Wednesday, February 23, 2011

New Study Highlights Hatchery Effects on Wild Productivity




In one of the most comprehensive studies ever undertaken to examine the effects of hatchery supplementation on the productivity of wild stocks, Mark Chilcote of NOAA Fisheries in collabortation with two ODFW biologists found that hatcheries dramatically depress the productivity of wild runs of coho, steelhead and Chinook. Using populations from the Washington and Oregon Coast as well as the entire Columbia basin, they found that hatchery spawners are on average only 12% as productive as their wild counterparts and that there was no apparent benefit of using wild broodstock hatcheries. Using a model which included the proportion of hatchery spawners, the species in question, whether there is a hatchery in the basin and the number of dams the fish must migrate past, the authors were able to explain 72% of the variation in year to year recruitment. The study adds to the already large body of evidence suggesting that hatchery supplementation hinders wild populations, however it is unique in its scope.

mean recruits per spawner as a function of the proportion of hatchery spawners (Ph)

Among the most important findings of the paper is the fact that wild-broodstock hatcheries a major emphasis of recent hatchery reforms hinder wild productivity as much as segregated hatchery programs. Futhermore the authors caution that fish recovery plans should not lean too heavily on hatchery supplementation saying that reintroduction efforts should, "plan on a period of lower productivity and seek to reduce the number of generations that hatchery fish are allowed to spawn in the wild." Excellent advice, particularly considering a number of high profile dam removal projects currently on the horizon in Washington State. On the Elwha WDFW and the Lower Elwha tribe plan to release millions of smolts annually throughout the dam removal period meaning that the spawning population will be predominantly hatchery origin. It is critical that state and tribal fish managers consider the long term impact of these hatchery programs for wild populations and scale their releases accordingly.

Read the paper here:
http://dl.dropbox.com/u/1234/FishStudies/chilcote2011.pdf

2 comments:

chaveecha said...

By capitalizing chinook, you imply that you are refering to people of the Chinook nation. And just because everyone is doing it doesn't make it right ;-)

Osprey said...

the fish are named after the tribe, hence the proper noun