Spawning syndrome in Utah brown trout

Occasionally, anglers in the Provo, Ogden, Blacksmith Fork and other rivers notice numbers of sick or dying brown trout. This condition usually affects large, mature fish and is most often noticed in the autumn during periods of low, clear water when the fish are spawning and more aggressive than normal.

Anglers usually notice fish with large red open sores, or skin covered with a white cottony substance which is a fungus. Typically, less than 10 percent of the fish in the stream are affected, but their dramatic appearance in clear water often alarms anglers.

This condition is commonly called "spawning syndrome," although it can occur at other times of the year. It is thought to be caused by the stress and aggression of spawning behavior or other unknown stressors, at a time of year when flows are low and fish are more crowded than usual. Fight wounds and abrasions from spawning can lead to secondary bacterial infections and/or fungal infections. Open sores can lead to loss of fluids and electrolytes in fish, causing death in some individuals.

Elaeophorosis

Elaeophora schneideri is an arterial worm commonly found in mule deer in the western and southwestern United States. Larvae accumulate in the blood capillaries of the head and face and are picked up and transmitted by horseflies. Elk and moose are considered abnormal hosts and do not have the resistance to heavy infection. In these hosts, the nematode remains in the arteries that furnish the head and brain with adequate blood supply. Lowered levels of blood can lead to brain damage, blindness, and cause extremities, such as the ears and nose, to freeze and fall off during cold months. During years when weather conditions are favorable for horsefly activity, extremely heavy infections can occur and elaeophorosis is found more frequently in elk and moose.