Carbaryl, Carbofuran, and Methomyl - National Marine Fisheries ...

Status and Trends
The CCC steelhead DPS was listed as a threatened species on August 18, 1997(62 FR
43937). Its threatened status was reaffirmed on January 5, 2006 (71 FR 834). Busby et
al. (1996) reported one estimate of historical (pre-1960s) abundance. Shapovalov and
Taft (1954) described an average of about 500 adults in Waddell Creek (Santa Cruz
County) for the 1930s and early 1940s. Johnson (1964) estimated a run size of 20,000
steelhead in the San Lorenzo River before 1965. The CDFG (1965) estimated an average
run size of 94,000 steelhead for the entire DPS, for the period 1959–1963. The analysis
by CDFG (1965) was compromised for many basins, as the data did not exist for the full
5-year analytical period. The authors of CDFG (1965) state that “estimates given here
which are based on little or no data should be used only in outlining the major and critical
factors of the resource.”
Recent data for the Russian and San Lorenzo rivers (Reavis 1991; CDFG 1994; Shumann
1994) suggested that these basins had populations smaller than 15% of their size 30 years
earlier. These two basins were thought to have originally contained the two largest
steelhead populations in the CCC steelhead ESU.
A status review update in 1997 (Gustafson, Wainwright et al. 1997) concluded that slight
increases in abundance occurred in the three years following the status review. However,
the analyses on which these conclusions were based had various problems. They include
the inability to distinguish hatchery and wild fish, unjustified expansion factors, and
variance in sampling efficiency on the San Lorenzo River. Presence-absence data
indicated that most (82%) sampled streams (a subset of all historical steelhead streams)
had extant populations of juvenile O. mykiss (Adams 2000; Good, Waples et al. 2005).
The majority (69%) of BRT votes were for “likely to become endangered,” and another
25% were for “in danger of extinction”. Abundance and productivity were of relatively
high concern (as a contributing factor to risk of extinction), and spatial structure was also
of concern. Predation by pinnipeds at river mouths and during the ocean phase was noted
147