Archeological records showing widespread and consistent Pacific herring abundance on B.C’s coast suggest fisheries officials are massively overestimating the current health of the fishery and misinterpreting spawning patterns, according to a Simon Fraser University study released Monday.

Dwindling and inconsistent spawning returns characterized in Fisheries and Oceans Canada (DFO) analysis are in stark contrast to the picture of herring abundance and consistency over the past 2,500 years, shown in nearly half a million fish bone samples collected from 171 First Nations archeological sites ranging from Washington State to Alaska.

The authors, Iain McKechnie, Dana Lepofsky and Ken Lertzman, argue the data should be used in fisheries management to set a new “ecological baseline” for herring populations.

The data used for science-based fisheries management dates back only 60 to 80 years, decades after the large-scale harvest of herring was underway.

“The baseline (data) that is used to assess biomass of herring and the allotment to the commercial fishery only begins in 1951,” said McKechnie. “The data doesn’t go back far enough, and it conveniently limits the goal of recovery as well.”

Accurately assessing the impacts of climate change, overfishing and predators on herring is only possible with information on the abundance and distribution of herring before its depletion, the study says.

Herring is an important food source for Pacific salmon and sea mammals, and is the first or second most common fish found in 80 per cent of First Nations archeological sites in the study.

Although the archeological record cannot say with accuracy what happened in an individual year, “wherever we look within a site and across sites, they always seem to have an abundance of herring,” said McKechnie.

The researchers identified 34 B.C. locations that show evidence of thousands of years of herring processing by First Nations people, places that are now so bereft of herring that the DFO doesn’t even monitor them for spawning.

The researchers used the DFO’s own data to determine where herring have been spawning since the late 1920s and compared that to the archeological record, which spans 10,700 years up to the 1860s, just before to the beginning of the industrial fishery.

“Where we see lots of herring today, we see lots of herring in the past, but also we show that there are places that have a lot of herring archeologically, where little herring is recorded today,” said McKechnie. “We used to have a much broader spawning population.”

The archeological data suggest that herring returned to spawn in the same locations very consistently over millennia. DFO data collected beginning in 1928 — about 50 years after the start of the industrial herring fishery — reveal a different pattern.

A 2013 DFO review of herring spawning areas in B.C. notes that roughly 19 per cent of the coastline has been used for spawning in the past 75 years, most of it sporadically. Only one to two per cent is used repetitively over a number of years.

The existence of so-called “resident” herring stocks that consistently return to spawn in a specific location has long been a source of conflict over herring fishery management between First Nations and the DFO, which asserts that genetic and tagging studies do not provide evidence of such populations.

The west coast herring fishery was closed for four years between 1968 and 1971 after a complete collapse of the population. DFO documents note that even after numbers rebounded, “some previously-favoured spawning locations were no longer utilized on a regular basis.”