Wednesday, February 3, 2010

Orcas in the Puget Sound

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Southern Resident Orcas
All orca photography by Annette Colombini
Used with Colombini's explicit permission.

The orcas who frequent the Puget Sound are known to the National Oceanic and Atmospheric Administration as the Southern Resident community of orcas. The community was listed in November of 2005 as endangered by the Endangered Species Act. The Southern Resident community consists of pods J, K, and L. There are approximately 88 orcas alive and belonging to the Southern Resident community (2009).

J-Pod consists of some twenty-eight individuals. They are commonly identified near San Juan Island, and stay through winter.

K-Pod consists of some nineteen individuals. They frequent the western shores of San Juan Island from May through June (which is peak whale-watching season).

L-Pod consists of some forty-one individuals which I think is enormous! I read that, because of L-Pods size, it will often break into subgroups and it is rare to see all members of L-Pod traveling together at once.

How do we identify each member of the pods?

Every individual is given a common name and then a letter (J, K, or L) to identify which pod they belong to. Following the letter, a number is then assigned to the whale. The number represents a whale's order in which it was identified since the study of Puget Sound orcas began in 1976. We could probably assume that the lower the number the older the whale. For instance, Granny J-2 is one of the oldest matriarchs in the Southern Resident community. Granny belongs to pod J, and was the second whale to be identified since 1976.

There are members of the Southern Resident community that are believed to be 90 years of age! This is significant since it is generally agreed that female orcas live to be around 55, and males live to be 30.

In what way are are J, K, and L pods special?

The reason why the Southern Resident community is defined as a subgroup species (the ESA defines it as a "distinct population segment") is because these three pods choose not to reproduce with other pods or transient orcas even though frequent contact with other orcas occurs. Its believed that the reason for segregation is a matter of culture. According to Howard Garrett, the J, K, and L pods are exhibiting behavior never before seen outside of humans.

Animal culture is defined as "the transfer of information between individuals by imitative or social learning" by Aoki (1991), view my source Rendell where he writes about the development of culture in orcas and dolphins. Our Puget Sound Orcas are transferring their willful behavior and acoustic sound to their offspring.

Do the orcas mate with pod members?

In his article "Our Neighbors with Fins" Garret specifically states that members of the Southern Resident community mate with other members, not within their own pod. The pod is a family of orcas generally lead by a few matriarchs. Orcas are the only mammals whose offspring, be they male or female, remain with their mother and the pod for their entire lives.

How are "communities" identified?

By sound. I'm confused, myself, about the specifics. I've read that pods use a number of calls that are specific to that pod alone and although the calls may evolve through generations they are very pod-specific. I've also read that communities consisting of one or more pods are identified by similar acoustic sound and they often share/overlap a geographic area. You'll have to check me on that, though!

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