|
|
Posts: 32785
Location: Rhinelander, Wisconsin | Again, that's anthropomorphism. Not a good idea if you ever want to truly understand your prey, but really a common issue...especially with Muskie anglers.
When researching the subject, be wary of any 'study' funded by 'animal rights groups' PETA, or the like.
Here's a good start:
http://books.google.com/books/about/Behaviour_of_Teleost_Fishes.htm...
http://www.springer.com/life+sciences/ecology/book/978-0-412-42...
Also as a point of interest, look at the structure of the fish's brain, and study how each part of the fish's brain functions.
|
|
| |
|
Posts: 32785
Location: Rhinelander, Wisconsin | BrianF. - 10/15/2014 8:27 PM
Read this...Genetic Effects of Harvest on Wild Animal Populations by Fred W. Allendorf, Phillip R. England, Gordon Luikart,Peter A. Ritchie, and Nils Ryman...and tell me if they would agree that 'luck' is exactly how fish attain maximum size. I'm sure luck plays some part, but so do many other variables, including apparently angler exploitation. After researching the issue scientifically this team of researchers state the following, "Many resource managers have been reluctant to accept the potential for harvest to cause genetic change, and many are doubtful that any such changes are harmful. However, intense and prolonged mortality caused by exploitation will inevitably result in genetic change. Harvest need not be selective to cause genetic change..."
When I hear stories from a waitress at a restaurant on the shores of Lake Vermilion who tells me that one of her customers caught and harvested a musky bigger than the angler's 6 year old son - and produced a photo showing the harvested fish next to the boy as photographic proof of the claim - and the next day catching an even larger fish from the same spot and also harvesting that fish - a part of me thinks, "Hmmmm, that kind of harvest could someday impact this fishery." Seems to me that the research is backing this up, but maybe I haven't seen all the research or understand the results correctly.
Brian
Lots of holes in your interpretation of the quoted work. The first sign should be:
"Many resource managers have been reluctant to accept the potential for harvest to cause genetic change, and many are doubtful that any such changes are harmful. However, intense and prolonged mortality caused by exploitation will inevitably result in genetic change. Harvest need not be selective to cause genetic change..."
That doesn't address what you are claiming/insinuating, in fact, quite to the contrary.
1) Far too short a time frame. The population of Muskies in Vermilion is by comparison pretty new to the base natural populations of 10,000 years, and yet were introduced from stripping a lake that is part of the natural range...and still, despite decades of pressure and only very recent CPR still kicks out giants every year.
2) Read that last statement again. There are a couple terms in there that are key:
"Intense" and "prolonged". Neither applies to Vermilion and muskies.
3) Take a look at the genetic studies done by Dr. Brian Sloss. Some of the populations he studied were hit pretty hard by harvest for over 50 years, had other strains stocked over them, and remain genetically the same fish none the less. |
|
| |
|
Posts: 1969
| BrianF. - 10/15/2014 8:27 PM
When I hear stories from a waitress at a restaurant on the shores of Lake Vermilion who tells me that one of her customers caught and harvested a musky bigger than the angler's 6 year old son - and produced a photo showing the harvested fish next to the boy as photographic proof of the claim - and the next day catching an even larger fish from the same spot and also harvesting that fish - a part of me thinks, "Hmmmm, that kind of harvest could someday impact this fishery." Seems to me that the research is backing this up, but maybe I haven't seen all the research or understand the results correctly.
Brian
Do you want to expand on this thought process, because I'm not sure I follow your logic. Two very large fish are caught from same spot on back to back days (right place right time) and kept and this could someday impact this fishery? Lots of big fish get caught multiple times a year on that lake..these two were unlucky to be caught by an angler that didn't want to put them back. Are you still suggesting there are "smart" ones in Vermilion passing on genes?
Edited by IAJustin 10/15/2014 9:19 PM
|
|
| |
|
Posts: 284
Location: Eagan, MN | IAJ, the example I cited is simply meant to be illustrative of the potential mortality that can be exacted on our preferred gamefish at the hands of a single angler. Two upper end fish, perhaps more genetically inclined to 'bite', removed from the population by one guy in one 24 hour period. This story is more common than you might think. Multiply this event by however many times you want based on all of the angler effort exerted on this, or any other body of water, over the days, weeks, months, years, decades. Now, combine this intentional mortality with the inadvertant mortality of CPR-only anglers and you begin to wonder what the exact toll is being taken on the fish population. Some would suggest they are all very vulnerable to anglers. But are they all that vulnerable?
So, what I'm wondering is whether: 1) fish genetically pre-disposed to a higher level of aggression and angler catchability are being removed from the population through intentional or unintentional mortality, leaving a population dynamic that is changing and becoming more skewed towards fish less genetically pre-disposed to 'bite'; 2) the fish population that remains, skewing towards fish that are harder to catch, are passing on their genetics more frequently than fish that are, by genetics, more inclinded to 'bite'; 3) aggressive tendencies are heritable; and 4) mortality over time is changing the size structure and top end potential of the fishery.
Pretty complex questions here, with lots of variables to consider, and 'holes' in the thoughts with which I'm playing. I give you that. I will also admit to taking some liberties with the research results done on other species, but the leap to muskies and how angling pressure impacts them isn't that far IMO. I just can't believe that years of angler-induced mortality isn't affecting the population of fish in the bodies of water in which we pursue them - some how and some way. So, yes, I'm suggesting that there may be fish less susceptible to anglers that are passing on genes. Sounds kinda dumb, huh.
Brian
Edited by BrianF. 10/16/2014 9:35 AM
|
|
| |
|
Posts: 1937
Location: Black Creek, WI | Brian,
The idea that the "biter" gene gets weeded out and eventually dominated by the "less aggressive" gene due to angler harvest and angling related mortality is interesting. I can see how the idea may have some merit. Selective harvest is a common concept. In this case, however, the "selection" is not intentional by the angler... but because of the genetic disposition of the fish.
When speaking specifically of Lake Vermilion, I'm sure there are more factors impacting the "feeling" that it is more difficult to catch a 50+ incher today than only a few years ago.
In my opinion, BigV is unique in that it is a young musky fishery that was "jump started" with intense early stocking. Those efforts created some huge early year classes that thrived and grew quickly to trophy size. Looking at the creel survey data, this skewed size distribution was very apparent (there was a time when there were more 50 inchers than 40 inchers in the lake). As these early stocking year classes of fish die off, the size distribution will eventually take on a more "normal" distribution. Thus, with fewer trophy size fish available than before... it will naturally become more difficult to catch one due to simple probability.
No doubt, BigV will remain a trophy fishery.... however if the angling pressure remains higher than other musky fisheries.... it will be a tough place to fish as you must share those trophies with more anglers... reducing your chances for success in comparison to a system with equal numbers of "biggies" but with less angling pressure.
The reality of it is... those big fish are eventually going to die. Whether caught by an angler or not. And when they do... the size distribution will return to "normal". When it does (and its almost there now)... BigV will just be another musky lake with trophy potential due to is acreage and forage base. It will always be a special place, but not as special as when it was originally "stacked" with giants. |
|
| |
|
Posts: 44
| I admit that I did not read all of the posted replies extremely closely but wanted to offer my own opinion none the less. It is a fact that a certain percentage of muskies will die after being caught (whether they are harvested (put on the wall) or die from the stress/damage of the fight after being released). We could also reason that the most aggressive muskies ultimately feed more and are caught more often. If we assume that the more aggressive muskies have the same probability of dying from being caught as the less aggressive muskies (This seems like a minor assumption - in fact, the more aggressive muskies may be more likely to die from being caught due to the stress of being caught over and over), then it follows that the most aggressive muskies will, on average, die sooner than the less aggressive muskies. If this is true, we would actually expect that the less aggressive muskies would be more likely to be the "big" breeders (i.e. we expect that the less aggressive muskies will be more likely to pass on their genes than the more aggressive muskies)
A commonly accepted viewpoint is that catching a musky puts a lot of stress on that fish. This stress can limit the growth of the musky (with respect to both length and girth). If the more aggressive muskies do not grow as quickly (or grow as easily to "trophy" size), it is less likely that they will be harvested, all else constant. This may offset (to some degree) what I wrote in the previous paragraph because this would imply that the more aggressive muskies might be less frequently harvested (put on the wall), due to their smaller average size. However, since a lot of muskies die not from being harvest, but instead die after the release, I put more faith in my first hypothesis.
I am not a biologist so I could be very far off. And the fact of the matter is that most musky lakes are not self sufficient (stocking is required). So it ultimately all goes back to the muskies that the DNR is using to provide the fingerlings. That said, it seemed like an interesting thought exercise and helped me kill some time waiting for an appointment. That's my two cents. |
|
| |
|
Posts: 8717
| I think the notion of altering the genetic makeup of the musky population is a bit absurd.
Muskies reach sexual maturity at around 4-5 years of age at a size of about 32". The large musky that gets harvested at 52" is likely 20 - 25 years old. Fish of that size have already had 15-20 years of breeding to spread their genes. With the popularity of catch and release, combined with higher size limits in many of the areas where natural reproduction occurs with any regularity, I doubt we're diluting the gene pool.
Delayed mortality is a possibility with any catch, but there again, the small ones never seem to have any trouble swimming off. Some of the big ones take longer to revive. The large aggressive fish might be more apt to fall victim to C&R mortality then their more reluctant counterparts, but can we assume that trait is genetic?
If angling pressure affects their growth, it does not affect their genetic potential for growth.
I think the only viable explanation is simple conditioning. The more lures they see, the less likely they are to eat them. It's just something in the environment that's always there.
Another possibility that nobody talks about is that all the commotion we create with our boats and lures disrupts the entire food chain. Have you ever seen what a school of minnows or a perch or a panfish does when you pull a musky lure within a few feet of them? The water displacement from a double 10 might get the attention of a hungry musky, but to their food, it's obviously perceived as a threat.
After 3 or 4 boats go through throwing musky lures, you've now altered the behavior and location of musky food.
What are you gonna do if someone throws your beer and your pizza across the street? (after you finish beating them, that is...)
Jlong is on the right track.
We're creating a condition in their ecosystem that alters their behavior. Understanding that process is step #1. Step #2 is figuring out how we as anglers can adapt to it. The fish aren't going anywhere. They're still in the lake. And they will never become "smart" enough to evade capture. If we as anglers became that dumb where we can't outsmart a fish with the brain the size of a pea, we deserve to go home empty handed.
|
|
| |
|
Posts: 32785
Location: Rhinelander, Wisconsin | Addict has quite a few points that are spot on.
Taking any 'big fish' out of the system will not alter genetics or the overall population's behavior one whit, that fish has contributed to the population since it was 5 years old and that fish's offspring are in play for as many as 10 years and as few as 5. That's allot of fish.
It also MADE it to really large size, so how are we to know if it wasn't one of your 'less aggressive' fish? Isn't the entire premise a contradiction?
Mr. Long is describing what our friend Dave Neuswanger, a highly respected fisheries manager who knows Muskies calls 'new reservoir syndrome'. Mr. Long is also...spot on on that point. |
|
| |
|
Posts: 284
Location: Eagan, MN | But... But... But, what about...
Oh, never mind...
D#% you JLong! 
Brian
Edited by BrianF. 10/16/2014 8:11 PM
|
|
| |
|
Posts: 44
| As I mentioned at the end of my previous post - most musky waters in any given state did not historically contain a native strain of muskies - stocking is how these lakes maintain their population. Thus, it doesn't matter what the anglers are doing in the lake, it doesn't affect the genetics of the fish in that lake in any meaningful way.
|
|
| |
|
Posts: 1937
Location: Black Creek, WI | Sorry Brian 
I like the term "New Reservoir Syndrome".
It is that concept that lead to MRoberts' proposal for a new stocking strategy in smaller WI lakes. His proposal was..... Instead of stocking 500 fingerlings in a lake every year, stock a larger quantity less frequently. Perhaps 2500 fingerlings every 5 years would produce a better result? Better, however is all in one's perspective. And from an angler's perspective, a higher number of Big fish (strong year class) is often desired. Unfortunately, MRoberts is only a Barstool Biologist and his ideas never went any further than some controversial M1st discussions a decade ago.
As for the future of Lake Vermilion... the best thing that could happen there is that MN establishes the next "New Reservoir Syndrome" somewhere else to draw away some of the angling pressure. Fewer fish is fine if there are fewer anglers. Even if those fish are "smarter" according to Brian  |
|
| |
|
Posts: 8717
| Which brings us back to the original question: Are we altering their behavior in a significant way, therefore making them more difficult to catch? I'd say yes. All bets are off when nature tells them it's time to eat, and often all at once. It's the rest of the time that we need to change how we fish. |
|
| |
|
Posts: 173
| Might be interesting for some of you to Google the research papers on the impact of slot limits on Pike in the Baltic Sea. Surprising to me how the male to female ratio changed. Unintended consequences you would never think about.
Edited by larryc 10/18/2014 9:03 AM
|
|
| |
