Evaluation of spawning habitat requirements for a sympatric pair of large and small bodied Lake Utopia Rainbow Smelt / by D. MacDonald. : Fs97-6/3193E-PDF

"While Rainbow Smelt are known to be spawning habitat generalists, certain characteristics of Lake Utopia Rainbow Smelt (LURS) spawning streams were found to be unique and play an important role in determining where LURS spawn. Temperature profiles of Large-bodied (LbP) smelt spawning streams were significantly warmer (x̄=3.59°C ± 2.0°C) than Small-bodied (SbP) spawning streams and non-spawning streams during the large-bodied smelt spawning and incubation periods (late March through April) (H(6)=29.2901, p < 0.0001) and they continued to be warmer throughout the SbP spawning and incubation periods (12.01°C ± 3.56°C) (late April through May). Small-bodied smelt spawning streams were not significantly different from most other unselected streams around the lake during their spawning and incubation periods but were significantly cooler than the large-bodied streams (e.g. Smelt Brook 6.89°C ± 2.16°C). Other habitat attributes that showed significant difference between selected and unselected stream sections for SbP spawning were: 1) habitat feature-type, with riffles and runs containing the most egg deposition; 2) presence of partial barriers, most eggs were found just below a barrier or between an upstream and a downstream barrier; 3) substrate type, most eggs were found on sand and gravel. The only unselected stream that was similar to SbP spawning streams in temperature and habitat features and attributes was Big Hike Brook and this should be monitored for possible spawning activity in the future. LbP smelt spawning was not evident in Mill Lake Stream in 2014 or 2015, likely the result of a culvert at the downstream portion of the stream impeding upstream passage due to water flows exceeding the maximum swimming speed of smelt. Confirmation of the presence of SbP smelt in Mill Lake Stream and their likelihood of spawning in this stream should encourage further monitoring of Mill Lake Stream as important spawning habitat for both populations of LURS."--Abstract.

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