they said they had 53 trackers and only 36 "returned usable data" so theoretically some of those unaccounted for 17 could have been recycled... I mean they don'

they said they had 53 trackers and only 36 "returned usable data" so theoretically some of those unaccounted for 17 could have been recycled... I mean they don't know what happened to them. I think they could have at least highlighted that in the article.