Oregon Sea Grant

3/30/23

By Steve Lundeberg, OSU news writer

CORVALLIS, Ore. – Larvae produced by black rockfish, a linchpin of the West Coast commercial fishing industry for the past eight decades, fared better than expected during two years of unusually high ocean temperatures, according to research partly funded by Oregon Sea Grant.

“We found that despite fears of doom and gloom with recent anomalous warming of the waters off Oregon’s coast, some young black rockfish grew faster as the temperature increased and, surprisingly, there was both high and low survival during different years of the heat wave,” said Will Fennie, the study’s lead author and a former Malouf scholar who was funded by Oregon Sea Grant.

Survival was highest in years characterized by moderate larval growth rates, reduced predation and sufficient food to support growth, he added. When growth was highest, however, rockfish survival was very low, likely due to lack of food to sustain that high growth.

The research, which was published in Nature’s Scientific Reports, involved dissecting the juveniles' otoliths, or ear bones, to estimate age and growth rate. The fish were collected in nearshore waters from 2013 to 2019, a time frame that included a marine heat wave between 2014 and 2016.

“The study is important for gauging the conditions and making management plans that will affect the species’ survival as the ocean experiences increasing variability because of climate change,” Fennie said.

Rockfish, a diverse genus with many species, are ecologically and economically important fishes found from Baja California to British Columbia. They are known for lifespans that can reach triple digits, an ability to produce prodigious numbers of offspring, and variable survival during their early life stages, during which they are highly sensitive to environmental conditions.

“Oceanographic conditions dictate water temperature, which influences larval dispersal and food availability. These affect the early growth and survival of fish larvae,” Fennie said. “Larval survival and performance then can influence later life stages. For example, rapid larval growth contributes to increased juvenile survival following settlement to rocky reefs.”

Fennie, a former OSU doctoral student who is now at the National Oceanic and Atmospheric Administration, worked with OSU College of Science researchers Su Sponaugle and Kirsten Grorud-Colvert on the study.

In addition to the support from the Malouf scholarship, the study was funded by the National Science Foundation, the Ocean Science Innovation Fund at OSU, and scholarships administered by the Hatfield Marine Science Center.