In population ecology, maximum sustainable yield or MSY is the largest long-term average yield/catch that can be taken from a species' stock without depressing the species' ability to reproduce. In ideal situations. the MSY will be exactly half the carrying capacity of a species, as this is the stage at when population growth is highest (due to the logistic model growth of most species, producing a n shaped hump in a graph comparing growth rate and population size). The maximum sustainable yield is usually higher than the optimum sustainable yield. Population ecology is a major subfield of ecology—one that deals with the dynamics of species populations and how these populations interact with the environment. ... Yield may mean: In economics, yield is a measure of the amount of income an investment generates over time (related to return on investment). ... Baseball In baseball, a catch occurs when a fielder gains secure possession of a batted ball in flight, and maintains possession until he voluntarily or negligently releases the ball. ... In biology, a species is the basic unit of biodiversity. ... The logistic map is a polynomial mapping, often cited as an archetypical example of how complex, chaotic behaviour can arise from very simple non-linear dynamical equations. ... In economics, optimum sustainable yield is the level of effort that maximizes the difference between total revenue and total cost. ...

This logistic model of growth is produced by a population introduced to a new habitat or with very poor numbers going through a lag phase of slow growth at first. Once it reaches a foothold population it will go through a rapid growth rate that will start to level off once the species approaches carrying capacity. The idea of maximum sustained yield is to decrease population density to the point of highest growth rate possible. This changes the number of the population, but the new number can be maintained indefinitely, ideally.

Unfortunately errors in estimating the population dynamics of a species can lead to setting the maximum sustainable yield too high. An example of this was the New Zealand Orange roughy fishery. Early quotas were based on an assumption that the orange roughy had a fairly short lifespan and bred relatively quickly. However, it was later discovered that the orange roughy lived a very long time and had bred very slowly. By this stage stocks had been largely depleted. Binomial name Hoplostethus atlanticus Collett, 1889 The orange roughy or red roughy (Hoplostethus atlanticus) is a relatively large deep-sea fish belonging to the slimehead family (Trachichthyidae). ...