Pulling out of the sheltered bay you can see the boats clustered off Beechey Head, on the southern tip of Vancouver Island, on Canada's West Coast, where the tides and winds clash to create a roiling sea. It’s a high energy place, and the boats are there for good reason, looking to hit a school of winter springs cruising the edge of the tidal flow.

You glass the horizon before rushing to join the milling fleet of sports boats, and see a disturbance far off to the East. Birds, circling high. Then they start to drop, falling into the sea and emerging moments later, wings flapping wildly. By the time you pull up to the melee, a hundred or so gulls have gathered. They plunge their heads in, fighting against their own buoyancy, or they fly up and dive down, submerging briefly.

When you turn off the motor you realize how loud it is, with all of them calling at once. They have found a herring ball, and are making the most of it.

A quick cast is made along the edge of the ball, where you can see the flash of silver bait fish below the stirring surface. The streamer flutters down through the water, vanishing in the dark - then it stops with a dull thump and the rod bends all the way back into the cork handle.

A seagull with a meal in its beak

The fish runs, making a deep diagonal dive, then rushes up close to the surface, where it swirls, far out. You strain to see it. Then it’s deep again. After a few minutes it’s directly under the boat. You pull, it pulls back, and there is a real question as to who’s in charge here. Finally, a glint of silver, then, after a few short runs it’s in the net. A nice spring salmon of about 12 pounds, with a bulging shape.

When you lay it on the deck, it coughs up herring. Amazingly, one of the fish is still alive. You put it over the side, and it swims off - probably to be eaten by a bird or a salmon, but who knows. Maybe it will live to spawn in March.But chances of that are slim - particularly on the North Pacific Coast, where a massive harvest of herring continues despite widespread protests from sports fishermen and conservationists.

Canada's Department of Fisheries and Oceans will allow seine and gillnet boats to take nearly 24,000 tons of herring along the British Columbia coast this spring. It is a massive harvest, right in the prime rearing area for Pacific salmon.

In addition to the net harvest of herring, the government is allowing other commercial interests to directly harvest herring eggs - which is highly valued on the Asian sushi market.

Traditionally coastal native people harvest herring roe by cutting spruce and fir branches, and laying them out on the tidal flats, weighed down by rocks. When the tide carried the spawning fish in, they would deposit their eggs and the conifer needles. And the natives would have a nice haul for their spring larder.

But the process has been greatly commercialized in recent decades, and now large pens are built and kelp is hung down to entice spawning herring.

Fish conservationists, like David Ellis, head of the Fish For Life Foundation, have long challenged the herring harvest, arguing it has a devastating effect on salmon stocks.

Biologists with Canada's Department of Fisheries and Oceans have found that herring make up 62 per cent of the diet of chinook . Coho are almost as dependent, with about 58 per cent of their diet consisting of the small, silver fishes. Ling cod (71%), halibut (53%) and Pacific cod (42%) also feed heavily on herring.

When the herring vanish, as they have at various locations on the coast, all the way from California to Alaska, finding salmon can be a very difficult business.

All of which explains why sports anglers are increasingly calling for a halt to commercial herring fishing, at least in the Strait of Georgia, an inshore body of water that provides crucial rearing habitat for salmon. Anglers argue that herring are more valuable in the water, feeding the salmon, than they are being killed so their eggs can go to sushi bars in Japan.

The Department of Fisheries, a government agency dedicated to maximizing the ocean's economic yield, argues, however, that herring stocks, in general, are healthy and growing.

Fisheries scientists acknowledge that in some areas, herring have vanished, but say the total biomass has increased. The prevailing view is that in the non-productive areas, fish have simply moved away, probably because of local increases in ocean temperatures. Herring in the Strait of Georgia are regarded as one, great herring ball. The government does not believe there are separate, regional populations.

Many knowledgeable sports anglers, however, feel that herring, like salmon, have developed many distinct, local populations. And they argue that if too many tonnes are netted, irreparable damage will be done.

If the government is right, everything will be OK. If they are wrong, herring balls will become increasingly rare. And so will chinook