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Small Fish


Debbie MacKenzie <[log in to unmask]>


Scientific forum on fish and fisheries <[log in to unmask]>


Fri, 10 Mar 2000 22:49:09 -0400





text/plain (1 lines) , Small Fish.wps (12 kB) , text/plain (1 lines)

Hello again "Fish-sci" people,

Gary Sharp wrote:

>"The improver of natural knowledge absolutely refuses
>to acknowledge authority, as such. For him, scepticism
>is the highest of duties; blind faith the one unpardonable sin."
>Thomas H. Huxley

Robert Kenney wrote:

>> Are the right whales starving?
>The short answer is no.

>But I am becoming convinced that
>food limitation is a serious concern at present.

>During the 1990's the most dramatic observed change in the right whale
>population has been an increase in the average interval between calves. In
>1980-1992 the average was 3.7 years (the modal interval is three years -
>one each for pregnancy, lactation, and replenishment of energy stores).
>The average for 1993-1998 is over 5 years,

>A decline
>in food availability for right whales might be expected to manifest itself
>first in reproductive effects, including an increase in the time needed to
>accumulate the surplus energy needed for pregnancy and lactation.

Robert, I hope you are right and they are not starving, but the sceptic
would like to see stronger evidence than this.

Regarding my pet peeve, the widespread trend of declining weight-at-age in
fish, Steve Oakley wrote:

>There is a growing body of evidence that the selective pressure of marine
>fisheries has reduced size at maturity. I think Jim Bonsack first proposed
>it but small rapidly reproducing fish have come to dominate trawl fished
>areas. So it is quite possible that heavily fished salmon stocks have
>taken the reproduce quickly before we get caught option.

I have received quite a few comments from others that blame the declining
trend in fish sizes on "high fishery mortality rates" and "mesh
selectivity." I persist in questioning these ideas but possibly I am taking
up too much time and space here - and since I'm long winded on this one,
I'll "attach" it.

Debbie MacKenzie

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