Thursday, January 5, 2017

ADDENDUM TO PART 1- 2016/2017 RE-CAP/OVERVIEW :STEELHEAD/FLOODING


 I discussed how weather was a significant factor in 2016's potamodromous salmonid (freshwater to freshwater) river migration timing and success. With heat and droughts, and than again sub-zero and ice-up, these 'extreme' events cause marked restructuring of LSS (Life Survival Strategy for successful procreation) of steelhead.

Several positive factors occur with extreme spring weather flooding and also extreme summer heat and drought we often take for granted.

1. Smolting Success

When wild Michigan strain hatchery smolts are stocked the first week of April and rivers are flooded, there is a very good chance that they will smolt quickly and with good success to the big lake with minimum predation by other river predators: fish/birds/mink etc. River coloration and visibility is good for cloaking them. Also, the long dark runoff plum at river estuary mouths gives them additional protection for large predator fish and cormorants once they meet the crystal clear waters of the Great Lakes. With two strong flood years behind us, we should see excellent returns in the spring of 2017. 
2.Multi-Year Class Survival of Returning Spawning Adults
DNR and Federal biologists often fail to underestimate the significance and importance of repeated multi-year spawning by steelhead. Especially on larger river systems with wild reproduction and stocked smolts like the Grand, Muskegon, Big Manistee, where flooding is significant.
Flooding allows thousands of spawning steelhead to enter the river, dig redds/gravel, spawn and vacate downstream to the big lake in a big hurry- especially when coupled with warm water temperatures. Our last two years floods had exactly those scenarios.
So the chance for the fish to grow larger and return the following year is very good. Often , as in Michigan, steelhead studies ( a.k.a. Seelbach studies of Michigan) are done on very small streams like the Little Manistee. Here the low waters and difficult stream negotiations for movement often don't favor repeat spawners and there is greater mortality. 
Also a very important point on small rivers is that they have tons of wooded structure. Many large spawning steelhead run for trees/obstructions when hooked and break off anglers, often by doing some damage to their skin/jaws/mouths etc., which often become infected with bacteria and cause deadly lesions. These coupled with the rigors of spawning and teeth jousting by males also finds greater mortality.

Also, not that I'm implying or implicating, ;),  but many fish are still "illegally snagged' on gravel, or legal "lining" is severe in low water conditions ( throughout the Great Lakes). These have major implications on wild river systems that depend on spawning for their steelhead populations- both more difficult in heavy stained river flows.

3. Heat/Drought Positives
Though you can time Skamania summer steelhead runs by late June/ July/August like clockwork, extreme heat and drought will benefit the fish by allowing them to stay in more comfortable conditions in the big lake- some still forage and grow, but most are already emptying their stomachs for river migration. 
If they run rivers on drought/heatwaves ( some do/most don't), they would surely die upstream as they often do, especially after a cool front/ two day thunderstorm event- then reverting back to 90F heat and mortality. Like they did last year, many steelhead will forgo running altogether which should make for magnificent runs in 2017.

4.Flooding and Zebra mussels
Floods kill zebra mussels by causing runoff sediment to clog their inhalation process and bury many-also they are still water ocean/sea organisms that don't take kindly to heavy flowing waters. After severe floods , mounds of dead zebra mussel shells appear on banks. Mussels cause serious depletion's of caddis and other benthic insects that fry/smolts and parr need. Also they increase diptera midge populations that feed on plankton and decaying detritus.

So next time you are sitting home and bitching about rivers being flooded or cancelling guide trips, there is a literal 'silver lining' to all this madness.


FOR MORE INFORMATION, MY BOOK HAS A TON MORE INTERESTING NOTES ON ALL THINGS STEELHEAD

Hope to see you in 2017!!!!
Cheers!
Matt