Deaths of southern resident killer whales raise fears for population
Credit to Author: Matt Robinson| Date: Thu, 08 Aug 2019 00:32:02 +0000
The recently declared deaths of three highly endangered southern resident killer whales have brought the population down to 73, a number not seen since the mid-1970s, and have raised the spectre the population could be reaching a genetic bottleneck, experts say.
The dead killer whales are a 42-two-year-old matriarch known as J17, a 28-year-old male called K25, and a 29-year-old male called L84, according to the Washington State-based Center for Whale Research.
Marty Haulena, the head veterinarian at the Vancouver Aquarium Marine Science Centre, called the deaths “really bad.”
“You want to see those numbers heading the opposite direction, so every time we lose one of these animals it really brings us closer to losing the whole population.”
Haulena said some deaths are expected, like among calves, whose mortality rates are relatively high, and among older adults.
“But what’s scary is we’re losing animals kind of in the middle of that population curve. Included in the last three whales that we’ve lost are two males that are pretty much prime aged males. That’s really concerning,” he said.
Among the measures being introduced to protect the endangered killer whales is a mandated 200-metre buffer zone for commercial whale watchers.
J17 is survived by two daughters and a son, K25 is survived by two sisters and a brother, while L84 was the last of a matriline of 11 whales, 10 of whom had died. J17 was the mother of Tahlequah, also known as J35, which carried her dead calf for an unprecedented 17 days last year.
Southern resident killer whales are fish specialists that are not finding enough chinook salmon, and they face threats from toxic pollution and noise and disturbances from boats.
Peter Ross, the vice-president of research at Ocean Wise, said that in the early 1970s, when southern resident killer whales were targeted by aquariums that took them for collections, the population was thought to be as large as 1,500. But when a photo identification method was devised to help determine the population’s true number, it was found to be fewer than 75 whales — “a shocker” at the time, Ross said. The population slowly recovered to a high in the late 1990s of nearly 100 whales.
“If we look at this number today, we haven’t seen this few whales since the mid-1970s,” Ross said.
Lauren McWhinnie, a Marine Environmental Observation Prediction and Response research fellow with the University of Victoria, said the overall population figure does not capture the fact that the number of remaining breeding females — and their potential to produce calves — is significantly less now than it was decades ago.
“Even if all of a sudden things start getting good for them — they start getting fish, they start getting a better, cleaner environment — are we at the stage where genetically they can still come back as a healthy population? That’s another question mark,” McWhinnie said.
“We are nearing that point where I suspect that genetically it’s not going to become a viable population if we lose so many crucial individuals.”
Southern resident killer whale J17 (top) is pictured when she was believed to be pregnant in 2015.
McWhinnie said “it’s not a case of there’s no hope,” but we need to see more reproduction within the population, and the survival of their calves. “That requires us to have fat, healthy whales.”
Ross said everyone in the region who live in the watershed that surrounds the whales’ critical habitat can make choices that reduce the impact on them. That’s millions of people who decide what to flush down their toilets, when to drive and how to wash their cars, whether to apply fertilizers and pesticides, and how to use boats, among other things.
Haulena said people can also be careful about what seafoods they choose to eat, and can use the Ocean Wise seafood program as a guide.
Haulena said he’s hopeful that some of the measures put into place recently by the federal government can help turn things around for the animals.
The Department of Fisheries and Oceans announced a number of rules to protect whales off British Columbia’s coast, including requiring ships to stay 400 metres away from the animals, closing a few salmon fisheries, and implementing initiatives to support habitat protection and restoration of chinook salmon.
The Center for Whale Research said the whales now rarely visit the core waters of its designated critical habitat including Puget Sound, Georgia Strait, and the inland reach of the Strait of Juan de Fuca “due to the scarcity of suitable Chinook salmon prey.”
With files from Canadian Press and Scott Brown
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