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Author Topic: An excellent example of how paradigm prejudice impacts fisherey science  (Read 832 times)

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Dire Wolf

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Dire Wolf

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Re: An excellent example of how paradigm prejudice impacts fisherey science
« Reply #1 on: August 21, 2017, 06:30:29 AM »

Notice first that all the authors are employees of the USGS.  The lead author is actually a post-doctoral fellow at MSU, employed by the USGS. I really had to chuckle a bit when I read Bo Bunnell's statement about stocked Chinook proportion on the fishery model simulations...with 71% of the Chinook stock wild origin fish, this is EXACTLY what you would expect, near-zero impact on the dynamics of the salmonine stock via manipulation of hatchery Chinook numbers. Combine this with the reality that their survivorship is lower than their wild brethren, magnifying the continued stupidity of single species Chinook stocking reductions as a means of enhancing alewife survivorship.

Now, let's throw-in the stable isotope salmonine food habits data worked-up by the USFWS that indicates that, while all other salmon and trout species have shifted over to feeding primarily on the more abundant juvenile alewife stock component, lake trout were documented to feed preferentially on adult alewife, when they fed on alewife.

It doesn't seem odd to me that the authors conclude that steelhead and lake trout are the best fit as productivity has diminished and alewife stocks have declined when lake trout forage preference is likely the major factor in driving the alewife stock's decline by sequentially truncating the age distribution of adult fish-just like what occurred in Lake Huron.

Do you find it odd that sport fishers view lake trout as part of the problem, while the USFWS/USGS folks will argue ad infinitum that they are the solution to Great Lakes restoration, looking past the PCB-like dioxin congener issue as well as the muscle tissue methyl-mercury trends.
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Dire Wolf

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Re: An excellent example of how paradigm prejudice impacts fisherey science
« Reply #2 on: August 21, 2017, 09:42:55 AM »

Finished my first read of the study. There are several limitations to the authors conclusions, chief among them that their use of Ecosim/Ecopath models set at 2004 base parameters and run for 100 year intervals consistently underestimated wild Chinook biomass in all scenarios where adjustments of salmonine stocking rates, Quagga sp. mussel density, and/or Total Phosphorus were manipulated. The second conclusion that I would challenge is that prey-switching behavior exhibited by steelhead and lake trout diminished their impact on alewife stocks, which based on the stable isotope food habits data for Lake Michigan salmonines, totally ignores documentation that lake trout preferential predation on sexually mature adult alewife.

They conclude that stocking species array manipulations would have little or no impact on forage biomass levels, largely because the consumption component of the model specific to lake trout is inaccurate and grossly understates their foraging impacts on the alewife stock. They contend the bottom-up impacts have the greatest impacts on constricting biomass, arguing the Total P enhancement would have marked beneficial impacts on the salmonine biomass lakewide.

The authors go on to conclude that no wide-scale salmonine food habits data in the current era exists for Lake Michigan fishes. Gee, I thought that stable isotope food habits data derived by the USFWS essentially trumps all stomach analysis techniques, since it yields a tissue level chronologic signature of what a species consumes over many months of feeding, not a couple of days or weeks within a seasonal sequence of samples.  The other point of interest is that stable isotopic food habits signatures can be employed to determine quite accurately the degree and temporal extent of food habits overlap, as well as degree of interspecific competition among species.  Then again, if you ignore its existence, it actually does have no validity or impact as a guide to management decisions or, for that matter, direction.

Now, let's toss-in the Quagga sp mussel colony conduit that taps dry fallout of methyl-mercury out to depths of nearly three hundred feet in lake sections and time intervals absent stratification...  IF round goby are deemed "the new alewife", then I would also rightfully and accurately conclude that lake trout are still the "toxic box of fish fillets" that they were in the interval two decades prior the our current fishery's existence.
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Redrover

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Re: An excellent example of how paradigm prejudice impacts fisherey science
« Reply #3 on: August 21, 2017, 11:34:53 AM »

I have always felt that that the users have never really had much of a say in wildlife management and a prerequisite
of  leading these agencies should be demonstrated abilities to take
(go out in the field and catch/fish/hunt—not net or shock, tranqilize or tag),
as well as manage according ot the books.

I always see these outreach and public forums and then watch as the ship steers in an entire different direction from anything mentioned there

Activists—or the very least, urbanites with very little fisheries and wildlife experience—have made their way into these high ranking positions as indicated by the skew/ environmental mission they seem to be on.

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Dire Wolf

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Re: An excellent example of how paradigm prejudice impacts fisherey science
« Reply #4 on: August 22, 2017, 04:26:14 PM »

Dexter was a bass fisherman when I spend time around him. Jay Wesley maintains he is a pier fisherman.

The whole lake trout are the answer thing is so ingrained into the USFWS and USGS personnel that they cannot see any other option. They maintain that their goals are longterm best for the Great Lakes. Maybe that is why they have been so willing to throw taxpayer money at lake trout rehabilitation in the lower Great Lakes for five decades without it actually happening. Even more odd when you consider that salmon did it on there own (developed strains that reproduce naturally, despite being susceptible to EMS like all other salmonines)-truly odd, and stupid. When you layer-in that they receive no funding from D-J monies; no incentive to manage to maximize sport fishery revenue.  But, their concern is purely for the resource's well-being, just ask.

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