Scholz N.L.,National Oceanic and Atmospheric Administration |
Myers M.S.,National Oceanic and Atmospheric Administration |
Labenia J.S.,National Oceanic and Atmospheric Administration |
McIntyre J.K.,National Oceanic and Atmospheric Administration |
And 11 more authors.
PLoS ONE | Year: 2011
Several Seattle-area streams in Puget Sound were the focus of habitat restoration projects in the 1990s. Post-project effectiveness monitoring surveys revealed anomalous behaviors among adult coho salmon returning to spawn in restored reaches. These included erratic surface swimming, gaping, fin splaying, and loss of orientation and equilibrium. Affected fish died within hours, and female carcasses generally showed high rates (>90%) of egg retention. Beginning in the fall of 2002, systematic spawner surveys were conducted to 1) assess the severity of the adult die-offs, 2) compare spawner mortality in urban vs. non-urban streams, and 3) identify water quality and spawner condition factors that might be associated with the recurrent fish kills. The forensic investigation focused on conventional water quality parameters (e.g., dissolved oxygen, temperature, ammonia), fish condition, pathogen exposure and disease status, and exposures to metals, polycyclic aromatic hydrocarbons, and current use pesticides. Daily surveys of a representative urban stream (Longfellow Creek) from 2002-2009 revealed premature spawner mortality rates that ranged from 60-100% of each fall run. The comparable rate in a non-urban stream was <1% (Fortson Creek, surveyed in 2002). Conventional water quality, pesticide exposure, disease, and spawner condition showed no relationship to the syndrome. Coho salmon did show evidence of exposure to metals and petroleum hydrocarbons, both of which commonly originate from motor vehicles in urban landscapes. The weight of evidence suggests that freshwater-transitional coho are particularly vulnerable to an as-yet unidentified toxic contaminant (or contaminant mixture) in urban runoff. Stormwater may therefore place important constraints on efforts to conserve and recover coho populations in urban and urbanizing watersheds throughout the western United States.
Gayeski N.,Wild Fish Conservancy |
McMillan B.,Wild Fish Conservancy |
Trotter P.,4926 26th Ave. S
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2011
We used reported commercial catch data and historical information regarding unreported catches to estimate the abundance of winter steelhead, Oncorhynchus mykiss, in Puget Sound rivers in 1895, the year in which the peak commercial catch of steelhead occurred. We employed a Bayesian analysis to address the uncertainties associated with the estimation process and report abundance estimates for four large northern Puget Sound rivers and for the remaining aggregate of rivers and streams in Puget Sound. The central 90% of the posterior distribution of total abundance ranged from 485 000 to 930 000, with a mode of 622 000. Compared with the 25-year average abundance for all of Puget Sound of 22 000 for the 1980-2004 period, our results show that current abundance is likely only 1%-4% of what it was prior to the turn of the 20th century. Loss of freshwater habitat alone can account for this reduction in abundance only if there was an extraordinary decline in productivity. Our estimates of historical abundance should better inform the development of recovery goals for Puget Sound steelhead.
Winans G.A.,National Oceanic and Atmospheric Administration |
Gayeski N.,Wild Fish Conservancy |
Timmins-Schiffman E.,University of Washington
Conservation Genetics | Year: 2015
Recognizing the genetic diversity within and among collections of allopatric rainbow trout is an important step in understanding and monitoring the dynamics of the metapopulation structure of a species like Oncorhynchus mykiss with resident and anadromous life history forms. Prior to the removal of a barrier and the recolonization of Icicle Creek with anadromous steelhead, we report the degree to which collections of above-barrier resident rainbow trout from 13 sites differ from downstream steelhead, and the pattern of genetic diversity and connectivity among resident collections using 14 microsatellite loci. Measures of genetic variability (He, AR, and A/L) are low in the upper-most collections of residents and estimates of Ne change approximately 4-fold from the upper tributaries (Ne~90) to the lowest main stem collections (Ne~360) over 35 river kilometers (rkm). The overall comparison of resident rainbow trout versus below-barrier steelhead is FST = 0.053. A STRUCTURE analysis of all 1,730 fish indicated three populations within the above-barrier collections of resident fish. Notably, two sets of upstream collections of rainbow trout, separated at a minimum of 16.4 rkm, had a mean FST = 0.128. Natural passage barriers account for some of the observed stock structure in Icicle Creek but the strongest differences are not associated with barriers by our analysis. No significant temporal variability was seen within four rainbow trout sites and one steelhead site; and no hatchery rainbow trout ancestry was detected in the watershed. In general these results highlight the need for conservation efforts to include fine-scale evaluations of population structure of riverine fishes above barriers to increase the accuracy of understanding and monitoring intra specific diversity and the biological effects of dams and dam removal. © 2014, Springer Science+Business Media Dordrecht (outside the USA).
Thompson A.M.,Wild Fish Conservancy |
Glasgow J.,Wild Fish Conservancy |
Buehrens T.,University of Washington |
Drucker E.G.,Wild Fish Conservancy
Fisheries Management and Ecology | Year: 2011
Hidrostal pumps have been successfully employed in live fish transport, yet their effectiveness in fish passage is incompletely understood. This study investigates juvenile salmonid mortality in experimental passage trials through Hidrostal pumps at an agricultural pump facility in Washington State, USA. The effects of impeller pitch, rotational speed and fish body size on passage survival were examined. Hatchery-reared salmonids [Oncorhynchus mykiss (Walbaum) and Oncorhynchus kisutch (Walbaum)] were introduced to low- and high-pitch impeller assemblies operating at two speeds. Instantaneous mortality rates ranged from 0 to 4% for high-pitch trials and from 3 to 10% for low-pitch trials. Larger fish experienced sublethal injury at higher rates (approximately 60% injured) than smaller fish (approximately 23% injured) and exhibited greater susceptibility to injury at higher pump speed. Injury between trials was compared by ranking according to severity and summed for each treatment; greater injury severity was found for the low-pitch impeller and from higher rotational speeds. Although injury and mortality rates to fish passing through Hidrostal pumps may be reduced through the use of higher-pitch impellers and lower operational speeds, the use of pump-bypass facilities may be warranted where acceptable impact thresholds are low. © 2011 Blackwell Publishing Ltd.