The Colville Tribe has been collecting baseline information on the rainbow trout in tributaries to the San Poil River since 1990 through the Lake Roosevelt Rainbow Trout Habitat Improvement Project.  Much of the focus has been towards identifying and improving habitat while minimally assessing the abundance of adult and juvenile migratory (adfluvial) fish in relation to habitat improvements.  Detailed information on the population dynamics has never been collected especially relating to life history characteristics.  Some of the difficulty in understanding the ecology of rainbow trout in this basin is due to the varied life history types thought to exist.  Some adult fish migrate into the drainage from Lake Roosevelt (in both the spring and summer) to spawn while others are thought to be resident in the drainage year round.  Some juvenile rainbow trout are known to migrate out of the drainage into Lake Roosevelt in the spring, but others may migrate in the summer or fall or may reside in the drainage all year.  

Some research has been conducted on migratory populations of rainbow trout that use the drainage.  Spawners return from Lake Roosevelt to tributaries between ages 3 and 6 years.  Upstream traps have been used to examine these fish; these data indicate that spawning populations have fluctuated from less than 13 individuals in 1997 (5 tributaries surveyed) to 428 individuals in 2007 (6 tributaries surveyed) (Sears 2006).  Fall escapement surveys conducted from August to November (kokanee monitoring) indicate that rainbow trout migrating upstream into the drainage range from 10-15 individuals per year (CCT unpublished data).  However the research efforts mentioned above do not supply a complete picture since data are not available from periods when traps were not operated or when surveys were not conducted.  In addition, no surveys have been conducted on the mainstem San Poil River.  

Adult rainbow trout abundance is thought to be low compared to the number of miles of habitat available in the San Poil Basin.  To alleviate this problem, the Tribe has conducted habitat improvements to some tributaries by removing barriers.  These improvements have increased rainbow trout abundance where they never occurred or minimally occurred (Sears 2006).  Specifically, passage and habitat enhancements have been conducted on Louie, Iron, South Nanamkin, North Nanamkin, Bridge, Thirty Mile, Thirteen Mile, Gold, and Roaring Creeks.  Rearing habitat remains restricted due to intermittent flows in the lower reaches of several of the streams that have spawning habitat. In recent years work to improve flows, reduce sediment delivery and increase water retention in the individual watershed has included road abandonment, riparian plantings, cattle exclusion fencing, and relocation of beaver into upper reaches of the watersheds.

Unfortunately, little is known about the populations that reside the entire year within the drainage. A few populations have been observed in Bridge Cr., West Fork San Poil and Gold Cr. during fall habitat surveys.  It was determined that the Bridge Cr. fluvial population was genetically pure and has recently become part of the Tribes brood stock program.  Although, some spawning surveys have been conducted to identify spawning areas, these were done only in the lower reaches and were directed at the adfluvial population that is the focus of the LRHIP. Additionally, high velocities and high turbidity limited any observations of redds during surveys in the lower tributaries and San Poil mainstem (Sears 2006).
  
Juvenile rainbow trout survival and abundance is also not well understood within the basin.  Surveys of juveniles in select tributaries suggest that their abundance is low.  In the spring of 1998, 19 adult rainbow trout moved upstream into North Nanamkin Creek.  During the next spring, a total of 96 juveniles were captured in downstream traps (Jones 1998).  Six segments of Gold Creek (a tributary to West Fork San Poil) were electro-fished in the fall of 2004 and a total of 1,134 juvenile rainbow trout were captured.  During the following spring of 2005 a screw trap was placed at the mouth of the West Fork San Poil that captured only 119 juveniles; additional juvenile traps were set in the stream the same year and captured 606 juvenile fish (Sears 2005).  Three distinct age classes were present (young of year, one year “parr” and two year “pre-smolt”) and consisted mainly of age 1 fish.  These data indicate however that juvenile abundance may decrease between fall and spring (Kirk Truscott, Colville Confederated Tribes, Personal communication), or that the majority of fish did not migrate out of the West Fork during that time.  However, environmental factors and trap efficiency limit an accurate assessment of the numbers of fish in the drainage, when they migrate, or how many migrate when.  Juveniles may migrate in late fall or early spring before traps are set.  Juveniles have been documented migrating into mid August (Sears 2000) however recent surveys have been limited to June due to low flows and occasionally extremely high flows.  Attempts were made to determine egg to fry survival with red caps but high flows blew the traps out and future attempts were abandoned.

Intermittent streams such as N. Nanamkin and S. Nanamkin provide good spawning habitat for adults however nursery habitat becomes limited by mid to late summer as flows decrease or go subsurface.  Juveniles are then subjected to migrating to the San Poil River or reside in a few left over pools.  

Management objectives for the San Poil River are to increase adfluvial rainbow trout abundance to support recreational and subsistence harvest (i.e., 1 fish/hr) while maintaining a genetically diverse and natural reproducing population (CCT Fish and Wildlife Management Plan, 2007).  However adult spawner abundance objectives have never been determined because limited information exists on each life history type.  The Tribe suspects that the bulk of the population is adfluvial with some resident fish.  Resident fluvial populations have been found above barriers in many of the tributaries. Because these were not the focus of the habitat improvement project little data has been collected on these populations beyond genetic analysis. Until the Tribe determines what life history forms exist, the extent of their movements and habitats used, what population levels are and how much habitat is available, developing accurate objectives is unattainable.  The current proposed study addresses adult and juvenile life history information and habitat use information that will help the Tribe with determining appropriate management actions.  Further investigations into juvenile survival are proposed currently through additional resources.  Information collected from the proposed study and other studies will be used to develop new studies that address limiting factors identified in previous years and assist in making management decisions.

The goal of this project is to determine what life histories of rainbow trout (Oncorhynchus mykiss) exist and how each life history operates within the San Poil Subbasin by examining spawning and overwintering movements and habitat use among each life history.  Specific project objectives include identification of spatiotemporal patterns in spawning movements and areas used for spawning among life histories within the San Poil Subbasin, the identification of overwintering areas of rainbow trout, the investigation of how winter ecology of each present life history is associated with warm groundwater presence, river ice, and other habitat parameters and preliminary investigations of juvenile rainbow trout.