Runty Lingcod?

well, I'm in over my head but I'm still curious.

siblings have half of their genes in common. but not the other half.

If a ling that maxes out at 42" and a ling that maxes out at 23" breed, then lots of things could happen,
but one of them might be half the offspring are big and half are shrimpy.  no?

what does it mean for "non-selective traits to be 'heritable'". damn it jim. I'm not a geneticist!

The enviornment does not effect your genetic makeup.  It will effect how those genes are regulated, but not their existance, and this is the important point for what gets passed on to furhter generations.

Normally if all is stabilized, yes, the enviroment does not affect genetic makeup of an organism. But if there is a pressure it surely does affect that gene's appearance in the population. The uncertain part is whether fishing is far-reaching enough to affect that change.

No.  A specific organism is set in its genetic makeup.  The environment will determine which animals survive and which genes get passed on.  Evolution requires many generations.

As for the idea that if you kill Shaq you do not make his brother have smaller children:
If you kill off a lot of the peopel Shaq's size you definitely do affect the population average size. That point would work for why it might be okay to harvest one giant fish but I don't know if it applies to a population where you kill off many organisms.

this is not getting to the argument of the earlier model which did not take into account age and distribution.  No one is going to argue that if you kill all the animals with large growth potential that you wouldn't affect future generations.  The issue was that it is not the case that by killing large fish that the large fish genes are removed as their offspring (while small because of age) still swim.

You're arguing the merits of virginity in relation to something that's been bent over a barrel for the last 100-20,000 years. We already have altered most species permanently, and will continue to do so as long as we're around.  Evolution is inevitable, and as long as we're intentionally and unintentionally causing things to die, from bacteria to blue whales, we will influence it.  Should those affects be random and indiscriminant, or should we actively intervene to prevent bad outcomes?

But the idea that I was working on isn't that we should not have any effect. It is that we should not have a directed altering effect to suit or own needs especially blindly.

MolBasser

this is not getting to the argument of the earlier model which did not take into account age and distribution.  No one is going to argue that if you kill all the animals with large growth potential that you wouldn't affect future generations.  The issue was that it is not the case that by killing large fish that the large fish genes are removed as their offspring (while small because of age) still swim.

Thanks..."WORD" back at you.

Getting this thing back to lings in particular, we can ALL rest assured that we are currently selecting for age and not size, becuase if you saw what a fully mature population of virgin biomass looks like bsteves would have gotten last place in Elk last year.  Currently, there is a fully recovered biomass, but not at age.  As that biomass from the 1999 and later recruitment matures, you are going to see ling fishing that hasn't been seen since the early 1900's

Wanna see a pic that will make you shat yourself?

Not sure I have much to add except that I am glad there is a place where such a discussion is happening.  This is very interesting.  I am impressed with the level of knowlege and the well thought out and clearly expressed opinions.  Keep it up and thanks. 

Quote from: gatohoser on August 01, 2006, 11:55:26 pm
Quote
The enviornment does not effect your genetic makeup.  It will effect how those genes are regulated, but not their existance, and this is the important point for what gets passed on to furhter generations.

Normally if all is stabilized, yes, the enviroment does not affect genetic makeup of an organism. But if there is a pressure it surely does affect that gene's appearance in the population. The uncertain part is whether fishing is far-reaching enough to affect that change.


No.  A specific organism is set in its genetic makeup.  The environment will determine which animals survive and which genes get passed on.  Evolution requires many generations.

Molbasser, I understand what you are saying. The environment does not change genes in each single organism. But we are talking about a selective pressure which is greater than the organism. That is on the scale of the population. So in that case then yes genetic makeup does change.

It's still not the heart of the argument which is whether or not large fish are mostly just older or just genetically larger because if they are just genetically larger we are no doubt being a selective pressure. I think that what I need to know before going either way would be to know as fact if larger fish are just older or genetically regulated to be larger. Scwafish you may be trying to tell us that but I couldn't understand the post too well. Could you elaborate?

I think that what I need to know before going either way would be to know as fact if larger fish are just older or genetically regulated to be larger.

Yes.  This is the meat of what we are discussing.  I would posit that we are just catching young fish (haveing harvested all the older ones already) and that is why they are small.

This would be easy to determine, as you can age a fish by its otoliths.

MolBasser

Seems like we're out of stuff to discuss 

Steve,
Do you know where to find that info or know yourself whether the larger fish are usually just older or are just a little bigger? That seems like it would be so easy to discover if we were to send in the heads of our legal lings to a marine biologist to examine their otoliths for age. Maybe I just found my thesis project....

I'm going to UCSC and we need to do a senior thesis so maybe this could be it!

In general, larger fish do tend to just be older.  However, there is some variation in the age to size relationship such that you could have a younger fish larger than an older fish.

I'm still really confused as to why everyone seems so confused.

Lamark believed in evolution, he just had the process wrong.
Darwin also believed in evolution and his hyposthesis concerning the role of natural selection is currently the basis of our theory of evolution.

Evolution is the change in frequency of genotypes (the genes for heritable traits) of a population over time (generations).  Natural selection however works on the phenotypes (the expression of the traits) of individuals. 

So, with natural selection, individual organisms with certain favorable phenotypes (traits) are more likely to survive and reproduce than those that do not share that trait.  This is not to say that all individuals with the trait survive and those that do not have the trait die.  Rather, natural selection simply changes the frequency of that trait within the population as a whole.

Over time, random mutations and gene flow among populations introduce new genes and phenotypes into the population.  Those new traits are subjected to natural selection and those that are beneficial often increase their frequency of occurence in the populatoin.  Other traits don't do so well and natural selection decreases their frequency in the population. 


Back to the case of "runty fish"....

Case 1.)   No fishing pressure...

Larger fish produce more eggs of potentially better quality.
Some fish put their energy into growing old and large and then reproducing.
Some fish start putting their energy into reproducing at a smaller size when they are still young.
The fish that wait until they are larger, produce over their lifetime more offspring than those that reproduce early.
The frequency of the "wait until your older/larger" gene is greater.

Case 2.)  Add lots of fishing pressure for larger fish.

Larger fish produce more eggs of potentially better quality.
While most fish started out putting their energy into growing older and larger before reprocding, many of these fish get caught before they actually get to reproduce and pass along the genes for this trait.
Intially, only a few fish had the genes for reproducing at a younger smaller size, but these fish find that they can reproduce several times before they are cuaght by the fishery.
Eventually, enough of the "wait until your older/larger" fish are gone from the population and they haven't had the chance to pass this trait to their offspring.
Meanwhile, the "can't wait till I'm older" fish are increasingly accounting for more and more of the total reproduction of the population.  This trait is being selected for by the fishery and on a whole the population of fish are reproducing at a younger age and smaller size.  They're runts!

Your model once again ignores age and general distribution of genes.

What is to stop an angler from catching a "reporduce late" fish when it is small but still legal?

What is to stop an angler from catching a spawn early fish when it is old and large?

As far as I know (and I could be wrong) fish grow throughout their life (albeit at different rates).  It is pretty clear that the longer a fish lives the larger it grows.

Natural mortality would offer a greater pressure against the population of lings for the "breed early stay small" gene as we are talking about the entire biomass here, not just the portion that is subject to angling pressure.

The dynamics are far to complicated for a person to say that because anglers catch fish, they produce a runty population.

MolBasser

Well there is the conclusion to my thesis project! 

Thanks Brian!

So what would a proposed solution be? I have never heard of the slots people were talking about earlier. I love to fish but I'm also a naturalist and would like for my two hobbies to coincide. I know a solution is a tall order but any idea of something that's in the works?

Ah after I wrote that part and tried to post I see MolBasser's new post.
The question would be then are the fish populations young or old right now. I think SCWAfish suggested they are young. If so then the young fish which reproduce early, and are therefore smaller, are illegal to keep and therefore we are not pressuring them in the way that we pressure the grow fat, get big, reproduce fish. I think it does take in the effect of age.

Distribution is something that I don't think we have really discussed much yet as to whether the genes scatter enough to overcome fishing pressure or not. Does anybody know how far a ling cod larvae will move from its birth place once released?

Your model once again ignores age and general distribution of genes.

What is to stop an angler from catching a "reporduce late" fish when it is small but still legal?

Let's see... regulations like size limits, for commercial fisheries you have the guage of the net mesh, oh and greed.

What is to stop an angler from catching a spawn early fish when it is old and large?

Nothing, but you see this fish had a chance to spawn already when it was young.  Maybe even several times.  It's traits have been passed along already where as the "wait till I'm older" fish have not.

As far as I know (and I could be wrong) fish grow throughout their life (albeit at different rates).  It is pretty clear that the longer a fish lives the larger it grows.

True, but if almost every fish over a certain size gets caught, then what?  You can't grow once you're dead.

Natural mortality would offer a greater pressure against the population of lings for the "breed early stay small" gene as we are talking about the entire biomass here, not just the portion that is subject to angling pressure.

That might be true, but the scenario is concerned with increasing the mortality rate by means of an intense fishery on larger fish.

The dynamics are far to complicated for a person to say that because anglers catch fish, they produce a runty population.

MolBasser

Again this is probably true, but that's why scientists like Conover are doing experiments to test individual aspects of the dynamics. 

While it is not stated in the paper, their seems to be some generalization of the term fishery and fisherman here.  For the most part, a lot of the concern is with commercial fisheries like cod in the North Atlantic.  You really can't blame that one on water levels, pollution, or habitat distruction.  They pretty much fished that population down.

Also, I think there is some confusion as to what a "runty" fish is.  I believe that in this study a "runty" fish is one that matures at a much smaller size than what is otherwise considered normal. That is not to say that this fish, if allowed to continue to grow, wouldn't reach a normal maximum size.


I think we need to do some experiments on private bass ponds.  Anybody now of about 20 equal sized bass ponds where we can control the fishing pressure?


Brian

>Does anybody know how far a ling cod larvae will move from its birth place once released?

Lingcod migrate from deep water to coastal waters to spawn, so they're at least moving east/west by tens to scores of miles.

Keep in mind that there is a lot less food in the ocean than there used to be with depressed stocks of most of the fish that lingcod eat.  It would be difficult to say if lingcod average size at age has gone down if it were do to them evolving due to fishing pressure, or being affected by the food supply.

There is a significant size difference in lingcod from socal to norcal, and norcal to alaska, and much of this may be because lingcod grow at different rates, and to different sizes, in different temperature water.  I breed kilifish and find they grow faster and have better spawns at cooler temperatures (less energy to metabolism, more to growth/eggs).

Yes there are many complecating factors, but underlying that all is the fact that if we are a significant cause of death for lingcod, and if there is a method to our mayhem, it will eventually affect the gene pool.  If the 120' depth limit carried on indefinitely, lingcod might evolve to spend their entire adult lives in deeper water with the bocaccio.  Lings that like it deep live twice as long and produce 10x more eggs, while lings that like it shallow don't.

Interestingly, a slot limit would actually favor fish that grew fast, quickly passing through the 'danger zone'.  In that case some scientist would extrapolate 30 foot man-eating lingcod in 1000 years and reccomend MPAs to avoid it...

Here's proof that MPA's will not work to address anthromorphic genetic drift: guppies (same example as the scientist used ironically).  Fancy guppies are bred for many different charachteristics.  However these characteristics are only displayed in the male fish.  Effectively half the population (the female fish) are in MPAs since they are not selected by the criterion that the males are.  Perhaps biggest, healthiest, but not for a darker blue color, ect.  Even with half the fish exposed to un-natural selection and the other half protected, people are still able to breed new strains of guppies in relatively short order. 

I wouldn't expect lingcod to change this quickly, perhaps the effects would only be noticeable in 100 years or more, but I'd like for people to still be fishing with the same quality (or better) catch in 10000 years as they do today.  That will require taking into account the evolutionary pressures that fishing methods create and acting to ensure that fishing (or human influence in general) has a neutral effect on the fishes evolution (or the opposite effect to undo damage that has already been done).

As it is we're arbitrarially protecting some species, whales, GWS, pinnepeds, garibaldi, ect. unconditionally, while taxing most other species to significantly reduced levels.  If that is maintained for 1 million years we'll have 30lb garibaldi subspecies filling the niche that the (extinct) lingcod used to fill.

I largely agree with what bsteves posted, however, I think the confusion arises from the study not really translating to the application.  They were actively selecting bigger fish from the same year class in a confined population.  We are selecting big fish from a mix of age classes, where immigrantion and emigration are wide open.  They sound similar, but they are very different.

As to the age of our population, I don't think the population is young, it is young.  This is why the regs were changed, and we are already seeing the benefits because lings are fecund, and grow quickly.

As to runts, I see a runt as small, not sexually mature at an early age, I call that precocial.

I feel captively bred guppies are a sad case for MPAss irregardless of position on the topic 

What is to stop an angler from catching a spawn early fish when it is old and large?
Nothing, but you see this fish had a chance to spawn already when it was young.  Maybe even several times.  It's traits have been passed along already where as the "wait till I'm older" fish have not.

The 24" size limit is there for a reason.  Lings are sexually mature below 24" and this reg ensures everyone gets at least one swing at bat both early and late bloomers.  Although I have never seen anything that suggests there is an early/late split in the ling population.

As far as I know (and I could be wrong) fish grow throughout their life (albeit at different rates).  It is pretty clear that the longer a fish lives the larger it grows.
True, but if almost every fish over a certain size gets caught, then what?  You can't grow once you're dead.

Like many fish ling growth may never stop, but it slows exponentially near the end.  In reality, they have a maximum size, besides, they aren't really a long-lived species.  Females, do however get significantly bigger.

I think we need to do some experiments on private bass ponds.  Anybody now of about 20 equal sized bass ponds where we can control the fishing pressure?

Interestingly, this has been done many times over.  They will generally have the same overall biomass, but the pond with fishing pressure will have BIGGER fish while the pond with no pressure will have lots of small ones.  This applies to any centrarchid...whacky but true. 

In that case some scientist would extrapolate 30 foot man-eating lingcod in 1000 years and reccomend MPAs to avoid it...

Hard to imagine that with a species that only lives to be about 25.

There is a significant size difference in lingcod from socal to norcal, and norcal to alaska, and much of this may be because lingcod grow at different rates, and to different sizes, in different temperature water.

This is a reflection of fishing pressure, not biology.  This pic is from Elk...these look as big as anything your gonna see in AK.  Hope it rebounds to this in my lifetime...

Keep in mind that there is a lot less food in the ocean than there used to be with depressed stocks of most of the fish that lingcod eat.

Not really true either.  While lings love a free rockfish dinner ir is not the majoirty of their diet.  One of my guys on my PFMC committee has done a fair amount of ling diet studies and contrary to popular belief they eat what most of the other kids are eating...chovies, herring, and cephalopods.

they eat what most of the other kids are eating...chovies, herring, and cephalopods.

Cool! Didn't know what they ate most of the time. My last catch gave me a good idea when he barfed up 2 octopus in my lap fresly eaten.

Thanks Sean,

That's a sweet picture from Elk.

I agree, most of the confusion seems to center around the application of a research study (silversides), to a hypothetical fishery (overfished runts), and to a real fishery (lingcod).  To that end, I don't believe we are breeding runty lingcods, which I guess was the title of this thread.   I just go off sometimes when people confuse speciation, evolution and natural selection.  I'm just happy, no one brought up creationism or ID (intelligent design).  Oh, and don't bother with doing it now, becuase I'm not going to bite.

Back to the fishery bit, we can and do deplete fishery stocks.  MPA's are just another tool we as humans have to try and prevent this from happening. Other tools include seasons, quotas, limits, size limits, gear restrictions, etc...  Do MPAs work?  Well, we don't know becuase no one has been able set up a system of MPAs large enough to have an impact.   Fishermen don't want MPAs, not becuase they don't think they will work, but because they don't like the idea of having more restrictions on fishing.  The "there is no scientific evidence that MPAs will work" puts us in a bit of a catch-22.  We have no evidence of a series of large MPAs working, becuase we don't have a series of large MPAs.   We don't have a series of large MPAs becuase we don't have evidence that they work.  And of all the fish scientists that I know that promote California's MPA initiative, I don't know any that are PETA members or other wacko anti-fishing types.  These are people who study fish, eat fish, and even like to fish for fish.  On the other hand, I suppose if they wanted to set up a no-take MPA between Pt. Reyes and Pt. Arena, I'd be pretty upset myself.  But that isn't going to happen, they may eventually take away a large stretch like Fort Ross to Salt Point, but I can deal with that.

So let's see, I've now opened myself up to all the creationists as well as the agro-anti-MPA fishermen on this board.   See you at Elk, I'll be the one with the bulls-eye painted on my wetsuit.

Brian