RANDOLPH — Jacob Kubel is a man on a mission. The 36-year-old conservation scientist with the Massachusetts Division of Fisheries and Wildlife’s Natural Heritage and Endangered Species Program crisscrosses the state every year in search of the Commonwealth’s rarest salamander — Ambystoma opacum, also known as the marbled salamander — to document where it is breeding and to get a feel for how the population is doing.

“I feel like I can’t stop searching for these guys while I have a hot hand,” Kubel said recently, about his luck in finding the elusive amphibians. With the help of others — including personnel from the Division of Fisheries and Wildlife and the state Department of Conservation and Recreation, as well as academic institutions, land trusts, other nongovernmental organizations, and biologists in the private sector, he has documented marbled salamanders from Bolton to New Bedford, Attleboro to Berlin, and several places in between.