I think what you're referring to is the fact that Pacific Northwest societies initially confounded anthropologists who had learned to draw a fairly rigid distinction between nomadic hunter-gatherers and sedentary farmers.

What were found in the Northwest were societies that still subsisted on fishing, hunting and foraging, but had learned to use these resources effectively enough (developing refined techniques for marine mammal hunting, learning to harvest salmon runs at natural choke points, for example) that they not only could live in sedentary villages as opposed to moving around in search of food, but develop more complex social structures as well—property ownership, specialized forms of labor, a hereditary nobility, even slavery. These are all things that traditionally had been seen as dependent on the development of agriculture.

(Source: Calloway, Colin G. One Vast Winter Count: The Native American West before Lewis and Clark. Lincoln, U. of Nebraska Press, 2003.)

Northwestern Pacific Indians adhered to a system called potlatch, if that's what you're talking about.

Potlatch was basically a ceremonial feast, usually held to show the social standing of a tribesman, that entailed the host giving away a large amount of food and other goods to the invited recipients, as a way of expressing superiority and high social standing.

An example of when a potlatch would occur is when a new chief is validating his rank as chief. In order to prove to other people his ability and social standing to be chief, the new chief would hold a potlatch to prove his new social status. However, potlatches could be held for most anything of import, and many of these sort of potlatches were periodically held simply to prove the host's claim to their social status.

As you may have noticed, potlatch itself is not so much an economic as it is a ceremony, deeply engrained in Northwestern Pacific Indian culture. However, the concept of the giving in potlatch and the preparation for it could be considered economic practices.

In Marvin Harris' book Cows, Pigs, Wars, and Witches, Harris sheds light on an interesting view on potlatch; namely that a larger gift-giving entailed higher rank because it meant the host was able to dedicate more of his personal time (or tribe's time) to amassing goods for the potlatch.

Through this lens, preparation for potlatch and the ensuing gift-giving is a sort of economic system, since it allows for the amassment and then redistribution of goods amongst the peoples of the region. Potlatch can also be seen as an economic system due to the highly competitive nature of it (if a chief wants to prove himself to be of higher status than another, he has to hold a larger potlatch). As to how sound of an economic practice it is I cannot say, since by the time of European observation many potlatches had increased in magnitude to the point that the host would bankrupt himself and destroy property to provide more gifts for the potlatch.

A particularly well-documented tribe's form of potlatch is that of the Kwakiutl, but as to your specific example of the Tlingit, they practiced an interesting form of potlatch in which a deceased member of the tribe would be given a memorial potlatch, where the person's social standing was realised and shown a final time (unfortunately, I don't know if other tribes of the area practised this as well). This example, for me at least, shows perfectly well why I personally lean more towards viewing the potlatch as a ceremonial rather than economic process.

Hopefully that helps a bit, and here are some sources:

Marvin Harris, Cows, Pigs, Wars, and Witches http://peabody2.ad.fas.harvard.edu/potlatch/default.html http://www.britannica.com/EBchecked/topic/472732/potlatch www.unc.edu/~emgriggs/tlingit.doc‎ (this one is a link to a document about the Tlingit)