This is interesting, but it seems like quite a stretch. Still worth the read.
University of Victoria researcher Roberta Hamme suggested in a recent study published in the journal Geophysical Research Letters that the iron in the volcanic ash spurred an algae bloom that fed ocean-going zooplankton, a food source for sockeye.
Turbulent weather spread the dust over a large area causing the largest algae bloom recorded in 12 years, according to Hamme.
The article has sparked a lively debate among scientists. The scientific journal Nature quoted SFU biologist Randall Peterman calling the idea “far-fetched,” while UBC Fisheries Centre expert Carl Walters noted that a massive Fraser River salmon run in 1958 was preceded by a huge volcanic eruption on the Kamchatka Peninsula.
via Volcanic eruption could have boosted sockeye salmon returns – The Green Man.