Metropolitan research scientist Corey Phillis garnered national attention last week as the lead author of a study about salmon migration in the Sacramento-San Joaquin Delta that was published in the journal, Biological Conservation.

In a joint study with UC Davis, Lawrence Livermore National Laboratory and NOAA Fisheries, Corey and his team found that baby salmon use rivers differently than previously thought, a finding that may impact how agencies protect endangered fish.

The findings came after researchers collected tiny ear bones called 'otoliths' from adult fish. These bones function like tree rings - distinct layers form around the edges over time as the fish grows. As they grow, otoliths absorb isotopes found in the water. 

From this, Corey and the other scientists created a chemical map to retrace the juvenile visits to various rivers while they make their journey to the ocean. The fish use the Sacramento River as rearing habitat but after hatching they also venture into the river's tributaries, including creeks that drain Mount Lassen, and larger rivers like the Feather and the American. 

Corey joined Metropolitan in 2015 with 15 years of experience working with salmon and steelhead fish populations in California, Oregon, Washington and British Columbia. Corey, who works in Met's Sacramento office, uses fish and environmental monitoring data to better inform management actions and decisions. He has also authored several scientific articles on the migration of fish species and conservation science.