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Proceedings of the National Workshop on Effects of Habitat Alteration on Salmonid Stocks

Colin D. LevingsLeslie Blair HoltbyMichael A. Henderson

出版	Department of Fisheries and Oceans, 1989
主題	Nature / Animals / FishScience / Life Sciences / Zoology / General
ISBN	066013232X9780660132327
URL	http://books.google.com.hk/books?id=MGcRAAAAYAAJ&hl=&source=gbs_api

註釋Participants in a National Workshop on Effects of Habitat Alteration on Salmonid Stocks were generally uneasy about our ability to make quantitative predictions regarding the effects of habita changes on salmonid production. Fish habitat management was revealed as a complex business that must deal with an instrinsically variable resource living in an often unstable environment and harvested by a dynamic fishery. Habitat managers need the best possible information available to them and even then substantial judgement is needed to interpret data and make the best possible decision. Methodologies for predicting effects are becoming available through such techniques as linking life history models, an approach requiring long-term data sets consisting of many different variables for model development and verification. It was recommended that for each species of concern there should at least be an outline of a life history model which indicates stages sensitive to various habitat alterations to guide management actions. It was acknowledged that physical changes, including landscape effects and water quantity, are more easily measured than chemical effects, possibly because physical variables are usually measurable by standard engineering techniques. Chemical effects are more subtle and frequently the substances thought to be deleterious cannot be easily measured in the field. Sublethal effects may lead to increased mortality due to predation, disease, or food limitation and these effects are very difficult to evaluate for populations. With both physical and chemical effects, the consequences of the habitat changes must be assessed through a population model. Because of the current scientific difficulties in quantifying the effects of habitat change on salmonid populations, it appears that significant judgement or inference is required to interpret even major project data bases that deal with impacts on salmonid population.