In fishing

Fishing

Fishing is the activity of trying to catch wild fish. Fish are normally caught in the wild. Techniques for catching fish include hand gathering, spearing, netting, angling and trapping....

, a gaff is a pole with a sharp hook on the end that is used to stab a large fish

Fish

Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

 and then lift the fish into the boat or onto shore. Ideally, the hook is placed under the backbone

Vertebral column

In human anatomy, the vertebral column is a column usually consisting of 24 articulating vertebrae, and 9 fused vertebrae in the sacrum and the coccyx. It is situated in the dorsal aspect of the torso, separated by intervertebral discs...

. Gaffs are used when the weight of the fish exceeds the breaking point of the fishing line

Fishing line

A fishing line is a cord used or made for angling. Important parameters of a fishing line are its length, material, and weight...

 or the fishing pole. A gaff cannot be used if it is intended to release the fish unharmed after capture, unless the fish is skilfully gaffed in the lip, jaw, or lower gill using a thin gaff hook.

A "flying gaff" is a specialized type of gaff used for securing and controlling very large fish. The hook part of the gaff (the head) detaches when sufficient force is used, somewhat like a harpoon's

Harpoon

A harpoon is a long spear-like instrument used in fishing to catch fish or large marine mammals such as whales. It accomplishes this task by impaling the target animal, allowing the fishermen to use a rope or chain attached to the butt of the projectile to catch the animal...

dart. The head is secured to the boat with a length of heavy rope or cable.