Spawning season has begun for Pacific herring (A group of pallas) in the waters of British Columbia, Canada. From mid-February to early May each year, thousands of small silver fish congregate in the shallows off the coast of Vancouver Island and create a spectacle that can sometimes be seen by satellites.
The sheltered waters of Barkley Sound, on the southwest side of Vancouver Island, are popular natural habitats. On February 19, 2026, the Landsat 9 satellite received the first glimpses of an ongoing period off the coast near Forbes Island. In these cases, the female herring produces eggs that stick to a variety of things, from kelp and sea grass to rocks. Males secrete a fluid containing sperm into the water called milt, which gives it a cloudy green or turquoise appearance.
Spawns near Forbes Island have been observed for many years since the 1970s, according to Fisheries and Oceans Canada (DFO) reports. Jessica Moffatt, a biologist at the Island Marine Aquatic Working Group (IMAWG), which works to strengthen First Nations fisheries through traditional knowledge, modern science and management guidance, Jessica Moffatt said: “Barkley Sound hits the sweet spot” on many of these factors, she said, adding that collective memory, initial pressure, and other factors also play a role in the size of nature and space.
Spawning events last from a few hours to several days. On Forbes Island in 2026, local observers saw fish in the area on February 13 (schools can arrive two weeks before spawning, Moffatt noted), and activity was reported to IMAWG from February 19 to February 21.
Along with changes in water color, spawns often come with an increase in wildlife, which can include whales and sea lions swimming alongside eagles, wolves and bears lurking on the shore. After spawning, the fish will return to summer feeding grounds in deep, nutrient-rich waters, sometimes sticking to their large school for several years.
Reports of spawning activity have been constrained by the timing of aerial and submersible surveys, the availability of records from distant locations, and fishing priorities. But satellite observations, including Landsat, can help monitor herring activity over large areas and over long periods of time. Researchers at the University of Victoria in Canada have used satellite observations for decades to augment natural history records and develop methods to facilitate future analyses.
Herring and their roe are important both as a traditional food source and harvesting practice by First Nations and for fisheries in British Columbia. As a forage species, the Pacific herring is important to salmon and other marine life, and a complete picture of the spawning grounds can provide information about changes in the marine environment.
NASA Earth Observatory images by Lauren Dauphin, using Landsat data from the US Geological Survey. Photos by Ryan Cutler. Story by Lindsey Doermann.
- California Marine Species Portal (2024) Pacific Herring Enhanced Status Report. Accessed March 26, 2026.
- CBC (2026, February 25) Early signs of herring spawn spark excitement on Vancouver Island. Accessed March 26, 2026.
- Fisheries and Oceans Canada (2026, January 20) Pacific herring fishes. Accessed March 26, 2026.
- Ha-Shilth-Sa (2024, November 29) There will be no commercial fishing in 2025, although there is an increase in the herring population, says Ha’wiih – but spawn-on-kelp is being investigated. Accessed March 26, 2026.
- IMAWG (2026) Island Marine Aquatic Working Group. Accessed March 26, 2026.
- Island Marine Aquatic Working Group, via Facebook (2026) Pacific Herring Spawn Reporting – IMAWG. Accessed March 26, 2026.
- NASA Earth Observatory (2025, May 5) Spawning Spectacle. Accessed March 26, 2026.
- Spectral and Remote Sensing Laboratory, University of Victoria, Herring Spawn Habitat: Spatiotemporal analysis of ancient spawning habitats by satellite sensing. Accessed March 26, 2026.
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