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Biologists use various styles of electrofishing boats to collect
fish for scientific analyses and to help manage the fishery.
Fishery biologists have college educations and special training
to operate this equipment safely.
Electrofishing boats use a generator to create an electric current
to shock the fish and temporarily stun them.
A biologist who also drives the boat sets the specific current
based on the conductivity of the water.
Biologists also use a Secchi disk
to see how clear the water is,
and record other information about the type of plants, specific location,
temperature of the water and the amount of oxygen.
This is useful in determining why certain fish may be present or absent.
At the front of the boat another biologist has control of a pedal switch
that releases the electricity.
It then travels to the poles, called booms, at the front of the boat and into the water.
The electric field they produce does not kill the fish
but temporarily stuns those that swim within 6 to 8-feet of the booms.
The fish are scooped up in nets and placed in a live well.
The electricity’s effect on the fish are typically minimal.
Several factors contribute to how long the fish remains stunned,
including the size of the fish, the species, the water temperature
and how easily the electricity travels through the water or the water conductivity.
In most cases, stunning occurs within a few seconds of the fish entering the electric field
and lasts less than a couple minutes once the fish is removed from the electric field.
The fish are typically identified to species, counted and measured including their length and weight.
Depending on the study, blood samples may be taken, the fish may be tagged to help determine
how many fish are in the lake, and occasionally tissue samples are taken to determine
mercury and pesticide levels, or the fish’s genetic makeup.
Electrofishing can be much less damaging than methods that entangle or trap fish,
which may injure or kill them.
Electrofishing also does not harm the eggs of female fish.
In fact, biologists use electrofishing to collect brood fish to take to hatcheries to use as parent fish.
In freshwater you find a great variety of fish. Let's check some out:
Basically fisheries biologists perform a physical exam on the fish,
just like you might receive from your doctor.
They want to be sure the fish is eating well, growing quickly, and doesn’t have signs of disease or parasites.
Largemouth bass are the most highly sought after freshwater sport fish in Florida.
Getting the length and weight is a key step in the process.
Largemouth bass grow to over 20 pounds, and in Florida those over 8 pounds
that are caught-and-released by anglers who take pictures of them are eligible for rewards.
This is a bluegill sunfish, another popular sport fish in Florida.
An easy way to identify this fish is the dark area in the back part of the top or dorsal fin.
Some things to be careful of are the sharp, pointy spines in the fins of sunfish like this one,
as well as on bass and the many introduced cichlids and tilapia that can be found in Florida’s waters.
Redbreast are another of the bream or sunfish family that are popular with anglers.
The long ear flap and reddish belly help distinguish this fish.
Biologists call the ear flaps the operculum or gill covering of the fish.
They protect the gills, which are delicate and used by the fish to breathe underwater.
You should keep your hands and dehooking tools away from this opening
to prevent damaging the gills or cutting yourself, since some species have very sharp gill covers.
If you get to handle a catfish, be especially careful.
The safest way to handle a channel catfish is to make sure your fingers and hand
are behind the two pectoral spines (part of the arm-like fins)
and away from the big dorsal spine on the back.
In sunfish those spines can be pressed down flat to the fish’s body
to make the spines less dangerous while handling bream.
A catfish’s spines won’t lie down against the body,
so you put your hand behind them.
Catfish have bones in their body that lock these three external spines out
to make it more difficult for predators to eat them.
Also, notice the external characteristic that gives the catfish its’ name.
The whisker-like barbels are important for catfish to “taste” things
on the bottom of the lake to help them decide if it is something to eat or leave alone.
Gar have hard scales and a long pointy snout with sharp teeth.
They have been around for 65 million years—back to the age of the dinosaurs.
For bluegill, redbreast, catfish, gars and many other fish that you catch on hook and line,
you can attain a Big Catch certificate if the fish is either heavier or longer than the qualifying weight.
Check out MyFWC.com/BigCatch to learn more.
Electrofishing is one of the main tools that Florida’s fish biologists use
to determine how healthy the fish population is in a particular pond, lake, river or canal.
They then use that information to try to ensure the fish and their habitats are taken care of
and to make fishing more enjoyable.
While the generator is running, the booms are in the water,
and the biologist has his or her foot down on the on/off switch,
no one wants a hand, foot or body to touch the water.
If they did, the biologist would receive the same electric stun as the fish.
Safety is always job number one.
And if you were wondering, fishing with electricity is illegal for any angler to use.
Only fishery biologists can use this method when conducting scientific sampling.
But, it is a fun possibility for a career, if you like nature and the outdoors.
To learn more about the Florida Fish and Wildlife Conservation Commission’s effort
to create the Next Generation that Cares
visit us at MyFWC.com/Youth.