Dear Jon Eynon:
As you know, in the field of fishery management, we need to know the
dynamic of the fish populations. However, there are so many factors
which always influence the fluctuations of the fish populations. So, I
don't think that it is necessary to use a complicate model to estimate
the fish stock. I think a model with the characters of simply
understanding, esaily explaining, and quickly calculation will be more
appreciable. Like as surplus production model: a very simple model
U=a-bX can be used to provide many information for fishery management.
And, a little change of this model: U=a+b*ln(Bt/Bt+1)-cX. also being a
rather simple model. This improved model also developed directly from
the Schaefer model. It can be used to estimate the carrying capacity(K),
intrinsic growth rate(r) and catchability(q) simultaneously, due to the
parameters a=qK, b=qk/r and c=(q^2)K/r. And then, it is easily to calculate
the historlic fishing mortality(F), biomass(B) and increment(dB=rB(1-B/K).
Hence, it seems useful for understanding the uncertainty and
fluctuation of fish stocks under human exploitations. Really, it is too
simple to understanding the uncertainty and fluctuation of the fish
population sufficiently. But, it does also provide so much information
of the exploited fish sotcks.
Apr. 09, 1997.
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On Thu, 27 Mar 1997, Jon Eynon wrote:
> Date: Thu, 27 Mar 1997 10:59:04 -0600
> From: Jon Eynon <[log in to unmask]>
> To: [log in to unmask]
> Subject: fish model help
> >Hello all,
> >Some of you I have met only once, some I have never met, only e-mailed, and
> >some I have had the privilege to work with. All of you I believe can help
> >me greatly in my upcoming thesis project. I understand that many of you
> >are very busy so I will make my questions as short as possible.
> >I believe that I have an opportunity here at IUPUI to greatly help the
> >fisheries community. The computer lab that I work in designs interactive
> >software for use in biological classrooms. Up to date they have designed
> >two projects: The Virtual Forest, a program that allows students to take a
> >virtual field trip through a central hardwoods forest stand, and Rocky
> >Intertidal Zone, a learning tool used to teach students about experimental
> >design and interpretation of data. Both have been very successful.
> >I have proposed building a fisheries educational program for my thesis.
> >The school's biggest question to me is this, "Is there a need for such
> >programs in the fisheries community?" What a better way to find out than to
> >ask those that are out there!
> >If you had to list what is lacking the most in fisheries education, what
> >would you answer? Where are there holes in the present curriculum that
> >could be filled by some sort of interactive computer model? Would an easy
> >to use population model be helpful to students learning population
> >dynamics? Habitat restoration modeling? A model showing varying gear catch
> >success rates?
> >I want any input possible. I want to ensure that I am building a program
> >that has some use. From my present searches independently and through the
> >AFS, I have not found many fisheries educational tools, only programs that
> >crunch numbers and are usually not user friendly.
> >Thanks for your help,
> >Jon Eynon
> >Graduate Student-IUPUI
> >Indianapolis, IN 46202
> >[log in to unmask]