9689

• UCREFRP Catalog Number: 9689
• Author: Recovery Implementation Program.
• Title: Recovery Implementation Program For Endangered Fish Species In The Upper Colorado And San Juan River Basins - 27th Annual Recovery Program Researchers Meeting Program.
• USFW Year: 2006.
• USFW - Doc Type: Moab, UT.
• Copyright Material: NO

RECOVERY IMPLEMENTATION PROGRAM
FOR ENDANGERED FISH SPECIES
IN THE UPPER COLORADO AND SAN mAN RIVER BASINS
27m ANNUAL RECOVERY PROGRAM RESEARCHERS MEETING

ABSTRACTS

1. Population dynamics of adult Lost River suckers and shortnose suckers in
Upper Klamath Lake and its tributaries, Oregon

Author: ERIC JANNEY, U. S. Geological Survey, Western Fisheries Research Center,
Klamath Falls Field Station, 2795 Anderson Ave, Suite 106, Klamath Falls, OR 97603,
541-273-8689; rip_shively @usgs.gov

Abstract: Lost River suckers Deltistes luxatus (LRS) and shortnose suckers Chasmistes
brevirostris (SNS) are both long-lived species endemic to the Upper Klamath Basin of
Oregon and California. Both species were listed under the Endangered Species Act in
1988. We analyzed empirical length data, a relative spawning output index, and survival
estimates to assess population dynamics and status of adult sucker populations in Upper
Klamath Lake, OR. Length data indicate that at the time of listing, both SNS and LRS
populations were comprised mostly of old individuals with no evidence of recent
recruitment. An influx of smaller individuals recruited into both spawning populations
during the mid 1990's. Relative reproductive index values for LRS indicate a precipitous
decline (98%) in spawning output between 1995 and 1998. A 95% decrease in spawning
output was observed for SNS. These declines coincide with consecutive summer fish kill
events resulting from poor water quality conditions that occurred in 1995 - 1997. Using
a random effects model, we estimated mean annual survival probability for the years
1995 - 2004 to be 0.83 for LRS and 0.79 for SNS. Survival modeling efforts indicate fish
kill events during the summers of 1995 - 1997, and 2003 were very important sources of
LRS mortality and survival probability during those years was markedly lower than in
years without observed fish kill events. Shortnose sucker survival probabilities also
varied tremendously with time and estimates indicate very poor survival from 1996 -
1998.

2. The use of remote 125 KHz and 134 KHz PIT tag detection stations to increase
recapture probability of Lost River suckers and shortnose suckers in Upper
Klamath Lake, Oregon.

Authors: BRIAN HAYES and ERIC JANNEY
U.S Geological Survey, Western Fisheries Research Center, Klamath Falls Field Station,
2795 Anderson Ave, Klamath Falls, OR 97603.541-273-8689; [e-mail]

Abstract: The U.S Geological Survey has monitored endangered Lost River (Deltistis
Luxatus) and shortnose (Chasmistes brevirostris) sucker populations in Upper Klamath
Lake, Oregon since in 1995. Population parameter estimates from these data are used to
monitor population status and recovery efforts. Prior to 2005, sampling required suckers

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