Adding Cover Habitat for Fish

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Photo credit: Peter Williams and Megan Harris

Topic 2, Adding Cover Habitat for Fish

What is cover habitat? Cover is anything that fish of various sizes can use to hide under to avoid being eaten by overhead predators like osprey, kingfishers and great blue herons.

Why do you need to add cover to streams? A natural, healthy stream would have lots of woody debris, cobble, boulders and deep pools in it where little fish and adults can hide. However, most Island streams don’t have a lot of woody debris because the original Acadian forest has been cleared and there is little left to decay and fall into the water. Boulders and cobble have been buried under sediment and the West River doesn’t have a lot of deep pools in it. Also, we often take out woody debris temporarily, so that we can flush all of the sediment from the bottom of the stream. If we leave woody debris in, the sediment piles up behind it instead of flushing out into brush mats and sediment traps.

What do we do to correct this? Once the sediment is flushed from the stream, CQWF crews go back and return woody debris to the stream, in the form of split or half logs. Split logs are just a log slab (the rounded edge left over after wood has been milled into planks) with one end made into a point to be more hydrodynamic in the water. The split log is secured to the bottom of the stream using steel rebar, with wood spacers underneath to keep it up off the bottom sufficiently that fish can swim in underneath it. As long as the wood is completely submerged, even during low flows, it will last indefinitely without rotting. CQWF places dozens of these split logs into the West River as cover for brook trout and Atlantic salmon.

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