Conservation groups: Bull trout plan must include population numbers USFWS and last updated 2021-06-15 19:31:43-04 MISSOULA â Conservation groups want a new bull trout management plan to ensure that biologists measure the size of a threatened speciesâ population before deciding to take it off the Endangered Species list. On Monday afternoon, federal Magistrate Judge Kathleen DeSoto heard arguments on whether the U.S. Fish and Wildlife Service violated portions of the Endangered Species Act in its 2015 Bull Trout Recovery Plan. The plaintiffs â Save the Bull Trout, Save the Wild Swan and Alliance for the Wild Rockies â argued that the U.S. Fish and Wildlife outlined methods to try to protect the bull trout but didnât give clear direction on how biologists would decide the populations had recovered enough to delist the species.