منابع مشابه
Humane harvesting and slaughter of farmed fish.
The overwhelming majority of farmed fish produced throughout the world are killed with little or no consideration for their welfare. Fasting periods can be excessive, transport stressful and killing inhumane. At the time of writing, the salmon industry is the only sector in which consideration of the welfare of the fish at slaughter has resulted in significant improvements throughout most of th...
متن کاملEXPLOITATiON OF FISH POPULATIONS
The tcrm "exploitation" implies the idea of making use of the population, and in fisheries is generally regarded as a process which should be continued indefinitely without destroying the population. Very intense exploitation leading to the complete destruction of the population, or at least its reduction to a level so low that further exploitation is not worthwhile, is rarely, if ever, deliber...
متن کاملOptimal harvesting of stochastically fluctuating populations
We obtain the optimal harvesting plan to maximize the expected discounted number of individuals harvested over an infinite future horizon, under the most common (»erhulst-Pearl) logistic model for a stochastically fluctuating population. We also solve the problem for the standard variants of the model where there are constraints on the admissible harvesting rates. We use stochastic calculus to ...
متن کاملAsymptotic harvesting of populations in random environments
We consider the harvesting of a population in a stochastic environment whose dynamics in the absence of harvesting are described by the logistic Verhulst-Pearl model. Using ergodic optimal control, we find the optimal harvesting strategy which maximizes the asymptotic yield of harvested individuals. To our knowledge, ergodic optimal control has not been used before to study harvesting strategie...
متن کاملHarvesting Models for Resource-limited Populations
’Extensive’ herbivore/vegetation models and ’intensive’ grazing models yield two conclusions for sustained-yield harvesting of populations regulated by an interaction with their resources. First, the growth curve for the population, relating growth rate to current density, and the equilibrium yield/effort curve under harvesting, are likely to be asymmetric, with peaks displaced to the right and...
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ژورنال
عنوان ژورنال: Nature
سال: 1976
ISSN: 0028-0836,1476-4687
DOI: 10.1038/263091a0