Water temperature is a key factor in fish activity. In simplest terms, extremes in water temperature are generally detrimental to angling. No place is that more true than in the shallow saltwater flats on the Southwest Coast of Florida. Common sense tells us that a precipitous drop in water temperature will initially slow or even kill the bite in shallow waters. The narrow water column will cool or heat up quickly since it has less mass.
As with all natural factors, cycles of heating and cooling have normal effects on the biomass in waters. One very important effect of water temperature is the capacity of water to carry and contain its most vital component, oxygen! Very warm water contains less absorbed oxygen in its extreme cases. It is not uncommon for shallow flats waters to reach 90 degrees in midsummer. Thus there is less activity on the open flats. This low oxygen content and most fishes inability to control their body temperature—endothermic control—leads to slow fishing. Lethargy sets in and normal functioning slows. Some fishes have a rudimentary lung function in their swim bladder and are, therefore, less affected by low-oxygenated environments: tarpon, mullet, and catfish just to mention a couple of local “lungers”. A sort of environment parboiling occurs that can deplete oxygen and, at best force, a migration of gamefish out of the shallows and, at worst, generate a fish kill in isolated waters. Fishing deeper areas can counter the effects of drastic overheating in the water column.
Cooling waters within a reasonable comfort zone have a generally less drastic effect on fish. Although our regional top gamefish are what might be describe as “subtropical” they do tolerate a wide range of water temperatures from 90 degrees to the high 50s. Snook become torporific or can even die if the waters hover in the low 60s. Redfish and sea trout are very comfortable in waters in the mid 60s. Cooler waters do require a review of fishing patterns; slow going is always best as a preliminary presentation. Sort of a contrary point, one typical of overheated waters, is that colder surface water will find fish nearer the bottom where temperatures are more stable.
Your water temperature feature on your depth finder is an invaluable tool and is especially useful when water temps climb or descend into the extremes. Feel like a fish, act like fish, be a fish!
Capt. Ron Kowalyk