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A critical assessment of the ecological assumptions underpinning compensatory mitigation of salmon-derived nutrients

Environmental Management

By:
, , , and
https://doi.org/10.1007/s00267-015-0538-5

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Abstract

We critically evaluate some of the key ecological assumptions underpinning the use of nutrient replacement as a means of recovering salmon populations and a range of other organisms thought to be linked to productive salmon runs. These assumptions include: (1) nutrient mitigation mimics the ecological roles of salmon, (2) mitigation is needed to replace salmon-derived nutrients and stimulate primary and invertebrate production in streams, and (3) food resources in rearing habitats limit populations of salmon and resident fishes. First, we call into question assumption one because an array of evidence points to the multi-faceted role played by spawning salmon, including disturbance via redd-building, nutrient recycling by live fish, and consumption by terrestrial consumers. Second, we show that assumption two may require qualification based upon a more complete understanding of nutrient cycling and productivity in streams. Third, we evaluate the empirical evidence supporting food limitation of fish populations and conclude it has been only weakly tested. On the basis of this assessment, we urge caution in the application of nutrient mitigation as a management tool. Although applications of nutrients and other materials intended to mitigate for lost or diminished runs of Pacific salmon may trigger ecological responses within treated ecosystems, contributions of these activities toward actual mitigation may be limited.

Additional publication details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
A critical assessment of the ecological assumptions underpinning compensatory mitigation of salmon-derived nutrients
Series title:
Environmental Management
DOI:
10.1007/s00267-015-0538-5
Volume:
56
Issue:
3
Year Published:
2015
Language:
English
Publisher:
Springer
Contributing office(s):
Coop Res Unit Seattle
Description:
16 p.
First page:
571
Last page:
586
Online Only (Y/N):
N
Additional Online Files (Y/N):
N