Calculations that will enable an experimenter to estimate the volume of material viewed by an air‐borne gamma‐ray spectrometer are presented. The effects of altitude, air density, source density, and gamma‐ray attenuation coefficient were investigated. It is shown that the altitude is the most important parameter in the determination of the volume of material that produces a given percentage of the total observed signal.
The Atlantic salmon has been harvested by both commercial and recreationalfishers for many years on the river systems of the province of New Brunswick on Canada 's Atlantic coast. The commercialfisheries were closed and controls were placed on the recreational fisheries following the 1983 collapse of the salmon stocks. This management policy remains in effect. A preliminary analysis using a linear control model showed this to be an economically efJicient harvest allocation policy on New Brunswick's Miramichi River. The analysis is extended to the more realistic nonlinear framework here to determine whether the harvest allocation decision would be significantly changed. Both fisheries are found to generate positive net economic beneJts, although the recreational fishery is determined to be more valuable than the commercial fishery. Permanent closure of the commercial$shery is not indicated.
Le saumon de 1 'Atlantique est, depuis de nombreuses an&es, recolte autant par les pecheurs commerciaux que par les pecheurs sport@ dans les rivieres c&i&es de la province du Nouveau-Brunswick.L 'effondrement des stocks de saumons en 1983 a entraine la fermeture des pecheries commerciales et 1 'imposition de mesures de controle a la p&he sportive, mesures qui aujourd 'hui encore demeurent en vigueur. Une analyse preliminaire utilisant un modele de controle lineaire avait mis en relief 1 'e@cience economique de cette methode de regulation des prises dans la riviere Miramichi. Cette analyse est ici &endue a un cadre non lineaire plus proche de la realite, afin de determiner si cette m&ode mod$erait signtjicativement les decisions en matiere d httribution des permis. On constate que les deux types de pecherie generent des avantages economiques nets, quoique la p&he sportive semble en generer davantage. Rien ne semble justtj?er la fermeture permanente de la p&he commerciale.
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