Thursday, April 14, 2011

Why the dolphins are back

Great article in the North Shore Outlook, worth quoting in full:

There’s a change in Howe Sound.

Residents in Lions Bay have spotted them. People in West Vancouver and on Bowen Island are talking about them. Then there’s the boaters who have watched them play out in the waves.

Scientists are trying to figure out why the Pacific white-sided dolphins are back. But there’s speculation it can be partly contributed to a small group of marine enthusiasts and a fish.

This fish story starts in the early spring of 2006. West Vancouver resident John Matsen had been told herring were spotted around the Squamish Terminals. Historically, herring are no stranger to Squamish’s shoreline. In the mid-60s, 2,000 tonnes of the silver-coloured fish came up Howe Sound to spawn. But runoff from the community’s former wood preservative plant killed hundreds of thousands of them and by the 70s the herring had all but disappeared.

So when the co-ordinator of Squamish Streamkeepers got the call that they were back, he was pretty excited. But when they went in search of the herring, what they found instead was a mysterious orange slime covering the pilings under the Squamish Terminals.

“We questioned whether it was fungus,” Matsen says.

Matsen turned to the Internet to find out what the slime was. He found his answer in a report about San Francisco’s subtidal habitat. The document, written by several marine biologists, highlighted the need for the removal of creosote pilings from the bay. In it were notes on how creosote kills herring eggs and how, when the eggs are dead, they turn into an apricot-coloured goo.

That's when Matsen realized that what they'd seen on the pilings were millions of dead herring eggs. The herring had returned, laid their eggs on the pilings but the eggs had been killed by the creosote.

The Streamkeepers set about changing this. The next year, with the permission of Squamish Terminals, the Streamkeepers wrapped 60 of the east dock’s creosote-covered pilings with various materials. In March, when they returned, the organization discovered the eggs on the black landscaping fabric had successfully hatched; the eggs laid on plastic material didn’t boast the same survival rate.

“Each year [since 2006] we have doubled the amount of wrapping we have done,” Matsen says.

Last year, the herring switched their spawning location to the large concrete pilings under the west dock. Concrete has also proven to kill herring eggs. Fortunately, the Streamkeepers had wrapped 30 of these piles the year before. Between February and mid-April, the piles were spawned on four times. This year Matsen expects three spawnings.

What’s even better news is that the herring that spawned in 2007 have returned.

“We had great expectations when we started this, but we didn’t quite expect this would happen so dramatically,” Matsen says.

Other than the herring eggs covering pilings, a big indicator that the Streamkeepers initiative is working are the dolphins.

“We originally had the idea to bring herring back for the salmon,” Matsen says. “We had no idea it would bring back the dolphins.”

During much of the 20th century, Pacific white-sided dolphins were thought to be an open-water species, says Andrew Trites, UBC’s director of the Marine Mammal Research Unit in the university’s Fisheries Centre. Before 1984, they had not been reported in the Strait of Georgia, but were common along the outer coast. However, scientists did know that they once called the inner waters their home since archaeologists had discovered Pacific white-sided dolphin bones in First Nation middens – domestic waste dumps – along the strait.

In recent years, there have been a growing number of dolphin sightings. This year three pods were reported in the strait. Whether they are all members of the original pod or different groups that have ventured in from the Pacific is unknown, Trites says. There is some speculation that the main group of approximately 100 dolphins is a residential pod based around Nanaimo, but scientists don’t know for sure. Nor do they know why they returned or what they are eating. Herring would be a good guess, Trites says.

“We have more questions than answers,” he says. “They haven’t had a lot of people studying them.”

Erin Rechsteiner is one of the few people in B.C. trying to find answers. It’s speculated that the Pacific white-sided dolphin population along B.C.’s coast sits at 24,000, but without enough information it is difficult to back that figure, she says, adding that estimates range from 12,000 to 50,000. What is known is that the survival rates among the young are low, Rechsteiner notes.

Last summer and early this year, the UBC student started a report on the diet, distribution and food requirement of the Pacific white-sided dolphins. By looking at the mammal’s dinner plate and how many calories it needs to function, Rechsteiner hopes to find clues to their lifestyles and possibly figure out if the dolphins are following specific prey types along the coast.

Dolphins need four to five times more calories per day than humans, Rechsteiner says. Herring are high in calories and lipids, such as Omega-3 fatty acids. Before they spawn, the fish’s fat count is at its highest, Rechsteiner says.

“I am learning a lot about fish,” she jokes.

For five weeks last summer, Rechsteiner spent 12 hours a day trawling the sea on the hunt for feeding dolphins. When spotted, she would drag nets behind the boat which would pick up the scraps from the dolphins' meal, allowing her to figure out their menu. Rechsteiner is the first person to ever collect fish scale samples from dolphins feeding in the Strait of Georgia. It is the same technique adopted by zoologist Kathy Heise, who studied Pacific white-sided dolphins for years after they caught her attention in 1986 while working as a lighthouse keeper.

Some of Rechsteiner’s most successful sightings occurred after her pilot field work project. On Jan. 28, around the same time that the herring were spawning in Squamish, Rechsteiner was out on a boat in Howe Sound surrounded by more than 150 dolphins. While no one can say for sure that the dolphins are back because of the growth in herring runs, it’s certainly a good guess.

“The dolphins are a good indicator of ecologic health,” she says. “My guess is if there are a lot of dolphin around there is a lot of herring around.”

By learning more about the dolphins we could learn more about the health of our local environment, but without funding Rechsteiner is not sure if she will be able to continue her field work. She is currently on the hunt for grants.

“There is just so little known about them,” Rechsteiner says of her flippered friends.

As for the group behind the possible the surge of life in local waters, Matsen is now one of the world experts in herring spawning material, he jokes. Jokes aside, the Streamkeepers' work has caught the attention of the Department of Fisheries, among other organizations. A group of residents in Lions Bay is also interested in wrapping creosote pilings and Matsen has been in discussions with the Rotary Club in Pender Harbour. The creosote piles are a problem, but a problem that can be fixed, Matsen says.

“The best part of this fish tale is now we know the dynamics in the ocean are there,” Matsen says. “We are just help nature do its job.”

Reporting Dolphins

You can help Rechsteiner and other scientist in their studies on all cetaceans (whales, dolphins and porpoises). The B.C. Cetacean Sightings Network, a conservation and research program of the Vancouver Aquarium, in partnership with Fisheries and Oceans Canada (DFO) have set up a Wild Whales website where anyone can report a sighting. The organization collects reports on all cetaceans (whales, dolphins and porpoises) and sea turtles from British Columbia and surrounding waters. Visit the site at www.wildwhales.org or call 1-866-I-SAW-ONE.