Brook trout (Salvelinus fontinalis) embryo habitat and timing of alevin emergence in a lake and a stream

We assessed redd characteristics of brook trout in a lake and a stream and alevin emergence in the lake. Both populations spawned over upwelling groundwater. In the lake site fish deposited eggs 7–19 cm in the sediment in an egg pocket that contained large-particle substrate. A similar vertical distribution of eggs (16–20 cm) and substrate occurred in the stream; however, in addition to the digging action of the female, the flow conditions in the stream appeared to produce coarser surface sediment conditions. Groundwater offered a high concentration of dissolved oxygen and, relative to lake water, less variable temperature and pH regimes for incubating eggs. Alevin emergence extended over a 71-day period, coinciding with the spring thaw and an episodic pH depression.