For the EMERALD project, we are investigating the spatial and temporal distribution patterns of two iconic sentinel species that rely on the nearshore waters of the Northern California Current (NCC): harbor porpoise and gray whales. To do so, we are harnessing a rich, rare, long-term dataset that comes from a dedicated study of marbled murrelet abundance over the past 30 years between San Francisco Bay and the Columbia River. Occurrence patterns in relation to environmental correlates have not been assessed for either focal species in this geographic range across such a long temporal scale. Therefore, critical knowledge gaps remain regarding the drivers of harbor porpoise and gray whale distribution and temporal trends along the coastal region of the NCC that, once filled, will greatly enhance regional management efforts.
The NCC drives enhanced productivity and supports a diverse food web. The nearshore region of the NCC is further shaped by complex bathymetric features including sloping sandy bottom substrate, rocky reefs, and kelp forests, creating a rich mosaic of habitat for numerous species of conservation interest. Humans rely on coastal regions for shipping and commerce, fisheries, industrial development, and increasingly for the development of marine renewable energy. Despite its ecological and economic importance, the nearshore realm poses significant challenges for vessel-based data collection, and therefore these regions remain relatively poorly monitored or understood, including in the coastal waters of Oregon. This data and knowledge gap make the EMERALD project unique and valuable.
The primary objectives of the EMERALD project are to identify persistent hotspots in harbor porpoise and gray whale sightings over time, and describe temporal patterns and environmental drivers of sighting hotspots. The long temporal sampling period, standardized data collection, and large sample sizes in this dataset are unique and will enable robust analysis, and novel findings that can inform population management of these two protected species.