The estuarine growth and residency of juvenile Pacific salmon in North America: a compilation of empirical data

The value of estuaries as nursery habitat for juvenile anadromous salmon is likely variable across estuaries and species. Here, we compiled published empirical data on juvenile salmon estuarine growth and residency. We aimed to quantify the range and variability of these aspects for five species of Pacific salmon across estuaries, methodologies, and life histories. The majority of studies focused on Chinook and coho salmon, and largely from their southern range. While there is some evidence of higher growth in wild-origin fish relative to hatchery-origin fish, the wide range of metrics employed made identification of trends among life histories challenging, and unification of reporting could strengthen future research. Different salmon life histories exhibited different residencies, with natural-origin subyearling coho exhibiting the longest mean residency (~3 months) and 1+ sockeye salmon exhibiting the shortest (3.7 days). Across life histories, hatchery fish exhibited much shorter estuary residencies than wild fish. Collectively, our review highlights key patterns in salmon estuary ecology, knowledge gaps, and lays the foundation for future studies to quantify the importance of estuaries for specific salmon.