The NOAA biologist who led a satellite tagging expedition earlier this year is apologizing after the tagged whale died.

"We were really just devastated by having one of the animals we worked with wash up dead. At the time we were extremely concerned," Brad Hanson said. "As the investigation progressed it became increasingly likely it was related to the tagging. It made us feel much, much worse."

Related: Satellite tag infection killed orca

Hanson's team deployed a tag on L-95 in February. Soon after, the 20-year old male orca developed a fungal infection at the tag site and died.

"We knew there was a risk. We felt it was fairly small," Hanson said. "It's not been easy. It won't be. It's something I'll carry with me for the rest of my life."

The fungus may have been on the whale's skin, but one of the scientists did not follow proper sanitation protocol. The tag fell into the water and instead of using both bleach and alcohol, only alcohol was used.

Hanson takes the blame, saying it was his fault for not communicating, because he was too focused on keeping pace with the whales.

"I realize that my actions have let a lot of people down and I'm sorry for that. I'm not going to let this defeat me. I'm going to try to figure out how we move this forward," he said.

Rough conditions made the deployment challenging, Hanson says. Critics have called the tagging risky even in good conditions, alarmed the tag wounds could eventually lead to injury and death.

Hanson, however, points to more than 500 tags on 18 species with no confirmed deaths. He believes the satellite data was necessary to establish critical habitat to protect the whales, including establishing more specific Chinook runs whose own demise has paralleled the whales'.

"The agency just can't act in a vacuum. We have to have data to back up what our management actions are," Hanson said.

For Hanson, knowing what happened to L-95 provides opportunity amid tragedy. The fungus that killed him may be a risk factor that needs more scientific attention, but the chance to learn doesn't make L-95's death any easier.

Hanson is done tagging Southern Residents for now. NOAA suspended the program pending expert panel review.

For the longtime orca biologist, L-95's death has strengthened his resolve to save the lives of many more.

"I feel like I have a strong connection to these animals that goes back to when I was a child in the Pacific Northwest growing up," Hanson said. "If I make a mistake, I'm not going to run from it. I'm want to let people know, this is something that happened. I'm going to take responsibility for it. Let's move forward."