Salmonfly reintroduction, spring 2006 update

[nightfish 0]

This past saturday we had our latest bug movement. 2,000-3,000 nymphs were moved from the Blacksmith Fork of the Bear to the Logan (also a trib of the Bear river). Nearly 60 volunteers assisted with the gathering and relocation, followed by a barbecue hosted by the Utah State University BugLab.

 

It seems that we are seeing some success with this project. Last spring several exuvia (nymphal shucks) were found near the nymph release site, and immature nymphs have been found in the monthly samplings done by the USU students.

 

At first we were doing biannual transfers. That has changed to spring nymph movement supplemented by capture and relocation of emerged adults. This may be more effective, since an egg-laying female deposits 350 eggs on average.

 

For complete information on this ongoing project, visit:

 

http://www.usu.edu/buglab/projects/project%20Salmonfly.htm

 

And feel free to ask questions here. I'll answer or find out as much as possible.

[Alex C. 0]

Glad to see you post an update, it's funny I was just wondering about this a couple weeks ago. When do you think things are really gonna take off? Any clues yet as to why they dissappeared in the first place?

[nightfish 0]

No, no clues yet as to the cause of depletion...just theories. Bugs kept in traps have lived over a year, so it is proved they can live in the system. (Our traps placed last spring were lost weeks later due to heavy runoff. No traps were placed this year since freeliving nymphs have been found in the monthly surveys)

 

As far as when the population should really take off...I think that is too hard to say at this point. The Logan is around 30 miles long & our efforts are at miles 8 & 12 (from the mouth going upstream). I'll see if Vinson has any info on average lifecycle mortality & recruitment in a healthy system. I'll also see if I can get some average density numbers for the Blacksmith Fork.

 

We may also find areas that the nymphs can't or won't recolonize. A lot has been learned about the Logan river system in the past 20 years. The system is part of a Karst formation, with very noticeable flow and temperature changes in localized stretches. It is quite possible that one stretch of water has ideal habitat, while an adjacent stretch could have unacceptable temperatures, oxygenation or chemistry. Aside from that, the river has excellent basic habitat, and good populations of goldens, little winter, and sallies, with a lesser population of skwala.

[Redwings1 0]

Sounds like a pretty neat process, I am interested to see how it turns out.

[Ethan Bright 0]

Hi:

 

One should probably also consider hydrological characteristics as well. Water chemistry can be important, but salmonflies (Pteronarcys spp.) are principally shredders and grazers of organic matter (and facultative predators). Being large clingers, they're susceptible to being blown out by storm flows. If their habitat gets blown out (e.g., woody debris dams, undercut banks with large substrates, etc., then one won't find many unless there is ample time for habitat resetting and individual recolonization.

 

Cheers, Ethan