The Herring Spawn

Being that it is the first week of March, around the southern BC coast it means that one of the major annual events in the near shore marine ecosystem is taking place – the mass gathering of herring for the purpose of spawning. Not only is this important for the herring themselves but for many other creatures large and small that depend on herring at some stage of these fishes lives, from eggs to adults. And included in this are fishermen of various kinds, who either target the herring directly or who pursue other fish like chinook and coho salmon, lingcod and halibut that depend to some if not a large degree on herring. All in all there’s a lot riding on the success of the annual herring spawn.

Herring are a schooling fish present on the northwest North American coast from southern California right around to western Alaska and are what are known as broadcast spawners. Rather than one-on-one pairings, as with salmon for example, schools of herring gather along a suitable shoreline and when the circumstances are just right males and females simultaneously release both milt and eggs in an act of mass fertilization, with the milt turning the water a milky blue colour. In common with so many other fish species the act of reproduction is triggered by temperature so in the southern part of their range spawning is long finished and at the top end may be a couple of months away yet – I once saw seine boats working a roe herring fishery by Alcatraz in San Francisco Bay in late January.

In British Columbia DFO assesses and manages herring in 5 main populations – Haida G’waii, Prince Rupert/northern mainland, Central Coast, west coast of Vancouver Island (WCVI) and the Strait of Georgia. There are a couple of other more “minor” populations, and all are considered part of one meta-stock, but the five named are what the management of herring is structured around. Perhaps in consideration of all that afflicts the Strait of Georgia – human population, waste disposal, industry, shoreline alteration, boat traffic etc. etc. – it may be surprising to know that the SoG herring stock is easily, and perhaps more importantly, consistently the largest of the five. In fact the current estimate of the SoG herring stock abundance is that it is twice as large as the other four stocks combined. So much for the idea that remoteness somehow equates with more fish!

The separate herring stocks are named in relation to where they spawn but for much of the year may be some distance away. For example after spawning some of the SoG herring stock migrates out onto the continental shelf off WCVI for the summer and not so long ago the majority of this stock did so. In more recent years conditions have been increasingly favorable inside and more of this stock has spent much of the year in the Strait of Georgia, driving increased angler success as chinook keyed on this prime food source for them.

Herring are targeted in BC for two quite separate purposes, the winter food and bait fishery and the spring roe fishery about to get under way now. Properly prepared the female herring roe sacs are considered a delicacy in Japan and, although the market is slowly weakening over time as tastes change there, the market remains strong enough to drive considerable interest in the roe fishery here in BC when opportunities occur.

Of course fishing on any species at their most vulnerable time, whilst spawning, raises many questions, especially so in context of the very important role herring have in the coastal food chain and there are many individuals and interests that have called on DFO to end the roe fishery. As a fisherman myself, participating in a different fishery that likewise some interests don’t think well of, I have learned (I hope) to try and be objective when judging the merits of those fisheries I have no direct involvement with and in this instance I am persuaded that the herring roe fishery in the Strait of Georgia as presently managed is sustainable.

DFO manages the SoG herring stock to a 20% harvest rate cap, which includes both the bait and the roe fisheries. This means that the intent is to leave at least 80% of the fish in the water, which to me sounds precautionary. I realize harvest rates vary between species, and a 20% HR is completely unsustainable for rockfish for example, but with relatively short-lived and fast growing fish like herring I think it defensible. And in some years not all the allowable catch is actually caught – last year the gillnet boats struggled as the spawning herring were unusually spread out around the Strait of Georgia and therefore less available in the large masses that enable a successful gillnet fishery, while several years ago the seine fleet didn’t fish at all because of concerns relating to the size of fish and hence their roe.

Within a high and low range of probabilities DFO is forecasting the SoG herring stock biomass will be about 150,000 tons, with a roe fishery target of about 30,000 tons to be shared almost equally between the gillnet and seine fleets. These fisheries will start any day now, as soon as the buyers are confident the roe is of sufficient maturity to be marketable. The winter food and bait fishery ended in early February with an additional harvest of about 6,000 tons.

One of the positive developments associated with a sustained large abundance in recent years is that herring are beginning to spawn in areas around the Strait of Georgia they haven’t been seen to do so for a long time. In part facilitated by work undertaken by a stream keepers group to make some shoreline areas near Squamish more attractive to mature fish the herring population spawning in upper Howe Sound has increased significantly, in turn driving a revitalization of the food chain there. Elsewhere in the northern strait adjacent to Powell River and around some of the islands nearby localized but strong herring spawns have been observed with increasing frequency.

So if you live along the coast for the next few weeks keep an eye out for the distinctive milky blue coloration in the water that is a sure sign of a recent herring spawn. There will be other clues as well, many birds and sea lions for example, but these events are one of the important occurrences in the BC coastal ecosystem.