Wintering Coho Fry (Yearlings)For Christmas I purchased a GoPro Hero 5 to assist with my stream keeping, and to bring along for snorkeling during my Mexico trip for mid January. I had taken it out a few times for practice runs on the Fell and Griffin Channels, but as happens during the Winter months the fish seemingly all but disappear. On a whim before going to the gym at Delbrook Recentre I decided to take the camera to my absolute favorite spot on the Mosquito Watershed. Where I have spotted many winter Coho fry and Cutthroat in the past. As well as spawning adults in the fall. This pool is literally the only refuge pool on the entire watershed. It is about 3ft deep during normal flows and can be in excess of 6ft deep during peak flows. Which is totally unheard of on this system. It is also very large about 15ft x 15ft, filled with both woody debris and leaf litter. Again, something no other pools on Mosquito Creek has. It is seemingly the holy grail of pools and the most critically important piece of water for Mosquito Creek. It is actually part of the tributary known as Thain (or Mission) Creek. The Refuge PoolI was super excited the second I laid eyes on the pool. I was a bit worried as to if it held up during the heavy periods of rain we experienced this year. To my delight it was still in place, looking as strong as ever. There were two times this Fall during the rains, where I had been down and actually removed some logs from the jam to relieve pressure as it had, by my estimate, multiplied its volume by 400%. The FrySure enough as I walked closer I was able to immediately see fry holding, it was great to see! I couldn't believe how many there were. Last year there were approximately 100-150 fish holding. This year there was at least 400, maybe more. I think I only spotted 2 or 3 adult Cutthroats, but that was ok. The shear amount of Coho fry in the shoal was astonishing. This is literally the future of the Coho on this creek and the numbers were great to see. I reall hope the District/DFO/Squamish Nation does something to protect this section of creek. Without it I don't think there would be any Coho left. Below find the Video - *Also* be sure to read the bio beneath the video on this page. The Importance of Winter HabitatDid you know that Coho fry spend a year in their Creek/Stream before leaving to the Ocean?
This extended rearing phase is often the limiting factor for the species success. In the Summer months the fry have to deal with hot temperatures and low flows, and during the Winter they rely on deep slow moving pools for refuge. Mosquito Creek like many urban streams have their challenges. One of which is they generally have large storm drain networks that are fed by our roads. Mosquito has seen mass fish kill offs in the past from neglegent residents. Low flows during Summer and Winter months make this a very challenging time for the life under the water. Also, many urban streams have lost complexity created by large fallen trees and the deeper pools that come with it. These deeper pools are few and far between. It is likely almost every fish within several hundred meters has come to seek refuge in this one pool, making it critical to the species success on this watershed. The challenge here is there is literally so few of these refuges that you can count them on 1 hand. Another challenge is that Mosquito Creek has a large off leash dog area and with it these refuge pools have become dog swimming pools. There are 4 areas on Mosquito that were created specifically to help the Salmon. 1) The channel south of the skateboard bowl (Griffin Channel) 2) The channel below HWY 1 which runs parallel to Fell Ave (Fell Channel) 3) The two Alcoves that hold deep still water, there's one just south east of the trailhead coming down off Fell Ave hill (West Alcove) 4) The other just a few steps up from the closed trail sign from the access on 19th to the East trail (East Alcove). Although Fell Channel is highlighted at every entrance as a "No Dog" zone, many trail users ignore these signs. There is very little water that enters this channel regardless of the time of year, and very little summer and wintering refuge, so dog pressure is magnified. East Alcove has significant dog pressure, especially during Summer months when dog activity kicks up silt and sediment to suffocate the fry.
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AuthorKeegan Casidy Archives
January 2020
CategoriesMosquito Creek,
North Vancouver, British Columbia |