Skagit bull trout

Discussion in 'Fly Fishing Forum' started by Smalma, Oct 30, 2012.

  1. Smalma

    Smalma Active Member

    After a number of decades of being "captured" by the enigmatic critter we call bull trout (aka Dolly Varden) I attempted to pass on what I have learned about them in an article for the "Article & Reference info" forum on this site.

    I hit the high points on the little that I have learned over the years and it occurs to me that others may share my passion and wish to discuss some aspects of the article or expand areas covered as well as share their own insights.

    I based the article on Skagit bull trout because it has one of the most robust populations here in the PNW and are the most likely to exhibit much of the diversity of behavior found in the region.

    If there is that kind of interest it probably is more appropriate to have our discussions here rather on the "Article" forum.

    Curt
     
  2. Jason Rolfe

    Jason Rolfe Wanderer

    Can't wait to give it a read, Curt. Thanks for sharing your experience.

    J
     
  3. KerryS

    KerryS Ignored Member

    Excellent article Curt.

    I have seen bulls adapt to feeding situations. One is the release of coho parr from the Baker River facilities. Bull trout will gather at the mouth of the Baker and have a feast. Un-natural food source to some extent but a perfectly natural reaction from the bulls.
     
  4. zen leecher aka bill w

    zen leecher aka bill w born to work, forced to fish

    I had occasion 15 years ago to fish bull trout waters for about 3 years in a row. It was surprising where they ended up. This was a tributary of a tributary of a tributary of the Skagit. I believe the spot where we camped has a bridge out below it. Guess it's a bit underfished now.
     
  5. Smalma

    Smalma Active Member

    Wadin boot asked the question -

    "...given the efficiencies of the Bull, why aren't they far more prolific? "

    The short answer is that the population limiting habitat piece for the species is their spawning earlier rearing habitats. The bull trout have very specific requirements for the successful incubation of their eggs. The best survival of their eggs is dependent on the water temperature in the grave. surrounding the eggs. The optimum temperature for egg development and survival is in the 35/36 degree range with mortalities increasing significantly as the temperatures creep above 40 degrees. Those temperatures are below the desired threshold of early developing salmon eggs.

    With that temperature requirements the desirable habitat in the Skagit is pretty limited. Essentially it is limited to the upper reaches of habitat accessible to migrating fish and a small portion of the total habitat available to anadromous fish in the basin. Given the population bottle neck from the limited spawning habitat the species does a remarkable job of finding ways to expand the potential habitat for the surplus juvenile fish and exploiting diverse feeding opportunties for sub-adult and adult fish to support a surprising abundant over all abundance.

    Curt
     
  6. TD

    TD Active Member

    How long is the incubation period? I'm wondering how long the water temperature needs to remain in that cool range. Are they main stem spawners or do the spawn in feeder creeks/streams?
     
  7. TD

    TD Active Member

    I apologize if this was covered in the article. I should have read it first before adding to the thread. I just read this and the questions popped to mind.
     
  8. Smalma

    Smalma Active Member

    TD -
    Great questions!

    No it was not covered in that kind of detail. That is one reason I thought have a discussion here on the general forum would allow us to get ito more details if of interest - hard to tell how much detail to get into in a general article.

    The bull trout are the most successful if those temperatures are present throughout the incubation period. The length of the incubation can be quite variable depending the temperatures experiecned during the egg incubation. In the kinds of habitats that bull trout spawn during prolong cold snaps it is not uncommon to see anchor ice forming on the stream bottom. In that situation the water temperature is essentially at freezing though the bull trout attempt to mitigate those impacts by selecitng spawning sites with upwelling flows. Depending on the average temperature it can take 4 to 7 months for the eggs to hatch and another month or so until the fry to emerge from the gravel; coming out of the gravel from early to lte spring. Those newly emerged fry are typically about an inch long and at that small size remained relate closely to the bottom substrates.

    The bull trout are tributary/side channel spawners and are typically found in mid to small size tribs. An especially important spawning habitats are side channel habitats -especially those that are stable over flow channels with log jam blockages at the head of the channels that act as a flow controls. Those types of channel while rare providesome of the most stable habitat to found during high flow events and on years with large floods represent the habitats the produce the majority of the eggs/fry that survive.

    Curt
     
  9. wadin' boot

    wadin' boot Donny, you're out of your element...

    That temperature stuff is interesting. I guess another way of thinking of it is they love the Sauk, they love the Hoh- those glacial feeds...Probably scads of them in the upper Skagit above the dams. I've certainly caught some in Ross lake. Thinking of Thunder creek...Do you think there is a glacial silt/dust preference for the fish independent of the temperature? Alternatively, do/can they change coloration based on silt content in the rivers? Some of the fish out of those summer rivers are so perfectly silt-gray camoflaged it is uncanny
     
  10. Ryan Higgins

    Ryan Higgins Active Member

    To my knowledge Bull trout are actually highly susceptible to sediment intrusion into the redds. Due to the length of the incubation period the eggs are at a higher risk for mortality due to sediment intrusion. The fry are also susceptible as they tend to hang very close to the bottom, sometimes even in the substrate itself.
     
  11. Smalma

    Smalma Active Member

    Wadin Boot -
    While bull trout do use some glacial streams for spawning the majority of the spawning in the Skagit basin as well as the rest of Puget Sound happens in the clear water tribs.

    Interesting that you mentioned Thunder Creek (trib to Diablo Lake). Recent DNA sampling confirms that Thunder is one of the few streams in the North Cascades that support Dolly Varden - not bull trot. Diablo has bull trout andit is probably they use the lower Thunder Creek for spawning but the fish from the upper of the basin appears to be Dollies.

    Like most fish bull trout have some control on their coloration and it is likely glacial streams they take on a paler coloration. Though to be fair except for the males in the spawning suits bull trout as a group whether in a glacial or clear water stream are typically well camouflaged.

    Alpine -
    yes like all salmonids bull trout are sensitive to sedimentation of the redds though the females are pretty effective in selecting redd sites given their eggs the best chance. Beacuse the bull trout live in such harsh environment bed load movement and redd scour is likely a larger issue for redds/fry in most years and locations.

    Curt
     
    wadin' boot likes this.
  12. zen leecher aka bill w

    zen leecher aka bill w born to work, forced to fish

    Which fish is in Downey Creek? I was told they were dollys.
     
  13. Smalma

    Smalma Active Member

    Zen -
    15 years ago there was consderable confusion what were Dolly Varden and what bull trout. With widespread genetic testing over the last 20 years it is now known expect for a few isolated headwater populations the region's native char are bull trout. The fish in Downey Creek (both the migratory adults and the resident forms above the falls) have been tested and like all the rest of the Sauk basin and Skagit below the dams proved to be bull trout.

    Curt
     
  14. Rick Todd

    Rick Todd Active Member

    I've caught bull trout in the Skagit in BC and their seems to be a healthy population there. Other places I've tangles with them are the Skagit around Marblemount and the N Fork of the Nooksack. Snorkeling the Methow in summer is always good for a few bulls and I caught a very nice one in the Methow last summer while fishing streamers for trout. Now I'm going to read the article! Rick
     
  15. zen leecher aka bill w

    zen leecher aka bill w born to work, forced to fish


    Curt, That's what I figured. My info and source was old and based off a temp biologists report of a study he did along with snorkeling with the fish. Old data was the dividing line was the Puyallup River. North were dollys and south were bulls. Looks like it was proved wrong. Thanks for the clarification. There were some nice dollys...errr... bulls caught back then.
     
  16. Jonathan Tachell

    Jonathan Tachell Active Member

    Curt you are a wealth of knowledge! I love reading your informative posts. It is absolutely amazing how much you know about our fisheries here in Washington. I hope to meet you sometime and maybe wet a line.
     
    Jeff Dodd likes this.
  17. porterHause

    porterHause Just call me Jon

    I agree with Jonathan T. Curt, awesome posts. Just out of curiosity, do you know why S.Malma (sorry, I had to make the connection), Dolly Varden is only covered under "similarity of appearance?" I thought they were in a similar situation to the Bull Trout. Or maybe that's the subject of a future article...
     
  18. Smalma

    Smalma Active Member

    porterHause-
    The endanger species act provides for coverage under similarity of appearance in the following situation -

    "Section 4(e) of the Endangered Species Act authorizes a species to be treated as if it were endangered or threatened if it so closely resembles a listed species that law enforcement personnel would have substantial difficulty telling the two species apart. The similarity of appearance provisions can also apply to a subspecies or a population segment. Species listed under these provisions receive some but not all of the protections of the Endangered Species Act (Act). "

    Clearly when it takes detail genetic testing to separate the two species it would extremely difficult for the enforcement personnel or the lay person to tell the two fish apart. That coverage applies only to the Puget Sound/coastal distinct population segment (DPS). While this provisionis provided to insure that the listed fish gets the full protect (by avoiding confusion with the similar speices) it also has the unintended benefit of providing ESA like protection of Dolly Varden in the DPS without having to go through the expense and time of listing evaluation. I think you are correct in that if that evaluation were made that Dolly Varden would also likelbe listed.

    Curt
     
  19. BDD

    BDD Active Member

    I have not read the bull trout bio that Curt wrote but look forward to reading it with much anticipation along with the rest of this thread.

    In the meantime, my head is still spinning from Curt's tale of a monster bull trout he caught. It was a jaw-dropping story! If I didn't respect Curt so much, I would have called him a liar, causing him to shoot me if we were in the old days. I'm glad I believed him and we are not living in the 1870s. :D
     
  20. skyrise

    skyrise Active Member

    curt, too much to read in one sitting. do have some questions.
    given the overall degrading of many upriver tribs (skagit area) do we know what kind of loss has occurred in bull trout populations ?
    and do you see a numbers drop for bull trout across their range in say Skagit county waters ?
    my guess is that they are down.
     
    Diehard likes this.