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Member
Posts: 2680
Location: Essexville, MI./Saginaw Bay. | Heres an e-mail corrispondence between me and my Mich. DNR fishing biologist buddy, that you may all find interesting.
Dave.
Got a question for you. With what we know now about the recent HUGE natural reproduction on the Saginaw Bay last year. I'd like to know if you could give me an idea about what size female walleyes you think made up the viable reproductive majority last season?
Through other questions and discussions on the many web site Fishing boards I visit, I have discovered with amazement that it's not the Monster Females that are the most fertile when it comes to natural reproduction on Lake Erie. But have also noted that their females seem to mature faster, with many 3 to 4 year olds in the 22 inch range, already sporting big belly full of eggs.
I have not personally seen many of our female walleye in that size category, bulging with mature eggs. Is Erie's (young female spawner) phenomena strictly a Reef spawning specie and ours a river spawner specie? Or do you think if this (natural reproduction) keeps up for a few years on the Bay, we to would start to see younger, smaller, viable spawners?
And lastly. If we do start to get better natural reproduction, wouldn't it also be a good idea to protect our best spawners through expanded seasonal regulations (i.e.the Bay) during peak spawn times? Your bud. Dan.
Dan:
All good questions.
Its impossible to know for sure which sizes of females contributed the most reproductively to the record 2003 year class but we have some idea from our annual monitoring of the walleye spawning run in the Tittabawassee River. As you know, many of Saginaw Bay's walleyes migrate up into the Saginaw River and then into the Tittabawassee River (a tributary of the Saginaw R.) for spawning each spring. We believe that the spawning activity in the Tittabawassee River to be one of the largest contributors of natural reproduction each year (another big one is the walleye migration up the Flint River).
In our annual monitoring, we have learned that we typically don't see sexually mature female walleyes until age 3 or 4 and often not in a big way until age 4 or 5. In the 2003 run (that contributed to the record year class), a full 26% of the female spawners were just age 5. This is still fairly young as female walleye go. 26% is a large proportion for a single year class in a spawning run. In 2003, the age 5 fish trace back to the 1998 year class (which was our previous record until 2003 came along). The strength of the 1998 year class explains why they comprised such a large proportion in the spawning run that year. The average age of female spawning walleye in 2003 was 7.4 years old and some were as old as 14.
In answer to your original question, there have been studies done that indicate that egg viability is often greatest in the youngest mature female members of a fish population as opposed to the oldest members. It stands to reason that there is vitality that often comes with youth. Now typically the larger (and older) a female is, the more eggs she will produce so there is some trade off. I know many anglers feel strongly about preserving the very largest, oldest females for spawning purposes. I think its debatable if these fish contribute any more than their younger counter parts. Probably not given that there are naturally fewer of them and that egg viability may be somewhat less.
An important thing to remember is what actually shapes year class strength each year in a fish population. Biologists generally believe that environmental and habitat conditions far outweigh general egg production numbers in most years and at normal population densities. In other words, we rarely are brood stock limited. Consequently, I would never fault an angler for wanting to keep a large female walleye. You might ask then why Michigan maintains so many closed seasons during the spring. The answer is that spawning fish are sometimes more vulnerable to harvest (because they are congregated for example) and could be susceptible to over harvest in some situations. It is possible that a fish population could be harmed if too much harvest took place just then.
You asked if we should add additional fishing regulations to protect walleye in the bay. I'm not sure if you mean spawning closures or length limits. The spawning closure isn't necessary (in the bay) because we don't think there is much reef spawning taking place any ways. Its nearly all in the rivers. Another reason is that the amount of fishing activity (pressure) is very light in the bay during late March / early April (weather is just too crummy usually). Closing it really wouldn't save much any ways. Additional lengh limit protection isn't necessary (at this time) for the reasons I mentioned earlier (year class strengh isn't ususally a function of spawner numbers) and because the overall exploitation rate (proportion harvested each year) is within an acceptable range. Jim Baker, the fishery manager for the bay, (and I) have indicated, however, that we will continue to monitor the situation and as recovery progresses, we will continue to reflect on the on-going appropriateness of the current harvest regulations in place.
An interesting side question is; was the large 1998 year class (maturing in 2003) one of the factors contributing to the record 2003 year class? It certainly didn't hurt any. Could be one more factor that lined up just right last spring. Generally though, we still think it was primarily ideal spring weather and low alewife abundance that set the stage for very good production.
By the way, I just returned from our annual walleye tagging and spawn collection effort in the Tittabawassee River. We again tagged and released 3,000 walleyes and the hatchery folks collected their necessary egg numbers for stocking purposes (back into the bay). I know everyone has been wondering where the walleyes were this winter. All I can say is that it appeared to us that this years migration was as strong as ever in numbers, and yes the 98's seemed to be there in force.
-Dave
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Location: Rhinelander | Great information, thanks! The info from the DNR is a great read. | |
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Member
Posts: 299
Location: Wind lake, Wi | So Dan what is the average size of the 98' class? What are the daily limits set for saginaw? And do anglers seem to take any size fish for the frying pan, much like an erie charter would? Just some questions I am interested in. Thanks, eyefever. | |
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Posts: 2680
Location: Essexville, MI./Saginaw Bay. | Fever.
Not a biologist, but I'm guessing between 5 and 7 pounds depennding on what sex the fish is. I'm still in shock thinking that they shocked a walleye that was 14 years old while taking eggs. That's like a 100 year old man in human years.
Edited by walleye express 4/2/2004 10:20 PM
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Member
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Location: Kaukauna WI | Dan
Thank you for sharing this information. Saginaw is one of my favorite places to go and fish and this information is good to know on thoughts of harvesting of bigger fish. One question comes to mind when you say they shocked up a 14 pound fish do DNR feel that possible a State Record is swimming in the bay or by the Islands and if so could you have a Grady White ready to catch it with me on board. HEHEHE.
Thanks again for sharing information we all of us.
Michael Dutton
Michagain record is just over 16 pounds I think
Edited by irishwebs 4/2/2004 10:36 PM
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Member
Posts: 299
Location: Wind lake, Wi | Thanks Dan | |
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Member
Posts: 2680
Location: Essexville, MI./Saginaw Bay. | Mike.
Similar to our phone conversation, we're on the wrong page again. Even though I have personally held in my hands a 15 pounder while helping the DNR take eggs two years ago. Daves e-mail mentions a 14 YEAR OLD walleye that they shocked, not a 14 pounder. And even though Dave has held a lot more walleyes in his hands than me during the very best times to see a new state record. He says he's never seen one bigger then the exsisting one of 17.3. | |
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Member
Posts: 714
| Dan,
I understand that each body of water has its own eco-system and inherent characteristics in regards to fish within that system, but up here on Mille Lacs, it is not that uncommon to see 14 year old fish. Granted, some of that is caused by slot restrictions preserving them from the filet knife though the years, but that is not always the case. Many times we see old fish coming in to spawn that are very old, and probably beyond their prime for spawning, but still following natures intended ritual. Two years ago a DNR officer measured a female that was 36+" in a stream during the spawn. 
Have you seen or know of any studies from the "Bay" that outline average life expectancies for the fish in your system? I only ask because you seem surprised by the age factor here and it makes me wonder. You know, I'm sure, the therories about rich forage base, faster growth, shorter life span....ect. versus the colder water, slower growth, longer life. I was told once by a DNR agent that our 16" walleyes are 4 years old, and that the growth rate slows as they get older, to the point that a 28" trophy female could be as much as 25 years old, and that the 22-24" males we catch are every bit as much a trophy as those big females because they are the same age! | |
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Posts: 363
Location: Kaukauna WI | I see the way of my error and thank you for pointing out so gently hehehe It must be my dyslexia I read the post to quick. But I always wondered if the next state recorded would come out of this body of water. I have had the privilege of catching few over ten pounds there and look forward in coming back this coming year and fishing Saginaw Bay again.
Michael
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Member
Posts: 2680
Location: Essexville, MI./Saginaw Bay. | Jack.
That is indeed the case on the Saginaw Bay. Our fish grow faster and bigger and live shorter life spans that many many other bodies of water. They figure a 10 pounder could be as young as 7 years old on the Bay. | |
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Concerning the Saginaw Bays natural reproduction last year.