Thursday, 17 April 2014
ORCAS and DOLPHINS
Last week from the ferry from Campbell River to Quadra , which is just ten minutes, I saw two orcas (killer whales) . They were a little too far to get a good photo. But later I remembered this photo which looks like possibly one of the same animals. The whale experts can really do this and accurately identify individuals by their fin shape and the unique pattern of the white patch on their "saddle", which are documented in a catalogue of photos.
We see orcas all year round now. But this wasn't always the case. In summer, salmon eating orcas are quite dependable to set up camp in the funnel shape of Johnstone Straits and feed on the mature southbound migrating salmon. But there are two types of orcas around here, and the second type eats primarily mammals. They just turn up unpredictably as they hunt for smart prey like seals and porpoises and dolphins. For a couple of decades the seal population in Georgia Strait ( the Salish Sea ) was growing madly. Then several years ago some orcas discovered , or rediscovered , this bounty.
There is something good happening right through the food chain in these inside waters on the sheltered side of Vancouver Island. I described good prospects for salmon in a previous post titled Bright Future.
Pacific White Sided dolphins are also quite common to see now, whereas they were not here regularly prior to the mid 1990s. Over recent years we have been seeing them more often and in larger groups. These energetic showoffs are probably eating mostly herring. Herring spawn in massive collectives in a strategy to overwhelm predators by shear numbers, and one of the dominant locations for the whole coast of British Columbia is the mid-section of Georgia Strait on the Vancouver Island shore. DFO ( the federal fisheries department ) keeps track of that population of herring, especially for determining the acceptable harvest amount. This year's measure looks smaller than in the previous few years. But, there isn't much attention given to herring spawning in other locations. Those minor populations were disappearing for years, and now some seem to be making a comeback. As always, the message is mixed and complicated.
A special good news story has been the reclamation of the terribly polluted old industrial zone around False Creek right in downtown Vancouver and this year had the first successful herring spawn in 100 years, estimated at 20 tons. http://globalnews.ca/video/1166178/herring-return-to-spawn-in-vancouvers-false-creek
This follows the rebound of spawning herring at Squamish, at the head of Howe Sound, with help from a group of volunteers, which is a larger story for another time.
So in recent times, lucky people have observed orcas chasing seals or dolphins in various locations around
Georgia Strait. More herring, more dolphins, more orcas to see. It is amazing to think of the vitality of the soup to feed the forage fish that support pods (herds) of large, 300-400 lb, warm-blooded, energetic dolphins, swimming in cold water, with big brains that also need lots of calories. And they certainly need reserve energy to dodge those Orcas.
Orcas in downtown Vancouver http://www.aquablog.ca/2013/06/vancouver-orca-sighting-quite-a-biggs-deal/
Orcas chasing dolphins at Squamish http://www.piquenewsmagazine.com/whistler/dolphin-day-in-squamish/Content?oid=2548633
Orcas chasing dolphins at the Nanaimo ferry landing https://www.youtube.com/watch?v=foW-Uq0nTU4&noredirect=1
Orcas chasing dolphins , Hyacinthe Bay, Quadra Island https://www.youtube.com/watch?v=4-9fdzhn5ic
Interestingly, when the Pacific White Sided Dolphins started appearing here in larger numbers, it took a couple of years for the Orcas to learn strategies to catch them. . http://www.vanaqua.org/learn/aquafacts/cetaceans/pacific-white-sided-dolphin
Pacific White Sided Dolphins, and Bradley.