Elton Creek (2013)
Electrofishing on Elton Creek.
In August 2013, Region 9 Fisheries staff along with angler volunteers completed trout population sampling in both the stocked and wild trout sections of Elton Creek, in Cattaraugus County. Six sites were electrofished, duplicating sites sampled in 1991, 2001 and 2013. In 1991 and 2001, the area where all six sites were located was being stocked with hatchery brown trout. However in 2013, only the lower two sites were in the stocked section, stocking having been removed where the upper four sites were located in 2002. Sampling in 2013 was done to monitor the wild trout population and to evaluate the effects of removal of stocking on the wild trout.
Electrofishing Results for Wild Trout
Nineteen-inch Elton Creek wild brown
For all sampling sites combined, the estimated abundance of adult (yearling and older) wild brown trout was 164/mile, which is lower than that found in 1991 (231/mile) or 2001 (243/mile) (Table 1). Conversely, the abundance of wild rainbow trout in 2013 for all sites combined (525/mile) was much higher than 1991 (117/mile) or 2001 (335/mile) (Table 1). A similar pattern of abundance was apparent when looking at just the sites in the unstocked section. However, both species were more abundant in the unstocked than the stocked section in all years, especially rainbow trout. This was likely due to better water temperatures for the survival and growth of trout in the upstream, unstocked section.
While wild brown trout abundance declined from 1991 to 2013, biomass of wild brown trout almost doubled for all sites combined during that period (17-31 pounds/acre), indicating the population was made up of much larger individuals in 2013 (Table 1). In fact, in 2013, of the estimated 164 adult wild brown trout per mile, 70/mile were >10
Twelve-inch Elton Creek wild
inches and 49/mile were >14 inches. Similar increases in biomass were observed for wild rainbow trout with the biomass increasing from 4 to 21 pounds/acre, for all sites combined, from 1991 to 2013 (Table 1). It is likely that the reduced abundance of fall-spawning wild brown trout was due to poor spawning and rearing conditions through the fall/winter the past couple years. The increased wild brown trout biomass may be related to more trout surviving to older age/larger size, due to decreased brown trout abundance and/or due to reduced angling harvest since stocking was eliminated in the upper section of the creek. The increased abundance and biomass of spring-spawning wild rainbow trout is likely due to successful spawning and rearing conditions, decreased angler harvest following the elimination of stocking in the upper section of the creek and/or increased voluntary release of trout. This phenomenon is similar to what we have seen on other Region 9 streams in recent years.
Electrofishing for Hatchery Trout
In 2013, at the two sampling sites in the stocked section, a very low abundance of hatchery brown trout were found from the previous spring's stocking. This is similar to 1991 and 2001 sampling and indicates that water quality in that section of stream may not be conducive to survival of the stocked trout through the summer months in the lower section of the stream.
|No. adult wild brown trout/mile - all sites combined||231||243||164|
|No. adult wild rainbow trout/mile - all sites combined||117||335||525|
|No. adult wild brown trout/mile - stocked section||181||227||133|
|No. adult wild rainbow trout/mile - stocked section||5||54||49|
|No. adult wild brown trout/mile - unstocked section||271||252||183|
|No. adult wild rainbow trout/mile - unstocked section||208||502||820|
|Biomass (lbs/acre) of wild brown trout - all sites combined||17||17||31|
|Biomass (lbs/acre) of wild rainbow trout - all sites combined||4||11||21|
|Biomass (lbs/acre) of wild brown trout - stocked section||-||11||7|
|Biomass (lbs/acre) of wild rainbow trout - stocked section||-||1||1|
|Biomass (lbs/acre) of wild brown trout - unstocked section||-||23||51|
|Biomass (lbs/acre) of wild rainbow trout - unstocked section||-||19||36|