Fish hook designs, shapes, and materials are all variable depending on the intended purpose of the fish hook. Fish hooks are manufactured for a range of purposes from general fishing to extremely limited and specialized applications. Fish hooks are designed to hold various types of artificial, processed, dead or live baits (bait fishing); to act as the foundation for artificial representations of fish prey (fly fishing); or to be attached to or integrated into other devices that represent fish prey (lure fishing). The fish hook or similar device has been made by man for many thousands of years. The world's oldest fish
Bait ball in diameter and extend to a depth of 10 metres. The bait balls are short-lived and seldom last longer than 10 minutes. However, bait balls are also conspicuous, and when schooling fish form a bait ball, they can draw the attention of many other predators. As a response to the defensive capabilities of schooling fish, some predators have developed sophisticated countermeasures. These countermeasures can be spectacularly successful, and can seriously undermine the defensive value of forming bait balls. Small pelagic fish live in the open water, so unlike demersal or reef fish, they cannot hide among kelp, or in crevices