Adult Population
The adult steelhead population in the McIntyre River has undergone a significant change since the early 2000's (Figure 1). Following the daily limit reduction from five to one fish over 69 cm total length in 1999, a strong year class was produced in 2004. In 2007, 2008 and 2009, bumper crops of juveniles survived to maturity (Figure 2).
With the presence of four good production years, the adult steelhead population increased to 1500 in 2008 and over 2000 in 2010 (Figure 1, Appendix C). The increased population size can be attributed to the reduction in harvest (bag limit reduction) and ideal environmental conditions in the stream (stream temperatures and flow). The minimum harvest size allowed the adult steelhead population to survive to become older and larger fish. The minimum size also protected the adult population so the maturing steelhead had the opportunity to spawn at least once maintaining the genetic diversity of the entire population. The minimum size restriction enabled the early maturing adults to spawn several times before being susceptible to harvest. Having a large, diversified population maximized the opportunity to produce strong year classes as shown in Figure 2.
Ages three to six years (Figure 2) are generally the most common year classes in the McIntyre River spawning population. At these ages, the adults are 45 to 65 cm fork length. Populations with low harvest and strong year classes will often have adults surviving up to age ten years and be up to 75 cm in fork length. Small, early maturing males (two years of age) range from 28 to 35 cm in fork length. The average size of a year class varies considerably depending on the stream and lake environmental conditions.
