Recently, I summarized survey information from the Bay-Delta on Sacramento splittail that depicted a potentially grim picture of the future of this special status species. In that post, I did not include trawl survey info from Suisun Marsh Fish Study collected annually by UC Davis (Figure 1), which indicates a core population of adult splittail still present in Suisun Marsh. Other core populations exist in San Pablo Bay (Petaluma and Napa Rivers). Peter Moyle and Teejay O’Rear (UC Davis, personal communications) believe the Marsh core population is sufficiently strong and resistant to extinction.
Looking at Figure 1, the Suisun Marsh population survived the 1987-1992 drought, building in numbers with strong recruitment (ages 0 and 1) in the wet years of 1995-2000. Recruitment declined during the 2007-2009 drought, but there was strong recruitment in the wetter 2010 and 2011 water years. Recruitment declined in the 2012-2014 drought years, but remains substantially higher than at the end of the 1987-1992 drought. Teejay O’Rear states the population has remained strong through 2015 and 2016, with some recruitment in the wetter 2016, and likely strong recruitment in the spring of 2017, presuming it stays wet.