A salmon run is when salmon, after living most of their adult lives in the ocean, migrate back to the freshwater rivers and streams where they hatched to reproduce. This journey often involves traveling significant distances upstream against currents and overcoming obstacles. Salmon runs support a wide range of wildlife and human communities by providing a food source. Understanding the timing of these migrations is important for observing this natural spectacle.
The Annual Salmon Migration
Salmon undertake these migrations as part of their anadromous life cycle. Anadromous fish are born in freshwater, travel to the ocean to mature, and then return to freshwater to spawn. After hatching in gravel beds, juvenile salmon spend months to years in freshwater before transforming into smolts, which are physiologically adapted for saltwater.
Smolts migrate downstream to the ocean, where they spend one to five years growing and maturing. Once mature, they instinctively return to their natal streams, often traveling hundreds or thousands of miles. This upstream journey culminates in spawning, where female salmon deposit eggs in gravel nests called redds, which males then fertilize. Most Pacific salmon species die shortly after spawning, their bodies enriching the ecosystem, while some Atlantic salmon may survive to spawn again.
Species-Specific Run Timings
The timing of salmon runs varies depending on the species and geographic location. Chinook salmon, also known as King salmon, often have runs peaking from July through September, though some populations can begin migrating as early as May. They can be divided into distinct runs (spring, summer, fall, winter) based on when they enter freshwater, with fall-run Chinook being common on the West Coast.
Sockeye salmon runs peak in July. In Alaska, sockeye runs can begin in late May and intensify through June, with the bulk of activity in July and into mid-August. Coho salmon, also called Silver salmon, generally run from July through October, peaking from September to November.
Pink salmon, or Humpies, arrive in late summer, with peak availability in July and August. Chum salmon runs can peak from October through December. In Alaska, summer-run chum salmon peak from mid-July to mid-August, while fall-run chum peak in September or later.
Environmental and Geographic Influences
The timing of salmon runs is not fixed and can be influenced by environmental factors, leading to variability year to year and across different regions. Water temperature is a significant factor, as salmon generally prefer cooler waters for migration. Temperatures exceeding 18°C can affect migration speed, cause delays, and alter salmon distribution, while lethal temperatures are typically in the 21-24°C range. Warmer water temperatures can also increase a fish’s metabolism, depleting energy reserves faster.
River flow rates, often influenced by rainfall and snowmelt, also play a role in triggering and facilitating migration. Heavy rainfall can increase upstream migration rates for adult Chinook salmon. Conversely, low flows can impede upstream movement. The interaction of temperature and flow dictates the optimal conditions for salmon to begin their journey, ensuring they arrive at spawning grounds when conditions are suitable for egg development.
Geographic location creates variations in run timing for the same species. For example, Pink salmon in different parts of the Lower Mainland of British Columbia can show up at different times. This regional variability means that a species might run earlier or later in one river system compared to another, even within the same general area. Localized conditions contribute to the diverse schedules observed across different salmon populations.
Locating Current Salmon Run Schedules
For those seeking up-to-date information on salmon run schedules, several reliable sources are available. State or provincial fisheries departments, such as the Alaska Department of Fish and Game, are primary resources for current conditions and regulations. These agencies often publish detailed run timing charts, emergency orders, and other relevant data.
Local conservation groups and park services frequently provide information on salmon runs within their areas of operation. These organizations may offer insights into viewing opportunities and local conditions. Reputable fishing forums and tourism websites can also offer community-sourced information, though official government sources remain the most accurate. Checking these resources helps in planning to observe the salmon run.