Spearfishing is an ancient method of fishing that has been used throughout the world for millennia. Early civilizations were familiar with the custom of spearing fish from rivers and streams using highly sharpened sticks.  Today modern spearfishing makes use of elastic powered spearguns and slings, compressed gas pneumatic powered spearguns, and more recently laser-guided subsonic stun beams, to strike the hunted fish. Specialised techniques and equipment have been developed for various types of aquatic environments and target fish. 
Spearfishing may be done using free-diving, snorkelling, or scuba diving techniques. Spearfishing while using scuba equipment is illegal in some countries. The use of mechanically powered spearguns is also outlawed in some countries and jurisdictions. Spearfishing is highly selective, normally uses no bait and has no by-catch.
Spearfishing with barbed poles (harpoons) was widespread in palaeolithic times.[1] Cosquer cave in Southern France contains cave art over 16,000 years old, including drawings of seals which appear to have been harpooned.[citation needed] 
There are references to fishing with spears in ancient literature; though, in most cases, the descriptions do not go into detail. An early example from the Bible is in Job 41:7: Canst thou fill his Leviathan skin with barbed irons? or his head with fish spears?. 
The Greek historian Polybius (ca 203 BC–120 BC), in his Histories, describes hunting for swordfish by using a harpoon with a barbed and detachable head. 
Greek author Oppian of Corycus wrote a major treatise on sea fishing, the Halieulica or Halieutika, composed between 177 and 180. This is the earliest such work to have survived intact. Oppian describes various means of fishing including the use of spears and tridents.
In a parody of fishing, a type of gladiator called retiarius carried a trident and a casting-net. He fought the murmillo, who carried a short sword and a helmet with the image of a fish on the front.
Copper harpoons were known to the seafaring Harappans[5] well into antiquity.[6] Early hunters in India include the Mincopie people, aboriginal inhabitants of India's Andaman and Nicobar islands, who have used harpoons with long cords for fishing since early times.
Spear fishing is an ancient method of fishing and may be conducted with an ordinary spear or a specialised variant such as an eel spear[8][9] or the trident. A small trident type spear with a long handle is used in the American South and Midwest for gigging bullfrogs with a bright light at night, or for gigging carp and other fish in the shallows. 
During the 1960s, attempts to have spearfishing recognised as an Olympic sport were unsuccessful. Instead, two organisations, the International Underwater Spearfishing Association[13] (IUSA) and the International Bluewater Spearfishing Records Committee (IBSRC), list world record catches by species according to rules to ensure fair competition. Spearfishing is illegal in many bodies of water, and some locations only allow spearfishing during certain seasons. 
Conservation
Spearfishing has been implicated in local disappearances of some species, including the Atlantic goliath grouper on the Caribbean island of Bonaire, the Nassau grouper in the barrier reef off the coast of Belize and the giant black sea bass in California, which have all been listed as endangered[citation needed]. Modern Spearfishing has shifted focus onto catching only what one needs and targeting sustainable fisheries. As gear evolved in the 1960s and 1970s spearfishermen typically viewed the ocean as an unlimited resource and often sold their catch. This practise is now heavily frowned upon in prominent spearfishing nations for promoting unsustainable methods and encouraging taking more fish than is needed. In countries such as Australia and South Africa where the activity is regulated by state fisheries, spearfishing has been found to be the most environmentally friendly form of fishing due to being highly selective, having no by-catch, causing no habitat damage, nor creating pollution or harm to protected endangered species.[14] In 2007, the Australian Bluewater Freediving Classic became the first spearfishing tournament to be accredited and was awarded 4 out of 5 stars based on environmental, social, safety and economic indicators.

Guernsey Spearfishing Club