|Citation||Damborg, J and Pellett, K. 2008. Ash River nutrient enrichment for fish habitat restoration, 2007. Prepared for Hupacasath First Nation.|
|Organization||Hupacasath First Nation|
|Abstract/Description or Keywords||In 2007, pollock fertilizer additions and salmon carcass plants in the Ash River provided
remediation for reduced biological productivity stemming from Elsie Lake Dam and the
Ash River Hydro Project. On July 3, 2007, BCCF and HFN technicians applied 1,800 kg
of Alaskan pollock bone meal at two sites between Elsie and Dickson lakes. Between
October 19 and 23, 2007, 680 chinook and 18 coho carcasses were transported from
Robertson Creek Hatchery and distributed at three sites in the same reach. Fisheries
staff from the BC Conservation Foundation (BCCF), BC Conservation Corps (BCCC),
and the Hupacasath First Nation (HFN) conducted project activities, overseen by
Ministry of Environment (MoE) staff.
Acting as a nutrient sink, the reservoir and diversion have reduced low level nutrients
(primarily orthophosphate and nitrogen) in downstream reaches of the Ash River
resulting in decreased primary productivity (BC Hydro 2000). With higher than normal
flows and lower than normal temperatures, overall project effectiveness was reduced
compared to previous years.
Water quality and flow/temperature monitoring was conducted throughout the
enrichment period in the Ash River. On September 11 nitrate/nitrite levels were
noticeably elevated, ranging from 0.045 to 0.242 mg/l. This increase was measured
across all sites and thought to be a result of increased organic material entering the
stream (i.e. leaves). Monitoring was also completed on Lanterman and Wolf creeks to
determine their feasibility for stream enrichment in the 2008 season. Preliminary results
were positive with indictable levels of phosphate in water samples.
Periphyton accrual was quantified by analyzing chlorophyll a concentrations on foam
core samples taken from collectors. Concentrations were two to three times higher in
treated areas than in upstream controls or in areas more than 4km downstream of a
treatment. At Ash Island Falls, 4.7 km downstream of the first fertilizer site, algal growth
was similar to control samples. The effective distance of each application was therefore
estimated to be no greater than 4.0 km.
Juvenile fish sampling occurred on September 14, 2007, to evaluate treatment efficacy.
There was no significant difference in the mean weights of steelhead fry from treated
and control reaches (95% C.I.). A late start date combined with a cooler, wetter
summer as well as very low nitrogen levels were likely contributing factors. In general,
stream enrichment programs across Vancouver Island were considered to be less
effective due to cooler temperatures and higher than average base flows. Nitrogen
limitations should be addressed in future Ash River enrichment programs.
|Regional Watershed||Vancouver Island North|
|Sub-watershed if known||Ash River|