GL alewives, rainbow smelt, chinook - Spey Pages
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post #1 of 12 (permalink) Old 03-22-2016, 01:48 AM Thread Starter
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GL alewives, rainbow smelt, chinook

Just read an article (below) re Huron chinook collapse following alewife/smelt collapse (due in part to zebra, quagga mussel influx). Said Michigan and other lakes to follow. No mention made of steelhead status. Do they depend on the same prey?
Seemed to suggest that the time is ripe to 'restore native species'. GL fishers… teach me. Whats up back there? What do you see for the future re fish, fish management?

Invasive Zebra, Quagga Mussel Spread Contributes To Collapse Of Lake Huron (Non-Native) Chinook
Posted on Friday, March 18, 2016 (PST)
Lake Huron's chinook salmon fishery will likely never return to its glory days because the lake can no longer support the predatory fish's main food source, the herring-like alewife, according to a new University of Michigan-led computer-modeling study.

The study's results suggest that Lake Huron resource managers should focus their efforts on restoration of native fish species such as lake trout, walleye, lake whitefish and lake herring.

The findings also suggest that if current trends continue, Lake Michigan will likely experience an alewife collapse similar to Lake Huron's, followed by the crash of its chinook salmon fishery there.

"These results serve as a reality check for those who continue to pressure the resource managers to stock chinook salmon in Lake Huron," said study co-author Sara Adlerstein-Gonzalez, a fishery scientist at U-M's School of Natural Resources and Environment.

"The findings are also good news for native fish species and for the restoration of the entire Lake Huron ecosystem. Maybe we should celebrate the improvements in the native fish populations and try to adapt to this new situation."

A paper Assessment of Top-Down and Bottom-Up Controls on the Collapse of Alewives (Alosa pseudoharengus) in Lake Huron - Online First - Springer summarizing the findings was published online in the journal Ecosystems on March 14. The paper's first author is Yu-Chun Kao, who conducted the work for his doctoral dissertation at U-M under Adlerstein-Gonzalez. He is now a postdoctoral researcher at Michigan State University and works at the U.S. Geological Survey's Great Lakes Science Center in Ann Arbor.

The other author of the Ecosystems paper is Edward Rutherford of the National Oceanic and Atmospheric Administration's Great Lakes Environmental Research Laboratory in Ann Arbor.

Pacific salmon were introduced into the Great Lakes 50 years ago to establish a new recreational fishery and to help control alewives, a non-native species that entered the lakes in the late 1940s and early 1950s. Alewives soon became the main prey species for chinook salmon and lake trout, which are staples of a Great Lakes fishery valued at more than $4 billion per year.

Lake Huron's alewife population collapsed in 2003, and a sharp chinook salmon decline soon followed. The state of Michigan and the province of Ontario stopped stocking chinook salmon in southern Lake Huron in 2014 but continue to stock in the northern part of the lake.

In Lake Michigan, where populations of both alewives and salmon are declining, stocking of chinooks continues at significantly reduced levels.

The new study is the first attempt to use a food-web modeling approach to assess the various factors behind the 2003 collapse of Lake Huron alewives and the implications for future fish populations there. The total weight or "biomass" of alewives in Lake Huron plunged by more than 90 percent between 2002 and 2003, and the exact causes of the collapse are still debated by anglers and biologists.

Some researchers have suggested the alewife collapse was mainly due to too much predation by chinook salmon and native lake trout. Others say it likely resulted from a drop in food availability tied to the explosive spread of zebra and quagga mussels starting in the late 1980s.

The computer simulations in the new study show that the collapse was caused by a combination of predation and food limitation--and that predation alone would not have caused the crash.

The spread of the non-native mussels, coupled with declining levels of the nutrient phosphorus entering the lake from rivers and streams, were essential factors, according to the new study.

The Lake Huron dominoes fell sequentially, according to the report.

First came increased predation of alewives, due initially to heavier stocking of chinook salmon and later the result of increased natural reproduction of salmon and a drop in sea-lamprey mortality.

Predation of Lake Huron alewives by chinook salmon likely peaked in the mid-1980s and then remained roughly constant until the alewife collapse, according to the new simulations.

Beginning in the 1990s, quagga mussels spread quickly at a time when the level of phosphorus flowing into the lake from rivers and streams was dropping in response to nutrient abatement programs initiated in the 1970s. Mussels in Lake Huron's Saginaw Bay compounded the problem by sucking up and storing nutrients near the shore, preventing them from making it into Lake Huron's main basin.

The loss of essential nutrients in the main basin reduced the amount of algae at the base of the Lake Huron food web. Zooplankton, tiny animals that feed on algae and that provide food for small fish such as alewives and rainbow smelt, suffered.

At the time, alewives and rainbow smelt were the two most important prey species for chinook salmon in Lake Huron. The new computer simulations show that rainbow smelt suffered significant declines before alewives did, dropping 78 percent by 2002. Deprived of a favorite food, chinook salmon began to rely more heavily on alewives, and this increased predation hastened the alewife population collapse, according to the study.

This sequence of events can be used to assess the likelihood of an alewife and chinook salmon collapse in lakes Michigan and Ontario, the researchers said.

"We are seeing all the same warning signs in lakes Michigan and Ontario," Kao said. "We're seeing decreasing nutrient loads, a decrease in soft-bodied, bottom-dwelling invertebrates due to the mussels, a decrease in rainbow smelt and, as a result, chinook salmon feeding almost solely on alewives."
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post #2 of 12 (permalink) Old 03-22-2016, 11:37 AM
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The alewife is an evasive species itself sooooooo........
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post #3 of 12 (permalink) Old 03-22-2016, 12:06 PM
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The chinooks were successful in erradicating the alewives... which is what they were here for in the first place...

The steelhead and lake trout seem to have adapted to eating other critters like the invasive round gobies. The salmon didn't, so goodbye salmon.

Steelies are prettier and more fun to catch anyways.
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post #4 of 12 (permalink) Old 03-22-2016, 12:08 PM
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The alewife is an evasive species itself sooooooo........
They certainly have trouble 'evading' the Chinook and BIG Mackinaws

This article is pretty much a summary of what people paying attention have been reading, pondering, and experiencing for over a decade.

Important to remember that each of the Lakes is individual, with varying habitat even within each individual Lakes basin. Yes they are all connected.. but definitely not the same.

The way I see it shaping up is less fish overall with a continuing re-focus on what management paths take.. no shortage of politics involved here. Pacific Salmon are not nearly as adaptive to alternate food sources as are Rainbows, Brown Trout ..and potentially even Atlantics on a broader scale than current.

"Like Brook Trout, fishingbums can be particular about their habitat and most will either leave or die if needs are not met" Eric Shoemaker

Word origin & history; Wander "move about aimlessly.. wanderlust" http://local-wanderings.blogspot.com/
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post #5 of 12 (permalink) Old 03-22-2016, 05:25 PM
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It is kind of a weird scenario that the success of the chinook and steelhead programs depend on the availability of alewives yet a constant diet of alewives causes a vitamin deficiency of B1 that reduces not only adult vigor but also reduces juvenile survival should they spawn successfully. Also read that the extra stresses on the alewive population from the cold 2014-15 winter increased the enzyme level in alewives that causes the B1 deficiency in salmonids. I think in Lake Erie there is more of an emerald shiner and gizzard shad population than alewives, although I could be mistaken on that.
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post #6 of 12 (permalink) Old 03-22-2016, 05:26 PM
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I'm a native of Michigan now in Pennsylvania. I remember the days (70's) when we would dip net running smelt on the shores of St. Clair River, filling several garbage cans within an hour. Catching 100+ perch 13" or better in a half a day on Lake St. Clair. Watching with wonder the reflection the size of a whale of alewive beneath the surface changing direction in the pristine blue water on lake Michigan. Chinook, Kings, Cohoo running the ladders near Traverse City. Mayfly hatches so prolific that they would cover the streets and anything that was colored white. Every church, bar, restaurant having perch dinners as the main entree. Everything caught was eaten, not going to waist. Yes the fishermen's paradise. Hundreds of millions of tons of food waiting to be caught ! It just seemed like an endless supply !

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post #7 of 12 (permalink) Old 03-22-2016, 10:22 PM
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I find it ironic that a reduction in water pollution from feeder rivers led to the initial alewives collapse.

The method doesn't matter to the fish.
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post #8 of 12 (permalink) Old 03-23-2016, 12:50 AM Thread Starter
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Many would consider the transplant of Pacific salmon and steelhead (also invasives) to have been a positive thing. The more recent focus on any organism that meets 'native' criteria and the required actions taken as a result, leave fish and wildlife managers with few management options. The height of irony is that the huge majority of the human population is, yep, invasive. Some latitude to manage for the common good (which has regional distinctions) would make stewardship responsibilities more achievable.
Our GL spey brothers and sisters have given much to our collective enjoyment of this wondrous sport. Their continued means to indulge their interests close to home seems at risk.
PNW management challenges have had my nearly undivided attention… didn't know much about problems elsewhere. Thanks to all that provided some input.
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post #9 of 12 (permalink) Old 03-23-2016, 10:01 AM
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Many would consider the transplant of Pacific salmon and steelhead (also invasives) to have been a positive thing. The more recent focus on any organism that meets 'native' criteria and the required actions taken as a result, leave fish and wildlife managers with few management options. The height of irony is that the huge majority of the human population is, yep, invasive. Some latitude to manage for the common good (which has regional distinctions) would make stewardship responsibilities more achievable.
Our GL spey brothers and sisters have given much to our collective enjoyment of this wondrous sport. Their continued means to indulge their interests close to home seems at risk.
PNW management challenges have had my nearly undivided attention… didn't know much about problems elsewhere. Thanks to all that provided some input.
Not sure if I am misreading your post but I don't think any great lakes spey fisher cares at all about Chinook. At least none that I have ever met.

Steelhead on the other hand...
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post #10 of 12 (permalink) Old 03-23-2016, 10:05 AM
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I not sure that the human population is the invasive species. I would like to see if fishing licenses in Michigan increased over the last thirty years. Is there any data on this ? Rather I was under the impression many new plankton eating species are competing. Now we have the Chinese Carp coming into the mix. In the 70's Lake St. Clair had a greenish/blue color (plankton). I'm now told its clear, so clear, that the sun can now penetrate to the bottom of the lake and weed growth is prolific. I've been under the impression that clear (not clean) water is less fertile (plankton). The Amazon River, as tea/brown that river is, it contains more species of fresh water fish than anywhere else in the world. The invasion in Michigan began with the Foreign Ships emptying the ballast at port.
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post #11 of 12 (permalink) Old 03-23-2016, 10:53 AM Thread Starter
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Earlier post described how steelhead adapted to loss of alewife feed. While speyfishers might not have an angling interest in chinook, there are reasons to care about a fish that spawns and dies in rivers that will later nurture juvenile steelhead. No action acts in isolation. We watch that truth played out in the ravages of cormorants, terns, seals and sealions on PNW salmon and steelhead smolts and adults. Each predator has its advocates. Hard to watch the effects, though.
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post #12 of 12 (permalink) Old 03-29-2016, 11:51 PM
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Lots of GL spey interest in Chinook and Coho.I agree there is more interest in Steelhead but, still lots of salmon interest on Ontario tribs.
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