PNNL larval‑dispersal model shows El Niño conditions raise green crab settlement risk

Researchers from PNNL and the Salish Sea Modeling Center demonstrated larval‑dispersal modeling that tracks virtual green crab larvae from release to potential coastal settlement. The model couples hydrodynamic outputs with species‑specific larval behavior to estimate where larvae released at one site are likely to settle elsewhere along the coast.

"We released them in the model and can track their position in time," PNNL researcher Lily said while running model visualizations that showed larvae moving from the Salish Sea and Oregon–Washington coasts northward toward Vancouver Island in some scenarios. The team reported that settlement success in the hindcast period is correlated with warmer El Niño years — when surface temperatures rise, modeled settlement increases — a finding the team said could help explain recent increases in detections.

Researchers said the model can be used to prioritize early detection and targeted suppression by identifying areas most likely to receive larval influx from a new detection. The group plans to compare model outputs to trapping data in follow‑up work and to migrate to a higher‑resolution hydrodynamic model (SSM 2.0) for improved nearshore accuracy.

The council asked for more nearshore resolution (especially for small bays such as Grays Harbor) and urged researchers to make route and model outputs available for operational planning.