Moving Targets and a Changing Climate - Aligning Bull Trout Recovery Planning with an Uncertain Future

USFWS is revising the Bull Trout Recovery Plan.  We used the Cold-Water Climate Shield Model to derive map comparisons between projected (2040) thermally suitable spawning and rearing patches and existing (2010) distribution across 35 bull trout core areas of the Columbia Headwaters Recovery Unit (western Montana and North Idaho).   The Climate Shield Model allowed us to strategically examine watersheds to ascertain where cold-water habitat is likely to persist, where it’s likely to disappear, and where further assessment is needed.  Presence of cold thermal refugia in lakes or reservoirs has a demonstrated beneficial impact in supporting the adfluvial bull trout life history, but occupancy upstream of lakes was not well predicted by the model.  We further compared distribution to 2080 model projections in the Columbia Headwaters.  Thermally suitable bull trout habitat was predicted to shrink by roughly half from 2040 to 2080, threatening persistence of some core areas and placing a premium on long-term protection.  Comparisons between known distribution and model projections also identified patches where bull trout distribution mismatches with predicted cold-water refugia, indicating a need for refined presence/absence surveys.  Additional examples of how the Climate Shield Model can be used for bull trout recovery planning rangewide will be presented.