Progress is being made for the NOBROOK project!
Earlier this fall we have removed brook trout from one of our study streams in Borås. This process involved fishing the whole stream twice using electro fishing with the help of our collaborators at Sportfiskarna. We did this before spawning time to reduce the reproductive success for the brook trout and ensure that we could remove the vast majority of brook trout in the stream. While fishing we also found evidence that spawning between brook trout and brown trout has been ocurring, because we fished several tiger trout. See the video at the bottom to get a close up look at this interesting hybrid!
Moving forward the plan is to examine the effects this removal has had on brown trout in terms of behavior and ecological niche. Several of the brook trout we removed have contributed in different ways back in the warmth of the lab:
We have artificially infested both brook trout and brown trout with larvae of the freshwater pearl mussel in the lab at zoologen. Our master’s student, Isac (as seen in the picture above to the right), has used these fish for experiments testing
i) Whether brook trout may serve as suitable hosts for the glochidia larvae, and
ii) How infestation of the brown trout affects their dominance in one-on-one competition situations with both brook trout and conspecifics.
His thesis will be finished soon and will contribute to WP4 of the NOBROOK project.
When keeping the brook trout in the aquariums at zoologen we also wanted to test the potential for social traps as an effective catch method. This experiment is still going on, and should there be clear indications that baiting a trap with another brook trout is effective we will consider expanding this to the field.
Until next time, please enjoy this video!