Scientists Study Fish Movements on PV Shelf
Scientists Study Fish Movements on Palos Verdes Shelf
Map shows where the acoustic receivers are located on the Palos Verdes Shelf and Los Angeles Harbor.
This past fall, biologists Dr. Chris Lowe and graduate student Barrett Wolfe from California State University Long Beach began a study to track the movement patterns of White Croaker and Barred Sand Bass along the Palos Verdes shelf. One of goals of this project is to identify the home range of each species and to determine whether that range encompasses the contaminated areas of Palos Verdes. White Croker and Barred Sand Bass are bottom-dwelling fish that are known to accumulate DDTs and PCBs in their tissues, for this reason there are “Do Not Consume” advisories for both fish species caught between the Santa Monica Pier and Seal Beach Pier. The California Department of Fish and Game also maintains a commercial catch ban for White Croaker in parts of the Palos Verdes Shelf and adjacent waters. EPA is providing funds for the acoustic arrays and fish tagging activities. MSRP has provided technical guidance throughout the project and partial funding.
Why is this important?
Understanding the movement patterns of these fish will provide regulatory agencies with the scientific information they need to make informed decisions about updates to human consumption advisories. It will also enable the EPA to design remedial actions for sediment capping based on the amount of time that White Croaker spend in highly contaminated areas.
Using an intricate array of acoustic telemetry devices, biologists from the Lowe Lab are able to obtain detailed information about the geographic location of individual fish, the time spent in each location, the direction of their movement, distances traveled, and even travel speeds.
Graphic shows how an array of acoustic receivers calculates the position of an individual fish.
How do they detect fish movement?
Acoustic receivers are deployed in several arrays across the Palos Verdes shelf. Fish captured on the shelf are fitted with acoustic transmitters and released back into the water. The receivers then record data from the transmitters each time a fish swims within the range of an array. The receivers record date, time, and location data every time an individual passes by. Combining these data from multiple arrays of multiple receivers allows the biologists to track the movement patterns of individual fish. Biologists have also partnered with local charter fishing boats to carry and deploy receivers while on site at favored fishing locations such as the flats of Santa Monica and Huntington Beach.
