REDD Counts
The spawning beds of salmonid fishes are called redds. This term is probably derived from the word “ridden” meaning "to clear" and no doubt refers to the effort of the female fish to sweep the gravel clear of debris as she deposits her eggs. This results in a clean area with a characteristic “pit and tailspill” that may be as large as a pickup truck bed. Redds are counted in high density spawning reaches, known as "index streams," to get an estimate of the reproductive effort of a particular fish species. This is not a population estimate; but instead is an index to compare the reproductive effort across years. In other words, if there are significantly more or fewer redds in one year as compared to another, then there could be more or fewer young produced depending on streamflow and habitat conditions during the winter incubation period.
Bull trout spawn in the fall when the water temperature generally declines below 50° F, usually in mid-September to mid-October in Montana. Each bull trout redd contains about 2,000 to 10,000 eggs, with higher numbers for larger females. The eggs stay buried in the redd for about six months before the young emerge. The redd count procedure is to walk a given section of an index stream immediately after the spawning season, counting and documenting the number of redds in that section. That same reach of index stream is counted at approximately the same time annually. This provides a legitimate comparison between years.
The Wigwam River originates in the Ten Lakes Scenic Area in the U.S. near Eureka, Montana, and fishhooks north into British Columbia, Canada. The Wigwam flows into the Elk River, which flows into the Kootenai River, which flows back south into Lake Koocanusa (the reservoir impounded by Libby Dam) in the U.S. The bull trout from Lake Koocanusa spawn in the Wigwam and its tributaries as well as several other streams, mostly in B.C.
Since 1994, the biologists from the East Kootenay Region in British Columbia have counted the redds in the Wigwam River. This count takes place in mid-October of each year. Because it is such an important index stream, the local B.C. biologists try to conduct the count in a single day. Therefore, they recruit others to help them count the 22 miles of stream. Over the years, people from the Kalispell and Helena offices of the U.S. Fish and Wildlife Service have participated. Biologists from the Montana Fish, Wildlife and Parks office in Libby count the redds in the U.S. portion, which usually account for less than 5% of the total. The number of bull trout redds in the Wigwam has steadily increased for a decade in a nearly perfect linear fashion, from 512 in 1996 to a high of 2,298 redds in 2006. In 2007 and 2008, the counts have dropped to just below 1900, perhaps reflecting the addition of a harvest fishery, beginning in 2004, that allows anglers to keep two bull trout per year from Lake Koocanusa. The Wigwam River has a "catch and release" only bull trout fishery. The Elk River has a bull trout fishery that allows anglers to keep just one bull trout over 75 centimeters (just under 30 inches) per year.
The annual migration of over 5,000 adult bull trout from Lake Koocanusa up the Wigwam River is a spectacularly successful fish recovery story. This population is the strongest known run attached to any U.S. bull trout core areas and rivals some of the salmon migrations seen on the coast. Coincidentally, the super-abundant population of kokanee salmon available as forage for bull trout in Lake Koocanusa - spawning runs of perhaps a half million fish - is largely the driver that has made the Wigwam River the strong success that we see today.
