Can Fish Read a Thermometer?

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Posted by: Captain Woody - Comments Off on Can Fish Read a Thermometer?

Understanding water temperature is possibly the single most significant matter between fishing and catching. Appreciation of temperature and its affect on fish can make your angling life simpler.

Fish are cold-blooded or presumed cold-blooded. Then again, like most creatures they do produce limited forms of metabolic heat derived from oxidation or burning of food. So if they produce heat why are they cold-blooded? Cold-blooded means no way of controlling the body temperature, which is dependent on surrounding environments. To clarify means knowing how their circulatory system operates. A very simple system, it circulates blood, through a two-chamber, single pump heart, carrying blood and oxygen to and from the gills. When you consider that blood passing through gills, which is open to external temperatures it is easy to grasp the cold-blooded concept. Any heat whether metabolic or otherwise rapidly dissipates as it enters and leaves the gills. This explains why fish feel cold to the touch them.

Although we consider fish as cold-blooded, there are some exceptions. Tuna, billfish, and some sharks use a system of parallel blood vessels named countercurrent heat exchange, which operates with remarkable efficiency. Because veins run close together, it allows the transfer of heat from one to the other. In other words, veins carrying warm blood to the gills, transfer heat to veins returning with cool blood. This remarkable system allows otherwise lost heat to remain within the body. Large muscles like those of Tuna require heat to function effectively. Tuna are a prime example of countercurrent heat exchange used so effectively you could refer to them as warm-blooded. Their semi-constant body temperature allows faster muscle contraction, which increases speed thus enabling them to catch food, and escape danger.

Bodily functions in cold-blooded fish are temperature dependent and being unable to control temperature, any changes, especially sudden affect their appetite, heart rate and respiration. To control unbearable water temperatures fish have but one alternative move to more comfortable surroundings.

Temperature changes normally take place gradually allowing fish time to adapt. However, severe fronts can force rapid drops or rises, thereby initiating uncomfortable and stressful conditions. Humans are no exception as uncomfortable circumstances often influence our activities or patterns of behavior. Subsequently when fish become uncomfortable, they too change and may stop eating until acclimatized, move to tolerable temperatures, or become lethargic transitioning into a survival mode.

The metabolic processes increase as water warms and decreases as it cools. A 10 to 18 degree rise in water temperature causes metabolic rates to double often affecting feeding and digestion processes. However, extremes on either side can be devastating. Water that is too cold or too hot has a direct correlation to oxygen levels. In most cases, cold water slows them down and warm water speeds them up but only to a point. Rapidly fluctuating water temperatures frequently impair breathing consequently; oxygen rich waters with steady temperatures are more comfortable. Occasionally they instinctively move away from a comfort zone to feed provided they can return. Clearly, fish are appreciably in touch with their surrounding especially temperature. In addition, the more you learn about their preferences, the more success you enjoy.

Most creatures hot or cold-blooded have comfort ranges for the simple reason… temperature affects everything. Since improving your catch ratio which is often the discussion among anglers it’s important you become skilled at reading the water; along with understanding temperature, habitats, and how they affect behavior patterns, that is all it is, just discussion.

Today’s electronic packages usually include provisions to monitor horizontal surface and often vertical temperature readings. Understandably, many anglers cannot afford these pricey tools. Here is an easy solution if you are not equipped with electronics, a simple everyday thermometer will suffice simply attach it to a string or secure it inside your live well.

Highly regarded lines of attack to becoming a better catcher are research and understanding. Gain knowledge of your preferred species temperature ranges, habitat, then study their feeding patterns. Remember, education should consist of a desire for knowledge raising an individual to a higher level of consciousness and comprehension for those things desired.

Here are a couple of closing thoughts to ponder when the fish are not biting.

  1. They call it “fishing not catching,” becoming a better catcher means research, study, and practice. There are no free rides.
  2. Temperature has a direct influence on the comfort level of fish and “Happy Fish… Make Happy Anglers.”

This article is owned by Capt. Woody Gore and is copyright protected. Permission to republish this article in print or online must be granted by Capt. Gore. wgore@ix.netcom.com