The Sacramento River Salmon Harvest: More Bad News
By Tom Cannon
The harvest of Sacramento River fall-run salmon – the largest of California's dwindling salmon runs – is managed by both state and federal agencies and is based on past-to-present figures of long-term adult escapement (i.e., fish that aren't caught and survive to spawn) (Figure 1).
The harvest is coordinated under the federal Pacific Fishery Management Council because many of the ocean fisheries take mixed stocks from both the US states and Canadian provinces. The "fishable" Sacramento River fall-run population is defined as the total number of adults returning to Sacramento River hatcheries and natural spawning areas. This metric is reasonable, given many hatchery salmon spawn in natural areas. Because natural-born salmon are often the offspring of hatchery salmon, there is neither the need nor the ability to separate “wild” from hatchery fish.
Figure 1
The PFMC has declared an adult Sacramento River salmon escapement of 122,000-180,000 as a target goal, a figure that theoretically provides a sustained yield for the fishery. However, because escapement estimates are not available until the end of the fishery harvest, total escapement usually has fallen below the maintenance goal – especially during drought years or after multiyear droughts.
In some years, sanctioned harvests have led to over-fishing (e.g., 2007, Figure 2) This is because the harvest control rules the PFMC employ often are based on inaccurate estimates of the size of the harvestable stocks and the relative effectiveness of the fisheries – how good they are at catching salmon (very good, it turns out). The harvest model errors and biases that have led to over-fishing are not new problems. Excessive harvests led to fishery closures in 2008 and 2009.
The Pacific Fisheries Management Council and its constituent states and provinces are now developing harvest control rules for the 2023 fisheries. For the Sacramento River fall-run population, the preliminary estimate of the 2023 harvestable stock is approximately 180,000 fish; accordingly, the PFMC is anticipating a sanctioned harvest, and is now preparing harvest control rules.
But it would be a grave mistake to authorize a 2023 Sacramento River fall-run harvest. Why? There are multiple reasons.
First, the 2019 to 2022 population trend was decidedly downward (Figure 1). The salmon stock was overharvested in 2021 and 2022; also, 2021 was a critical drought year with poor survival of the 2020 brood year fish. Due to drought conditions, 2020 brood year salmon experienced poor spawning, incubating, rearing, and emigration conditions. As a result, the fishable brood year 2020 stock now in the ocean is likely small, and their return to their natal rivers will probably be minimal. Indeed, the return numbers for the 2020 brood year fish could be even lower than those for 2009, 2017, or 2022 – all abysmal years for returning salmon.
The bottom line: any hopes of recovering a wild or natural-born salmon population in the Sacramento River and its tributaries will be dashed if a fishery is allowed this year; there will be too few remaining fish to sustain any meaningful restoration effort. Indeed, there is the very real danger that a 2023 fishing season could prove an extinction event for wild and natural-born Sacramento River Chinook salmon. If we err, we must err on the side of caution.
Figure 2. Note harvest in 2007 and 2015-2017 resulted in not meeting escapement goal of 122,000 adult salmon.
Figure 3. Note a fishery occurred in 2022. Note 60,000 escapement for 2022 was only a third of the target goal of 180,000.
Tom Cannon is an estuarine fisheries ecologist and biostatistician who has researched Delta fishery issues for more than 35 years. Mr. Cannon has worked or consulted for the California Department of Fish and Wildlife, the U.S. Bureau of Reclamation, the National Marine Fisheries Service, the CalFed Bay-Delta Program, the State Water Resources Control Board, PG&E, the California Striped Bass Association, the Fisheries Foundation, and the California Sportfishing Protection Alliance.