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Wednesday, December 7, 2011

Lake Huron Predator Diet Study

Here is a report from Jeff Schaeffer of the U.S. Geological Survey (USGS) Great Lakes Science Center: 
The third and final year of the Lake Huron predator diet study has once again been successful.

We still have many frozen samples, but expect that once again anglers were able to again provide about 2,000 stomachs during 2011.
Our total count for three years will be over 7,000, which is almost unheard of in a diet study, especially with large piscivores.

The study has been an unqualified success. We learned (and are still learning) how predators have responded to food web changes in Lake Huron, and study results are already being used in management decisions and as inputs in several models being developed to better understand Lake Huron's aquatic community. Results have been presented at a variety of venues including fishing club meetings, national fishery meetings, and even to the Great Lakes Fishery Commission and Michigan's Natural Resources Council. At least two graduate students have used study data as part of their theses, and more will likely use the data over the next few years. In addition, the story of how we came together to achieve these results has been "the talk of the town" in several meetings. The idea that citizens can do great science is topic of discussion among many scientists, but we simply did it.

The data collection part of the study is now over, and we will not collect stomachs during 2012. There are many people who have asked that the study be continued, but we need to move into the next phase with these thoughts in mind.

1. The study is continuing, but we have a huge amount of data to summarize, analyze, and publish. This much effort deserved publication in journals and we need to make sure that happens. This is a full time job that will occupy our time during 2012.

2. We believe strongly that we have already asked too much of you, and we can not ask any more.

3. The Lake Huron fish community has not changed that much over the past three years in that alewife are still scarce and prey biomass is likely low compared to the years prior to 1994, and especially during the 1980's when the previous diet study was performed. Three years of great data given that situation are more than adequate to answer all the questions that this study was designed to answer.

4. We are faced with shrinking budgets, and may not have the resources to fund additional sample processing. Ed and I also have additional responsibilities and new projects that require our time and attention. The new projects are one of the reasons you have not heard much from us over the fishing season.

For all those reasons, it is time to stop collecting new data and devote our attention the data we have. If any of you have stomachs that we have not picked up, please email Ethan Bright (Ebright@usgs.gov) so we can make arrangements to pick them up.

In summary, we can't thank you enough, although I will remind you that I made a wager three years ago at one of the spring workshops. Someone in the audience stated that "I would love to help with this, but we have done this before and we never see any results". My response was this: "if you guys get us enough stomachs for a publishable study, I will present results at your club's spring banquet or meeting". I would have to say that you won that bet, and I don't think that I was ever so happy to lose a wager. So our plan is to share study results as soon as we can, and hopefully begin that process by next spring.

We wish you happy holidays and best of luck for next year's fishing season.



Jeff Schaeffer
USGS Great Lakes Science Center
1451 Green Rd. Ann Arbor, MI 48105
734-214-7250 (voice)
734-994-8780 (fax)

Thanks to Julie shafto for sharing this information.

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