Scientists push for joint effort to better understand Pacific salmon trends

Forecasting models used to determine stocks and expected landings of Pacific salmon have been rendered obsolete by climate change, and a global effort is needed to update them, a conference of leading marine scientists has concluded.

The conference, "Abundance Dynamics, Stock Status, and Artificial Reproduction of Pacific Salmon in the Northern Pacific," took place in late February and was initiated by the Russian Federal Agency for Fisheries. Held in both online and offline formats at the Sakhalin branch of the Russian Research Institute of Fisheries and Oceanography (VNIRO), in the Russian city of Yuzhno-Sakhalinsk, the event was attended by 500 participants from Russia, the United States, Canada, South Korea, and Japan. 

The Russian Federal Agency for Fisheries deemed the conference a necessity after the country's 2020 salmon season brought unexpected and disappointing results. Scientists had forecast a catch of 384,000 metric tons (MT) of salmon, but only 300,000 MT were caught. That large difference between the forecast and the catch led to an understanding that new factors had come into play to make previous scientific models obsolete. 

The event sought to pinpoint the new factors affecting salmon life-cycles and achieve a better understanding of why older models have begun to fail, according to VNIRO Director Kirill Kolonchin. In a recorded speech opening the conference, Kolonchin also called for the study and creation of new, more accurate forecasting models.

The maximum average yearly salmon catch across the Northern Pacific of 1.138 million MT was seen in the period spanning 1995 to 2019. The record volume caught by a single country was in 2018, when Russia harvested nearly 680,000 MT – accounting for 63 percent of the world’s harvest. 

Russia’s 2020 salmon haul was above the average from the last depressive period of catches that spanned from 1959 to 1973, when the global annualized output was just 407,000 MT – declining to 331,000 MT in its lowest year. But, Russian Federal Agency for Fisheries Head Ilya Shestakov acknowledged last year could mark the beginning of a negative trend.

“Timely discovery of the trend gives us a chance to prevent it from developing, or, ideally, drastically change the course,” Shestakov said. Shestakov declared salmon will be the main focus of Russian fishery science near-term. “We have declared 2021 the year of salmon in Russia. We have designed a target program for salmon-related research and increased funding for it despite the overall decrease in financing the fishery science in Russia.”  

At the conference, scientists discussed the various factors affecting salmon stocks in the Northern Pacific. Richard Beamish, an emeritus scientist with Canada's Department of Fisheries and Oceans’ Pacific Biological Station in Nanaimo, British Columbia, talked about the relation of survival of salmon with their accelerated growth during their marine period of life. VNIRO Anadromous Fish Department Head Sergey Marchenko said that climate change was a major factor impacting the stocks. Warming waters have resulted in the widening of habitats, allowing fish to move further north, restructuring the stocks.

“In all areas of capture where several kinds of salmon are fished, there is a decline in humpback salmon, with increases in chum and sockeye,” Marchenko said.

Scientists in attendance at the conference agreed to continue their monitoring and research of Pacific salmons stocks. They also agreed to hold another conference in 2022 with a focus on the social and economic aspects of fishing in the Northern Pacific.

Meanwhile, scientists of the Kamchatka branch of VNIRO released research that noted a decline in catches of chum and sockeye in years to come. Olga Zikunova, head of the salmon lab, conducted a retrospective analysis of past forecasts and real catch over the past 10 years. Trends show that a decline in catches of the two species will be accompanied by a decrease in both the lengths and mass of fish. But this negative trend will not apply to humpback salmon. 

That decrease could be an issue for Russia, as Kamchatka is the region where the vast majority of the country’s salmon is caught.   

Photo courtesy of the Russian Federal Research Institute of Fisheries