> Salish Sea Ecosystem Conference
Doug Hay, Nearshore ResearchFollow
General species and food webs
In late April 2014, while experimental fishing for eulachon in the lower Fraser River, we incidentally captured herring (Clupea pallasii). Cursory analyses revealed two surprising observations: (1) herring were feeding on pink salmon fry; (2) herring gonads were maturing but not ripe, typical of herring captured several weeks prior to spawning. If so, these herring would spawn in May. There was a local sports-fishery targeting these herring. Fishers used lures resembling pink salmon fry. Fishing success appeared episodic but some fishers took home buckets of herring. From these collective observations we concluded that there was probably a substantial population of sexually ripening herring in the lower Fraser in late April. Spawning after April is a rare event in the Canadian waters of the Salish Sea, with only 17 documented occurrences among over 6200 records of spawning between 1928-2014. Such a late spawning is, however, typical of nearby Cherry Point herring in Washington State, where spawning in May is the norm. Therefore we hypothesized that the herring we caught were from the genetically-distinct Cherry Point population. If so an important biological implication is that Cherry Point herring may have an enduring connection to the Fraser River, perhaps by using the estuarine waters as a larval retention area. It is widely accepted that some form of larval or juvenile retention area is a pre-requisite to the development and maintenance of reproductive isolation in marine fish populations. Estuarine circulation from the Fraser River may provide such a retention mechanism. If Cherry Point herring routinely inhabit the Fraser River or estuary for early development stages then the management implications are substantial. This is especially so if future work showed that the present depressed state of Cherry Point herring is linked to conditions in the Fraser River or adjacent estuarine waters.
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Do Cherry Point herring have a Fraser River connection?