A "Transient" Invasion?
The last few days have been exciting and unpredictable: Exciting, because we've had some fantastic whale encounters; unpredictable, because those whales have been (largely) mammal-eating "transient" orcas!
Most of our guests that have joined us in the summer months have become intimately familiar with the fish-eating "southern resident" community of killer whales, a large extended family that works our nearby inland waters for Pacific salmon. During the winter these whales spend long periods on the open ocean, and start poking their noses into the San Juan Islands as spring matures. Both J pod and L pod (two of three "southern resident" pods) have made passes through the Islands this May, and we anticipate their return -- following the salmon -- at any moment.
In the meantime, however, a different ecotype of killer whale -- the "transient" -- has seized upon the absence of the fish-eating "residents" to case the inland waters for grub. This observation begs two questions: 1) What is an ecotype? and 2) Why should the presence of one ecotype of killer whale influence the travel patterns of another?
The term ecotype was invented to distinguish between populations of animals within the same species that occupy different "ecological niches." That is, they relate to their environment differently: they eat different things. Some killer whales eat salmon, others penguins, and (in the case of our "transients") mammals like seals and gray whales. These different ecotypes also seem to have different social structures: fish-eating "residents" travel in large matrilineal pods, while "transients" travel erratically in small pods whose members may or may not be directly related.
In my opinion, the terms "resident" and "transient" are no longer helpful in distinguishing the two ecotypes of killer whale most often found in the Salish Sea, and may actually stifle their conservation.
The terms derive to the first census of northeast Pacific orcas, conducted by the late Michael Bigg starting in 1972, and is based on the simple observation that during the summer months the large pods of fish-eating orcas remain relatively centralized in the inland waters (hence "resident"), while the mammal-eating varieties come and go with relative unpredictability (hence "transient"). I believe that the use of the term "resident" has been a huge part in the personalization and development of community ownership of our fish-eating killer whales over the past few decades; this evolution of public consciousness, I assert, has been the dominant cause of progressive management and conservation efforts on the whales' behalf.
As we have learned more about these two ecotypes of killer whale, however, the "resident"/"transient" dichotomy loses its footing. First, our "southern resident" orcas actually range from Monterey Bay to the Queen Charlotte Islands: some 1,500 miles of coast. Second, our "transient" orcas were probably here first: one of the leading hypotheses concerning the origin of salmon-eating "residents" is that they diverged from the shark-and-squid-eating "offshore" ecotype of the open ocean as Pacific salmon moved into the inland waters and became anadromous (migrating from sea to freshwater to spawn). Presumably the mammal-eating "transients" had already been working the coast for quite some time.
What fascinates me is the apparent territorial priority of "residents" over "transients" in these waters. When the fish-eaters are around, transients are rarely seen. But in these shoulder weeks, when the "residents" are feeding offshore, "transients" start popping up everywhere! Just yesterday afternoon there were "transient" pods racing around Lawrence Point, sneaking into Peavine Pass and two large groups near Protection Island.
In my experience, the "resident"/"transient" distinction not only excludes mammal-eaters from a public sense of ownership, but evokes a kind of pejorative attitude. I have heard people refer to "transients" as "the bad orcas," pronouncing emphatically their distaste. But what about "porpoise football," and the non-predatory harassment of minke whales by fish-eating "resident" orcas? As elegant and beautiful as these animals are, they are more wolf than panda -- no matter what they happen to be eating -- and their moral standing is to us as much an enigma as their eerie calls and ritual displays.
Furthermore, the "transients" may need active conservation just as much as the "residents." While there doesn't seem to be a shortage of harbor seals, the fact that these mammal-eaters eat at a higher trophic level than the fish-eaters means that they carry on average twice the toxic load. Some of the chemicals that seem to affect them the most, like DDT and PCBs, have been banned. But others, like certain forms of PBDE (a fire retardant) are still in widespread use. Although these chemicals affect "resident" orcas, too, bringing the mammal-eating killer whale out of its gypsy-esque relegation and into the spotlight of public affection might add a powerful punch to legislative efforts at both the state and federal level.
There is something deeply mysterious about seeing these mammal-eating orcas in the wild. The sudden slice of glinting black fin and burst of billowing blow brings an urgent, desperate clarity to the ancient basalt bluffs and faceless silver sea along the north shore of Orcas Island. The sudden appearance of this enigmatic ecotype of killer whale is, I believe, not so much an invasion as it is a revelation. And just as Moses descended Mount Zion with a violent glow about him, we carry away from our brief encounter an aura of wonder and vivid memories.
Labels: orca, transients
posted by Erick Peirson @ 8:34 AM
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