From: plh@eos.ncsu.edu (Pat L. Heron)
Subject: Re: weather and fishing
Organization: North Carolina State University
Distribution: rec
Date: Tue, 8 Sep 1992 14:23:55 GMT

In article <NARTEN.92Sep6090936@percival.albany.edu>, narten@cs.albany.edu (Thomas Narten) writes:
>Can someone summarize the conventional wisdom regarding best weather
>for fishing?  Specifically, I have read reports (usually lacking in
>either detail or concrete evidence) that indicate that fishing for
>bass and walleye picks up as a front starts to move through an area
>and the barometric pressure falls.  In contrast, high pressuse tends
>to disfavor good fishing.  Can someone recommend a book that describes
>the affects of weather on fishing in a fair amount of detail?
>-- 
>Thomas Narten
>narten@cs.albany.edu

As far as I have been able to determine (mostly from the InFisherman and 
Fishing Facts publications) the conventional wisdom is that light 
penetration is the major factor and causes pre-frontal fishing 
to be good, while post frontal fishing can be difficult.
Before a cold front, the 
skies are cloudy, the wind blows, and it rains.  These are the perfect 
conditions for catching fish (but not necessarily for fishing).
After a cold front, the temperature drops, the wind blows a little, 
and the skies are clear and bright with substantial light penetration 
into the water.  

I have discussed these ideas with J.Stonick and we have come to the 
concensus that these factors are important, but rapid 
changes in barometric pressure are at least as important.  
We always watch the weather maps when we plan a day or two per week 
to skip work and fish.  These factors are always alluded 
to on t.v. by tournament bass anglers, but perhaps they are not 
conversant with Archimedes principle and so cannot offer a coherant 
explanation of what they know from experience. 

Recent radio telemetry studies of large bass in Lake Fork, and 
other Texas lakes have shown that they have a preferential depth
where perhaps temperature/light/oxygen/pH are preferred.  Bass will 
susped over deep water at that depth when inactive (how many times have 
you seen these fish on your sonar, but could not catch them!).  
When active they will move toward the shore at that prescribed depth 
until they find cover, then they will hunt.  Bass are able to mantain 
this depth because they, like scuba divers, have buoyency compensation 
by way or the swim bladder. 

When the low pressure trough, which preceeds a cold-front,arrives
the barometric pressure drops, the fish cannot release the higher 
pressure gas from it's swim bladder (done slowly by osmosis), so 
the swim bladder expands and the fish has positive buoyancy.  To 
mantain depth control the fish must swim and thus must become active 
and feed (light and wind conditions are often favorable at 
this time).  When the front passes, a high pressure dome 
dominates, compressing the swim bladder giving the fish negative 
buoyancy, during this time the bass will often lie inactive on the 
bottom on a rocky (i.e. hard bottom) area, or swim into heavy cover 
and lie there (light and wind conditions are often not favorable 
for hunting).  A few days are needed for the bladder to compensate 
for a large barometric change.

This effect does not manifest itself on fish that must swim constantly, 
i.e. fish in rivers, streams or the ocean. 



>>In article 92Sep6090936@percival.albany.edu, narten@cs.albany.edu 
>>(Thomas Narten) writes:
>>
>>My experience is that high pressure dampens the fishing too, but is
>>this due exclusively to pressure or the attendant hot weather ?
>>
>>I have read (in more than one source) that fish tend to go off the feed
>>if the water temperature gets to 23 degrees C (73 degrees F), and that
>>seems to make sense as the oxygen content of the water will then be
>>lowered, making the fish sluggish.

Post frontal conditions are usually cooler (i.e. after the Canadian low 
comes through).  Temperature does effect oxygen solubility in water 
(as well as fish metabolism)
which explains seasonal changes in fish behavior.  The optimal temperature 
is, of course, dependent upon the species of fish.

This is a whole lot of opinion for me to put in one place...


			-Pat.