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Morgan-E

Salmon genetics - something to think about

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Posted (edited)

This is just for thought and I do not claim to know for sure or have access to data to fully support or refute what is written below.  It will take a little bit of time to read and digest.

Something to chew on.

Also note that the DEC biologists have read this and are looking at data relative to the thoughts below - thank you to them.

 

The Scientific Answer / Cause of Reduced Chinook Size in Lake Ontario?

 

Background:

 

                A recent study was concluded and published by the University of Helsinki and published in Sustainability News, “Salmon are Shrinking and it Shows in Their Genes” on November 14, 2018.  This study was conducted on Atlantic salmon using 40 years of genetic material and concluded that the “gene version that tells salmon to mature at a later age and thus grow bigger is becoming less common, while the version that urges them to hurry up and get on with it is getting more prevalent.” Two alleles have been identified and the one that urges the salmon to mature earlier has become overwhelmingly dominant in the population while the allele that has been dominant in the past has become increasingly scarce.

                The theory behind the age and size shift is “that the salmon today are more likely to die during their time at sea either because of fishing or other reasons, and would thus benefit from returning to the rivers to spawn sooner rather then later”.

Genetic Ties:

 

                Many times other factors are thought to influence the size of fish and may in fact do so over a very short period of time such as temperature, hormones determined by photo period, food availability, illness, competition, and others.  However, in Lake Ontario there has been a noticeable decline in size using the derbies and individual observations over the past three decades.  It was probably occurring prior to this but there were still enough large fish to make it unnoticeable.  If it is indeed linked to genetics as it has been shown to be in Atlantic salmon it is an evolutionary change and not an environmental phenomena, meaning it is here long term and would take a shift in the allele (gene version) frequency to shift the trend.

Lake Ontario Trends:

 

                The Lake Ontario salmon have been getting smaller over the decades but not due to bait fish availability.  If it was tied to baitfish availability the fish would resemble the emaciated salmon of Huron and Michigan, but the “plumpness” of the salmon has remained relatively constant since it was first used as an indicator of fish health.  This has remained the same while the overall size of the average fish has declined in the lake and the upper size expectancy has continued to decline.  In the 1980’s people would expect to catch salmon in the upper 30’s and hope to catch one over 40lbs.  This declined to expecting to catch fish over 30 and hoping to catch one in the upper 30’s in the 90’s.  This has continued to decline to the present day where people expect to catch salmon in the lower 20’s and are hopeful to get one around the 30lb mark.

                At the hatchery the age structure of the fish has also shifted over the years and the average size has shifted down but not by as much as shown in the creel census, angler observations, and the lake-wide derbies.  The explanation for this may be due to the constant fishing pressure on the Salmon River since the inception of the fishery.  This will be discussed further in the artificial selection and adaptive value of the smaller / earlier maturing allele phenotype. 

On the Canadian side they have also seen a shift in the salmon size, but it has been a slower decline than on the U.S. side, but seems to have caught up to, or shows no real significant difference in reported observations.  This may be tied to the lower tributary fishing pressure their fish have experienced when compared to the Salmon River.  Again, this will be discussed later.

                In more recent history there have been greater highs and lows in the fishery that would suggest a single year determination in terms of year class rather than a subtle shift if multiple year classes were available to compensate for a single age class failure.

Selecting agents giving adaptive value to maturing earlier rather than later:

 

                Lake-wide angling pressure will select against the salmon that are in the system longer by giving anglers an extra year or two to catch and remove the fish prior to spawning.  Early in the fishery anglers knew that fish of like size tended to school together so they would leave the “smaller 20lb fish” in search of schools of larger fish.  Any fish in the 80’s and early 90’s under 20lbs was considered small.  However, these small fish that were not targeted or in many cases released in pursuit of larger salmon to fill the creel limit were the two year old fish.  In the first decades of the fishery the larger fish were genetically selected against and the smaller fish were genetically selected for, increasing the frequency of the smaller, early maturing salmon.  This was and is true for the entire lake regardless of where the salmon was spawned and or stocked.

                Tributary angling pressure has always selected for the largest of the salmon on the U.S. side.  Early in the fishery to the present the largest most visible salmon have had a skewed amount of fishing pressure when compared to the less visible and less desired smaller salmon.  Again, the largest are targeted because it is human nature to want the largest fish to fill the creel limit for a number of reasons.  This greatly reduces the percentage of the 4 and 3 year olds successfully spawning by natural means or making it into the hatchery system.  Within the hatchery there is a much smaller percentage of large fish compared to the number in the lake and that enter the mouth of the Salmon River.  This may also be an explanation of why anglers accuse the DEC of spawning only the “small” fish (that is mostly what has and continues to be available within the spawn house). 

                The slower fall in size on the Canadian side may be due to less pressure to no pressure on the tributaries compared to the U.S. side.  The Canadian fish are still exposed to the same lake pressures which have had them decline in size and age structure, but without the tributary pressure the allele shift has taken longer and they have not had the extreme shift in fishing quality until recent years that the U.S. side has experienced.  The natural wandering (around 10% from natal waters) would also allow the influx of the early maturing allele into waters where the late to mature fish may have otherwise maintained a genetically isolated population (namely in the clean tributaries of Canada where there has been reports of natural reproduction occurring for quite some time).

Chinook compared to Atlantic salmon:

 

                Atlantic salmon may have actually taken longer to get to the point where the salmon are maturing early compared to the Chinooks.  Since Atlantics spawn multiple times and can live up to seven years on average the “older” alleles should persist longer when compared to a fish that spawns only once.  An Atlantic that manages to have good behavior and high fitness that happens to mature at a later time could spawn multiple times with fish that may have spawned for the first time at age two.  This would allow the alleles to persist in a higher frequency than those of chinooks where the fish dies after spawning and has only a two, three, or four year old spawning allele. 

                The shorter life cycle of the chinook compared to the Atlantic salmon makes it a better candidate for evolution than the slightly longer lived and slower to mature Atlantic salmon.  Those species with shorter life cycles and higher reproductive potential are able to evolve more quickly to changes in the environment or selecting agents.

                Additionally the fishing pressure on the lake is far more concentrated for the entire life of the chinook in the lake system compared to the open ocean environment of the Atlantic salmon.  This is based on the simple size of the area available to forage and disperse and with the new technologies and information sharing on the internet of fish location within the lake system.  If the fishing pressure of the modern day has indeed influenced the genetic shift of the Atlantic salmon, then the chinook salmon should respond in a similar and more rapid shift due to the more acute fishing pressure experienced.

Chinook compared to coho salmon:

 

                Coho salmon spawn at age two consistently.  The size of the coho has not varied much from their introduction to Lake Ontario on a decade to decade average basis.  A big coho in the 80’s was in the teens and today a big coho is still in the teens with the average mature fish being in the upper single digits to lower double digits.  The very large infrequent coho of the past may have been undocumented hybrids. Some very large verified hybrids are still being taken out of the lake on occasion.  Coho have not had the heavy selecting pressures placed on them that the chinook have been exposed to.  They are seldom targeted in the lake (mostly an incidental catch) and are overlooked in the river when swimming amongst chinooks.  This may be why there has not been any “need” to change as a species.

Chinook compared to brown trout:

 

                Brown trout have remained relatively consistent over the decades with expected above and below averages in numbers and size.  The brood stock has not changed in decades and that has lead to survivability issues and genetic health related problems, but those are not associated with human pressures on the lake or tributaries.  The browns that successfully spawn may have changed behaviors as well due to fishing pressure in the lake and especially in the tributaries.  This may be why tributary anglers are not seeing the brown trout that they have in the past (they too have changed their behavior and regardless of regulations or stocking numbers they may not return to the tributaries the way they did in the past in number or duration).  Fishing success on the lake is tied to weather conditions more than anything in the Spring. The number of brown trout is highly influenced by predation at stocking, health of the trout including their size at stocking, and in some parts of the state poaching of brown trout in small tributaries has been reported.

Chinook of today compared to the chinook of the past:

 

                The chinooks of Lake Ontario have already been identified as likely being a new subspecies through evolution of the species in terms of behavior compared to the original population from which they came.  The fish do not stage as they did back in the 70’s through the mid 90’s in front of the river mouth.  Instead their behavior is so erratic that they cannot fit any known models used to predict salmon migrations and staging behavior.  Once in the tributaries they no longer spend a lot of time pool hopping as they used to, but instead swim to the hatchery or upper parts of the river and its tributaries in quick fashion.  The chinooks used to be in the rivers in high numbers around Labor Day weekend, but these fish would have been exposed to higher and longer fishing pressure while waiting for optimal spawning temperatures a month away (their alleles have too been likely removed).  Instead there is a massive run that occurs later in September and closer to the time of which they are able to successfully spawn.  In the lake, the salmon move in and out of Mexico Bay and have staged in water as deep as six hundred feet in recent years off of Oswego which was unheard of or unknown of in the past.

                The chinooks are spawning at an earlier / smaller size than they did in the past only by percentage.  It is likely that there were some that did in the beginning, but no one noticed or cared because they made up such a small percent of the total population.  It is also likely that some behaved as erratically as those of today, but again they represented a very small percent of the population.  In both of these instances their relatives that behaved in a traditional and known way were exposed to far greater pressure and had a greater likelihood of being removed prior to spawning.

What does age two chinooks mean to the future of the fishery:

                Smaller fish similar to what we have been catching over the past two years will become the new normal.  There is no reason for the chinooks to be selected to go back to the larger, older size class in any large percentage without artificial selection at the hatchery, a trophy class limit on anglers, reduced pressure on the tributaries of spawning fish, or new genetics being introduced from their ocean cousins.

                Greater uncertainty of the fishery from year to year will occur because the majority of the fish available and targeted as mature salmon will be represented by a single year class.  If the lake trout population goes up so does the predation of the salmon stocked or that are wildly produced and the number of available salmon will decrease.  Also, natural spawn becomes that much more important as the stocking numbers at the hatchery have decreased.  If there is a poor natural reproduction year class the fishing will be directly tied to it.  This makes the net pen projects that much more vital to the long term success and stability of the fishery.

                The predatory biomass of the chinook may be represented by smaller fish that are removed from the system a year or two prior to the past.  This may require the alteration of the models used to project alewife consumption and sustainable stocking target numbers for these fish.

                A “cushion” fishery may need to be developed or developed further in the event of a year or two of poor survivability of the chinooks to sustain the economic fishery for the businesses that depend on the Lake fishery.  This may be increased brown trout stocking, new strains of brown trout to offer true trophy size fish, increased coho stocking once the study concludes concerning which size class is most successful, or some other out of the box thinking to address this real situation. 

This may partially explain the very low success of the fishing in 2014 to 2015 and the very high success in 2017 and 2018.  With the shift to primarily two year old chinooks the low fishing followed a higher lake trout population.  With the lower salmon fishing conditions the focus of many anglers shifted to lake trout and their numbers fell.  This lowered the predation of chinooks and with high natural spawn the exceptional fisheries of the past two seasons occurred. 

In conclusion:

 

                The study on Atlantic salmon may reveal an answer to a lot of the trends in the Lake Ontario fishery concerning the chinook salmon over the past three decades.  It may also show where the fishery is heading.  If there is a follow-up study to this on the lake or if data that has been collected at the hatchery and through the creel census supports this occurring in Lake Ontario, work will need to be done to correct many of the models used today that were developed around the “old” chinook.  In addition a re-education of the anglers and the expectations of the angling community may need to occur.  There may be numbers of large salmon from time to time, but it may be linked to less than ideal conditions not allowing the salmon to mature at age two as they would if they were healthy.  The greatest indicator of the overall health of the salmon may continue to be the plumpness of the 36” fish rather than the overall average size of the fish as the genetics may not allow for this to increase again.  More attention will have to be given to each year class of fish since there will not be a noticeable buffer class to make up for a failed year class as there has been in the past.

For Review;

Phil Lucason

Edited by Morgan-E
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Hmmmmm…… This sounds very familiar,  I would believe the DEC has already heard a lot of this information already for the past 30 years. THANKS for posting.

 

Jerry

RUNNIN REBEL

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Posted (edited)

https://www.sciencedaily.com/releases/2018/11/181114104356.htm

This is the study from the University of Helsinki that this article refers to. Study has 40 years of genetic data from over 150,000 salmon collected since the 1970's,  and this study is very recent November 2018


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Edited by RUNNIN REBEL
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This kind of confirms my suspicion that the kings are evolving to the LO  ecosystem . 

 

Time to get new eggs from the west coast . 

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Not buying the size decrease isn't because of bait fish. Lake michigan went years without producing 30lb kings. Now the last couple of years size has came back in a big way with even a 40+ lb king being caught.

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The truly interesting thing to me is the rapidity of the supposed changes. Usually significant genetic changes and adaptation have been thought to occur in much slower intervals as in thousands or millions of years.....this certainly suggests otherwise, and does it mean that there may be "forms" of genetic adaptation (e.g. short term and long term)? I'll leave it to the scientists but scratching my head nonetheless. :smile:

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Salmon are shrinking and it shows in their genes

Date:
November 14, 2018
Source:
University of Helsinki
Summary:
Male salmon are maturing earlier and becoming smaller, and it shows in their genes. This was the discovery of a study that examined scale samples from salmon over a 40-year period, and looked at the population genetic profile of a gene that determines salmon's age of maturity and size. The results show that the 'big salmon gene version' has become rarer in the population over time, and has been replaced by the 'small salmon gene version'.
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FULL STORY

 

Male salmon are maturing earlier and becoming smaller, and it shows in their genes. This was the discovery of a study that examined scale samples from salmon in the River Teno in Northern Finland over a 40-year period, and looked at the population genetic profile of a gene that determines salmon's age of maturity and size. The results show that the 'big salmon gene version' has become rarer in the population over time, and has been replaced by the 'small salmon gene version'.

The study, conducted by scientists from the University of Helsinki in co-operation with Natural Resources Institute Finland and the University of Turku, was published in the journal Nature Ecology and Evolution and was featured on the magazine's November issue's cover.

Previous work by the consortium has shown that the age at which salmon mature is getting younger, and consequently also the size of salmon that are spawning is getting smaller. They also identified a single gene Vgll3 that has a large influence in determining the age at which salmon reach sexual maturity. They identified two forms or alleles of the gene that appear to signal to the salmon to either mature later at a larger size or mature earlier at a smaller size. The later salmon mature, the bigger they grow.

"We knew from our earlier research that the age at maturity had been decreasing over this period. Now we wanted to see if there were signs of this also at the genetic level, that is, whether it was an evolutionary change," professor Craig Primmer from the Faculty of Biological and Environmental Sciences at the University of Helsinki explains.

"Basically, if we see that 'salmon are shrinking', we can't be sure if it is evolution. For that, we need to know there are also changes in their genes. Now we also have that information, and we can say that we can demonstrate 'evolution in action'."

The change in genes indicates that the size decrease is not just a 'plastic' or a temporary change brought on by other factors that do not necessarily require changes in gene sequences, such as changes in hormone levels. Instead the change has an evolutionary basis. Being big is not as much of an advantage to salmon as it used to be, and the salmon are adapting to this new reality.

"This is another example de-bunking the myth that evolution takes millions of years," said Yann Czorlich, the first author of the study from the Natural Resources Institute Finland and the University of Turku. "On the one hand, this can be considered a good thing seeing it means there is hope for salmon to adapt to their changed conditions. But on the other, it's bad news for anglers want to catch big salmon and join the '20 kilogram club' as there may be fewer big salmon in the future unless we can identify and halt the factors causing their decline."

As a part of his PhD studies, Czorlich is preparing to address the reasons for why salmon might benefit from being smaller in a future paper, but one theory is that salmon today are more likely to die during their time at sea either because of fishing or other reasons, and would thus benefit from returning to the rivers to spawn sooner rather than later.

The scale samples used for the study came from a long-term scale archive maintained by the Natural Resources Institute Finland. The archive keeps samples from more than 150,000 salmon individuals collected by volunteer fishermen since the 1970's from River Teno, one of the most prolific salmon rivers in Europe. The scales were then used to determine the age structure of the salmon population. They were also the source of DNA for genetic analysis

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Definitely makes a lot of sense. We look at thousands of stomachs each season and it is definitely not a bait shortage. We most certainly have lots of early maturing Salmon now. No complaints -they fight and eat better than ever. I appreciate the work you did on this Phil. 

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The truly interesting thing to me is the rapidity of the supposed changes. Usually significant genetic changes and adaptation have been thought to occur in much slower intervals as in thousands or millions of years.....this certainly suggests otherwise, and does it mean that there may be "forms" of genetic adaptation (e.g. short term and long term)? I'll leave it to the scientists but scratching my head nonetheless.

The theory is called punctuated equallibrium and has been part of the genetics curriculum since my college days it basically states that evolution happens in short rapid bursts separated by long stable intervals. It stems from the thought that major environmental pressures often change rapidly and the species whose genetics are most diverse to start have the best chance of individuals who are better adapted and there genes than become more prominent. For this case it's important to note that hatchery survivability is probably a major driving influence to the population genetics and any genes linked even partially to that will also increase over time. Fresh stock from the West coast would likely not do as well in the hatchery to start and be quickly bread out as a result. The lake o fish currently are the best evolved to survive in lake o the Dec should strongly consider experimenting with selective breeding of the biggest and oldest fish tagging the offspring to see if they are larger on average at return there is a very good chance the science would end up showing the benefit



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Posted (edited)

I would love to see a study of lake O salmon tissues looking for pharmaceutical based hormones that may be in the water. How about the stuff in plastics?  Stuff changing rapidly in evolutionary terms. The amount of largemouths with melanin black blotches is alarming. Nobody talks about a “fish bowl size” theory. The larger the fish bowl, the larger the goldfish. Perhaps salmon with an ocean evolution are evolving to the smaller lake setting. 

Edited by Gill-T

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Gill T your and ska8 are taking me back i did a research paper on "environmental estrogen" once upon a time back than it was a pretty newly discovered thing but it defiantly was having notable effects.  Aquatic environments were especially susceptible.  a lot of plastics and common pharmaceutical products break down into things with very similar chemical structures to estrogen. in one stream they found significant reduction in trout reproduction and it was due to the waste products breaking down into estrogen like compounds were causing a high percentage of fish to change gender (yes thats a real thing for some species) and or become sterile. the result was a population with not enough males to sustain reproduction.

 

i remember an article a couple years back that even on the west coast the oldest and largest kings were becoming very scarce to the point where we may never see a new record.   Part of the cause is defiantly attributed to fishing pressure and the tendency to target and keep the largest fish.  These giant had some specific tendency's and timings that allowed them to be targeted even within the larger salmon runs.   increased catch and release has shown promise but the genetics of 90lb kings may be gone 

 

i also believe that some of the staging behavior we have lost is more directly related to warmer water temps later in the year than we used to have but I have no temp data to back that up.

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Posted (edited)

 Ifishy - Thanks for the insights. I attended a talk given by a faculty member of a college near here discussing some of the things going on in the Finger Lakes and the actual estrogen aspect was discussed  along with a number of other similar structured chemicals such as those used in plastics and the potential impacts on the fisheries. It was also mentioned that they have found traces of things like Viagara, amphetamines, and a host of other chemicals that don't belong in the water. Many of these things are not routinely filtered out by conventional water treatment either so there are residual amounts in our drinking water also.They are monitoring some of the Finger Lakes tributaries looking for potential sources too. The fact that Lake O is at the bottom of the Great Lakes may make it something of a "reservoir" for some of this too but it is probably fortunate also that it may cycle through via the pathway to the sea further diluting the contaminants. 

Edited by Sk8man

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7 hours ago, jerryriggin said:

Not buying the size decrease isn't because of bait fish. Lake michigan went years without producing 30lb kings. Now the last couple of years size has came back in a big way with even a 40+ lb king being caught.

Been fishing both lakes for over 30 years. First trip to lake o was in 1987. What I witnessed on my graph was truly remarkable. 100 foot plus school of alewife. The water clarity was nil which allowed those big fish to move into trolling spreads and not be spooked. Your lake is now totally out of balance on the predator prey situation.  Over on Michigan my managers were very lucky after 2012 that natural recruitment took a serious crap or we would be looking like huron. Lake Michigan over the last three years have definitely produced larger fish than lake o but the numbers of matures has been greatly reduced. Thus making us having to work much harder for our fish. 

 

Kisutch

 

 

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Posted (edited)

Good read. Many, many theories out there. I’ve fished the lake since the late 80s and can testify to a lot of the trends mentioned. I think more than anything, the warm fall trib temps have formed the life traits of our current LO chinooks from when they first were introduced. There used to be huge staging beginning in mid-August with combat pierhead fishing in full force by Labor Day. By the 2nd week in Sept the major push was over. Tribs, including the salmon river, would be absolutely littered with salmon carcasses  throughout the month of Sept. All fish that would never pass on their genetics come egg collection at the hatchery in mid October. Many of us can remember what the Genny looked like mid September with the banks littered with rotting salmon. The fish left at the hatchery during egg collection in mid October were those that ran late and most likely didn’t stage for very long. Clearer water could also be a factor in the decreased near shore staging for salmon as well. 

 

I also remember good Spring catches of salmon, then vastly slowing down by mid-May, all but non existent in June, slowly picking back up in July, then a blood bath by mid August. I remember catching a 26lb king on June 20th while the DEC was doing their survey at Iron Bay and they said that was the first salmon they had seen out of Rochester that month. Nothing like the 20 plus fish days we experience all season long as of late. The larger staging activity back then could also simply be a factor that there were more mature salmon left in the lake in August because they were not being caught in abundance in June and July like they are now.

 

I believe that increased catch rates now compared to back then is because once the massive bait schools showed up by mid-may in the 80’s/early 90s our lures couldn’t compete. There were more salmon being put in the lake back then so logically there should have been higher catch rates. Sure we are all better fisherman now,  but I’m hearing stories of newbies nowadays going out and catching double digit numbers in June. In my opinion there is too much correlation to the decreasing salmon size, higher catch rates , and lower bait abundance being detected by the trawl analysis to come to any other conclusion that the decreasing size of our salmon is being most impacted by decreasing bait populations. As somebody mentioned earlier, Lake Michigan is actually starting to see an increased in the size of their salmon now that they have a better balanced predator/prey dynamic. If genetics and evolution were the major driving force behind reduced salmon size, what we are seeing in Lake Michigan should never be the case.

 

An alternative theory to selective harvesting impacting the age class of maturing salmon, could be that when a population feels environmental stress they tend to mature early, not later. Stress in LO being, reduced bait, therefore it is best to mature early and of a smaller size to insure your genetics stay in the mix. Another perspective regarding the plumpness factor of age two fish that is that it is well known that salmon feed the most in the last year of their life so they can live off their reserves during their spawning period. In the 80's/90s it was common for a 3 yr old 18-22lb salmon in May to gain 10-15lbs by August, with 2-5lbs weight gain attributed to growing eggs in females. That is just not the case anymore. We know more salmon are maturing at age 2 these days, therefore the plumpness of a 2 year salmon could simply be that they are putting the feed bag on to prepare for spawning as they normally do in their last year of life. The growing eggs in the female 2 yr olds can be misintrepted as a healthy, "plump" 2 yr old as well. We are nowhere near what was experienced in Lake Huron with the complete crash of their alewife population. Even the change in life traits aforementioned could not counter the total devastation of the bait population experienced in Huron that produced the emaciated salmon they experienced. 

 

Interesting mention of the little impact to size of the Brown trout and Coho salmon. This is most likely because they are more adaptable to different sources of food, Gobies, perch, emeralds, ect. All additional food sources that Chinooks refuse to eat. We should be capitalizing on the almost unlimited abundance of Gobies available and stocking more Browns right now. I also like the idea of introducing more strains, seaforellen mainly, which grow to 20 plus lbs with more regularity.  Browns are available pretty much 12 months of the year in either the tribs or lake, are easy to target and stay near shore providing opportunity for the small boat owners, and consume huge amounts of gobies which we happen to have a lot of right now. 

 

My two cents.

Edited by A-Lure-A
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Posted (edited)
10 hours ago, ifishy said:

Gill T your and ska8 are taking me back i did a research paper on "environmental estrogen" once upon a time back than it was a pretty newly discovered thing but it defiantly was having notable effects.  Aquatic environments were especially susceptible.  a lot of plastics and common pharmaceutical products break down into things with very similar chemical structures to estrogen. in one stream they found significant reduction in trout reproduction and it was due to the waste products breaking down into estrogen like compounds were causing a high percentage of fish to change gender (yes thats a real thing for some species) and or become sterile. the result was a population with not enough males to sustain reproduction.

 

i remember an article a couple years back that even on the west coast the oldest and largest kings were becoming very scarce to the point where we may never see a new record.   Part of the cause is defiantly attributed to fishing pressure and the tendency to target and keep the largest fish.  These giant had some specific tendency's and timings that allowed them to be targeted even within the larger salmon runs.   increased catch and release has shown promise but the genetics of 90lb kings may be gone 

 

i also believe that some of the staging behavior we have lost is more directly related to warmer water temps later in the year than we used to have but I have no temp data to back that up.

 

This gets my vote. It may very well be genetics, but I doubt it's evolution except in the most loose sense of the word. The same reproductive prematurity is showing up in humans, where girls are entering estrus an/or developing early, and this is suspected to be due in part to environmental impact. All the old meds dumped down the toilet, synthetic chemicals, and plastic nanoparticles are taking a toll. It just takes generations to see. Which is why I'm wearing a doomsday hat lately. It's not the 18-wheeler you see that gets you, it's the guy on the bicycle that you didn't see...

Edited by Gator

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Large salmon require a balanced harvest of all sizes of stocked fish. I remember a photo of a 120 pound King Salmon in Ketchikan taken in 1912. Today too many salmon are returned to the lake for being undersized, catch and released practice, foolish conservation measures and increased stocking numbers. Emerald shiner numbers are not studied, just alewives.Smelt are not studied also and the total forage is unknown . Just returning small fish is shooting your self in the foot if larger salmon is your desired catch.


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8 hours ago, A-Lure-A said:

Good read. Many, many theories out there. I’ve fished the lake since the late 80s and can testify to a lot of the trends mentioned. I think more than anything, the warm fall trib temps have formed the life traits of our current LO chinooks from when they first were introduced. There used to be huge staging beginning in mid-August with combat pierhead fishing in full force by Labor Day. By the 2nd week in Sept the major push was over. Tribs, including the salmon river, would be absolutely littered with salmon carcasses  throughout the month of Sept. All fish that would never pass on their genetics come egg collection at the hatchery in mid October. Many of us can remember what the Genny looked like mid September with the banks littered with rotting salmon. The fish left at the hatchery during egg collection in mid October were those that ran late and most likely didn’t stage for very long. Clearer water could also be a factor in the decreased near shore staging for salmon as well. 

 

I also remember good Spring catches of salmon, then vastly slowing down by mid-May, all but non existent in June, slowly picking back up in July, then a blood bath by mid August. I remember catching a 26lb king on June 20th while the DEC was doing their survey at Iron Bay and they said that was the first salmon they had seen out of Rochester that month. Nothing like the 20 plus fish days we experience all season long as of late. The larger staging activity back then could also simply be a factor that there were more mature salmon left in the lake in August because they were not being caught in abundance in June and July like they are now.

 

I believe that increased catch rates now compared to back then is because once the massive bait schools showed up by mid-may in the 80’s/early 90s our lures couldn’t compete. There were more salmon being put in the lake back then so logically there should have been higher catch rates. Sure we are all better fisherman now,  but I’m hearing stories of newbies nowadays going out and catching double digit numbers in June. In my opinion there is too much correlation to the decreasing salmon size, higher catch rates , and lower bait abundance being detected by the trawl analysis to come to any other conclusion that the decreasing size of our salmon is being most impacted by decreasing bait populations. As somebody mentioned earlier, Lake Michigan is actually starting to see an increased in the size of their salmon now that they have a better balanced predator/prey dynamic. If genetics and evolution were the major driving force behind reduced salmon size, what we are seeing in Lake Michigan should never be the case. An alternative theory to selective harvesting impacting the age class of maturing salmon, could be that when a population feels environmental stress they tend to mature early, not later. Stress being, lack of bait, therefore it is best to mature early and of a smaller size to insure your genetics stay in the mix.

 

Interesting mention of the little impact to size of the Brown trout and Coho salmon. This is most likely because they are more adaptable to different sources of food. We should be capitalizing on the almost unlimited abundance of Gobies available and stocking more Browns right now. I also like the idea of introducing more strains, seaforellen mainly, which grow to 20 plus lbs with more regularity.  Browns are available pretty much 12 months of the year in either the tribs or lake, are easy to target and stay near shore providing opportunity for the small boat owners, and consume huge amounts of gobies which we happen to have a lot of right now. 

 

My two cents.

Very well said, A lot of intelligent discussion here, let's hope 2019 is as good as 2018 and continues to be.!!!

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The one thing I would mention here is that the Seeforellen strain (grow to huge size) of browns was tried in Owasco and Seneca Lakes in the past and they didn't fare well. I know Lake O is a different environment but I don't think that pinning our hopes on them should be a primary strategy.

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They do well in Lake Michigan 

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If we really want 40 pound salmon, then we should release 20 to 25 pound salmon early in the year when they would have a few months to increase their weight.


Sent from my iPhone using Lake Ontario United mobile app

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1 hour ago, Gill-T said:

They do well in Lake Michigan 

 

 

They are doing extremely well on Michigan. I have personally talked to the Wisconsin bio running there seeforellen program. They are quite happy with their trophy brown trout fishery. Check out the Racine Salmon a rama website. They still put up some gorgeous fish.

 

Kisutch

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