Historical Disturbances

Transcription

1 MINNESOTA DEPARTMENT OF NATURAL RESOURCES The Science(s) behind Managing Stream Fishery Resources Lake Superior Area Office, Section of Fisheries Historical Disturbances Thaddeus Surber, 1923: Because of changed conditions brought about by the deforestation of great areas of this region some of the once famous Brook Trout streams are no longer tenable as such fires destroyed immense areas of swampland along with second growth in the slashings, giving the powerful rays of the sun access to the cold sphagnum swamps warm waters prohibit the presence of Brook Trout in certain parts of the streams the colder upper water have been destroyed trout in their search for cold waters have been compelled to descend many of the streams to Lake Superior. 1

2 Early Habitat Improvement Lessons Learned 2

3 A New Approach Root wads and woody material Bankfull bench moves stream away from eroding bank, dissipates energy Woody transplants slows high flow velocities, allocthonous energy inputs, shading Good for fish Protecting an Investement MNDNR Easements: Proposed natural channel design techniques be utilized for habitat improvement or restoration projects Develop criteria for post project assessments if feasible Assess biological response to habitat improvement projects 3

4 North Shore Angling Opportunities Kamloops Steelhead Brook Trout Rainbow Trout Regulations 4

5 Regulation History Steelhead Regulations Pre Assessment Techniques French River Knife River 5

6 Percent Survival of fry stocked Survival of Stocked Fish * 2009* 2010* 2011* 2012* 2013* 2014* Year-class Steelhead None Stocked Number of age-2 steelhead emigrants Smolt/Adult Relationship '01 '02 '03 '04 '06 '00 '05 '97 Steelhead R² = Number of steelhead females passed upstream The relationship between the estimated number of female adult steelhead spawning upstream in the Knife River and the estimated number of age-2 unclipped juvenile emigrants by year-class for the Knife River from 1997 through 2010 (adult/smolt relationship). '98 '07 '99 '08 '09 '10 6

7 Return of Stocked Fish percent return mean Q1 Q Kamloops 3.62 Percent return * 10* 11* 12* Year-class Creel Survey 7

8 Brook Trout Increased Effort Brook Trout 8

9 Percent in each size-class 50% 40% 30% 20% 10% Population Response to Regulation Brook Trout % Length category (inches) Brook Trout Genetics Duluth Finland Grand Marais MN (84%) Minnesota Strain Non-MN (7%) Tobin Harbor MI, Siskiwit Bay MI, Lake Nipigon ONT Mixed (9%) Mixed Grand Marais Fisheries 12 tribs 83% MN,10% non-mn, 7% Mixed Finland Fisheries 9 tribs 89% MN, 2% non-mn, 9% Mixed Duluth Fisheries 8 tribs 79% MN, 0% non-mn, 21% Mixed 9

10 When Fisheries and Social Science Collide Wild vs. Stocked Native vs. Non native Strain vs. Strain Stream Fishing vs. Boat Fishing Harvest vs. Catch & Release Stocking for rehabilitation vs. stocking for better catch rates Other resource users: The Passion for Natural Resources Photos courtesy of Ross Pearson 10