Effect of water temp on fish

[yanjarra]

hi

being that ive just gotten a flash water temp gauge on the boat i was wondering what the significance of temp is on fishing exactly?

sometimes... like at the moment i see posts saying the water wasnt cold enough...than in summer i see ones where it wasnt warm enough.....

is it pretty much the case that the colder the better in winter and the warmer the better in summer? ....if so..... is there sort of a given range that is generally considered as really good...... i.e under 18 or over 26 should really increase your chances...

does barometric pressure have a major role to play in this and what if so?

cheers
matt

[Scott nthQld]

Temperature does have an effect on fishing, but also tends to be species and area specific.

A prime example is barra. Up here if the water is anywhere near or below about 28-27 deg, the barra fishing is slow, higher temps produce more fish, BUT on the other hand, I find lower temps though producing much less fish in quantity, usually brings out the bigger ones, my theory is the larger ones, often being fatter, stay just that little bit warmer and are more active than the smaller ones.

Also Mackeral, up here I deal water temps start from 21 deg and below, this is when our mackies will be more prolific and in active feeding mode.

Fingermark is another prime example, ideal water temp is around the 30deg mark, but during the night, cooler temps, you have better chances during the daylight hours, though coller temp fingermark are usually around 1/2 the size of warmer weather choppa's.

As for barametric pressure, I don't have the slightest. There are many theories going around, but comparing results during low/high pressures is largely dependant on an individual's fishing style I think. EG, Bass, some blokes like to fish during periods of low pressure because they catch more, but others may swear by higher pressures for the same reasons. Like I said, i don't really have the slightest and rarely pay attention to it other than trying to work out what the wind will be doing.

[Jeremy87]

As Scott suggested, ideal water temp is going to be dependant on several factors to do with location, species etc. This you will need to work out for your own specific fisery.

You can probably divide the effects of water temp into two groups, direct and indirect effects.

Direct effects would be change in metabolic rate and oxygen levels. Most fish are referred to as ectotherms, ie their body temp is roughly equal to the surrounding environment. A few fish like marlin and tuna have developed mechanisms to heat their bodies above ambient but are still by and large ectothermic. As a consequence of ectothermy metabolic rate increases in proportion to change in temperature. So if your a fish in warm water and there is lots of food, you can catch more and process it more quickly, however if the water is warm and there is no food then you will chew through your reserves more quickly.

The other direct effect is shange in oxygen with water temp. Warm water has a lower oxygen carrying capactiy by a considereable margin which can lead to a whole bunch of problems associated with not getting enough oxygen.

Indirect effects would be something like how water temp has affected food sources, mating behaviour etc.

As far as barametric pressure goes i am not convinced it has a significant effect on fishing. Every time i have experienced bad fishing or a sudden shut down of the bite there has been at least half a dozen other reasons that could explain it. Its something i tend not to worry about.