Changes in phenology–the seasonal timing and distribution of life history events–are a common response to environmental change, yet remain poorly understood for highly migratory marine species. In pelagic systems, phenology is closely linked to the seasonal availability of suitable habitat, but understanding and predicting temporal shifts in habitat have received far less attention than spatial redistribution. Here, we use species distribution models for twelve ecologically and economically important pelagic predators to characterize historical habitat phenology in the Northwest Atlantic Ocean and project future changes under end-of-century oceanographic conditions. We define phenology as the seasonal distribution of modeled suitable habitat ("habitat phenology"), which serves as a proxy for species occurrence. Using this framework, we identify three general phenological archetypes–warm-migratory, resident, and cold-migratory–based on the timing and concentration of seasonal habitat. Projected climate-driven habitat changes alter both the timing and seasonal concentration of suitable habitat, with responses varying across species and archetypes. While some species exhibit minimal shifts in peak timing, many show reduced seasonality or expanded seasonal habitat, and several are predicted to transition between archetypes, including shifts toward more resident or winter-dominated patterns. These results demonstrate that climate-driven redistribution will reshape not only where species occur, but also when suitable habitat is available. Such temporal shifts have important implications for fisheries, conservation, and marine spatial planning, highlighting the need to integrate phenological dynamics into forward-looking, dynamic ocean management.

Keywords: phenology, species distribution model, highly migratory species, climate change, dynamic ocean management