November 29, 2007

Byrne Creek Sees Few Spawning Salmon

It's been a disappointing spawning season so far this autumn on Byrne Creek in southeast Burnaby, with only around 20 chum and coho salmon tallied. Another issue that has cropped up in the last few years is also being repeated -- the lack of spawning success in coho. We keep finding female coho dead before they have laid their eggs, and today Yumi and I processed another.

NOTE: My usual disclaimer -- it is illegal to disturb spawning salmon. Streamkeepers receive training and also have permission from the Department of Fisheries and Oceans to process dead spawners and record data about them. I think it is important to share our volunteer efforts with the public; however, I occasionally worry that people may get the idea that these fish and their eggs are fair game -- they are not!

Beautiful coho found in Byrne Creek today.

Unfortunately, this female did not spawn before she died.

Some people may also be confused about why these fish die. Salmon are anadromous -- that's a big word that means that during their lives they move from fresh water, to salt water, and back to fresh water again to lay their eggs. This entails major changes in their organs -- from ingesting minerals in fresh water to extruding salt in the ocean. Some species of fish can repeat this cycle, but when salmon come back to their birth creeks, streams and rivers to spawn, it's a one-way trip. They stop eating when they enter fresh water and their health begins to steadily deteriorate -- all of the energy in their bodies goes to keeping their reproductive systems and brains going as their flesh fails. If a fish cannot reach its native spawning grounds and find a partner within a set period, it will die before it can spawn.

After collecting data about the fish, Yumi and I voiced a brief appreciation for her efforts, and then we cut the carcass in half (this ensures that streamkeepers don't double count fish) and returned it to the creek where it will provide essential nutrients for the food chain.

Posted by Paul at November 29, 2007 03:27 PM