Understanding Recruitment Variability in Appalachian Brook Trout Populations

Like many other salmonids, brook trout have been shown to have strong stock-recruit relationships (SRRs).  However in some streams no such relationship is apparent.  Our long-term (9 yr) study of 25 headwater streams found 8 streams with strong SRRs (r²> 0.40) and 12 streams lacking SSRs (r² <0.20).  Because strong relationships were observed in some streams, the underlying reasons when no such relationship was observed were of interest.  Underlying geology was a primary factor in whether a stream possessed a SSR.  However, other factors such as pool area, mean benthic macroinvertebrate biomass, area of suitable spawning habitat, gradient, and habitat stability were important.   Population sinks or habitat degradation may be responsible for lack of SSRs in some streams.