We got an e-mail yesterday from a Burnaby environmental services worker that there were about 250 dead coho smolts in the Byrne Creek sediment pond. My wife Yumi and I called fellow streamkeepers Bert and Bob, and we were all down at the habitat yesterday afternoon.
Yumi and I walked down the ravine, checking the creek along the way, and found one dying coho smolt about 10m d/s of the footbridge.
Good news: We also saw live coho smolts and cuts in some pools, coho fry between the footbridge and the old weir, chum fry below the old weir, lots of chum fry below the new weir, tiny fry (new cuts?) below the new weir.
We counted 254 dead smolts in the sediment pond.
There were also live fry, coho smolts and cuts in the sediment pond, so perhaps the few live coho smolts we saw are indigenous and tougher having grown up in the occasionally polluted water.
Yumi and I then went through the spawning channel. Growth was very thick in places and it was hard to access all portions, but we came up with a total of 32 morts, mostly in the pools.
When we came out the bottom end of the spawning channel, we could see at least 25 morts in the overflow pond, and it would probably be safe to double that figure.
There were three morts visible from Meadow Bridge.
We then ran into Bob, and he joined us in going further downstream. There were four morts u/s of Byrne Bridge, and a crow snagged one of them as we watched, and carried it away.
It was difficult to walk the creek below Byrne due to thick growth. We gave up about two-thirds of the way to Marine Way, as we had not seen any morts. Saw one live small-smolt-sized salmonid in the creek about halfway between Byrne and Marine Way.
So of the several thousand coho smolts schoolchildren released last week, the death toll was:
Conservative total: 315
Probable total: 350
Possible total: 400+
We call this the "first flush" effect. It's the first heavy rain after a fish release that carries all sorts of stuff into the creek from storm drains. Oil and antifreeze from leaking cars, soap from washing cars, pesticides, herbicides, you name it.
If it's not too bad, the native fish survive, however it appears that it doesn't take much to kill hatchery fish that grew up in a pristine environment.
You can see my photos of a first flush in May 2003 here.
Posted by Paul at May 12, 2004 05:36 PM