Salmon Nutrients

All: The report below notes the importance of salmon carcass deposition, following large escapements of salmon, to the ecosystem as a whole. Bears, everything else within the ecosystem benefits from strong escapements, in short, as Mike Cramond used to say to me, "abundance creates abundance", the same principle stands with herring. The old idea of many BC fishers (and especially fish processors that simply want to make big catches NOW) that salmon "over escapement" hurts future returns has now been scientifically disproved. 

Regards,

DE

In the recent publication Fisheries (Vol. 25, No. 1, January 2000) there is an article about salmon decline and its effect on nutrients from salmon carcasses in west coast streams. The authors estimate the historic biomass of salmon returning to streams was from 160 million to 226 million kg. The amount now available has been reduced to 11.8 million to 13.7 million kg. This is just 6-7 percent of the historic nutrient input to west coast streams.
This reduction in nutrients, say the authors, is one indication of ecosystem failure that has contributed to the downward spiral of salmonid abundance and diversity and this further diminishes the possibility of salmon population recovery to self-sustaining levels.
The authors say, "Fisheries management has historically ignored such ecological implications of salmon spawning escapements. Harvests were regulated to provide the minimum number of spawners needed to seed the habitat. The contribution of 'surplus' salmon carcasses to the growth and survival of juvenile salmon was not considered when harvest and escapement targets were set."


ABSTRACT OF THE ARTICLE AND TITLE


An Estimation of Historic and Current Levels of Salmon Production in the Northwest Pacific Ecosystem: Evidence of a Nutrient Deficit in the Freshwater Systems of the Pacific Northwest.


By Ted Gresh, Jim Lichatowich, and Peter Schoonmaker


Abstract


We used historical cannery records and current escapement and harvest records to estimate historical and current salmon escapement to western North American river systems in order to determine the biomass and marine-derived nitrogen and phosphorous levels delivered by adult salmon, and the deficits corresponding to the diminished returns of adult salmon over the past century. We have estimated the historic biomass of salmon returning to the Pacific Northwest (Washington, Oregon, Idaho, and California) to be 160-226 million kg. The number of fish now returning to these rivers has a biomass of 11.8 to 13.7 million kg. These numbers indicate that just 6-7% of the marine-derived nitrogen and phosphorous once delivered to the rivers of the Pacific Northwest is currently reaching these streams. This nutrient deficit may be one indication of ecosystem failure that has contributed to the downward spiral of salmonid abundance and diversity in general, further diminishing the possibility of salmon population recovery to self-sustaining levels.

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David W. Ellis,
Executive Director,
The Fish For Life Foundation
3872 Point Grey Road
Vancouver, B.C.
V6R 1B4
Canada
Phone: (604) 221-7577
FAX: (604) 221-7544

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