Rusty crayfish impacts on waterfowl migration patterns?

RLLigman

Well-known member
I have been having an ongoing conversation with a fellow waterfowler who works for a water quality consulting firm that has several ongoing monitoring contracts with GLIFWC Tribes and private lake property owner associations in the western U.P. and northern Wisconsin. Recently, Bill brought-up an observation related to waterfowl migration and density on several large lakes his employer does monitoring on for invasive plants and "critters'. He mentioned he has observed a marked decline in wild celery density, as well as overall aquatic macrophyte distribution and densities in lakes now infested with invasive rusty crayfish.

Bill has concluded that this has had a marked negative influence on how long waterfowl (particularly divers) remain on these lakes, as well as to what degree they now concentrate.

Has anyone who hunts waterfowl noticed this trend in Iowa waters, northern Wisconsin and Illinois and Minnesota lakes or water bodies in the western U.P. of Michigan?

https://www.bing.com/...dex=1&ajaxhist=0
 
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Interesting, had not heard about this native invasive.
Given that they are native to other basins in the US, I wonder what natural predator or other control mechanism is not present in the "invaded" areas?
 
MAN relies most heavily on large shallow water bodies. Here we call them Game Lakes or Environmental Lakes.

I would be hard pressed to find anything more than a "contributing factor" from Rusty Crayfish.

Shoreline development, ag/residential/urban run off, common carp, zebra mussels, dams, and eurasian milfoil/hybrid cattail are much more likely "point" sources if degraded habitat, most notably for divers is our loss of Freshwater Shrimp.

I haven't pulled a decoy line with shrimp on it in 20+ years.
 
In the area you mention I'm not sure how you could narrow it down to any one invasive. They have plenty in that part of the country.

I do know there is a lot of worry about what they could do in SD. So far only in the lower Missouri river.

Tim
 
RobF, never heard of the lake terms you refer to. Yes, many of these lakes in northern Wisconsin and the western U.P. have residential development, but I would not rank this as the principal diver of waterfowl (divers) habitat declines or water quality degradation, since these lake systems are characterized by low carbonate hardness values with associated low carbonate/bi-carbonate buffering capacity. Significant nutrient inflows from fertilizer miss-use or over application within the watershed, leaking septic systems, etc. that would result in water quality degradation would initially manifest in an uptick in aquatic macrophyte densities, eventually shifting over to blue-green algal blooms as dissolved nitrogen becomes limiting. What is actually occurring is a near uniform decline in macrophytes throughout the photic zone, something that I would also not attribute to common carp feeding activity, since their impacts are limited to waters generally less than two meters in depth. Vallisineria sp. declines have been quite marked, based on observations conducted by Bill and his co-workers.

You also mention the loss of freshwater shrimp...which are generally known as Mysis diluviana, at least when I was studying them as part of my MS reseach.. Aren't you referring to amphipods...genus Gammarus sp.? I know lakes and vernal wetlands in Wisconsin have suffered diminished populations due to bluntnose minnow introductions via the bait industry, but I am not aware of any lake systems where they are lost completely. The other point of consideration is that their habitat is the stands of submergent macrophytes that rusty crayfish remove via their feeding activity. When I was in "cow college" we learned that micro-habitat degradations generally precede species declines, not the converse.
 
I can't speak to the midwest or to rusty crayfish impacts on waterfowl. But RL's question and the subsequent discussion highlight an important issue that we don't think about often enough--the role that the live bait industry plays in introducing non-native species into habitats where they did not previously exist.

Rusty crayfish has been in Maine for at least several decades and is believed to have been introduced here via the bait bucket. (Transportation of bait FISH across the state line is illegal, but crustaceans could be moved legally.) Non-native baitfish introductions--which may have occurred from accidental release of live bait fish; from illegal introductions to "improve forage"; or from bait dealers introducing species to ensure a supply of harvestable bait--have resulted in wide spread introduction of many non-native fish species. Introduction of rainbow smelt into northern Maine lakes is implicated in declines of lake whitefish, landlocked Arctic charr, and brook trout in Maine.

Many western states have very strict protocols on transport, sale, and use of live baitfish, and I know the Vermont has recently changed its rules in response to concerns about the viral disease VHS. (Maybe some of the Great Lakes states, too?)

Aquatic systems, especially northern lakes and ponds, are extremely vulnerable to ecological change from changes in the native flora and fauna. We need to be thinking about our own role introducing new species.

Fortunately, the days of live decoys and release of domesticated ducks are pretty much over, so perhaps we duckhunters have less to answer for than anglers do.
 
MN has 3 distinct biomes: coniferus forest; oak/sand/Savannah; prairie. I generally cover the 2 least like the UP. I cover small meso and large eutro.

The rusty crawfish MIGHT have a more pronounced affect in historical Bluebill areas like Lake Plataganet, Winnibigosh, Leech, Cass, etc. These are larger Mesotrophic Lakes; however, all of these IN MN are hyoerpopulated, run off city waste, etc., and contain enough nematodes to wipe Bluebills out by the 1,000s.

We've got so much crap on top to reason through in these waters that are low hanging fruit, no biologist in MN is going to say "Rusty Crawfish is Apex degredator.

So, if u have a hypothesis to prove, there's a bunch of lakes I'd start with.

I don't care what you call them, those little pink shrimp-spider looking things meant ducks across a wider species count and higher bags. There seemed like "the more the better" as compared to spiny waterfleas, round goby, zebes, carp, fatheads, etc, etc....
 
Rob, there is an old woodsman's saying that is quite applicable: You have to know what the woods look like, before you can recognize the unusual.
Understanding the mechanics of how nutrients and energy are cycled through a lake system by it biotic community takes you a long way toward prioritizing a remediation plan to counter Human activity and use associated degradations.


Jeff, a perfect example of what you underscore is offered-up by the current Lake Michigan. Lake Michigan contains 184 documented invasive species by current count. Yet, for fifty years the USFWS/USGS have been pushing lake trout as the keystone predator via their rehabilitation efforts...that's right fifty years of effort. Or, why I quit the USFWS Sea Lamprey Reseach lab staff and left for the private sector. Over the course of this "management interval" introduced Pacific salmon have developed naturally reproducing populations, unlike "native" lake trout. Recent data indicate that, absent thermal stratification dreissenid mussel colonies are capable of filtering the entire water column out to depths of 90m! One of the folks I used to work with at MSU's Great Lakes Research Lab. now heads the data analysis and collection arm in the MDNR that is responsible for publishing and updating the Fish Consumption Advisory. Quagga sp. are the dominant dreissenid mussel in the Great Lakes, displacing zebra mussels from substrates deeper than roughly ten meters. A couple of other Ponto-Caspian invasives came along with the Quagga sp. mussels, round goby, and Echinogammarus ischnus amphipods. Essentially these three organisms have developed symbiotic colonies and nearly all hard substrate surfaces where the excrement packets expelled by the mussels (pseudo feces) are cycled through the invasive amphipods who are in-turn eaten by round goby. Its a little more involved than this, but I am simplifying for brevity purposes. Dry fallout of inorganic mercury is the principal means of mercury contamination within the Lake Michigan watershed. Methylation of Hg is accomplished at the bacterial level in aquatic systems. Energy density analysis of round goby pegs them at roughly 50-60% of alewife and rainbow smelt stocks.

After viewing variety of data analyses at the Great Lake Fishery Commissions annual Lake Committee meetings, it became evident that these invasive mussel colonies would like be a conduit for methyl-mercury passage and bio-magnification to a variety of fish species that feed on round goby...nearly every fish in the system, except Pacific salmon, but, particularly lake trout since they are long-lived slow growing fish. Lake trout became the numerically dominant salmonine in Lake Michigan in 2007/2008 displacing Chinook salmon.

WDNR methyl-mercury lake trout fillet data now indicate that mercury content of a newly legal lake trout is the rough equivalent of that of a spawning Chinook salmon, that is about to expire and vacate the system. MDNR data now indicate that methyl-mercury content of lake trout has displace dioxin-like PCB congeners as the toxicant of greatest concern in fillets from the most recent sampling efforts.

What makes methyl-mercury a greater contaminant risk versus organo-chlorine insecticides is that it accumulates in muscle, and not adipose tissue like PCBs, endrin. dieldrin, toxaphene, and Dioxin-like PCB congeners.

A bit different impact of invasive dreissenid mussels from the more broadly communicated bottom-up impacts on lake wide productivity.
 
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RL- fabulous.

Recognize the woods you're in. The level of discussion it appears you are seeking likely lay in a different forest.

I count myself among the lucky that know what others mean when they say: hell diver, buffalo head, black jack, and cream sh!tter.

In my vernacular "fresh water shrimp" is to "things ducks eat that stick to anchor lines" as Kleenex is to facial tissue.

In MN I have not seen nor heard any mention of rusty crawfish being complicit in diver population reduction.

Call Al Afton, his team would likely be able to discuss biome biomass per X quantity of indigenous and invasive Flora/fauna.

Wish I could've have supported your thesis as it makes sense to me.

Very best,

Rob
 
Rob, I tend to mirror back how people treat me, so, when I ask a broadly subjective question and ONE of the responses contains a dismissive statement with an accompanying pronouncement regarding the loss of an organism I know to not be absent as the principal driving diver duck declines, I ask some defining follow-up questions. When those follow-up questions underscore that the individual that made them knows not only next to nothing about the organism, its habitat and life history, or its relationship within the food web that would define its importance; to divers as well as all other ecosystem components, I tend to get a bit prickly regarding the value of that person's perspective!

Thanks for underscoring why I don't write a check to your employer anymore!
 
Now, let's finish the Lake Michigan salmonine management efforts story...

All salmon and trout are susceptible to EMS (early mortality syndrome), which is induced via ingestion of high thiaminase content forage fish, specifically alewife and rainbow smelt. Nearly a decade ago NWF/USGS researchers documented that lake trout are particularly susceptible to EMS to the point that their principal forage base components, smelt and alewife, were likely the major negative impact factor on natural reproduction rates in the lower Great Lakes. In this background, highly altered food-web dominated by invasive species introduced Pacific salmon have slowly developed naturally reproducing stocks/races/demes, with these cohorts of naturally reproducing fish slowly expanding since the 1980s (Yes, that's right, right through the BKD era.) to current levels where they comprise roughly 60% of the open lake stock. These fish originate primarily from Michigan tributaries on the eastern side of the Lake Michigan basin, but there is also a large cohort of swim-over fish from Lake Huron's Canadian tributaries.

The Lake Michigan Management Committee, as well as the USFWS/ USGS recognize Atlantic salmon as a Great Lakes endemic species despite the historical records only indicating that they never existed west of the Niagara falls complex, limited to Lake Ontario. As early as the 1860s, alewife were described to exist in large numbers in Lake Ontario's basin as well, yet they are deemed an invasive...

There have been two principal drivers of the decline in forage fish abundance within Lake Michigan, mirrored as well in Lake Huron, eventually contributing to the forage base's collapse over the 2003-2006 interval in Lake Huron. The major characteristic displayed by the alewife stock which is the dominant forage stock component, both numerically as well as on a biomass basis is the slow truncation of sexually mature age-classes within the stock array over time. Lake Michigan had eight alewife age-classes documented in 2007, declining to one and some "change" in 2016 trawl samples conducted lakewide by the USGS . This has been attributed to over-consumption of alewife from a top down perspective, principally by Chinook salmon stocks, with additional forage pressure from the remaining salmonine stock array. The other issue influencing Lake Michigan's productivity is the bottom-up effects tied to driessenid mussel filter feeding and colony proliferation impacts, which have been profound. This has influenced alewife year-class success rates largely via reductions in the spring diatom blooms lake wide. Diatoms are a high omega free fatty acid content phytoplankton that larval alewife feed on at swim-up, after the have absorbed their yolk sac energy. Declines in the Deep Chlorophyll Layer of diatoms have likely also contributed to declines in Mysis diluviana abundance, and also the near total loss of Diporeia sp. deepwater amphipods I strongly suspect, based on preliminary data that declines in free fatty acid content in Diporeia sp. on a seasonal basis have markedly influenced their basin wide decline.

Two years ago the USFWS reported on a large sample size, multiple salmonine species stable isotope food habits analysis at the Great Lakes Fishery Commission Lake Committee annual meetings. The over-riding value of stable isotope food habits analysis is that the ratios exhibited in samples are essentially a multi-month snapshot of the subject's food habits, rather than the several weeks at a shot data derived from stomach content analysis done at multiple intervals over the course of a year. Matt Kornis presented the data, essentially interpreting it from both a 'this is where this species eats within the food web' perspective as well as doing an analysis of degree of dietary niche overlap for Lake Michigan salmonines. Stable isotope "signatures" of carbon and nitrogen were first determined for forage web constituents, both invertebrate and vertebrates, to enable interpretation of ratios obtained from sample fish. Lake trout were determined to have one of the broadest forage arrays among the salmonine stocks in Lake Michigan, while Chinook salmon were determined to have the most narrow forage base, essentially consisting of invertebrates in their first nine months in the open lake environment, shifting to a nearly entirely alewife dependent diet from that point on.

One of the most intriguing outcomes form the stable isotope analysis food habits study was the data on alewife stock consumption by the salmonine array. USFWS researcher obtained stable isotope signatures were submitted from other researcher's for BOTH adult and juvenile alewife. What the data actually indicated, post-analysis, was that all of the existing salmonine stock component species have largely shifted over to consume the more numerous juvenile alewife array as the alewife adult stock component has declined. Obviously, this has negative repercussions on age-class abundance as these fish move toward sexual maturity and the consequent opportunity to replace themselves in the stock and/or expand it. The standout finding from the S-I food habits data was the conclusion that lake trout fed preferentially on the rapidly declining adult alewife stock component. Do Pacific salmon eat adult alewife? Yes, but not on a preferential basis, which is key, given the reality that lake trout became the numerically dominant stock component in the in the 2007-2008. So, after a management program that has consisted of single species reductions of Chinook salmon stocking, with no beneficial stabilization of alewife stocks you would conclude that this finding would further support the rationale of a mixed species salmonine stocking reduction.

Now, let's toss-in that MSU's Quantitative Fisheries Center was contracted by the Lake Michigan Comm. of the Great Lakes Fishery Commission to develop a Decision Analysis Model that via multi-year runs of various stocking scenarios determined, from a very broad initial array, that four management options were the most viable to offer to the Public for input to guide fishery managers stocking efforts to maintain a biologically viable alewife stock within specific upper and lower bounds to maintain a stable sport fishery, while not allowing them to again overpopulate the lake basin. Each of these stocking options was loaded into the DA Model and 100 simulations of that stocking option were analyzed to be a best fit for the pre-determined Sport fishery stock management model. Option 4: A mixed species stocking reduction consisting primarily of Chinook salmon, but with proportional lake trout, steelhead stocking reduction components as well, had the best fit. Public respondents voted. Most of them voted for Option 4, by a narrow margin. Fishery managers enacted Option 1- a Chinook only reduction. Why? They had predetermined that no fish in multi-year hatchery rearing cycles would be tossed out! Economics trumps science once again!

Well, after much Public shaming and push-back over the last nine months, the Lake Michigan Management Committee has now backed away from enacting another Chinook only reduction in salmonine stocking, to now include reductions in lake trout stocking and liberalization of creel limits in southern basin waters. So much for science based management of an 8 billion dollar sport fishery!

No, to my knowledge no Public presentation of the USFWS Stable Isotope Salmonine food habits analysis has contained the data on differential preferential consumption of adult alewife by lake trout.

It is incumbent on all resource management organizations to periodically sit-down and assess whether the paradigm that guides their approach, management programs, and philosophies is realistic, based on current science, and relevant!
 
Whatever, Sheldon.

If you want to have a biological discussion with someone in MN, Peter Sorenson might be the best place to start:

104 Hodson Hall
1980 Folwell Avenue
St. Paul, MN 55108
soren003@umn.edu
+1 612 624 4997

His primary interest is invasive fish, but he's been working on establishing a larger coalition for invasive study. I believe he had a proposal to the State Legislature to found an Invasive Institute of some sort at the Univ of MN.

Game Lakes/Environmental Lakes in MN are Socio-Political terms used for certain types of lakes that have significant conservation value. I'm not a biologist, congratulations to you. In MN (not MAN, as my auto-correct LOVES), Rusty Crayfish are not readily known or discussed in conservation conversation. My comments were not dismissive, but a statement regarding the priorities discussed in Minnesota Conservation as it pertains to affects on our waters. If you want information on run off buffers to assist clean water, "we've" got TONS of that, where the "we've" is the collective body of information generally available to lay people such as myself. Looking for a study on Rusty Crayfish effects on MN waters, I'm hard pressed to provide one because I'd have no idea where to find it. Perhaps a trip to the Natural Resources Library at the U of M: https://www.lib.umn.edu/naturalresources

The Game Lakes Initiative started in the 1970's with the founding of the Minnesota Waterfowl Association, is a primary beneficiary of our State Duck Stamp (lobbied for by the Minnesota Waterfowl Association) and leverages multiple resources to reestablish biological priority. I should update my vernacular, "Game Lakes" is a term from the originating efforts, it appears at some point "Wildlife Lake" was adopted as it is broader and attractive to a larger constituency: http://www.dnr.state.mn.us/wildlife/shallowlakes/designation.html

Here is a project that highlights the typical effort and priority issues in MN of high water, runoff, and rough fish. It's a DU article so they take a very self-appreciative tone, even applying their own tag "Living Lakes"; however, this work was undertaken by multiple conservation orgs, private citizens, and multitudes of governing bodies with the aid of the MN Wildlife Lake designation. The pertinent article begins on page 4: https://www.ducks.org/media/Minnesota/MN%20Content/_documents/MN%20DU%20Winter%202014%20Newsletter%20-%20Lake%20Christina%20Comeback.pdf

As per not writing checks to my employer, I'm certain they would be as surprised as I am. I haven't pulled a W-2 since 2009 other than an overnight janitorial stint. Prior to that I worked for an accounting firm and a construction company.

If you've purchased products from my companies, the companies I've founded and own, and have been dissatisfied with your purchase, please send me a PM or contact me through the appropriate product website. I happily work with my customers to insure a positive experience, including money back guarantee.

As mentioned earlier, I am ALL FOR new research that explores effects on clean water and I am a HUGE believer in finding root cause. Got get 'em. Just surprised at your disappointment that the discussion on this site has been too elementary, most of us are awed at what Mr. Sanford does by incorporating duck heads into wooden handles.....
 
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