A Bird’s Eye View: Aerial Surveys of Nearshore Waters Provide Important Information for Managing Coastal Pelagic Fishes

aerial view of sardine school
An unretouched aerial photo of a sardine school off Southern California

Since August 2012, CDFW’s Coastal Pelagic Species (CPS) Project and the California Wetfish Producers Association have been working together to develop a nearshore aerial survey program for southern California waters. The valuable data collected by the program may be used to set sustainable harvest limits and prevent overfishing of CPS, including Pacific sardine, Pacific mackerel, and northern anchovy.

CDFW boat-based groundtruthing operations

A primary focus of the program is developing scientifically rigorous aerial survey methods. Over the first four field seasons, Pacific sardine schools were mostly observed close to shore along either mainland or island coasts. Boat-based groundtruthing confirmed the accuracy of aerial fish identification, and provided critical biological and environmental data.

Map illustrating sardine observations
Pacific sardine observations from all four seasons of the aerial survey

Starting in summer 2013, other CPS were quantified including northern anchovy and Pacific mackerel. Both aerial and boat survey methods have been refined to improve data collection efficiency and accuracy, and staff have begun integrating all CPS observations into the program. Information from the aerial surveys will help to increase our understanding of the abundance and distribution of CPS in southern California.sidebar

CDFW coordinates with NOAA Fisheries and other West Coast agencies through the Pacific Fishery Management Council (PFMC) to manage Pacific sardine and other CPS fisheries included in the federal CPS Fishery Management Plan. PFMC uses stock assessments to set sustainable harvest limits that prevent overfishing of CPS populations. Once enough data are collected, CDFW will request that the PFMC include the California aerial survey data in future stock assessments of Pacific sardine and, potentially, other CPS. California aerial surveys would complement other types of surveys currently included in stock assessments, such as the ship-based acoustic surveys and fish egg surveys conducted farther off shore.

For more information about Pacific sardine research and management, please visit CDFW’s Pacific sardine webpage.

post by Anna Holder, CDFW Environmental Scientist  ♦ CDFW file photos; aerial photo of sardine school by K. Lynn ♦ CDFW map by A. Kesaris

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