The Aquatic Commons is a thematic digital repository covering the natural marine, estuarine /brackish and fresh water environments . It includes all aspects of the science, technology, management and conservation of these environments, their organisms and resources, and the economic, sociological and legal aspects.
Subject = Conservation
Mostrando recursos 61 - 80 de 1,038
A historical review of the shad fisheries of North America - Mansueti, Romeo; Kolb, Haven
A review of the relative productivity and value of the shad fisheries of North America as reflected in recorded commercial catches.
A review of reasons for the decline that are biological and socioeconomic.
Factors that have been held responsible are: pollution; destruction or impairment of spawning and nursery areas; overfishing; hydroelectric and canal dams; natural fluctuations in abundance. Natural catastrophes, parasites, and predators are not considered important in causing the decrease in commercial production. Attempts to rehabilitate the fisheries by various means of stocking artificially-reared fry and pond-reared fingerling shad, appear to have failed in every instance. Introduction of shad...
Habitat degradation - its nature, causes and treatment
Since the latter part of the 19th century the Ribble and its tributaries have suffered habitat degradation
to varying degrees. This report examims the causes for its degradation, specific problems and their treatment, progress, plans and procedures, and benefits of restoration including species identified by English Nature as threatened or declining and which are listed in the UK Biodiversity Action Plan.
Compatibilización del crecimiento orgánico, estructura poblacional y mortalidad: aplicación para el árbol tropical Otoba gracilipes - Del Valle Arango, Jorge Ignacio
Resumen: En este artículo se propone un método indirecto para deterninar tanto el coeficiente de mortalidad exponencial (l.) como la mortalidad anual (m) deduciéndolos matemáticamente de un modelo de crecimiento orgánico (von Bertalanffy) y de un modelo de estructura poblacional disctáneo (Licourt y Meyer) empleado en árboles• forestales, el cual relaciona la frecuencia de los individuos -por clase de tamaño. Las ecuaciones obtenidas permiten determinar A o m de manera discreta, instantánea o promedia entre dos edades cualesquiera t1 y t2. Se emplean ambos conceptos de morltaiidad a sendos cálculos de dvida media (t0,5) en función de A y m....
Fishes of the Mekong River: conservation and need for aquaculture - Nandeesha, M.C.
Conservation and the potential and need for aquaculture of three major fish (Catlocarpio siamensis, Probarbus spp. and Pangasius gigas) of the Mekong River are discussed. Different steps being undertaken by the Cambodian government in doing such activities are highlighted.
Down to earth thoughts on conserving aquatic genetic diversity - Pullin, R.S.V.
A discussion is presented on the topic of maintaining genetic diversity in aquatic ecosystems, considering the various threats caused by irreversible damage or loss to the environment. The current situation in aquaculture and future prospects regarding the conservation and protection of endangered species are outlined, describing the case of tilapias in Africa as one particular example of fish conservation.
News from Academy Bay
Changes of Charles Darwin Foundation officers. Scientific staff. Training courses for wardens and guides. Volunteer observers. Flamingos on Isabela. Is there a mate for Lonesome George? Outbreak of matrimony at the Darwin Station. Visitors and events at the Charles Darwin Research Station (July - December 1981). Some recent books.