Biological Opinions - Bureau of Reclamation

LRSs assayed from UKL (Vanderkooi et al. 2010); and parasites, including Neascus spp., a
trematode flatworm (Simon et al. 2012, Markle et al. 2013), anchor worm (Lernaea cyprinacea),
a parasitic copepod (Simon et al. 2012), Trichodina sp., an external ciliate protozoan; and the
bacterium Flavobacterium columnare, which causes gill rot (Holt 1997, Foott 2004, Foott et
al. 2010). Markle et al. (2013) recently estimated an additional 3.7 percent daily mortality for
juvenile SNSs that were infected with Neascus spp. (black spot disease) compared to uninfected
individuals. There is new information concerning the bacterial flora on the skin of juvenile
suckers (Burdick et al. 2009b), but it is unknown if this negatively affects the fish.
The LRS and the SNS are known to have at least two groups of multicellular, invertebrate
parasites: Neascus and Lernaea. Neascus, or “black-spot disease,” is a catch-all term for a group
of trematode flatworms that cause similar infections in fish (Kirse 2010). The larval trematodes
(a parasitic flat worm)burrow under the skin of the fish, resulting in a black cyst. The Neascus
life cycle progresses through snails, then fish, and finally a fish-eating bird, all of which are
seasonally numerous at UKL. Parasitic infections can cause physiological stress, blood loss,
decreased growth rates, reduced swimming performance, lower overwinter fitness, and mortality,
especially in small fish (Marcogliese 2004, Kirse 2010, Ferguson et al. 2011). In some instances,
parasites can also make hosts more vulnerable to predators by affecting their morphology and/or
behavior (Marcogliese 2004). Limited evidence is beginning to emerge concerning the effects of
these parasites on listed Klamath suckers and it shows that parasites are likely an important
source of mortality for age-0 SNS (Markle et al. 2013).
7.4 LRS and SNS Life History
The LRS and the SNS are adapted to lake environments. The LRS is the only extant member of
the genus Deltistes (Miller and Smith 1967), and the SNS is one of three recognized species in the
genus Chasmistes (Moyle 2002). Both species are relatively large, with a maximum size between
24 to 31 in (61 and 80 cm). The LRS and the SNS feed on zooplankton and small benthic
invertebrates taken from or near soft substrates (Scoppettone and Vinyard 1991).
Both species spawn from February through May over rocky substrates in habitats less than 4 ft
(1.2 m) deep in rivers and at shoreline springs (Buettner and Scoppettone 1990). In UKL, it
appears that more than 95 percent of adults spawn every year (Hewitt et al. 2012). Females are
highly fecund, producing from 44,000 to over 200,000 eggs per LRS female and 18,000 to
72,000 per SNS female per year, of which only a very small percentage survive to become
juveniles (NRC 2004). Females typically broadcast their eggs in the company of two males
(Buettner and Scoppettone 1990), and the fertilized eggs settle within the top few inches of the
substrate until hatching 1 week later.
Approximately 10 days after hatching, larvae emerge out of the substrate (Buettner and
Scoppettone 1990). Most larvae spawned in streams quickly drift downstream into lake habitat.
Larval movement away from the spawning grounds begins in April and is typically completed by
July (Klamath Tribes 1996, Tyler et al. 2004, Ellsworth et al. 2010). Once in lake habitats, SNS
larvae predominantly use nearshore areas adjacent to and within emergent vegetation (Klamath
Tribes 1996, Cooperman and Markle 2004, Crandall et al. 2008), but LRS larvae tend to occur
more often in open water habitat (Burdick and Brown 2010) than near vegetated areas.
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