Early Life History of Fishes in the San Francisco Estuary and Watershed

Survival of Pacific Herring Larvae Is a Function of External Salinity

Frederick J. Griffin, Melissa R. Brenner, Heather M. Brown, Edmund H. Smith, Carol A. Vines, and Gary N. Cherr

doi: https://doi.org/10.47886/9781888569599.ch3

Abstract.—The importance of salinity to reproduction in Pacific herring Clupea pallasi was examined by studies of survivability at three salinities—4‰, 16‰, and 32 ‰—for yolk sac (0–2, 4–6, and 8–10 d posthatch) larvae that were obtained from in vitro fertilizations of gametes from San Francisco Bay fish. Posthatch age (up to 10 d) did not influence sensitivity to salinity. Greater than 68% of low salinity tolerant larvae, in all three posthatch age-groups, survived 7 d in 4‰ and 16‰, while only 0–31% survived in 32‰ salinity. Salinity during embryonic development and timing within the reproductive season were factors in determining salinity tolerance of larvae. Low salinity tolerant larvae raised through embryonic development in 4‰ or 16‰ had significantly higher mortality in 32‰ than in either 4‰ or 16‰. Larvae from embryos raised in 32‰ had elevated mortality regardless of larval culture salinity; mortality in these larvae was also greater than that of 4‰ or 16‰ raised larvae that had been kept in the lower salinity waters. Two different regimes of salinity tolerance were observed in larvae during the 2002–2003 reproductive season; cohorts produced during January and February had higher survival in 32‰ than 4‰, denoted as high salinity tolerant larvae. Those from March reproduction survived better in 4‰ than 32‰, denoted as low salinity tolerant larvae. Lastly, salinity tolerances of larvae were similar regardless of whether they were produced from in vitro fertilizations or from natural spawns in San Francisco Bay.