After a week in Bella Bella, we headed down South to the Hakai Beach Institute (HBI) on Calvert Island for the next two weeks of “Herring Season”. Brian Hunt (UBC Oceanography) and I (SFU Hakai Network) were helping to help set-up a long-term monitoring program for herring in the region around Calvert Island (HBI). This program would be based off of the work and knowledge we’d gained throughout the past couple of years of Hakai Network herring research on the Central Coast. HBI’s marine monitoring program is interested in documenting and quantifying long-term patterns in forage fish ecology. Herring, being a quintessentially important coastal fish in B.C., is a natural species to feature as this program develops. We planned to document, in detail, the areas where herring spawn in the region around Calvert Island (home to HBI), and gather information on the early life history of these fish, after they hatch out.
HBI personnel had been sending us e-mails in advance of our arrival, noting a lot of marine mammal activity in the region, including humpback whales, sea lions and scoters – signs that herring were gathering in the region. DFO had already reported a spawn event in Kwakume Inlet, but we had no reason to believe that the herring were planning a surprise for us. It turned out, however, that they had sent a welcome wagon to the head of Pruth Bay for our arrival on the last day of March.
That night, we heard splashing to the south of the HBI dock. I crept closer, over the slippery boulders exposed at low tide to look for sign of spawning herring. I found some eggs, stuck to the rockweed (Fucus) growing in the high intertidal zone, but it was pretty sparse. But as I stood there, quietly gazing for more signs of fish in the water, it became suddenly dark with a stampede of fish. Now I know why the analogy of herring as equivalent to Wildebeest in the Serengetti is actually a good one! Once the procession started, it didn’t stop, and from my very close vantage point I could seem them all, moving as a group under water, occasionally flashing their silver sides.
During my other sightings of herring in the nearshore, the water has been too opaque with milt to see them, and witness their behavior. But in the quiet of dusk, we could see a huge ball, growing and swirling around the mouth of Pruth Bay. The rest of the team, perched on high from the HBI dock did some preliminary sampling with a hook and line. They were indeed herring; come to welcome us to the head of Kwakshua Channel. I stuck my camera in the water, which doesn’t do the scene justice, but just to give you a sense, I’m posting it below:
There’s a lot left to learn about spawning herring: what lures them to a given location to spawn, which substrates they prefer to deposit their eggs on; what the ultimate trigger is to start a spawning event; how their spawning behavior is affected by age and size. Science has some answers to these questions, but there remains a lot more to explore, and we hope that a monitoring program will contribute to this.
The next morning we realized that the herring were still hanging out locally, in fact, they had started to spawn right underneath the HBI dock, on a beautiful patch of eelgrass. From our vantage point, it really looked like the herring were enjoying the eelgrass, rubbing up against every shoot they could find.
We were planning to do the first big herring oceanographic survey that day (April 1st), but as we pulled away we noticed that there was evidence of spawn, and bird life everywhere. We abandoned our original plans, and decided to do a detailed survey of the spawn length instead. By length, I mean the total amount of shoreline where herring had spawned (a measure also recorded by DFO). The usual throngs of eagles were aggregating along the shoreline, pouncing on incoming herring. We were pretty excited about all this activity as its been awhile since there was a big spawn in Kwakshua Channel – DFO has only recorded 4 spawning events here throughout the 2000’s. You can check out the DFO records here: http://www.pac.dfo-mpo.gc.ca/science/species-especes/pelagic-pelagique/herring-hareng/herspawn/085fig-eng.htm
Back in the ‘70s and 80s, and even throughout most of the 90s, there was almost always an annual spawning event in Kwakshua Channel, albeit its size (measured by its length and width; the distance to which herring roe extends along the coast and out from shore) varied between years.
Pruth Bay, Keith’s Anchorage and Kwakshua Channel – evidence of spawn says Grant Callegari