34 resultados para overlapping generations


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This is the River Yealm Salmon Action Plan Final document produced by the Environment Agency in 2003. This final Salmon Action Plan (SAP) for the River Yealm catchment has been produced after consideration of feedback from external consultation. It provides a list of the agreed issues and actions for the next five years to maintain and improve the River Yealm salmon stock. The actions presented within this Salmon Action Plan clarify the important issues and factors currently limiting the salmon stock on the river. The resolution of these issues should ensure that a sustainable salmon population will be maintained for future generations. An attempt has been made to cost these actions, identify possible sources of funding and to provide a timescale for action. The main objective of the River Yealm SAP is to maintain, improve and develop the River Yealm salmon stocks to a sustainable level that, on the basis of historic catch records, the catchment can clearly support.

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This is the River Lyn Salmon Action Plan Final document produced by the Environment Agency in 2003. This final Salmon Action Plan (SAP) for the River Lyn catchment has been produced after consideration of feedback from external consultation. It provides a list of the agreed issues and actions for the next five years to maintain and improve the River Lyn salmon stock. The actions presented within this Salmon Action Plan clarify the important issues and factors currently limiting the salmon stock on the river. The resolution of these issues should ensure that a sustainable salmon population will be maintained for future generations. An attempt has been made to cost these actions, identify possible sources of funding and to provide a timescale for action. This SAP aims also to promote long term collaboration between the Agency and other interested parties in managing the River Lyn salmon stock and fisheries.

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EXTRACT (SEE PDF FOR FULL ABSTRACT): Tree-ring chronologies, developed from cores from Pinyon pines growing on climatically sensitive sites in the north-central Great Basin, have been used to reconstruct precipitation and drought histories of the area from A.D. 1600 to 1982. Analysis of these hydrologic time series helps to place current climatic conditions into the perspective of the past 383 years (since 1600). ... The years 1934 and 1959 were the first and fourth driest while 1934 had the lowest July Palmer Drought Severity Index (PDSI) of the reconstructed records. Nevertheless, the decade of the 1930's is only the seventh driest since 1600; the decade 1953-1962 ranks as the second driest. The driest non-overlapping decade since 1600 was 1856-1865. Interestingly, the second wettest decade was 1932-1941. An examination of 30-year mean precipitation data shows that the driest 30-year period was 1871-1900; 1931-1960 ranks as the fourth driest. The current 30-year period (1951-1980) ranks twelfth.

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Western Atlantic synodontid species were studied as part of an ongoing effort to reanalyze Caribbean shorefish diversity. A neighbor-joining tree constructed from cytochrome c oxidase I (COI) data revealed 2 highly divergent genetic lineages within both Synodus intermedius (Agassiz, 1829) (Sand Diver) and S. foetens (Linnaeus, 1766) (Inshore Lizardfish). A new species, Synodus macrostigmus, is described for one of the S. intermedius lineages. Synodus macrostigmus and S. intermedius differ in number of lateral-line scales, caudal pigmentation, size of the scapular blotch, and shape of the anterior-nostril flap. Synodus macrostigmus and S. intermedius have overlapping geographic and depth distributions, but S. macrostigmus generally inhabits deeper water (>28 m) than does S. intermedius and is known only from coastal waters of the southeastern United States and the Gulf of Mexico, in contrast to those areas and the Caribbean for S. intermedius. Synodus bondi Fowler, 1939, is resurrected from the synonymy of S. foetens for one of the S. foetens genetic lineages. The 2 species differ in length and shape of the snout, number of anal-fin rays, and shape of the anterior-nostril flap. Synodus bondi and S. foetens co-occur in the central Caribbean, but S. bondi otherwise has a more southerly distribution than does S. foetens. Redescriptions are provided for S. intermedius, S. foetens, and S. bondi. Neotypes are designated for S. intermedius and S. foetens. A revised key to Synodus species in the western Atlantic is presented.