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Posts: 1828
| For the fisheries biologists, the lay-man nerds, and the know-it-alls:
Does anyone have average survival statistics for muskies from year to year? I understand these things are HIGHLY variable, so I'm looking for gross approximations. Even if you think it's such guesswork that it's worthless, I want to know what you know/think.
Specifically, for natural reproduction:
1) How many eggs does the average adult female produce, assuming she's unstressed, normal water level/temperature/etc.?
2) What is a decent survival rate to assume from hatchling to age 1?
3) " " Age 1 to 2?
4) " " Age 2 to adulthood?
To get more specific - for first time stockings (into lakes with no muskies present), what could one expect for:
1) survival rate from fingerling to age 1?
2) " " age 1 to 2?
3) " " age 2 to adulthood?
And now I'm just dreaming - for stocking into lakes w/ established populations:
1) survival rate from fingerling to age 1?
2) " " age 1 to 2?
3) " " age 2 to adulthood?
Again, I understand that there are so many variables that you can't say with any certainty how many fish are going to make it from egg to adult or from stocked yearling to adult. But I have to think that there are some "rules of thumb" or approximations used in determining how many fish to stock in a new lake in order to achieve a "fishable" population, etc.
I apologize if this has already been discussed at length. I have done a fair amount of searching in the past and haven't found much. Thanks for your time and input. |
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Location: Grand Rapids, MI | Didn't feel like going to the files for this and quoting biologists because I think we can only talk in generalities here since the factors vary so greatly.
1A - 40 to 150,000.
2A - 1% is the general estimate to adult I've never seen anything from hatch to year 1
3A - 50-60% survival annually
4A - 50-60% survival annually
1B - 40-50% survival annually
2B - 50-60% survival annually
3B - 50-60% survival annually
C - Same as above. Growth increases for first time stocking but survival is generally the same.
Edited by Will Schultz 2/28/2013 12:32 PM
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Posts: 8782
| Any estimates for what percentage of eggs actually hatch? |
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Location: Grand Rapids, MI | Not sure about in the wild, something in the range of 1-10% is probably reasonable. In the hatchery from egg to fry is highly variable. At most hatcheries you'll probably hear anywhere from 10-65%. I know our hatchery biologist used a buffer last year during the fertilization process that made a dramatic difference. Without buffer the hatch rate was 18% with the buffer the hatch rate was 62%. |
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Posts: 1828
| Awesome, thank you.
Will S., by "40 - 150,000", you mean 40,000 to 150,000, right? Not 40 (as in 4 * 10)? I'm pretty sure I know the answer, but just making sure. |
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Posts: 8782
| Okay, so let's break it down...
Let's say a muskie lays 100,000 eggs. 5% hatch. 5000 hatchllings. 1% of those survive a year. That leaves 50. You can basically cut that number in half for every year that goes by. 10 years out, about the time when said muskies would be reaching a size where you could enjoy catching them, you'd have a ratio of .09765 fish left out of that single batch of eggs. Obviously there's no such thing as 9% of a fish. But there are more than one fish in the lake.
So...
Let's take a 500 acre lake with successful natural reproduction. Let's say the population is 1 adult fish for every 4 acres of water. That would mean there are 125 muskies in the lake. Presumably half are female. Let's call it 62 fish. And let's presume that they all reproduce. Taking the original 10 year figure of .09765 per egg laying female x 62. I come up with 6 fish surviving to ten years out of every season of spawning. Maybe it's two, maybe it's ten. But it's sure not many! |
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Posts: 1828
| I used the term "adulthood" without even knowing what it means [for muskies]. At what age does a musky become sexually mature? |
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Location: Grand Rapids, MI | Yes, 40,000.
Age 5-7 is generally when muskies mature (females seem to be a year later than males, at least in my neck of the woods). It's an oddly wide age range and even wider range of size considering that a 5 YO male could be 28" and a 6 YO female could be 45". I was even involved in a project where we captured a 30" 7 YO female that was giving eggs, certainly not "normal" and another one of those times that just when you think you know something about these fish mother nature shows you her screwball. |
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Posts: 427
| To me those numbers only stress how important it is to CPR. With that being said how would you feel about keeping a smaller legal fish once in a while if you live in a state like Indiana that stalks its lakes at five fish per acre every year? |
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Location: Grand Rapids, MI | hoosierhunter - 2/28/2013 4:21 PM
To me those numbers only stress how important it is to CPR. With that being said how would you feel about keeping a smaller legal fish once in a while if you live in a state like Indiana that stalks its lakes at five fish per acre every year?
That smaller, legal fish, is going to have a hard time getting any bigger if it's killed. Besides that, think about that person that's never caught a muskie and the opportunity you're taking away from them. |
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Posts: 536
| Numbers here are probably pretty accurate! keep in mind though this does happen every year so thinking of it that way makes it a little better! I do think in my opinion that smaller lakes like 300-400 acres and less for example have higher average of fish per acre giving that everything is right suitable for them! |
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Location: Green Bay, WI | Interesting thread...didn't see it before today.
I don't have the literature in front of me at the moment, but seem to recall that the "rule of thumb" for natural mortality for stocked muskellunge is about 10% per year. I believe this is a number I've been told by a biologist (or two), and I think I've also seen it mentioned in the literature. I'll try to search a bit and see if I can come up with a more dependable number, and post back if I can. But I think 10% is what I've been told by a few different folks in the past. Kevin Kapuscinski (et al) might have published this in his 2005 paper on the Green Bay population, so I'll start with that.
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Posts: 2024
| Very interesting thread. I also wonder what the scientists say about water temps affecting the sex of the fry that do hatch? In some animals temperature during incubation can determine sex. If warmer means more males, the fisheries are going to be in trouble for a while. I know the spawn is triggered by water temps, but if the water continues to heat up fast after spawn I wonder if it woould have an effect. |
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Posts: 1291
Location: Hayward, Wisconsin | Jason:
It has been studied:
https://kb.osu.edu/dspace/bitstream/handle/1811/38873/20071201-AEL-D... |
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Posts: 2024
| Interesting stuff. Thanks! |
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Posts: 81
| Great information!!! I could be wrong, but I believe our biologist(in NC) quoted our club that 20-30 % of the stocked advance fingerling muskies survive to reach adulthood. They hatch-out around 100,000 muskies per year, but we only end up with 4-5000 to stock per year. However, our DNR guys do give/trade alot of fry to neighboring states(TN, VA). I believe we would end up with more if we wanted, but the main reason to give them away is to reduce canibalism.
The past few years our biologist have been producing and stocking triploid muskies. They use increased pressure during the incubation period, I believe, in order to produce fish with three chromosomes. For those that don't know, the suspected positive of triploids is more energy going towards growth than sexual development in adult fish. Thus greater growth rates in adult fish. We wont know for a few years if it works. |
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Posts: 246
| Aren't triploid fish sterile? The latest record rainbow trout is a triploid and in my opinion it should have its own category rather than be grouped with normal fish. |
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Location: Grand Rapids, MI | NCmusky - 4/28/2013 9:16 AM
The past few years our biologist have been producing and stocking triploid muskies. They use increased pressure during the incubation period, I believe, in order to produce fish with three chromosomes. For those that don't know, the suspected positive of triploids is more energy going towards growth than sexual development in adult fish. Thus greater growth rates in adult fish. We wont know for a few years if it works.
Awesome! I've been waiting for someone to try this and I can't wait to hear how it turns out.
Yes, they're sterile and this could present an interesting option for places that stock Tigers because they can't reproduce. |
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Location: Green Bay, WI | Wow...genetically-enhanced muskellunge! In a few years we'll maybe see ski's that are tarpon size, LOL.
"Look out Mr. Spray, we've got a REAL 70-pound musky for you!"
Very interesting possibilities. I wonder if there are references about this sort of thing in the literature? Does anyone know?
TB |
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Location: Grand Rapids, MI | Tom - I was at a coolwater conference a few years ago and one of the presentations was on triploid sauger created using the pressure method. I was sitting next to our hatchery biologist and said, "we need to do this with muskies!" He wasn't too excited about it since we had just spent the last ten years working toward changing strains for the entire state. If I remember right his reaction was "give me a break, let's do one thing at a time".
To the best of my knowledge this is the first attempt at triploid muskies
http://www.thefranklinpress.com/articles/2011/10/12/news/02news.txt
Edited by Will Schultz 5/6/2013 4:42 PM
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Location: Green Bay, WI | Interesting...
A simply Google turned up this PDF, that I am going to read right now. You'll notice the last name on the list of authors!
http://preview.tinyurl.com/d23mdoz
I also found a number of resources on other species they've tried this on as well, so there should be plenty of information in that sense.
EDIT: Well, that paper wasn't as helpful as I'd hoped it would be, other than that (on page 14) it talks about the concept of triploidy a bit, and states that the fish are "mostly sterile." But the concept seems logical--take fish that would be devoting energy towards gonadal growth, and get them to somehow redirect that bioenergy towards continued somatic growth. But I'd have a few questions about that though...
1) How effective is this for other species? There are a number of other links that show up in Google, so it should be relatively easy to get some answers there.
2) Does the nature of having three sex chromosomes have any impact on the longevity of these fish? For instance in humans, the sex steroids are generally though to have a protective effect on the body...especially in females. So if a triploidy state somehow impacts the levels of sex hormones in the fish (especially the females, as they grow largest), then that might have an effect paradoxical to the intended objectives.
Anyway, lots to think about and research in that sense. I can also talk to Kevin Richards and see if he has more information, perhaps in follow-up to that contained in the paper I referenced.
TB
Edited by tcbetka 5/6/2013 6:02 PM
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Location: Grand Rapids, MI | I hope Kevin has been in contact with NC so they can present their findings to date at the symposium. |
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Posts: 81
| Will,
Emory and Cheoah are the lakes they are studying and have only been stocked with triploids. Cheoah, is a deep, cold, trout lake, while Emory is is shallow, small, mostly river, and full of suckers. So the forage bases are different and could affect growth rates.
The biggest problem is re-caputuring them. This could be due to very few surviving. If you see them(triploids) at the hatchery they appear sluggish and dazed as compared to the normal muskies in the other tanks. Anyways, apparently the biologist only got one this spring and it was from this past fall stocking. I heard this fish was around 18''. The biologist expect growth rates as juveniles to be the same as normal juvenile muskies (since at that age almost no growth goes towards sexual development) and if I recall correctly, thats about the size of normal 1 year old muskies.
So leading to Tom's question on how big do they grow down here in NC? It seems that in most of our waters a 50'' musky is pretty rare. There have been a few 51-52'' and a big 53"(my buddy got her and released her) over the past 10 years. I believe, a normal musky(non-triploid) 38-41'' is 4 years old. A few years ago a close friend got a 50.25 x 26 (41lbs) and it was 10 years old. Another muskie club member had a 47.5'' (33lbs) die on him years ago and I believe it was supposedly 7 years old. However, in my opinion those deep, clear, and very cold lakes far in the mountains (like Cheoah) they could live longer, to obtain larger dimensions.
Derek |
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Location: Green Bay, WI | There may be something to the "long-livers, slow-growers" argument. It's been used here in the Green Bay fishery many times, mainly as an argument against protecting the fish with a larger minimum size limit. However one of the things they look at is the von Bertalanffy growth curve--especially the 'K' value, or slope. If it's steeper, the fish are said to grow more quickly--and they apparently may not live as long. If it's not as steep, they are said to grow more slowly and live longer. However there are many questions about that--and I haven't really seen any data that showed a head-to-head comparison of fish populations, plotting longevity against growth rates. If you search here in the research archive, I actually posted a bunch of stuff about this, including using some calculus to help define growth rates at various ages in the fish here in the bay system.
One big problem though, is that these models are built on data. And if you have a lot of data on the population, then i think you'll have a more accurate model of what the fishery can do. However if you have relatively little data (which was the case here in Green Bay back in 2007, at least for large fish), then I don't really know how you can say that the population will do this, that or the other thing. And that includes how well the fish perform against other populations on a von Bertalanffy model.
So I'd really want to know a couple of things:
1) Is the true difference between populations (in terms of grow rates) due to genetics...or is it more to do with geography (latitude, for instance), photo period for growth in the ecosystem, species of predominant forage, average size of the most prevalent forage, or any one of a number of other things?
2) What sort of sample size do we have in the populations where we are comparing vB curves? In the Green Bay population, Kevin Kapuscinski (et al) published a growth model back in 2006, but this only had one or two fish over 50" in it. Certainly the model is weighted by the smaller fish at the lower end, but the large fish MUST have an effect on the shape of the model. All you have to do is look at the definition of the model for that. And when you're using the upper limit of the model as the basis for making a judgement on just what a population might or might not be capable of, I'd think you would want more than a couple fish in that size range.
We do have some excellent data over here in Green Bay. Our biologists have done a very good job given the resources they have available. But lets not kid ourselves--the sampling that occurs outside the easily-accessible portions of the system is minimal at best. We simply don't know what we don't know, as far as I can tell. I suspect it's the same with this triploidy concept there, so to compare the two populations might not be as straightforward as one would like it to be.
TONS of opportunity for more study though. All it takes is money!
TB
Edited by tcbetka 5/17/2013 9:11 PM
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