New research published in the September Issue of the peer-reviewed journal Ecology demonstrates the need for comprehensive methods of revitalizing depleted salmon stocks.

The study by scientists James M. Helfield and Robert J. Naiman of the University of Washington shows that the viability of salmon populations and terrestrial ecosystems are mutually dependent, and therefore calls into question traditional single-species approaches to fisheries management, endangered species legislation, and ecological restoration.

The findings come at a time when Pacific salmon have disappeared from or are in serious decline throughout most of their historical spawning range in North America.

Salmon benefit from the riparian vegetation (named after the plants proximity to the rivers natural banks) which provides many of the necessary conditions for successful spawning. The riparian plants are a source of shade which helps to regulate the temperature of the spawning grounds. In addition, the plants are a source of large woody debris which retain sediments and help create sheltered areas within the river that can limit mortality among incubating salmon embryos and young fish, particularly during the winter.

This study allows ecologists to see that the relationship between riparian vegetation and salmon is a two-way street, Naiman said. As a main limiting factor for terrestrial plant growth in many northern and temperate forests, Nitrogen is of vital importance to plants, and the Nitrogen derived from spawning salmon is an essential addition to the ecosystem.

Helfield and Naiman compared the amount of Nitrogen in riparian vegetation adjacent to spawning sites with sites near regions without salmon along two rivers on Chichagof Island in southeast Alaska. They found that plants in spawning sites contained a higher level of Nitrogen than did their reference counterparts. Differences between spawning sites and reference sites were significant
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Contact: Andrew Freedman
andrew@esa.org
202-833-8773
Ecological Society of America
20-Sep-2001