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SIGNIFICANCE AND NEXT STEPS
Pacific Herring and other forage fish such as Northern
Anchovy, Sand Lance and Surf Smelt are important prey
for Coho and Chinook, as well as marine mammals, and
seabirds. The above-average age-0 herring condition
since 2007 indicates that fish are heavier for a given
length and may contain more energy for predators.
SSMSP results suggest that, to have a good chance of
surviving their first winter, juvenile Coho must be large
enough to eat the cohort of age-0 herring that are
available to them. Our studies showed that Coho
sampled 2012-2014 in the Strait of Georgia grew more
at the north end of the Strait than at the lower end,
and that this appeared to be related to the amount of
herring in the diet. Other studies focusing on Cowichan
River Chinook in 2015 and 2016 showed that only the
largest juvenile Chinook Salmon were able to consume
age-0 Pacific Herring. The ratio of age-0 herring size to
juvenile salmon size in late summer may be impacted by
temperature, prey availability, and competition effects
on both juvenile salmon and juvenile herring earlier in
the season. This predator to prey size ratio could be a
key regulator of survival for juvenile Chinook and merits
further study.
Continued warming of the Salish Sea may lead to greater
abundance and persistence of anchovy, with potentially
important consequences for the ecosystem as a whole.
Understanding trends in the populations of small pelagic
fish species and factors that affect their abundance and
condition requires long-term monitoring of the nearshore
pelagic ecosystem. PSF recommends the continuation
of the critically important DFO Juvenile Herring Survey.
Information on other important forage fish such as
Sand Lance and Surf Smelt are not routinely collected,
but we recommend identification and protection of
spawning habitats, and the development of biomass
surveys, for these forage fish species. An ongoing PSF
funded study of year-round adult Chinook and Coho
Salmon diets will provide new insights into the ecology
of Salish Sea forage fish.
Photo
by
Ryan
Miller
