I finally had the (delayed) opportunity to run some numbers from the 2009 Lower North Shore Spring Run and there are a few items of note. One important item illustrated here is the strong temperature-return correlation for Steelhead as well as Kamloops. While fish were undoubtedly in the streams as soon as they opened up (I saw a number of them in early April when there was still ice), once again we see that average stream temperatures which hit 40 degrees play a strong role in the start of upstream migrations of North Shore fish. You can use this information to your advantage when trying to locate active fish early in the run no matter what part of the North Shore you prefer. The following are plots of 2008-2009 Knife River Steelhead captures by date against both temperature and flow:
(Click images for larger version)
Note that while the temperatures listed are for a couple different streams (real-time data is hard to come by), the overall temps were tracking very closely with the Knife and other Lower Shore Streams. The temps depicted are daily averages. Knife River Flow is divided by 10 for better viewing against the return numbers and temps, so multiply the figure depicted to get the actual.
Using temp readings from sites such as Duluth Streams allows you to better pinpoint the times when upstream migrations really get going, and can make all the difference between forgetting all about cold hands while catching fish, or just having really cold hands. Once temps stay above 40, you need to shift your attention to flows as the subsequent increases will draw steelhead like a magnet - bad pun intended.
The second graphic illustrates the 2009 Knife Returns by Week against 2008 as well as the long-term average going back to 1996 when the trap first opened:
(Click image for larger version)
Couple things to consider: 2009 was pretty much a carbon copy of 2008 with regards to overall return timing. Unfortunately no capture data was available after May 20th 2009 to round out the numbers. What's interesting to note is that while 2008 and 2009 had strong flows early on starting right at ice-out, things really didn't get going until the daily temps began hitting that magic 40 degree mark. That seems a little counter-intuitive but again, early upstream migration activity really depends on temperatures as discussed above. Note also that high flow can actually limit upstream migrations. Understanding that flows above a certain level limit fish movement also helps the steelheader in deciding when to go fishing and which river might fish best.
The last thing to consider is that if conditions remain suitable, you can greatly extend your season by keeping tabs on what the Knife and French return numbers are telling you. The first is that fish remain in the system for a period of time after the peaks occur. On the Lower Shore, adult fish have been documented emigrating (returning to the Lake) up to 60 days after they initially enter the system. More typically though, fish will drop back after 20-30 days according to DNR reports. If you pay attention to the peak, you then have a good idea of when fish will likely be leaving the system; and while they are a little less predictable, you can still have some very good days well after "The Run" is said to be over and with the river all to yourself. The reported peak also gives you a good idea as to when the Mid and Upper Shore will be fishing well since they follow the Lower in a fairly predictable manner. Just watch those temps.
Regards-
NMF
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