Halfordian Golfer wrote:
On Mar 11, 3:01 pm, Willi wrote:
I was reading that a fish that has become piscavorius by their first
year they will be larger and stay larger than other fish in the same
year class. I also know that brook trout have voracious appetites.
Sounds like it's healthy enough that a slot limit would be perfect.
Your argument that the harvesting of "large fish" is good for the
fishery has been disputed. There are a number of new studies that have
shown that harvesting the larger fish leads to a population of small and
more timid fish. With a quick Google I wasn't able to find the studies
themselves but here's a discussion of two of them.

http://whyfiles.org/shorties/108big_fish/

http://www.msnbc.msn.com/id/23340940/

Willi

Appreciate the links. Good reads. The first study, you have to read
all the way down to see the contraindications. This is a very, very
small survey in a fairly unusual lab setup.

That said, there is a lot of data to back up this theory that,
removing the fastest growing fish yields slower growing year classes.

One issue I have with applying this logic too much to the fishery
management equation we're talking about is that it might not mean that
much, compared to the situations of the studies. That is that once a
large minimum was introduced you'd have a ton of fish just under the
slot that would be of varying age. This would be a good thing.

The other significant and as directly and equally important
complexity, especially in this equation, is the fact that it is the
fish that are piscavorius early are the largest and fastest growing
fish in the year class. If we protect the largest and fastest growing
fish it would be predictable that we'd see a dip in recruitment. Maybe
this is what is mistaken in some of these studies?

http://www.blackwell-synergy.com/doi...1999.tb02064.x

Halfordian Golfer


There are more studies. It seems to be an area that's an "in" thing to
study right now. Most of the studies I looked at indicate that removing
the largest fish changes the genetics. It just makes sense that removing
the fish with the genes that result in large sizes will result in
smaller fish over time. It's possible that some of the stunted
populations of Brookies we have out West were selected for by years of
keeping the larger fish. That likely could results in fish that reach a
maximum size smaller than what most anglers are willing to keep. It's
been MANY years since Brookies have been stocked and maybe the genes for
producing larger fish are gone in many populations. I have a property in
southern Colorado that has a small stream on it. It has VERY small
Brookies that will spawn at three and four inches. The largest fish I've
ever seen was about 6 inches. If there were Rainbows, Browns or Cutts in
this stream instead of the Brookies, the fish would be considerably
bigger. I know you've seen these stunted populations and often they're
not due just to stream size and fertility.

I'm not sure why you always want to target the largest fish for removal?

Willi