An analysis by NOAA Fisheries is showing so far that West Coast fisheries have been taking a small proportion of available chinook salmon favored by endangered Southern Resident killer whales.
The analysis comes in the form of a risk assessment evaluating the impacts of fishing on Southern Resident killer whales. It found that Southern Resident numbers have declined over the last two decades.
This has occurred even as chinook salmon abundance has varied and fishing harvest has decreased coastwide, said the assessment.
While salmon fisheries have usually been managed river-by-river, the risk assessment looked at them differently. It examined salmon abundance by geographic areas that at any given time include migrating fish from many stocks.
“This provides the most complete picture to date of the prey available to the whales in the areas where they forage,” said NOAA Fisheries on the West Coast region website.
“For example, in 2016, the last year with data available, ocean salmon fisheries off the West Coast caught an estimated six percent of the 2.8 million adult Chinook salmon in offshore waters. Off the Washington Coast, the science indicates prey abundance is consistently more important to the Southern Residents when migrating in the (Pacific Fishery Management) Council management area. There, fishing removed just 2.5 percent of the 1.4 million available Chinook salmon.
“This level of impact from coastal fishing off Washington on the Chinook salmon population overall is small compared to the natural year-to-year variations in salmon abundance. The continuing loss of vital nearshore habitat where young salmon feed and grow before they head to the ocean also limits fish numbers and recovery.”
Abundance of Chinook salmon ages three to five north of Cape Falcon, Oregon, which encompasses the Washington Coast. Orange indicates the total abundance of adult Chinook salmon and blue indicates the amount removed by ocean salmon fisheries off the West Coast.
Graphic: Ad Hoc Southern Resident killer Work Group/PFMC
The agency also noted that fishermen “in Canada often catch more Puget Sound salmon than local fishermen do. Alaskan salmon fisheries catch very few fish from Puget Sound. However, they often catch many fish from the Columbia River before they turn south to areas where they would be available to the whales.”
Killer whales, also known as “Orcas,” are probably one of the most well known of the cetaceans.
The killer whale belongs to the Delphinidae family (making it the largest dolphin), but due to its size over 30 ft. it is also considered a whale. The killer whales are found in all oceans. These whales can adapt to almost any conditions, and appear to be at home in both open seas and coastal waters.
Orcas are toothed whales, related to sperm and pilot whales, and are apex predators vulnerable only to large sharks. They have the most varied diet of all cetaceans, and can tackle prey of all shapes and sizes. They often use a coordinated hunting strategy, working as a team like a pack of wolves.
There are three ecotypes of killer whales on the West Coast of North America: Resident Killer Whales (Northern and Resident killer whales; salmon eaters); Transient Killer Whales or also known as Bigg’s killer whales (feed on marine mammals like seals, sea lions, whales, dolphins, and porpoise); and Offshore Killer Whales (feed on fish, squid, and maybe sharks).
New provisions of the Pacific Salmon Treaty renegotiated in 2019 between the United States and Canada have cut back catches of chinook salmon throughout their migration from the Northwest to Alaska, which are expected to increase prey available to the Southern Resident whales. The new agreement also invests millions of dollars in additional chinook hatchery production and habitat restoration to support salmon and Southern Resident recovery.
NOAA Fisheries West Coast Region works with the PFMC to set salmon fishing seasons. It also set harvest levels at sustainable levels consistent with the Magnuson-Stevens Act. Annual catch limits are set to achieve science-based conservation objectives that constrain fishing when abundance is low and to support recovery of the runs protected by the Endangered Species Act that co-mingle in the ocean with the abundant runs.
The Council begins the public process of setting salmon fishing seasons along the West Coast in March. Harvest levels depend on fish returns, which vary widely from year to year. The first step is to consider the scientific forecast for salmon returns to rivers along the West Coast.
Annually the Council’s abundance analysis estimates returns for each river, down to the specific stretch of river or tributary. The outlook for 2020 varies widely, with returns likely to be stronger in California but weak in the Pacific Northwest.
Many West Coast chinook salmon stocks migrate far into the Pacific before returning to West Coast rivers as adults. Several of those returning stocks, such as those from the Columbia River system, overlap with the range of Southern Resident killer whales, says NOAA Fisheries.
Each year NOAA Fisheries’ West Coast Region sends the Council a guidance letter. It summarizes key parameters for designing the upcoming salmon season consistent with the Endangered Species Act and Magnuson-Stevens Act and other recommendations and concerns about individual salmon stocks.
The agency included guidance about taking into account the chinook salmon prey needs of Southern Resident killer whales as well. And this year, for example, forecasts predict very low returns of Klamath River fall-run chinook salmon. Therefore, NOAA Fisheries urged a cautious approach in setting fishing rules for the stock. That is likely to limit fishing between Point Falcon on the northern Oregon Coast and Point Sur, California, to reduce impacts on the Klamath fish even if other stocks might be more plentiful.
Regarding the prey needs for the endangered Southern Residents, Regional Administrator Barry Thom noted in the letter:
“We are particularly concerned about years with critically low Chinook salmon abundance throughout the whales’ geographic range because of the potential effects to the whales’ energetics, health, reproduction, and survival.”
He advised that if chinook salmon numbers fall below the average of the seven lowest abundance years, then the Council should adopt additional precautionary measures. These could include reduced quotas or limits on salmon fishing time and areas. The guidance letter is specific to managing the 2020 fisheries. However, the workgroup and Council are continuing their efforts to incorporate the whales into a long-term fishery management strategy.
The Council will select one of the alternatives at their April meeting that runs April 4-10. They will recommend the alternative to NOAA Fisheries for approval and implementation into regulation. The new fishing year will start in early May.