fish report header
Striped bass tagging
Fish Tracking With Acoustic Telemetry

The concept of tracking fish is nothing new to anglers and fisheries scientists. For as long as we have been relying on fish as a source of food, we have wanted to know where they are and how to catch them. As fisheries scientists, understanding movement patterns on a finer scale is important in many ways. Acoustic telemetry can provide valuable information on the behavior and survival of individual fish, since every tag has its own predetermined signal that is emitted and the frequency is received and recorded by receivers (hydrophones). With the use of acoustic (or ultrasonic) tags, we can determine the type of habitat the tagged fish prefers, which route it will likely take and where hotspots for predation occur in the region.

 

The first known use of acoustic telemetry in the Sacramento - San Joaquin Delta was a 1964 study on adult Chinook salmon. The tags were large (up to 4 inches long) and were attached externally near the dorsal fin of adult fish. In recent years, tagging fish with acoustic tags has become more popular because tags have been made much smaller (under 0.5 inches) and can be surgically implanted in juvenile fish (Figure 1). As more fisheries researchers began utilizing acoustic telemetry technology, hydrophones became more widespread in the Delta. Soon, it became evident that collaboration would be beneficial and cost effective; thus, in 2007 the California Fish Tracking Consortium was developed to facilitate sharing acoustic telemetry information. There are currently over 300 hydrophones that range from the Sacramento River in the north (near Redding), down to the most southern part of the San Joaquin River (near Fresno) and out to the Golden Gate Bridge (Figure 2).

 

Some acoustic telemetry studies focus in on a fish's route selection and probability of survival, which could include predation rates, while others concentrate on determining a fish's behavior in relation to specific structures or facilities. In the case of the Vernalis Adaptive Management Plan (VAMP), an acoustic telemetry study evolved over time into a study that incorporates multiple factors that affect salmon survival. In the Delta, there are multiple routes to the sea, and the route that the fish chooses can affect its chance of making it to the ocean. Initially, the goal of VAMP was to estimate survival and route selection of Chinook salmon smolts at different flows and exports in the presence or absence of the head of Old River barrier (HORB), but as the study progressed it was apparent that factors other than flows and exports were important. During the VAMP study, immobile tags (tags no longer moving because the fish is dead) were frequently found in places that were well known for good bass fishing. Furthermore, some tagged smolts suddenly developed behaviors indicative of predators (e.g., milling around in one spot for long periods of time, or making long-distance movements back upstream), indicating that predation upon Chinook salmon smolts may be more prevalent than previously presumed. When predatory fish tagging was added to the program it was discovered that striped bass, black bass, and other predators were milling around the state and federal diversion facilities where fish are salvaged and trucked downstream before entering the pumps.

 

The use of acoustic telemetry in the field of fisheries has significantly increased our knowledge of fish behavior. The majority of the tags that have been used in the Delta are for tracking salmonids and a smaller portion of tags have been used on sturgeon. The results from salmonid acoustic studies have led many to believe that predation by non-native fishes is one of several factors in the decline of native salmonids in the Delta. As a consequence, more acoustic tagging has been conducted on predatory fishes to better understand their habits and how we can protect native fish populations.

 

Follow Us!  Like us on Facebook  View our photos on flickr  View our videos on YouTube

email list

Resources

Recent Blog Post
What's for dinner?
There are many ways to collect information on the Electro Fishingdiet of wild animals, including observing their consumption habits, looking through the contents of their stomachs, and even sifting through what comes out the other end. Fisheries researchers usually opt for analyzing stomach contents, which can be obtained by either sacrificing the fish and dissecting out the stomach or removing the stomach contents by non-lethal means, such as using tubes, suction, or water flushing (i.e., gastric lavage). Gastric lavage is usually the preferred method for obtaining the stomach contents of live fish since the fish are released a little hungry, but in relatively good shape. Stomach contents can be obtained by placing a polyethylene tube into the esophagus of a fish and flushing water into the stomach using a hypodermic needle (mechanized pressure)... Read more >

Recent Job Announcements  

 

Figure 1. Timeline of acoustic tagging projects in the Northern Basin (Sacramento River) and in the southern basin (San Joaquin River).

Hydrophone Map

Figure 2. Map of acoustic hydrophones in California's Central Valley.  Hydrophones are identified as Vemco or HTI and either California Fish Tracking Consortium or non-consortium.
IN THE NEWS: Recent stories you might have missed...
Regulation Requires Corps To Consider Others

Columbia Basin Bulletin 

For 28 years the Washington Department of Fish and Wildlife has been responsible for counting adult salmon, steelhead and other fish that pass upstream through Columbia and Snake River hydro projects each year. But a change could be in the offing. The U.S. Army Corps of Engineers, in accordance with the Federal Acquisition Regulation, has launched a process aimed at assessing whether there are "small business" interests willing and able to take over the counting activities, which peak during the spring, summer and fall... Read more > 

Prestigious panel agrees: Delta is stressed, with no easy fix

Sacramento Bee

A comprehensive new study on the Delta's environmental problems concludes there is no easy fix, only hard choices, if California wants to restore fish species and still satisfy its water demands. The study by the National Research Council, released Thursday, was conducted at the request of members of Congress and the Obama administration. The 17 participating scientists, from various disciplines and regions of the country, took two years to complete the report... Read more > 

Salmon are jumping this year

SF Bay 

Biologists report there are more than 800,000 Sacramento Chinook off the coast of California right now, which has the Pacific Fishery Management Council considering three options for the 2012 salmon season. All three options currently on the table will allow for more salmon to be caught than have been allowed in years. But the bumper crop has many people asking: Why? California has been attempting to preserve its salmon for nearly a century... Read more > 

Cowlitz River smelt data suggest run may be rebounding

The Daily News

Dalton Fry cast a finely meshed net into the murky Cowlitz River. He waited a few minutes, then hauled it in and poured the contents into a glass jar. There swam dozens of smelt larvae, their eyes protruding from barely visible bodies. "There's probably 100 in there, no problem," Fry, who works for the Cowlitz Indian Tribe, said last week. Seals swimming nearby off the boat launch at Gerhart Gardens indicated that adult smelt were cruising the river, too... Read more > 

A Coho Salmon's Journey
New York Times

The head, body and tail of a coho salmon smolt are about to be thrust from the incubating waters of the Fraser River into the wide, wild world of the Pacific Ocean. At the mouth of the Fraser, the largest river in British Columbia, where the current changes from a slow, steady riparian flow to the swift quaking waves of open ocean, I watch the smolt (a young salmon migrating from freshwater to saltwater) prepare for its big saltwater entry... Read more > 

U.S. reportedly blocks Canadian tuna fishermen

The Canadian Press       

The U.S. government has suspended a 31-year-old agreement that allowed Canadian vessels to fish for tuna in American waters, two British Columbia industry groups confirmed Wednesday, with one warning the decision could have a domino effect across the entire West Coast fishery. Both countries signed a treaty in 1981 that allowed cross-border fishing for albacore tuna, but it expired in 2011... Read more > 

fishbio.com     info@fishbio.com