and other sport fish species.

    Recent research suggests that two species may exist in lakes in the  

southeastern United States, but the impact of infestations is poorly  

understood. Researchers found that the abundance of the parasites is  

seasonal and cyclic and often reflects the overall condition of the  

host.

    

    Author Art Lander Jr. has been writing about the outdoors since the  

1970s. He is a staff writer for Kentucky Afield Magazine.