Runty Lingcod?

Wow, some really interesting responses to this.  Kayak fishers are definitely different.

Here's kind of a simplistic conceptual exercise i used to think about this.  I have no idea if I'm right or if this is "half logic."  Please have at it if it is, just throwing it out for fun:

Suppose we look at the dog population of California as being analogous to the ling cod population off the coast of California.  For this exercise (or whatever it is) let's suppose that Oregon, Nevada, Arizona, and Mexico all hate CA for its dog-matic policies and only allow slight dog migration in and out of the state.  This would be analogous to what our esteemed NMFS scientists refer to as an ESU (evolutionary significant unit), meaning there was significantly more breeding within the CA dog population than from input of dogs from outside the state.

So then CA's genetic dogospere would run a continuum from big toothy child-eating monsters to little bon-bon eating couch sitters.  The average size dog in this population would be around, say, 60 -70 lbs, with a variance of 50 lbs on each side (not really correct but good enough).  So a bell curve of this population would hump at 60 or 70 lbs.

Now suppose california was suddenly afllicted by big dog disease and most of the big guys were systematically culled out over time.  The hump of the bell curve of that population would start to migrate towards the foo-foo dogs and the area under the big dog part of the curve would get smaller.  The more big dog mortality, the fewer dogs in the population carrying those genes and the more fun the little bon-bon poppers are having.

If big dog disease ended, I think their recovery would be dependent on what proportion of the population were still carrying those traits.  i don't think the new weeny dogs would be a separate species, but a new race or breed.  In human races, i think it would take a long time for one race to change into another without significant outside input or some sort of selective process.

For this admittedly silly exercise to be of any value, the assumption that the CA ling population is an ESU (somewhat independent) needs to be established, and I don't know if that is true.  Do lings migrate?  I was under the impression that most genetic drift in benthic species happened during their larval phase, when the fish are nearly planktonic.  The California current runs down the coast from Oregon or washington, but does not really connect to the Alaska current, which hits the coast from japan somewhere around British Columbia (I think).  So I don't know if there's much mixing between the 2 populations.  maybe there is.

I think Josh and David Conover are correct.  We can't harvest these species and at the same time expect "natural" processes to take place.  Natural processes are happening.  The fish population is responding to it's most significant predator - us.  We like to get the bigger ones and leave the smaller guys, both commercially and sport.  Therefore smallness is a survival trait in this new dynamic.  If we want big fish on our coast we have to manage for them.  As he said in the article, any farmer would go out of business if he managed his stocks by only allowing the runts to survive.

I seem to have gotten a case of keyboard-aria.  Anyway, sure is interesting.

Therefore smallness is a survival trait in this new dynamic.

Not really.  This assumes the big fish and the small fish are the same age.  In most cases, you are likely not selecting for the gentetically encoded maximum potential size, you are simply removing the oldest fish.  The smaller fish that are left can still grow to a larger size, and give birth to offspring that can grow to a larger size.  You guys are toying with Lemarkism...not a good direction to go.

Fish achieving premature fecundity is not abnormal, and not all that uncommon.  I have seen coastal cutthroat fecund at 50mm!!!  Fish, and other creatures can do an amazing array of adaptive behaviors dependent on pressure applied to their population...some fish a can even change gender. 

What scwafish said.

Your model assumes that all fish are at the end of growth phase when caught and that if the big ones are caught the "big" genes leave the pool.

I don't think that is an accurate representation of the gene pool.

MolBasser

It seems that some of you have put a big "X" on the idea that is necessary to make this all feasible, thinking that the smaller fish are just younger and not actually smaller. Most populations have a naturally occuring variance in size. I couldn't tell you a ratio or anything as I am a beginning Marine Bio student (only junior year) but I would bet on a fish that maxes out about 40" that you can have full grown adults less than 24" that are reasonably matured. These fish have their fishing pressure completely removed (except as bycatch or injuries from being caught and thrownback) while any fish over 24" faces heavy fishing pressure. It is possible to remove a trait which is shown in this study. I sure don't know the solution but I do have to accept that I am doing some kind of damage by being selective in this way. The populations are not large enough that we do not make huge impacts on them. And as for the protected area ideas, if the larvae are planktonic then they would be reseeding the surrounding areas with a trait that either has become low in appearance in surrounding populations, or possibly removed, and would serve a great purpose. Where do they need to be and how many of them?  I just think that they do serve a purpose for the pressure that we are applying.

Wouldn't it be a fascinating tournament to define the winning fish as closest to some randomly selected length?

It seems that some of you have put a big "X" on the idea that is necessary to make this all feasible, thinking that the smaller fish are just younger and not actually smaller. Most populations have a naturally occuring variance in size. I couldn't tell you a ratio or anything as I am a beginning Marine Bio student (only junior year) but I would bet on a fish that maxes out about 40" that you can have full grown adults less than 24" that are reasonably matured. These fish have their fishing pressure completely removed (except as bycatch or injuries from being caught and thrownback) while any fish over 24" faces heavy fishing pressure. It is possible to remove a trait which is shown in this study. I sure don't know the solution but I do have to accept that I am doing some kind of damage by being selective in this way. The populations are not large enough that we do not make huge impacts on them. And as for the protected area ideas, if the larvae are planktonic then they would be reseeding the surrounding areas with a trait that either has become low in appearance in surrounding populations, or possibly removed, and would serve a great purpose. Where do they need to be and how many of them?  I just think that they do serve a purpose for the pressure that we are applying.

This may be true, but you cannot assume it.  There are a bazillion variables to take into account.

Growth rate
Overall population
Fish distribution

Etc.

I merely wanted to point out that the model is not just as simple as big fish small fish.  It makes analyzing this situation very difficult in a controlled manner.

This could easily be a thesis project.

MolBasser

Sure you cannot assume that but you as well can't assume that larger fish are just older. That is the idea that I was trying to challengel.

And I had wanted to write in the last post but had forgotten this point.

Some of the posters have shared there view that they wouldn't mind smaller fish if there were more of them. Unfortunately nature is something we do not understand as well as is required to make a decision to alter a species or its traits permanently. Man cannot oversee nature as well as nature can. If we were to have smaller fish it might become prey to something else and therefore we'd have even less of them. The outcome is unforseen. So  to decide that, if these effects are really happening we will be okay with it, is to decide you don't mind either way.

Brian, thanks for the reply. did you read the most-emailed article in the online new york times?
the one about how humans are larger than just a few hundred years ago and living considerably
longer. and I'm not just talking about obesity.  they are calling the change 'evolution'.

GH, I agree that the outcome of management action cannot be completely forseen.
Also that we should expect some effect on populations from the take that might be not as
simple as taking the older fish. Every once in a while tho, the effect is not quite as bad as
the one some folks predict, just like things often don't turn out as well as somebody hoped.
I'm also glad you jumped in on the discussion. Good to see some youngbloods.

Rove is pure evil I'm sure, but even he could not predict the effect of lowering the water in the klamath on the commercial salmon fisherman through the chain of events that unfolded.

p-spark, thanks for pointing out the politically defined aspect of the term 'threatened'.

Dave, I get the distinct feeling you are trolling for entertainment on ncka,  .

J

Dave, I get the distinct feeling you are trolling for entertainment on ncka,  .

J

I thought we all were.  Do other fishing sites have these type of discussions?  I appreciate the "variance" of ideas.  You learn something.  Like now I have to figure out what Lemarkism is.

>Unfortunately nature is something we do not understand as well as is required to make a decision to alter a species or its traits permanently.

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?

I'll stand by what I said about marine reserves not preventing evolution.  For that to be true, the reserves would have to be so vast that the fishing mortality would be lost in the noise in comparison to natural forms of mortality.  That is both impractical and unacceptable.  There might be some merit the the argument that it would provide a 'hatchery' for sedentary species like (some) rockfish, but that won't prevent the population as a whole from evolving to grow faster, spawn sooner and survive barotrauma better!  Fishing could make for better fish in that instance.

>You guys are toying with Lemarkism...not a good direction to go.

No, that would be the case if a ling became anorexic to stunt it's growth to avoid being caught, and we then expected her offspring to have the trait of being smaller in the next generation.

P-spark-From everything I've read, and reserves are a big part of my time at the PFMC, the jury is out.  There is no iron-clad evidence either way.

Like I said, they are toying with Lemarkist principals...e.g., non-selective traits becoming heritable.  If you kill Shack, his little brother won't have short kids...thats all I'm saying.


BTW-Lemark was a genius in some areas, just not ecology/evolution!
 

  If you kill Shack, his little brother won't have short kids...thats all I'm saying.
 

Word.

MolBasser

hmm, I don't really know the depth of the lemark stuff, and I might be too old and slow to learn fast enough.

especially from this clown:

More or less that was the theory Darwin put forward after his infamous voyage on the HMS Beagle took him to the Galapagos Islands. Darwin's wasn't the only theory of evolution to come out of the 19th century. Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarc proposed that animals would evolve because of their surroundings and that genetic changes would occur as they attempted to adapt to what was around them.

Unfortunately this theory doesn't stand up to close examination; what it implies is that a species notes a more efficient way of surviving and is able to change its genetic code at will. If this were the case don't you think humans would have grown an extra set of hands by now? How many times have you needed that in a multitude of situations.

As anybody who has studied evolution knows Darwin came up with his ideas based upon his observations of the different species of Finch on the Galapagos Islands. As he travelled from island to island he made note of the different styles of beak that individual species had, and how they were particularly suited to the food source available to them. As the concept of evolution wasn't a new thing, ancient Greeks and Indian scholars had written on the subject, he had a body of knowledge upon which he could base his theroms.

It's interesting to note that the big dispute about evolution in the 19th and early 20th century did not revolve around whether it existed or not, but whether it was caused by, as Darwin postualted hereditary means, or as Lemark said, adaptive means. As research into genetics grow more sophisticated, including discovery of D.N.A. it's become more and more obvious that Darwin's theory of inheritated characteristics caused by mutations is the correct explanation for evolution.

but basically I'm not buying the shack quote. the brother of shack could have the "short" gene.

and p-spark is right that the lings are not choosing to be small.

J

but basically I'm not buying the shack quote. the brother of shack could have the "short" gene.

J

That isn't the point.  The point is that killing Shaq has no effect on his brothers genetic makeup.  Once an egg is fertilized, that is the genetic makeup of the animial.  The genes don't change during life, nor are they altered before they are passed on (for all intents and purposes).

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.

MolBasser

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.

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.

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.