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Member
Posts: 2680
Location: Essexville, MI./Saginaw Bay. | Dan.
I've been wondering when you'd ask. Yes, we finished last week. It's
hard to answer your question this year, however, because there was such
a range of sizes and growth rates among the juvenile walleye, that it
was very difficult to recognize what was an age-0 (YOY) walleye and what
was a yearling and older. Normally we could just visually separate the
YOY and get a count and then see what the catch rate was and compare to
other years. This time, we'll have to wait until we age the fish so we
can be sure we know what year class each fish is from.
However, based on our best guess at what a YOY was, it looks like maybe
(and this still have to be confirmed) that the natural year class
produced this year was comparable to 1998 level. You will recall that
the 1998 year class was our old record before this string of strong natural year
classes came along beginning in 2003. So to say that this year class is
maybe like 1998, isn't too bad.
Previously we would have characterized that as a strong year class. Now, however, (with recent years to compare to) a year class of the 1998 proportion might only be characterized as "moderate" in size. Again, however, once we get to aging these fish (over the next few months) we will be able to put some specific numbers to this and our assessment may change up or down.
A more modest year class of walleye this year, however, is neither
unexpected nor necessarily a bad thing. Remember that its rare to have a
strong year class follow another strong year class in sequence in a
walleye population. We've had three in a row so far on Saginaw Bay so
its not surprising that this one is more modest (relatively speaking).
Also we observed that our overall prey base in the bay this year is some
of the lowest we've measured in many years. I feel pretty sure this is a
result of the much increased predation pressure from the growing
abundance of walleyes. You'll remember that increasing predation rates
was one of our recovery goals so this too isn't necessarily a bad thing.
The growth rates of walleye were anticipated to come down as abundance
increases and that's exactly what's happening. In the long run, year
classes as strong as 2003 - 2005 may not be fully sustainable, and a
series of more intermediate or modest year classes is probably more
desirable. By depending on natural reproduction (as opposed to
stocking), we are allowing the system to regulate it's self to the right
balance. At least that's our goal.
I still think the decision to not stock this past year was the right
decision. The decision to stock or not for the coming year won't be made
until about February.
In our survey nets, we caught a lot of older and adult walleye as
expected (mostly from the 2003 - 2005 year classes).
Of course we have similar information from our survey regarding perch
and other species too and we'll be better able to summarize all that in
a few months. Remember this is all very preliminary, based on initial
impressions. Check back around January or February for the complete
picture. | |
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Location: Rhinelander | Sounds like the future of the Bay is solid, many more happy anglers to come. | |
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Member
Posts: 2680
Location: Essexville, MI./Saginaw Bay. | Dave.
Refering to your results that the prey base seemed to be down.
What is the DNR classifying/calling prey?
Would your trawl nets get near the bottom where the Gobies live during these trawls?
Are you trawling certain zones in the water column, and would the small mesh nets capture all the smaller prey or just certain sizes?
Dan.
In general we index 'prey' as the soft rayed fishes that include: Alewife (usually YOY in the bay which there has been few of since 2004), smelt, gizzard shad (again YOY), spottail shiners, trout-perch, and round goby.
There are others that might be included but these are the main ones we index. Yes gobies are very vulnerable to the trawls (trawls do best on bottom-oriented species, and less well on suspended species). Gobies were down this year, YOY Alewives remain scarce, gizzard shad YOY were up some, spottails were up some. Emerald shiners (not normally part of this index) were also down.
This doesn't tell the whole story since we know that walleye will also eat spiny rayed prey too. We'll be assembling a more full and representative picture of the prey base in the coming months. It appears that the main prey index will be down but no one is necessarily saying there isn't enough forage or anything like that. We'll need to look at the whole picture. Also, remember that until now, there was a mismatch with too much prey and not enough predators in the bay (kind of the opposite of the main basin). One of our goals was to bring this more in balance. We'll be looking to the walleye growth rate to help us decide where that balance is. Again, this information is all preliminary and we'll have the full analysis later this winter.
Edited by walleye express 9/29/2006 7:43 AM
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2006 Preliminary Spring Spawning results for Saginaw Bay.