Equipment that is not sporting and takes large numbers of fish is not legal to use. Laws governing such equipment vary from state to state and are tailored to the needs of different locations. Most illegal methods are not something sport fishermen would want to do anyway, but some people want to find ways to take fish to eat without the challenge of catching them.
Telephoning — Another Name for Shocking Fish
Telephoning fish got its name from old hand-cranked telephones. When a person cranked the handle it produced an electric current, and fisherman found that they could drop the wires into the water and shock the fish. The fish would float to the top to be scooped up. Theoretically, the fisherman could go to a hole in a creek or river and shock up every fish in it.
There's nothing sporting about catching fish in this manner. You simply scoop them out of the water. And you can take all the fish in an area. This method of taking fish has been outlawed since it was first found, but some people still use it today.
Game and fish biologists use shocking as a legitimate way to count fish. They use a generator rather than an old telephone and send electric current through two booms out in front of a boat. Every fish between the chains hanging down from the booms come to the surface to be counted. They can be released after the count since the current does not kill them.
Traps Can Be Illegal
Fish traps are allowed in some locations for some kinds of fish but other places outlaw them completely. Traps are more common in salt water and can catch large numbers of fish at one time. Saltwater traps are often very big and consist of weirs. Freshwater traps are usually smaller basket-shaped devices for catching minnows and catfish.
Baskets can be used to catch catfish but the legal design makes it less likely game fish will go into them. Simple baskets with an open funnel at one end are usually outlawed, and baskets with trap doors and double funnels are required. In salt water, traps are used to catch many kinds of nonfish species like crabs and lobster, but they can be used for fish, too.
Minnow traps used to catch bait are usually legal but must comply with strict laws. You're regulated on the size, shape, and number of traps you can put out for bait. And you're required to check them regularly so the minnows in them don't die. A trap can be a fun and efficient way to get bait, but you're required to release any game fish you catch.
Certain Nets Are Illegal
Seines and gill nets are often illegal in fresh water but are allowed more often in salt water. The length and mesh size of nets are usually regulated if the nets are allowed at all. Gill nets work to tangle fish when they try to swim through the mesh, so requiring the mesh to be a certain size ensures fish larger and smaller than the mesh are not caught. Game fish can usually escape from a short seine so seine length is regulated to control what can be caught in it.
Cast nets are often used to catch baitfish and are about the only way to collect them. These nets are shaped like a parachute with weights around the edge. When thrown over a school of fish they sink fast and a rope pulls the bottom together around the fish. Any game fish caught in them must be released immediately. In some areas, especially salt water, you're allowed to take some kinds of game fish like mullet with a cast net.
Some states make double and treble hooks illegal and also regulate the number of hooks that can be attached to one line. Some trout streams have single-hook regulations to protect the fish, especially in catch-and-release streams. The hook usually has to be barbless in these streams, too. There are few restrictions on hooks in salt water.
Using hooks to snag fish is illegal in most fishing. Fish running up rivers to spawn are easy to snag under bridges. Fish on the spawning bed can be snagged. And big schools of saltwater fish are often thick enough that snagging works on them, too.
A big treble hook with a lead weight on its shank is usually used for snagging. It's lowered into the water and jerked up sharply, hooking into any fish that's swimming over it. It injures the fish and catches any size and species that happens to be there. Some states and provinces outlaw the selling of big treble hooks for this reason.
Snagging is legal for a few kinds of fish, like paddlefish, because certain fish can't be caught any other way. Some states have very strict laws that allow snagging certain fish, and only those fish, during a limited time each year.