Sustainable harvest applies to renewable resources; it is the harvesting resource without endangering the resource. To successfully harvest sustainably it must be economically and environmentally efficient. Sustainable harvesting has been a goal in the fishing and forestry industries, but has not been achieved yet. It is theoretically possible to achieve with the effort of a managing body and cooperation from the human population. Economics and politics add further difficulties to achieving sustainable harvest. An example of a successfully managed fishery is the Western Rock Lobster (crayfish) in Western Australia. When the breeding stock of crayfish declined in the 1990s stringent restrictions were applied to reverse this decline. Such restriction included a decrease in the number of pots to be used and an increase in the minimum size requirement. This fishery has advantage of monitoring the larval stages each year in the plankton. This predicted the allowable catch 4 years into the future, which meant that commercial operations could make adjustments accordingly. This is an example of a well-managed fishery.
An example of a poorly managed fishery is the Northern Cod. Populations of the Cod were sustainable for over 500 years. In the 1900s, boats became faster and more efficient at catching cod, which lead to a collapse in the fishery. Management efforts in this fishery were poorly carried out, the estimates of the stock were too high and mortality measurements were not measured properly.