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Thread: Question for Nerka.... Kasilof Section 1/2 mi

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    Default Question for Nerka.... Kasilof Section 1/2 mi

    Question for Nerka:

    When setnets are fishing the 1/2 mi zone in the Kasilof Section, what is the breakdown on stock composition of the catch (Kasilof vs Kenai) for sockeye harvested in that section?

    Is it simply a visual stock ID or is it confirmed by DNA sampling?
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    Default I asked Laryy Lewis this same thing...

    Quote Originally Posted by fishNphysician View Post
    Question for Nerka:

    When setnets are fishing the 1/2 mi zone in the Kasilof Section, what is the breakdown on stock composition of the catch (Kasilof vs Kenai) for sockeye harvested in that section?

    Is it simply a visual stock ID or is it confirmed by DNA sampling?
    I asked Larry Lewis this several years ago at the guide acadamy, but pertaining to Kenai/Kasilof Kings... He sais they didn't have any idea...

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    Of course Larry Lewis wouldn't have an answer for you about king salmon stock composition...why would he??? Lewis works for the Wildlife Division and spends most his time dealing with moose and bear issues.

    Perhaps you mean Larry Marsh?

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    Default Yeah, bummer.. That is exactly who I meant.. Larry Marsh...

    Quote Originally Posted by akfishinguy View Post
    Of course Larry Lewis wouldn't have an answer for you about king salmon stock composition...why would he??? Lewis works for the Wildlife Division and spends most his time dealing with moose and bear issues.

    Perhaps you mean Larry Marsh?

    Sorry guys, got my Larry's mixed up! I know he is retired know and Jason holds his position... Totally spaced the last name.

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    Doc is asking about sockeye stock composition. . . Not kings.

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    Default Thanks, I got that...

    Quote Originally Posted by Charholio View Post
    Doc is asking about sockeye stock composition. . . Not kings.

    My point is that ADFG has no idea... Although I am sure there have been genetic samples taken, pretty sure they have not been tested..

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    Default it depends.

    Contrary to what has been posted the ratio of Kasilof to Kenai sockeye changes through the season. Early in the season it is mostly Kasilof but as the season moves along the proportion of Kenai increases. The fisheries are sampled for age composition and that is used to estimate the ratio of the two stocks. In addition, in recent years genetic samples have been taken and the results have been reported - not all samples have been run but there are some data. I do not have that in front of me but one can get it from ADF&G.

    The main use of the 1/2 mile is to reduce exploitation on Kenai while allowing some harvest of Kasilof stocks. It is not a perfect set up and I am sure there are times Kenai is the predominant fish in the harvest. However, the idea is that some Kenai harvest can take place to keep Kasilof with a reasonable goal range.

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    Quote Originally Posted by Nerka View Post
    .... the ratio of Kasilof to Kenai sockeye changes through the season. Early in the season it is mostly Kasilof but as the season moves along the proportion of Kenai increases. ...

    The main use of the 1/2 mile is to reduce exploitation on Kenai while allowing some harvest of Kasilof stocks. It is not a perfect set up and I am sure there are times Kenai is the predominant fish in the harvest. However, the idea is that some Kenai harvest can take place to keep Kasilof with a reasonable goal range.
    Got it. Thanks.

    I guess my hang up is that when fish move to the beach in that section, regardless of Kenai vs Kasilof origin, they are ripe for harvest. The fish are basically susceptible to exploitation in proportion to their real-time abundance. If the Kenai fish are there, they're gonna be caught.
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    Default Hey Doc just remember.......

    Quote Originally Posted by fishNphysician View Post
    Got it. Thanks.

    I guess my hang up is that when fish move to the beach in that section, regardless of Kenai vs Kasilof origin, they are ripe for harvest. The fish are basically susceptible to exploitation in proportion to their real-time abundance. If the Kenai fish are there, they're gonna be caught.
    KRSA is just finishing up the Late Run Russian R genetic composition for the commercial, sport, and pu fisheries... This will be some very interesting information from 2006-09 that will show harvest rates of these fish in relation to the rest of the Kenai Late Run..

    The Kenai itself has many differnt genetic sub-populations that likely suffer from very large explotation rates. As Ken state every years is very different.

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    Default Some more info....

    Quote Originally Posted by Nerka View Post
    Contrary to what has been posted the ratio of Kasilof to Kenai sockeye changes through the season. Early in the season it is mostly Kasilof but as the season moves along the proportion of Kenai increases. The fisheries are sampled for age composition and that is used to estimate the ratio of the two stocks. In addition, in recent years genetic samples have been taken and the results have been reported - not all samples have been run but there are some data. I do not have that in front of me but one can get it from ADF&G.

    The main use of the 1/2 mile is to reduce exploitation on Kenai while allowing some harvest of Kasilof stocks. It is not a perfect set up and I am sure there are times Kenai is the predominant fish in the harvest. However, the idea is that some Kenai harvest can take place to keep Kasilof with a reasonable goal range.
    A minimum sample (n=403) of readable scales has been used to estimate the age composition of sockeye salmon in each stratum within 5% of the true proportion 90% of the time (Thompson 1987). These various data sources have been used to construct brood tables for late-run Kenai River sockeye salmon beginning with brood year 1968 (Tarbox et al. 1983), but the most consistent methods have been applied since brood year 1979 (Tobias and Willette 2004b). Two other methods have been used to estimate the stock composition of commercial harvests in UCI. In the mid 1980s, scale pattern analyses were conducted (Waltemyer et al. 1996). In the 1990s, genetic methods were used (Seeb et al. 2000). Due to budget reductions, the independent catch apportionment programs were dropped.

    Most annual catch apportionments have been based upon the weighted age-composition method. These catch apportionment are based on the assumption that we know total escapement of sockeye returning to UCI by stock and age; and that the harvest by age class for an individual stock is the same as that stock's portion of the total escapement on an age class by age class basis. The precision of these estimates is questionable and the estimates are undoubtedly biased. Sockeye salmon that originate from rivers where escapement is not measured or where total escapement is undercounted are misclassified through this approach. We do not know if the bias is substantial, if it varies across years, or if the historical recruit estimates are unsound. Most fish included in recruitment estimates for the Kenai River stock of sockeye salmon come from these potentially biased catch apportionment estimates.

    http://www.sf.adfg.state.ak.us/FedAidPDFs/sp07-12.pdf

    It appears that brood tables are the idea of catch aportionment, genetic anylasis is too expensive and regardless both methods are not implemented INSEASON as a management tool.

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    Default More data to fuel the fire........Burn baby burn!!


    Using a Markov yield analysis, as in the original 1999 analysis, the highest mean yields were obtained within a range of 400,000-700,000 spawners using both the 1969-1999 and 1979-1999 data sets (Tables 6-8). Spawner abundances below 300,000 salmon never produced yields exceeding 865,000. The highest yields were produced from spawner abundances of 566,000, 567,000, and 1,333,000 sockeye salmon (brood years 1982, 1983, and 1987). When spawner abundances exceeded 800,000, yields ranged from 1,281,000-8,197,000. In the updated data sets, two year classes have been added to this interval (Tables 7-8), but their yields were below the mean (1,654,000 and 2,264,000).

    Analysis of the data using a typical Ricker approach, as is fairly standard practice for salmon escapement goal analysis throughout Alaska, indicates the escapement level expected to produce maximum sustained yield is about 1.3 million fish (Table 4). Harvestable surplus expected with a range of escapements from 500,000-800,000 is considerably less according to a typical Ricker approach to analysis. Problems with this analysis, however, include the fact that no observational data are available at high levels of escapement; or in other words, escapements high enough to have density dependence strong enough to produce a number of recruits less than the parental escapement. Without such observations, the escapement level that produces maximum sustained yield from stock-recruit analysis is speculative at best. Lack of observational data at high levels of escapement inserts considerable uncertainty in stock-recruit analysis (Hilborn and Walters 1992); and as a result, often leads to nonsensical decision-making in escapement goal management.

    However, in order to implement a regulatory strategy to achieve maximum sustained yield as predicted from the brood interaction model, the fishery would have to be managed for little fishing in one year, followed by very heavy fishing the next, followed by little fishing the third year, and so on. Fried (1999) concluded that the department was unable to effectively control sockeye salmon escapement into the Kenai River given available regulatory and management tools at that time, so implementation of an alternate-year escapement goal policy would not be successful without substantial changes to the regulatory structure of the commercial fishery. Such an alternating escapement goal policy management approach would likely bankrupt fishermen and processors alike and might very well lead to collapse of the commercial fishing industry in UCI.

    A precautionary approach should be taken regarding change to the escapement goal range for Kenai sockeye salmon because of declining productivity in Skilak Lake. Euphotic zone depth, copepod biomass and the average size of fry in the fall have decreased markedly over the past decade (Figure 4). This decline is correlated with the decline in the summer ice balance in the Kenai Mountains (Edmundson et al. 2003). Since glaciers across Alaska are melting due to global warming and the rate of melting has accelerated (Arendt et al. 2002), this trend of declining productivity may continue. These changes may indicate that productivity of the stock is not stationary.
    Clearly things have changed in Skilak Lake and recent cool summers have left the turbidities in the lake quite high... It is entirely possible that the given productivity of this lake has changed a great deal and will inherintantly change again as environmental factors change.

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    Default age composition is used inseason.

    The age composition of the two rivers is used inseason to gain an impression of the relative abundance of Kenai and Kasilof.

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    Quote Originally Posted by TYNMON View Post
    Clearly things have changed in Skilak Lake and recent cool summers have left the turbidities in the lake quite high... It is entirely possible that the given productivity of this lake has changed a great deal and will inherintantly change again as environmental factors change.
    I am not sure what you are talking about Ty. Skilak is very clear right now. The water visibility between the Skilak and the Killey River systems is about 8 to 9 ft. It is the clearest the old timers have ever seen it. I haven't been on Skilak but if the water that it is dumping back into the Kenai is any indication Skilak has very low turbidity this year and last year as well.

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    Default That was excatly my oint!!

    Quote Originally Posted by yukon View Post
    I am not sure what you are talking about Ty. Skilak is very clear right now. The water visibility between the Skilak and the Killey River systems is about 8 to 9 ft. It is the clearest the old timers have ever seen it. I haven't been on Skilak but if the water that it is dumping back into the Kenai is any indication Skilak has very low turbidity this year and last year as well.
    Sorry if I lost you guys, I meant that the last three years the water has been exceptionally clear so that Skilak production could be greatly increased... May bad I say increased turbidity when I should have said decreased turbidity......

    My point was production with in the lake has likely changed dramitically sue to this fact.

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    Default Link from one of Nerka's Papers..

    Quote Originally Posted by Nerka View Post
    Contrary to what has been posted the ratio of Kasilof to Kenai sockeye changes through the season. Early in the season it is mostly Kasilof but as the season moves along the proportion of Kenai increases. The fisheries are sampled for age composition and that is used to estimate the ratio of the two stocks. In addition, in recent years genetic samples have been taken and the results have been reported - not all samples have been run but there are some data. I do not have that in front of me but one can get it from ADF&G.

    The main use of the 1/2 mile is to reduce exploitation on Kenai while allowing some harvest of Kasilof stocks. It is not a perfect set up and I am sure there are times Kenai is the predominant fish in the harvest. However, the idea is that some Kenai harvest can take place to keep Kasilof with a reasonable goal range.
    Here is a link: Evaluation of Scale Pattern Analysis for UCI.
    http://www.adfg.state.ak.us/pubs/afr...2/waltv3n2.pdf

    I find it very intruiging that in the conclusion they recommend AGAINST scale pattern anaylsis to differenciate between mixed stock harvest in UCI...

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    Quote Originally Posted by TYNMON View Post
    Here is a link: Evaluation of Scale Pattern Analysis for UCI.
    http://www.adfg.state.ak.us/pubs/afr...2/waltv3n2.pdf

    I find it very intruiging that in the conclusion they recommend AGAINST scale pattern anaylsis to differenciate between mixed stock harvest in UCI...
    Interesting paper, Ty (and Nerka).

    Funny how over 30 yrs later, managers have still been unable to achieve a RELIABLE way to differentiate stock composition in the the catch in real time (24-72 hr turnaround) to make critical in-season decisions.
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    Default Don't let the facts alter your decisions

    Facts may only confuse the issue IF they already made their decisions OR know which way they want to go.

    I agree - with all the advancements in science and measurment in the last 30 years - determing stock composition should not be be that difficult if they really want to know. If funding is an issue tax the industry - that it is how it works for everything else.


    Quote Originally Posted by fishNphysician View Post
    Interesting paper, Ty (and Nerka).

    Funny how over 30 yrs later, managers have still been unable to achieve a RELIABLE way to differentiate stock composition in the the catch in real time (24-72 hr turnaround) to make critical in-season decisions.
    Living the urban lifestyle so I can pay my way and for my family's needs, and support my country. And you?
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    Default EO's.... here they come!

    Well with Kasilof within 60K of "overescaping" its BEG and easily 3 weeks of countable passage left for the season, managers are gonna have to hold escapement to an average of 3000 fish a day or less. Might be tough with at least another daily spurt or two in the 10-20K range still to come.

    Old MacDonald should be breaking into a repetitive chorus anytime soon.

    E-eye, E-eye, O-h-h-h-h-h!
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    Default another misrepresentatition

    Quote Originally Posted by TYNMON View Post
    Here is a link: Evaluation of Scale Pattern Analysis for UCI.
    http://www.adfg.state.ak.us/pubs/afr...2/waltv3n2.pdf

    I find it very intruiging that in the conclusion they recommend AGAINST scale pattern anaylsis to differenciate between mixed stock harvest in UCI...
    Ty, yoiu must read to understand the papers. Age composition analysis comes from scales but that is not scale pattern analysis. Scale pattern analysis looked at the ratio of various components of the scales to see if those ratios could be used to separate stocks. They could not. However, age composition which is just the freshwater and marine age is used. So it is not intruiging at all in the conclusion. It is apples and nuts.

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    Default just plain out of touch

    Quote Originally Posted by tvfinak View Post
    Facts may only confuse the issue IF they already made their decisions OR know which way they want to go.

    I agree - with all the advancements in science and measurment in the last 30 years - determing stock composition should not be be that difficult if they really want to know. If funding is an issue tax the industry - that it is how it works for everything else.
    This has to be one statement for the all time out of touch list. Why would ADF&G spend thousands of dollars to research stock separation if they did not want to know. Tvfinak, I assume you cannot be this out of touch with reality. Stock separation is very difficult. The stocks spawn close together, rear in similar environments, and have straying to keep the gene pool close together. It does not take much thinking to see how difficult it would be.

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