Open this photo in gallery The B.C. Ferries vessel Queen of Alberni travels from Nanaimo to Tsawwassen, B.C., at sunrise on Dec. 5, 2017. DARRYL DYCK/for The Globe and Mail

The B.C. government will continue with plans to expand its ferry routes even though the National Energy Board concluded last week that ship noise, including that generated by BC Ferries, is threatening the endangered southern resident killer whales.

The NEB is recommending noise reduction measures for the B.C. government’s ferry fleet to help offset the impact on the endangered whales of increased oil tanker traffic associated with the Trans Mountain pipeline expansion.

But the B.C. government says connecting coastal communities is more important than shipping more Alberta oil through the Salish Sea.

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“Transportation for British Columbian communities is paramount,” B.C. Environment Minister George Heyman said in an interview Monday.

The B.C. government opposes the Trans Mountain pipeline project because of the increase in oil tanker traffic, saying the risk of a catastrophic oil spill is too high – for the whales and the rest of the marine environment.

But the NEB says the province’s ferry service is a significant source of noise pollution that is already threatening the whale population.

The southern resident killer whales (SRKW) are in decline because of starvation, pollution and underwater noise from ships. The NEB, in its reconsideration of the pipeline project, cited research that estimated that the whales lose about five hours of foraging time each day because of marine noise – mostly from passenger ferries, but also from tug boats and whale watching vessels.

The federal government put construction of the pipeline on hold last summer and set up the reconsideration hearing after the courts found that the original pipeline approval process was flawed.

In the report released Friday, the NEB found that marine shipping related to the pipeline expansion is likely to cause significant adverse environmental effects on the 74 remaining members of the SRKW, and on the Indigenous cultural values attached to that whale population. However, it recommended that Canada proceed with the project, with mitigation efforts to offset the impact.

“Ferry routes contribute the greatest inputs into the cumulative noise maps of the Salish Sea, with additional seasonal routes added during the summer when SRKWs use the area for foraging,” the report notes.

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BC Ferries averages 470 trips per day – more than 170,000 sailings each year – connecting coastal communities. On the same day the NEB report was released, the B.C. government announced it is increasing service on 10 ferry routes that were cut in 2014, restoring 2,700 round trips for coastal communities.

Mr. Heyman said BC Ferries is working to lessen its impact on the whales. “We are going to look at everything we can do to minimize the impact on the southern resident killer whales,” he said.

A long-term plan to reduce underwater noise was tabled last summer, but BC Ferries warns that change will be slow. “Each new class of ship we build is generally quieter than the ships before it,” the report says. “This is going to be a long process. We build our ships to operate for decades, more than 50 years in some cases. New, quieter ships will therefore arrive gradually in the Salish Sea.”

The NEB report, however, noted that Washington state, which also operates a large ferry fleet, has already launched strategies to reduce ship noise. But BC Ferries says it cannot retrofit current vessels, saying it is not feasible to change out the propellers that are responsible for 90 per cent of the noise.

The growing whale watching industry is also singled out in the report. According to the Department of Fisheries and Oceans, SRKWs "were observed to be within 400 metres of a vessel most of the time during daylight hours from May through September.”

The Pacific Whale Watch Association did not respond to an interview request. But in its submission to the panel, it rejected some of the measures proposed by Washington state to reduce the impact on whales. Instead, the industry proposed a plan to reduce the acoustic footprint from vessels in the vicinity of SRKWs, and a permit system to cap the industry.