world's prime source of high-quality protein: 14–16 percent of the animal protein consumed worldwide. Over one billion people rely on fish as their primary source of animal protein. Fish and other aquatic organisms are also processed into various food and non-food products, such as sharkskin leather, pigments made from the inky secretions of cuttlefish, isinglass used for the clarification of wine and beer, fish emulsion used as a fertiliser, fish glue, fish oil and fish meal. Fish are also collected live for research and the aquarium trade. Fish marketing Fisheries management Fisheries management draws on fisheries science to find ways to protect fishery resources so sustainable exploitation is possible. Modern fisheries management is often referred to as a governmental system of (hopefully appropriate) management rules based on defined objectives and a mix of management means to implement the rules, which are put in place by a system of monitoring control and surveillance. Fisheries science is the academic discipline of managing and understanding fisheries. It is a multidisciplinary science, which draws on the disciplines of oceanography, marine biology, marine conservation, ecology, population dynamics, economics and management in an attempt to provide an integrated picture of fisheries. In some cases new disciplines have emerged, such as bioeconomics. Sustainability Issues involved in the long term sustainability of fishing include overfishing, by-catch, marine pollution, environmental effects of fishing, climate change and fish farming. Conservation issues are part of marine conservation, and are addressed in fisheries science programs. There is a growing gap between how many fish are available to be caught and humanity's desire to catch them, a problem that gets worse as the world population grows. Similar to other environmental issues, there can be conflict between the fishermen who depend on fishing for their livelihoods and fishery scientists who realise that if future fish populations are to be sustainable then some fisheries must limit fishing or cease operations. Animal welfare concerns Historically, some doubted that fish could experience pain. Laboratory experiments have shown that fish do react to painful stimuli (e.g., injections of bee venom) in a similar way to mammals. This is controversial and has been disputed. The expansion of fish farming as well as animal welfare concerns in society has led to research into more humane and faster ways of killing fish. In large-scale operations like fish farms, stunning fish with electricity or putting them into water saturated with nitrogen so