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2009 Saginaw Bay Trawl Results and Question.


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Wrote my fish biologist buddy an E-mail asking a question and requesting the trawl results for this year. That question and his reply below.

Dave.

Been knocking the hell out of the walleyes on the river lately, both day and night. Attached is a picture of a small 5 incher I pulled out of the stomach of a 6 pounder from last night. I've also recently seen perch fishermen pulling up one juvenile walleye after the other on the river using small minnows, as the river is gorged with small shiners and shad. This whole scenario got me thinking about something. What is the science and thought processes for doing the Fish data Trawls in September on the Bay. Wouldn't a big amount of these juveniles that you base your spring spawn data and findings on, be in the river and out of Trawls way (so to speak). And please let me know what the Trawl result and findings were for this September on the Bay (if you have them). Thank's Dave. Dan.

Dan:

I'm glad to hear the fishing is keeping up. The thought process is that in the late summer or early fall, that year's production of juveniles (young-of-the-year or what we sometimes call age-0s) would be large enough to catch. If we trawled in the summer or spring, they would just be fry or small fingerlings. By September, they are catchable. What you and others are mostly seing and getting in the river are yearlings or age-2s. We see a lot of those in the trawls too and in our gillnets. Yes there are lots in the river but there are still lots in the bay too. We don't have to be able to access all the fish during a survey, just sample consistently in the same place and the differences we see from year to year should represent genuine change (trends). Also I suspect the concentration of fish in the river may be greater in October than early September when we do our survey.

And yes we have our preliminary findings for this past years hatch. The good news is that our September trawling catch rate of YOY or age-0 walleyes and the spring hatch year class of 2009 was yet another new record!. Huge numbers form all over the bay. Bigger numbers than any time we have surveyed (since 1971) and even bigger than the huge 2003 year class. This bodes very well for the continued high level of walleyes in the bay. The bad news is that the 2008 year class was much smaller (measured this year as yearlings), but we knew that. The bay now seems to be establishing strong and weaker year classes of walleye in an alternating fashion. This is a sign that the population is nearing capacity and "density-dependent" feedback mechanisms are beginning to kick in and regulate the population size.

This was fully expected and is not necessarily a bad sign. This is typical of most walleye populations, but most populations only pull off a strong walleye year class say every few years surrounded by two or three weaker ones. Saginaw Bay seems to only endure one weaker one and then its right back to very strong ones. This walleye population continues to impress.

We have yet to do all our aging of our specimens and then I'll know more about how growth rates are trending. I.e. we have more to learn from last months collections but this is our initial observations. Things are not perfect on the bay, our perch are still not surviving well and that population/fishery is at the lowest levels we have ever measured. Perch are important to the bay, I suspect that they drive fishing pressure (effort) as much or more than walleye even do.

Our initial observations are that the bay's prey base is holding up nicely. Despite the expansion of the walleye population, the abundance of prey has not declined appreciably (in abundance but it has changed in composition).

We have some new research planned for the bay including a statistical catch at age model that will help us understand the dynamics of the walleye population. We have some other ideas in the planning stage but are not funded yet. I'll let you know more about them if they get the nod.

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Funny deal with the boat. I get home from the bar and I have a message on my business phone from Lindys. "the motor is fixed, come pick up your boat". I almost stopped back in the bar on the way back home for the second time. Took Chet a whole 30 minutes after I droped it off to fix it. New Eletric Choke Solinoid $84.00. Ten minutes labor $40.00. And you guys thought the big money was in chartering.:no:

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Ya, I figure like this. I've had that boat and motor for 21 years will little more then time ware problems with it. Had the same set of plug for 9 years. So she really don't owe me a thing. I'm glad they fixed it so fast though, as when I got home I had another message, and I booked a trip for tomorrow on the river. Fate give'ith/fate take'ith away. :P

One more thing Adam, and this is embarrassing. I totally forgot your dads name yesterday. And it was driving me nuts. Hell, I've know him as long as I have your uncle Tom. I've always been a Faces man, just cannot remember names that well.:P:D

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