Backyard Habitat Notes: Have you ever heard a fisheries biologist mention the term ‘pre-spawn mortality’ and scratched your head about what it means? Pre-spawn mortality refers to the death of anadromous, salmonid fish, usually Coho salmon, while they are navigating their natal freshwater streams, before they actually spawn. Scientists are finding that a significant cause of pre-spawn mortality is polluted stormwater runoff flowing into streams. Toxic chemicals in stormwater runoff come from a variety of sources, including shedded brake pad debris and oil leaks from cars and trucks, excess nutrients from fertilizers used in agriculture and gardens, and improper disposal of waste. Even if salmon have successfully laid and fertilized their eggs, the eggs’ exposure to high levels of heavy metals, an unbalanced water pH and abnormal stream temperatures can hinder the development of the embryo and engender the deformation of fish, ultimately leading to premature deaths. For more information, here are some interesting news articles: nwifc.org/2014/12/coho-salmon-eggs-put-stormwater-test/ and salmonfarmscience/2013/01/23/highway-runoff-may-cause-pre-spawn-mortality-in-coho-salmon/
Posted on: Tue, 16 Dec 2014 20:13:07 +0000
Trending Topics
Recently Viewed Topics
© 2015