A BRIEF ACCOUNT OF THE SHORT LIFE CYCLE OF THE PACIFIC HERRING
A small, silver-coloured fish, Pacific herring are the most abundant fish species in Canada's Pacific coastal waters. These fish are plankton feeders and near the bottom of the food chain. Past records reveal that the once massive and numerous herring spawns were on of nature's most exciting spectacles on the B.C. coast. At one time 50,000 to 100,000 seabirds and thousand of sea and land mammals congregated to feast on the roe (eggs). Large schools of predatory fish, such as chinook salmon, dogfish, rockfish and sole, also once moved in to feast. Many kilometers of the B.C. coastline once turned milky-white every spring as a result of the male herring's release of countless billions of sperm around the roe deposited by the females on coastal seaweeds.
The great spawns formerly extended from February to April, but "serial overfishing" (see glossary page 3) in recent decades has reduced the early and late spawners to remnant levels. This has had devastating effects on chinook and coho salmon, Pacific cod, lingcod, and dozens of bird and mammals species.
Pacific herring generally begin spawning at age three. Survival and abundance of a herring "year-class" (herring born in the same year) vary considerably from year to year due to the effects of storms, which can dislodge many of the eggs from the seaweeds on which they were deposited, allowing the waves to wash them ashore where they die and rot.
The larval stage lasts from when herring eggs hatch (12 to 20 days after spawning) to the time when they can be recognized as small herring, in 6 to 10 weeks. The larvae float near the surface and are carried about by ocean currents and winds. The weather and winds are key to the successful survival and dispersal of the vulnerable larvae. Survival varies year to year 100 fold.
For example, if favourable winds do not disperse the larvae from the Hornby Island area (where the major herring spawn is now concentrated) to settle and grow on the east side of Georgia Strait, rockfish, sole and other fish species will not have the necessary food supply in that area, and will move away or not reproduce efficiently. All of the herring spawning areas on the east side of Strait have been reduced to remnant levels by "serial overfishing".
At the juvenile stage the young herring appear in large schools near shore. But after the first summer of life the small herring become "young of the year' herring, and most disappear offshore. Most only reappear near shore at age three, their first year of spawning. Herring can return to spawn for four years or more, but this rarely occurs today and few of these larger fish are encountered anywhere on the coast due to the massive roe herring quotas set by the Federal Department of Fisheries and Oceans (DFO).
It takes three years (to the first year of spawning) for a successful year-class spawn to produce an increase in the "spawning biomass". However, in areas such as the Strait of Georgia, massive industrial overfishing in recent years has removed almost all of the large herring over three years old. In 1998 this meant that the gillnet fishers worked for days as thousands of smaller fish went through their nets, some of them over and over again many suffering scale damage.
Formerly, large predatory fish such as lingcod and chinook salmon depended heavily on large (five and six year old) herring as an efficient, high yield source of food. But in recent years large lingcod and chinook salmon have not been able to find sufficiently large herring in Georgia Strait, and today are rarely found in the Strait. This has contributed, along with overfishing to the total collapse of the formerly large commercial and sport fisheries for chinook and lingcod in the Strait.
However, herring stocks can recover! Herring fishery closures of four years and more elsewhere in the world, such as were imposed in Norway, clearly show that the herring stocks can rebuild in a remarkably short time.
