A New Incubator for the Assessment of Hatching and Emergence Success as Well as the Timing of Emergence in Salmonids

Abstract

We devised a new incubator to estimate hatching and emergence success as well as the timing of emergence of brook trout Salvelinus fontinalis. The incubation basket is cylindrical and made of a polyvinyl chloride (PVC) grid that allows water to flow through from all directions. A fry trap is set on top of the incubation basket to catch the emergent larvae. A PVC coupler is fixed to the incubation basket and allows the fry trap to be easily removed and replaced so that one can sample larvae during emergence. In the field, the emergence success for incubators containing natural substrate ranged from 0% to 50%, compared with 0% to 77% for incubators that used Astroturf as a substrate. In the laboratory, the emergence success with Astroturf alone (75%) was comparable to that in the incubators that used Astroturf in the field (73%), suggesting that the incubator structure itself does not influence the survival of brook trout eggs. This incubator is easy to build and the materials needed for its construction are readily available. The collection of emergent larvae is easy and does not require additional equipment. Its advantages over other salmonid incubators are that it can resist adverse spring floods and freshets and it allows the assessment of emergence at various times in the field. This is important when determining the timing of emergence.