That stream was only three to five feet wide and had a wild, self-sustaining population.

They do not form self-sustaining populations in soil, as it lacks enough organic matter.

"We never expected to have self-sustaining populations develop," Pyle said.

Because at least 250 animals are needed for a self-sustaining population, the biologists say, new habitat must be found to support them.

A transfer was considered a success if a self-sustaining population developed in the new location.

There is no evidence that the island has ever supported a self-sustaining human population.

First, they say, the young fish now in coastal waters must be allowed to reach breeding age and begin a self-sustaining population.

But he said it would not be a self-sustaining population, relying indefinitely on human intervention.

The final goal for Mexican wolf recovery is a wild, self-sustaining population of at least 100 individuals.

These are not enough to insure the establishment of a new, self-sustaining population.