Author: United States. Forest ServicePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
VARIATION IN SALMONID LIFE HISTORIES: PATTERNS AND PERSPECTIVES... RESEARCH PAPER PNW-RP-498... U.S. DEPARTMENT OF AGRICULTURE... FEBRUARY 1997
Author: United States. Forest ServicePublisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Variation in Salmonid Life Histories
Author: Mary F. WillsonPublisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 60
Book Description
Research Paper PNW.
Author: Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 196
Book Description
A Year in Review for the Pacific Northwest Research Station
Author: Pacific Northwest Research Station (Portland, Or.)Publisher:
ISBN:
Category : Forests and forestry
Languages : en
Pages : 120
Book Description
Variation in Salmonid Life Histories, Patterns and Perspectives (Classic Reprint)
Author: Mary F. WillsonPublisher: Forgotten Books
ISBN: 9780260638083
Category : Science
Languages : en
Pages : 64
Book Description
Excerpt from Variation in Salmonid Life Histories, Patterns and Perspectives Salmonid fishes differ in degree of anadromy, age of maturation, frequency of reproduction, body size and fecundity, sexual dimorphism, breeding season, morphology, and to a lesser degree, parental care. The advantages of large body size in reproductive competition probably favored the evolution of ocean foraging, and the advantages of safe breeding sites probably favored freshwater spawning. Both long-distance migrations and reproductive competition may have favored the evolution of semelparity. Reproductive competition has favored the evolution of secondary sexual characters, alternative mating tactics, and probably nest-defense behavior. Salmonids provide good examples of character divergence in response to ecological release and of parallel evolution. The great phenotypic plasticity of these fishes may facilitate speciation. Patterns of variation and the processes that generate them are valuable tools for foresighted management practices, predicting the outcomes of anthopogenic changes, managing to maintain biodiversity or particular populations of wildlife consumers, and maintaining the viability of fish populations. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works.
Variation in Salmonid Life Histories
Author: Mary F. WillsonPublisher: DIANE Publishing Company
ISBN: 9780788179945
Category :
Languages : en
Pages : 50
Book Description
Because of the huge natural variations in the abundance of salmon from year to year and place to place, much of the attention to these species has been prompted by an interest in reducing the variation and simultaneously maintaining or raising the mean abundance. In contrast, the importance of salmon and their relatives to the ecology of other species dependent on them and to the ecology of riparian ecosystems has scarcely been noticed. This review summarizes variation in salmonid life history, with an emphasis on the salmonine lineage, and suggests ecological, evolutionary, and management implications. Tables.
Variation in Salmonid Life Histories
Author: Mark F. WillsonPublisher: Cascade Geographic Society
ISBN: 9780899046853
Category :
Languages : en
Pages : 60
Book Description
Variation in Salmonid Life Histories: Patterns and Perspective
Author: Bibliography of Agriculture
Author: Pacific Salmon Life Histories
Author: Cornelis GrootPublisher: UBC Press
ISBN: 9780774803595
Category : Nature
Languages : en
Pages : 602
Book Description
Pacific salmon are an important biological and economic resource of countries of the North Pacific rim. They are also a unique group of fish possessing unusually complex life histories. There are seven species of Pacific salmon, five occurring on both the North American and Asian continents (sockeye, pink, chum, chinook, and coho) and two (masu and amago) only in Asia. The life cycle of the Pacific salmon begins in the autumn when the adult female deposits eggs that are fertilized in gravel beds in rivers or lakes. The young emerge from the gravel the following spring and will either migrate immediately to salt water or spend one or more years in a river or lake before migrating. Migrations in the ocean are extensive during the feeding and growing phase, covering thousands of kilometres. After one or more years the maturing adults find their way back to their home river, returning to their ancestral breeding grounds to spawn. They die after spawning and the eggs in the gravel signify a new cycle. Upon this theme Pacific salmon have developed many variations, both between as well as within species. Pacific Salmon Life Histories provides detailed descriptions of the different life phases through which each of the seven species passes. Each chapter is written by a scientist who has spent years studying and observing a particular species of salmon. Some of the topics covered are geographic distribution, transplants, freshwater life, ocean life, development, growth, feeding, diet, migration, and spawning behaviour. The text is richly supplemented by numerous maps, illustrations, colour plates, and tables and there is a detailed general index, as well as a useful geographical index.