Cormorant harassment to protect juvenile salmonids in Tillamook County, Oregon

Abstract

The goal of the Oregon Plan is to restore wild coho and wild steelhead runs. Under the federal Endangered Species Act, wild coho salmon along the Oregon Coast are listed as Threatened and wild Oregon Coast steelhead are a candidate for listing. Although cormorants have been hazed at the Nehalem Estuary for at least 10 years and at the Tillamook and Nestucca Estuaries for at least three years, spawning ground counts of wild coho salmon, winter steelhead, and fall chinook have averaged less since hazing began. Thus, hazing does not appear to be useful in recovering wild salmonids. Hazing is not correlated with consistently improved hatchery returns. The survival of Coded Wire Tag marked coho smolts at the Nehalem was about the same whether hazing occurred or not, the percent return for coho smolts was not significantly greater at the hazed Nehalem than at the nonhazed Salmon River, and the number of returning adult coho salmon was significantly greater with hazing at the Nehalem hatchery but not at the Trask hatchery in the Tillamook Basin. For winter steelhead, the number of returning adults to the Nehalem and jacks to the Cedar Creek hatchery in the Nestucca Basin did not increase significantly with hazing, but the number of jacks returning to the Nehalem did. Changes in fisheries subsequent to hazing are mixed. Coho catches increased with hazing at the Nehalem but not at the Tillamook Basin. Nehalem steelhead catches averaged less with hazing, but chinook fisheries have grown. However, the increase in chinook catches occurred as the number of wild chinook at spawning areas declined, so the larger catch may be a consequence of a greater harvest of wild chinook rather than hazing. Returns may not have increased with hazing because it was ineffective in substantially reducing predation, because smolts saved by hazing died anyway, or because other factors such as unfavorable ocean conditions may have been much more important in affecting smolt survival than hazing. In any case, hazing does not appear to be a panacea for salmonid recovery, and it has costs. During 1996-1999, the Oregon Legislature spent $100,000 for cormorant hazing, and a biological cost of hazing is the disturbance of wildlife other than cormorants.