The old adage – be quiet, the fish will hear you – is very true. One of the amazing things about fish is that, like bats and bees they have senses which are not shared by humans. It is therefore difficult for us to imagine a whole special world underneath the water.
Fish have the extraordinary ability to feel vibrations in the water and this is tremendously useful to them. Vibrations are made by both prey and predator alike: swimming partners (for those fish that live in schools), a clumsy person walking too heavily on the bank, and even rippling water moving around a stone or a plant. All of these movements send out vibrations of various intensity, tone and speed. Fish can sense and read each one. The sound of a snake swimming is not the same as the sound of a frog swimming. Fish of prey sense the difference. The thrashing of an injured or entangled fish is sensed by predators long before they can see the fish that is in distress.
The extraordinary sense organ is in the lateral line and all fish have it. Bottom feeders like catfish, mudpout and carp have the most prominent and sensitive lateral lines. A catfish for example can sense the presence of a moving worm up to four metres away. The lateral line is really a long groove located on both sides of the body from tail to head. Small pores, each lined with receptor cells, which have hairs, fill the groove. Above the hairs and enclosing their tips is a mass of jelly-like material secreted by the cells. The receptor cells respond to waves, currents or disturbances in the water. The water moves the jelly-like material (cupula) and causes the hairs to bend. This results in messages being sent to the brain as to direction and intensity of the vibrations.
Of special importance is the arrival of spring that the lateral line communicates to a fish. A kind of thermostat, it tells the fish how many degrees the water has warmed to, and how long the fish should remain still until its body adjusts to the change. It then tells the fish to move to a higher and warmer spot. In this way the fish knows when to move upstream to the gravel beds where breeding occurs.
The lateral lines of the fish in our lakes and rivers must get quite a workout when the motorboats and snow sleds invade the surface of their world. There has not been enough study done to tell us just how much the fish are disturbed, whether they have adjusted to the underwater noise or how it affects their breeding habits.
One thing we are sure of is that fish populations are in decline. Are we killing them with toxic pollutants, altering their habitat with dams and modifying their basic breeding instincts with underwater noise? It’s time we found out -- and acted accordingly.
Photo by Clayton Rollins
Fish have the extraordinary ability to feel vibrations in the water and this is tremendously useful to them. Vibrations are made by both prey and predator alike: swimming partners (for those fish that live in schools), a clumsy person walking too heavily on the bank, and even rippling water moving around a stone or a plant. All of these movements send out vibrations of various intensity, tone and speed. Fish can sense and read each one. The sound of a snake swimming is not the same as the sound of a frog swimming. Fish of prey sense the difference. The thrashing of an injured or entangled fish is sensed by predators long before they can see the fish that is in distress.
The extraordinary sense organ is in the lateral line and all fish have it. Bottom feeders like catfish, mudpout and carp have the most prominent and sensitive lateral lines. A catfish for example can sense the presence of a moving worm up to four metres away. The lateral line is really a long groove located on both sides of the body from tail to head. Small pores, each lined with receptor cells, which have hairs, fill the groove. Above the hairs and enclosing their tips is a mass of jelly-like material secreted by the cells. The receptor cells respond to waves, currents or disturbances in the water. The water moves the jelly-like material (cupula) and causes the hairs to bend. This results in messages being sent to the brain as to direction and intensity of the vibrations.
Of special importance is the arrival of spring that the lateral line communicates to a fish. A kind of thermostat, it tells the fish how many degrees the water has warmed to, and how long the fish should remain still until its body adjusts to the change. It then tells the fish to move to a higher and warmer spot. In this way the fish knows when to move upstream to the gravel beds where breeding occurs.
The lateral lines of the fish in our lakes and rivers must get quite a workout when the motorboats and snow sleds invade the surface of their world. There has not been enough study done to tell us just how much the fish are disturbed, whether they have adjusted to the underwater noise or how it affects their breeding habits.
One thing we are sure of is that fish populations are in decline. Are we killing them with toxic pollutants, altering their habitat with dams and modifying their basic breeding instincts with underwater noise? It’s time we found out -- and acted accordingly.
Photo by Clayton Rollins
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