Distribution and condition of larval and juvenile Lost River and shortnose suckers in the Williamson River Delta restoration project and Upper Klamath Lake, Oregon

Abstract

Federally endangered Lost River sucker (Deltistes luxatus) and shortnose sucker (Chasmistes brevirostris) were once abundant throughout their range but populations have declined. They were extirpated from several lakes in the 1920s and may no longer reproduce in other lakes. Poor recruitment to the adult spawning populations is one of several reasons cited for the decline and lack of recovery of these species and may be the consequence of high mortality during juvenile life stages. High larval and juvenile sucker mortality may be exacerbated by an insufficient quantity of suitable or high-quality rearing habitat. In addition, larval suckers may be swept downstream from suitable rearing areas in Upper Klamath Lake into Keno Reservoir, where they are assumed lost to Upper Klamath Lake populations. The Nature Conservancy flooded about 3,600 acres (1,456 hectares) to the north of the Williamson River mouth (Tulana) in October 2007, and about 1,400 acres (567 hectares) to the south and east of the Williamson River mouth (Goose Bay Farms) in October 2008, in order to retain larval suckers in Upper Klamath Lake, create nursery habitat, and improve water quality. The U.S. Geological Survey joined a long-term research and monitoring program in collaboration with The Nature Conservancy, the Bureau of Reclamation, and Oregon State University in 2008 to assess the effects of the Williamson River Delta restoration on the early life-history stages of Lost River and shortnose suckers. The primary objectives of the research were to describe habitat colonization and use by larval and juvenile suckers and non-sucker fishes and to evaluate the effects of the restored habitat on the health and condition of juvenile suckers. This report summarizes data collected in 2010 by the U.S. Geological Survey as a part of this monitoring effort and follows two annual reports on data collected in 2008 and 2009. Restoration modifications made to the Williamson River Delta appeared to provide additional suitable rearing habitat for endangered Lost River and shortnose suckers from 2008 to 2010 based on sucker catches. Mean larval sample density was greater for both species in the Williamson River Delta than adjacent lake habitats in all 3 years. In addition to larval suckers, at least three age classes of juvenile suckers were captured in the delta. The shallow Goose Bay Farms and Tulana Emergent were among the most used habitats by age-0 suckers in 2009. Both of these environments became inaccessible due to low water in 2010, however, and were not sampled after July 19, 2010. In contrast, age-1 sucker catches shifted from the shallow water (about 0.5-1.5 m deep) on the eastern side of the Williamson River Delta in May, to deeper water environments (greater than 2 m) by the end of June or early July in all 3 years.

Health and condition of endangered juvenile Lost River and shortnose suckers relative to water quality and fish assemblages in Upper Klamath Lake, Oregon, and Clear Lake Reservoir, California

“…Juvenile suckers in Upper Klamath Lake appear mostly healthy until they disappear from catches, but health cannot be adequately assessed without reference to a surviving population of juvenile suckers of the same species. Juvenile suckers in Upper Klamath Lake grow rapidly throughout August and September each year, but growth slows in October (Bottcher and Burdick, 2010;Burdick and Brown, 2010). These fish also accumulate triglycerides throughout the summer, indicating prey is sufficient to provide energy storage (Foott and others, 2012).…”

“…Skeletal deformities usually occur in less than 10 percent of age-0 Lost River and shortnose suckers collected annually from Upper Klamath Lake, but have been reported in as many as 27 percent in some years (Burdick and others, 2009). The most commonly reported deformity is shortened opercula, but scoliosis and fused vertebrae also are observed in less than 1 percent of individuals (Burdick and Hewitt, 2012). Wild-caught and mesocosmheld juvenile suckers from Upper Klamath Lake rarely are diseased and histological abnormalities are uncommon and usually minor others, 2012, 2014).…”

Statistical analysis of the water-quality monitoring program, Upper Klamath Lake, Oregon, and optimization of the program for 2013 and beyond

“…Changes in daily bloom index values and air temperature or wind speed were calculated over 1, 2, 3, and 4 days, and compared using correlation analysis to investigate the relation between short-term changes in bloom activity and mesoscale weather on the lake. In 2005In , 2006, when more severe mid-season bloom declines occurred, correlations were more significant between short-term changes in daily bloom index values and short-term changes in meteorological variables than when daily values were compared (table 12). Furthermore, correlations between the short-term value changes generally were highest and more significant when calculated over 2-4 days.…”

“…In addition, blooms that develop during the latter part of summer contain toxigenic cells of Microcystis aeruginosa that produce microcystins, which have been associated with gastroenteritic and hepatic diseases and tumor promotion in humans, livestock, domestic animals, and wildlife (Sivonen and Jones, 1999). Juvenile suckers may be particularly susceptible to microcystins, and recent work shows that elevated concentrations of this toxin in the lake from late July to early September in some years (Eldridge, Wood, and others, 2012) may be the cause for a lack of juvenile recruitment into the spawning population (Burdick, 2012).…”

Using high-throughput DNA sequencing, genetic fingerprinting, and quantitative PCR as tools for monitoring bloom-forming and toxigenic cyanobacteria in Upper Klamath Lake, Oregon, 2013 and 2014

“…The USGS water-quality monitoring program in Upper Klamath Lake since 2005 has focused primarily on environmental parameters that affect the health and survival of endemic fish populations (Burdick and Hewitt, 2012;Hewitt and others, 2014;Hereford and others, 2016).…”