Karah Nazor: Interview with NOAA Scientist Flora Cordoleani, Ph.D., June 2, 2019


NOAA Teacher at Sea

Karah Nazor

Aboard NOAA Ship Reuben Lasker

May 29 – June 7, 2019


Mission: Rockfish Recruitment & Ecosystem Assessment

Geographic Area: Central California Coast

Date: June 2, 2019

Scientist Spotlight: Flora Cordoleani, Ph.D., NOAA NMFS, SWFSC, Fisheries Ecology Division (FED). Dr. Cordoleani is a member of the fish sorting team on this survey.

Interests: Rock climbing, surfing, reading, studying Japanese

Education: Dr. Cordoleani’s doctoral degree is in Marine Biology and Ecology from Aix-Marseille University in France. There she researched interactions between phytoplankton and zooplankton. During her postdoc at the University of California, Davis, in the lab of Louis Botsford, she studied the impact of marine protected areas on rockfish along the CA coast.  

Flora measuring anchovies
Flora Cordoleani, Ph.D., measuring Northern Anchovies after a sort on the Reuben Lasker.
Flora and Karah
Dr. Flora Cordoleani and Dr. Karah Nazor, Teacher at Sea.

Current Research: Dr. Cordoleani leads a research program at UC Davis on preservation of Chinook Salmon, Oncorhynchus tshawytscha, of the Central California Valley Spring Run, which is a threatened species. She explains that these Chinook Salmon are genetically different from salmon of other runs such as the Late Fall, Fall, and Winter runs that take place in the Sacramento River, San Joaquin River, the Delta, the San Francisco Bay, and all of its tributaries.

The primary objective of Dr. Cordoleani’s research is to develop a life cycle model of the entire Spring Run from the spot where the young salmon are reared in the river to their journey through the Golden Gate to the sea where they spend a couple of years before returning back to their home river to spawn, thus completing the life cycle.  She aims to uncover environmental factors that are impacting the survival at each stage of the life cycle.

Project 1: Dr. Cordoleani’s team placed acoustic tags in the stomachs of young fish to trace their journey from the river to the ocean.  She has found that water temperature, water velocity, and flow are the major factors impacting whether or not juvenile fish are able to make it from their place of birth to the Golden Gate. She has observed that drought negatively impacts survival and that the fish fare better in wetter years.  Her data helps federal agencies, such as NOAA, with fish stock assessments and informs them for making science policy decisions on fishing and setting fishing quotas.

Project 2: Since water flow and velocity affect the survival of young salmon called fry, Dr. Cordoleani is very interested in water usage in the Central California Valley and gaining a better understanding how freshwater habitats are managed and how this affects wild salmon.  A major obstacle these fish encounter are dams, which blocks the natural flow of rivers. Spring run salmon have an additional challenge of low water levels and low stream flow in the Spring. During the Spring months, there is less water available in floodplain habitats due to the heavy consumption of water by the agriculture industry during this time.   

To study the effects of water flow and velocity on salmon fry, Dr. Cordoleani made mesh fish cages and placed the cages in either shallow floodplain habitats or the main river.  She placed ten fry (measuring 40 mm in length) in each cage and allowed them to grow for 6 weeks. At the end of the 6 weeks, she again measured the fish and found that the floodplain shallow water habitat promoted fish growth.

Rice farmers use floodplain habitats for their crop and Dr. Cordoleani is working on partnering with this industry to explore how they can work together to manage land to benefit native salmon runs.  She is excited that the rice farmers, as well as duck clubs, are interested to learn how their land can be used to help wild salmon populations thrive and how they can be a part of the solution to some of the obstacles wild salmon face.

Project 3:  Fish otoliths provide a treasure trove of information to reconstruct the life history of fish.  The CA Department of Fish and Game has for many years been collecting otoliths from salmon carcasses after spawning events throughout various locations in the Central CA Valley.  They gave Dr. Cordoleani access to their 450 stored otoliths for her research on the salmon life cycle. She will analyze the otoliths using laser ablation mass spectrometry and stable isotope analysis (using the Strontium 64 or 65 ratio) to determine in which river the adult fish were reared, where they were present at each stage of their life cycle, and how long they spent there. She will also be able to determine if the fish were wild or farmed-raised because hatchery feeding produces a different strontium signal, she explains.

With data from the otolith project, Dr. Cordoleani will compare different cohorts of fish and assess how fast the fish grew in each type of habitat in order to understand which habitats are most ideal for salmon survival. Importantly, she will be able to determine whether and how their growth was affected by different environmental factors and seasons over the years.  Dr. Cordoleani uses USGS databases and other agency websites to obtain water data records for her research.

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