CALGARY - A reconsidered National Energy Board report endorsing the expansion of the Trans Mountain pipeline suggests potential limits on whale-watching boats and noise reduction efforts for ferries that ply British Columbia's Salish Sea.

The shipping route that is a critical habitat for southern resident killer whales would see a seven-fold increase in tankers carrying diluted bitumen to offshore markets if the federal government approves the project.

The board's latest report, released Friday, makes 16 new recommendations for the government, including reducing noise of ferries and incentives and requirements for quiet vessel design.

Robert Steedman, chief environmental officer with the National Energy Board, told a news conference the recommendations are broad and “not necessarily prescriptive.”

The solutions the government will want to examine are complex and all activities on the Salish Sea would have to be considered, he said.

The board has already made 156 recommendations on the controversial project, and Steedman said some of the latest ones relate to underwater noise generated by marine vessels and the possibility ships could strike marine species or disrupt their communication and behaviour.

“The recommendations relate to the entire system of marine navigation and marine traffic in the area and the panel feels strongly that as the recommendations are implemented they will offset the relatively minor effects of the project-related marine traffic and in fact will benefit the entire Salish Sea ecosystem,” he said.

BC Ferries spokeswoman Deborah Marshall said underwater noise has been reduced in the most recently built class of vessels to protect whales.

“As naval architecture gets more refined and we have an understanding of these different issues, our vessels are getting quieter,” she said.

Last summer, the company released a report saying it has reduced underwater noise on its vessels through improvements in hull design and by using alternate propeller styles.

“This is going to be a long process,” the report says. “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 report says replacements for BC Ferries' older C-Class vessels will be built between 2022 and 2030.

“BC Ferries will do all it can to make those the quietest large vessels we have ever built.”

Last week, the company and the Vancouver Fraser Port Authority launched on online tutorial to educate mariners about interactions between ships and whales in B.C. waters to protect the animals. The Whales in Our Waters tutorial is aimed at operators of large vessels including ferries, cargo ships or tug boats, and offers tips to identify and report whales and best practices in navigating around them.