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  • Over excapement

    In the UCI thread there is discussion about over excapement. Why is this a bad thing? I honestly do not know so if you do please tell me. I know that it means fish that could be harvested are not. But it seems that more fish spawning equals more fish returning.

    Thoughts?
    It ain't about the # of pounds of meat we bring back, nor about how much we spent to go do it. Its about seeing what no one else sees.

    http://wouldieatitagainfoodblog.blogspot.com/

  • #2
    There are a couple problems that come along with overescapement.

    1 - Too many rotting salmon after the spawn can cause a massive lowering of the dissolved oxygen content of the water. If the DO gets too low, it can cause a large (total?) die-off of all the biota in that section of the stream, including salmon fry, trout, aquatic insects, etc.

    2 - Too many fry in a system can lead to overcompetition. When too many fry are present, the result is often that they become low-weight smolt when they are heading to sea. Low-weight smolt have a far lower ocean survival rate. So even though more salmon migrate out to sea in the spring, it can lead to a significanly lower return of adult salmon in following years because of poor ocean survival.

    I think that the argument is often how much is too much?, or how to really define overescapement and set a number, rather than if overescapement can cause problems.

    Comment


    • #3
      If 3-4 million fish are returning to the kenai based on the spawners that are allowed through, whath hapened before heavy fishing and/or regulation?

      I understand the risk of disolved oxogen but I have never seen a problem with it except in extremely warm water and land locked lakes.
      It ain't about the # of pounds of meat we bring back, nor about how much we spent to go do it. Its about seeing what no one else sees.

      http://wouldieatitagainfoodblog.blogspot.com/

      Comment


      • #4
        Smoke and mirrors. . .

        Originally posted by garnede View Post
        If 3-4 million fish are returning to the kenai based on the spawners that are allowed through, whath hapened before heavy fishing and/or regulation?

        I understand the risk of disolved oxogen but I have never seen a problem with it except in extremely warm water and land locked lakes.
        Here's my take: Alaska's constitution mandates that our fisheries resources be managed for [maximum] sustained yield. Yield is the harvestable surplus—used for human benefit/consumption—beyond the "escapement" needed to sustain the resource at, what is hoped, maximum productivity.

        Before such management, what obtained was nature-in-the-raw with wildly fluctuating salmon returns—cycles of overabundance and scarcity. History records whole native villages having to move when salmons runs failed to produce harvestable surpluses. . . :eek:

        As I interpret it, the current hype that goes "there ain't no such thing as overescapement" or "let our streams be seeded as they were before commercial fishing (read "managed") or similar is a smoke-and-mirrors ploy to do away with commercial nets so that commercial sportfishing interests—guides, lodges, land speculation, etc.—can profit.

        Simple as that. . . if you didn't know . . .

        Comment


        • #5
          Originally posted by garnede View Post
          If 3-4 million fish are returning to the kenai based on the spawners that are allowed through, whath hapened before heavy fishing and/or regulation?
          A boom and bust cycle. There would be years of huge returns followed by years of dismal returns. The same thing is modeled in ungulate populations with relation to overgrazing or overpredation. (Or rabbits, for that matter.) It's not that the salmon would go extinct, but that there would be large fluctuations. As such, it is in the interest of both sport and commercial interests to keep returns within a consistent range.

          Comment


          • #6
            Thanks for the replies. I can see the goal of limiting excapement to maintain a consistant fishery. I can also see where an argument could be made for "what is too much". I haven't been here long enough to know how well ADF&G manages the fishery so I am just trying to educate myself.
            It ain't about the # of pounds of meat we bring back, nor about how much we spent to go do it. Its about seeing what no one else sees.

            http://wouldieatitagainfoodblog.blogspot.com/

            Comment


            • #7
              Originally posted by garnede View Post
              ......I haven't been here long enough to know how well ADF&G manages the fishery so I am just trying to educate myself.
              Check this out.

              Comment


              • #8
                Complaints about ADF&G. . .

                Originally posted by garnede View Post
                . . . haven't been here long enough to know how well ADF&G manages the fishery so I am just trying to educate myself.
                Depends on what special-interest user you listen to, garnede, most of whom, for one reason or another, will tell you ADF&G is doing a poor job.

                Take the "sport" folks, commercial especially but with a few private malcontents as well. Such will demonize the "commies," accusing them of expensive lobbyists, plots, collusion, black helicopters, and much, much more. All such complaints can be translated, "I ain't gettin' all the fish I want." . . . or ". . as easy as I want," or ". . when I want," or ". . at not as much profit as I want.". . :mad: You get the idea.

                As for the gill-net industry, one doesn't hear much from them, but rest assured they have their own interests to protect. .

                In the meantime, Alaska's fisheries are the envy of the world. . .

                Comment


                • #9
                  Mark thanks for the link. I started reading it and realized I better wait untill I'm off work. I will finish reading it over the weekend.

                  Marcus, I am a sport fisherman. Though I may add dipnetting as well. I grew up without having to compete for fish with commercial guys but we did not have near the abundance of fish here. If I am not successful then I usualy blame it on not using the right technique or not knowing a river. It took me 40+ hours to catch my first salmon and I blamed that on me not knowing how to fish for salmon.

                  I like being the envy of the world. I just wish the tourist would learn to drive the speed limit, at least.
                  It ain't about the # of pounds of meat we bring back, nor about how much we spent to go do it. Its about seeing what no one else sees.

                  http://wouldieatitagainfoodblog.blogspot.com/

                  Comment


                  • #10
                    We all like to eat fish. . .

                    Originally posted by garnede View Post
                    . . I grew up without having to compete for fish with commercial guys . . .
                    It helps greatly to realize you're not competing with "commercial guys." In reality, if any such "competition" exists, it is between you as a private angler and your fellow Alaskans and Americans who get their salmon in supermarkets and restaurants.

                    A favorite tactic of "sports-whiners" is to demonize the means (read "nets") when, if they were up-front about it, they are really demonizing their fellow man, fellow consumers of the resource. . . :eek: Tacky, tacky, tacky. . .

                    Peace. . .

                    Comment


                    • #11
                      Originally posted by Marcus View Post
                      It helps greatly to realize you're not competing with "commercial guys." In reality, if any such "competition" exists, it is between you as a private angler and your fellow Alaskans and Americans who get their salmon in supermarkets and restaurants.

                      A favorite tactic of "sports-whiners" is to demonize the means (read "nets") when, if they were up-front about it, they are really demonizing their fellow man, fellow consumers of the resource. . . :eek: Tacky, tacky, tacky. . .

                      Peace. . .
                      Garnede, you aren't getting the entire story. I realize this is going to be upsetting for some of you who view this differently than I, but I want to provide garnede with another point of view. Nothing personal, but there is more than one way to look at "overescapement."

                      Garnede, the theoretical concept of "overescapement" is just that--a theoretical concept based on computer modelling. As with any such model, the value of it is only as good as the data that goes in and especially the soundness of the assumptions it's built on. The assumption driving the overescapement model for sockeye in the Kenai is that at a certain level, increased numbers of fish on the spawning beds begin to have a detrimental effect on the system and the resource, theoretically causing the low oxygen conditions, etc. that can result in diminished returns in future yeas. In theory it sounds, well, sound. Plausible anyway. But is it valid, and is it necessary? Maybe is the answer to both of those questions. There is not enough data to give a yes or no answer to either of them.

                      I asked for specific examples of a naturally occuring case of "overescapement" on this forum board a while back. There are no documented examples for the Kenai, and the only example provided was for a small tributary stream of another system that was of an unusually large run that was inluenced by stocking that stream. In that case, when the die off of spawners occured, they did indeed have oxygen problems, and some other problems too though I'd have to look up Nerka's post to cite the specifics. We've had several discussions about the theory of "overescapement" in the past.

                      The bottom line is that you need to keep in mind that the theory of "overescapement" is just that--a theoretical concept, and there is no substantial proof to validate it. The commercial gillnetters embrace it with gusto because in addition to their regularly schedule openers, the have the opportunity to have additional periods to fish if the run projections indicate a trend that might lead to the dreaded, but not proven, possibility of "overescapement."

                      People push the theory of "overescapement" as fact. When you push those people and call them on the lack of data you will hear arguments such as "Well, I know there's no substantial proof that the theory of overescapement is valid, but do you really want to take the chance of it ever happening? We must manage for it, or the runs will be decimated!" The runs won't be decimated. Yes, without the theoretical concept of "overescapement" in place the runs will have naturally occuring peaks and valleys, and the commercial gillnetters will not have the possibility of what are essentially bonuses due to Emergency Orders giving them more fishing time. But the fish always did just fine before the theory of overescapement was created. Maybe not well enought to support the commercial gillnetters' economic engine (like that one, eh Marcus ;-), but the runs were completely naturally occuring and healthy for eons.

                      The Kenai system is primarily managed by ADF&G for sockeye salmon, and ADF&Gs principal tool to manage (play God with?) the sockeye runs has always been commercial gillnetters. The commercial gillnetters love this and do not want this to ever change, understandably. I bet there was some serious celebrating among the Kenai gillnetters when they realized the golden egg they were given (the implementation of the policy of managing to prevent "overescapement). They are never going to let go of the theory that makes their jobs more profitable.

                      Many will argue that the theoretical concept of "overescapement" is vital to the sustained health of the Kenai. That's not true, and it's commonly used as a front in my opinion. It's not vital for the Kenai, but it is vital for the sustained health of the commercial gillnetters who make their living selling the Kenai's (and other rivers fish--a gillnet is indiscriminant) salmon. In my humble, non-fisheries biologist educated brain, the answer is that managing for "overescapement" is only necessary to maitain the status quo on the existing commercial gillnet fishery.

                      I find it interesting and contradictory that so many who promote the unnatural use of gillnets to manipulate the natural system cry so loudly regarding in-river habitat issues. They want the in-river habitat to be as natural as can be and support measures to make it so (anti-develpment, concern over in-river hydrocarbon emissions, etc.). Yet they insist that playing mother nature by trying to manage for the theoretical possibility of "overescapement" is necessary. In essence, it is possible that the fisheries managers are managing to prevent something that doesn't pose a real threat, only an imagined one. Okay Marcus and Nerka, you can call me a blaspemer now

                      Comment


                      • #12
                        Heresy, not blasphemy. . .

                        Originally posted by Charholio View Post
                        . . . In essence, it is possible that the fisheries managers are managing to prevent something that doesn't pose a real threat, only an imagined one. Okay Marcus and Nerka, you can call me a blaspemer now
                        That's an accurate and succinct summation of your very lengthy post, Charholio. And while you're no blasphemer, you are in gross error. . . more heresy than blasphemy. .

                        If by "doesn't pose a real threat" you mean that lack of proactive management would not totally destroy the runs, you are correct. But what you're missing, whether on purpose or as an oversight, is that Alaska's constitution mandates that our fisheries be managed for [maximum] sustained yield.

                        And why wouldn't Alaska pursue such a policy? To not actively manage our fisheries for [maximum] sustained yield would be grossly irresponsible. It would be like a cattle rancher running, say, a thousand head of beef and failing to send cattle to market as the herd produces calves, missing the income from the sales while the public misses the beef. Stupid, yes?

                        And beyond that, as the unharvested herd increases, it eventually eats the pasture to the bone, the herd mostly starves to death leaving only a few, which begin the cycle all over again. . . nature-in-the-raw . .

                        Why would any sensible social order pursue such heretically irresponsible stewardship of its resources? . . :confused:

                        Comment


                        • #13
                          Charholio is wrong on many points

                          Overescapement is not a theory as Charholio references. The Kenai data set shows lost harvest from large escapements. The Kasilof data set shows lost harvest from large escapements and so do numerous other systems. If you want to read the ADF&G report on overescapement go to the following link:
                          http://www.boards.adfg.state.ak.us/f...ioverescap.pdf

                          Charholio is doing what a number of people in UCI allocation battle are doing = providing misinformation and confusion so a lay board of fish does something to their advantage.

                          Overescapement was defined as a loss of yield by Ricker over 50 years ago and has been a mainstay of setting escapement goals for fisheries biologist for years (numerous text books show real examples contrary to what Charholio says). There are also other production models that show the same thing based on real data. If you read the ADF&G escapement goal report you will see they define goals based on getting maximum sustained yield or at a minimum high sustained yields. If you took Charholio approach more fish in means more fish back then there would be no limit to what a system could produce - I think we all know that is silly.

                          Charholio you should not be misleading people who have a lack of understanding without researching this yourself. Read the ADF&G reports on the issue, look at text books, and then come back and tell us your theory approach is wrong. The fact you said low oxygen in the Kenai as causing issues shows you are not informed. The limitation on sockeye production is not low oxygen in the Kenai it is available food resources in the rearing lakes.

                          Comment


                          • #14
                            Overescapement


                            http://www.youtube.com/watch?v=AXtJfZIbbyU
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                            Killin' it!



                            Comment


                            • #15
                              excerpt from "overescapement" report

                              Charholio, you are wrong. The Overescapement report, linked to several times on this thread, does a good job of laying out the general concepts, as well as providing significant data to back it up. You don't even have to read very far into the document to see.

                              Here's the second paragraph from the report's abstract. (sorry of there's typos, I had to re-type it from the .pdf file).

                              “For 37 of the 40 [sockeye] stocks we reviewed, overescapement occurred at least once in a recent 15 year period. We examined the long term effects effects of overescapement on yields relative to MSY for 29 of the 40 stocks. This subset of stocks was chosen because the because the observed exploitation rate is less than or equal to the exploitation rate at Maximum Sustainable Yield (MSY) allowing examination of yields at levels of escapement that would exceed the escapement that produces MSY. Averaged across all of these stocks, long term yields decreased and variability in yields increased when current escapement goals were exceeded. This result is consistent with the generic theory of compensatory production, where spawning efficiency decreases with increasing escapement levels and stocks are limited by the carrying capacity of the habitat. Overescapement, in general, is not sustainable as it causes returns and yields to decrease in the next generation, which also result in lower escapements. Lower escapements then result in higher returns and yields in the succeeding generations. We also found evidence of delayed density dependence in five Alaskan sockeye salmon stocks. In three of these stocks, returns per spawner fell below replacement for 2 to 5 years following consecutive overescapements that were greater than twice the upper bound of the escapement goal range. “
                              "Fishing relaxes me. It's like yoga, except I still get to kill something." --Ron Swanson

                              Comment

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