PRINCE WILLIAM SOUND -

Locals say seeing new life in Prince William Sound is a refreshing sight 25 years after a devastating oil spill heavily impacted the region and many of its most prized wildlife species.

Of the many local species, the sea otter has been a main focal point when talking about the sound's wildlife recovery. The United States Geological Survey released a report indicating the sea otter population has rebounded to pre-spill numbers.

"In our last three to four years we've noted that now animals are getting old again, so the age distribution has gone back to the pre-spill pattern," USGS' lead research Bethany Ballachey said.

Basically, Ballchey is saying the majority of sea otters now have the opportunity for a full life cycle like they did before the spill. The population was struggling in Valdez till recently and now that life cycle has the potential to reach its natural completion.

While wildlife advocates are celebrating the increased numbers, they note the report doesn't tell the whole story. Marine biologist Rick Steiner says the present-day sea otter population in the sound doesn't yet meet his expectations for full recovery.

"We have to not only look at what the sea otter population was pre-spill, but we have to imagine where they'd be 25 years later," Steiner said. "The USGS study presumes sea otters were at equilibrium density pre-spill and therefore if they return to the pre-spill numbers now a quarter of a century later, they are fully recovered. I think that's a questionable presumption."

Another smaller species in the sound is also being studied and experts say it plays a huge role in the overall health of the ecosystem. Scott Pegau from the Oil Spill Recovery Institute says since a year after the Exxon Valdez oil spill, the herring has disappeared in the sound.

"We think the exposure combined with the nutritional stress made the herring more susceptible to disease so there's a large disease outbreak that caused the adult population to crash," Pegau said.

Pegau says the population prior to the spill was about 80 to 100 thousand tons. To open a fishery, there has to be an excess of 22,000 tons and Pegau says those numbers haven't been seen since 1998.