A Summary of Acoustic Tagging and Juvenile Salmon Acoustic Telemetry System Program in the Northwestern United States

By Brenna Bales, SRC intern

Before the existence of satellite and acoustic tracking technologies, the most we knew about a certain marine species’ range was from either visual observations or catch data. By developing these systems and scientists cooperating globally by sharing their data, we have learned that some “tropical” species like tiger sharks are not tropical at all but can in fact go as far north as Maine or Canada and out thousands of miles into the mid-Atlantic on a single migration from Florida ( In 1999, an estimated 11,800 electronic tags (both satellite and acoustic) were placed on marine mammals, fish, invertebrates, reptiles, and birds around the world (Stone et al, 1999). There is a major difference between these two technologies, however. While satellite tags will track an animal wherever it goes as long as it can communicate with a satellite (meaning the tag must hit the surface to be detected), acoustic tags (Image 1) must be within range to an underwater hydrophone for the signal to be detected. This enables acoustically tagged animals to be tracked on a much finer scale without the need for the animal to come to the surface.

Image 1: Differently sized acoustic tags that would be used internally to monitor movements of animals.

A research organization may set up a hydrophone array over a certain area to pinpoint their tagged animals’ locations; however, this array may also detect other animals that have been acoustically tagged by different research organizations. This can be helpful to everyone, as only one hydrophone is needed to track all kinds of animals and their tags, such as sawfish, sharks, and marine mammals; however, private interests may hinder this (Grotheus 2009). Lastly, acoustic tagging has benefits in that it can be used to track multiple individuals within a population in one location versus a small number of animals tracked over different time scales and locations (Huepel et al, 2006).

In 2001, the U.S. Army Corps of Engineers Portland District decided that they wanted to track juvenile salmon in the Columbia river basin through their migration to the Pacific Ocean. There were several goals to the JSATS (Juvenile Salmon Acoustic Telemetry System) project, including 1) assessment of survival and habitat use of juvenile salmonids migrating through the estuarine environment 2) estimation of route-specific dam passage survival of juvenile salmonids 3) determination of fish survival and migration behavior, and 4) to determine effects of water temperature stratification and dissolved gas ( By 2008, 4,140 JSATS  and 48,433 passive integrated transponder (PIT)- tagged yearling Chinook salmon (Oncorhynchus tshawytscha) had been tagged (McMichael et al, 2010). The dams are shown in Image 2 along with the route that the salmon migrated towards the Pacific Ocean.

Image 2: Study area used in JSATS in the Snake and Columbia river basins in 2008. Red circles demarcate the hydrophone array locations and the star marks the release location of the tagged yearling Chinook salmon.

The researchers on the project concluded that the JSATS tags gave more survival location data with higher precision than the PIT tags (McMichael et al, 2010). The JSATS tags also transmitted every 5 seconds, which is optimal for the current study in tracking such small-scale movements around the local dams. All components of the system were non-proprietary, unlike many other arrays currently established. A major outcome from this was the competitive nature in which the U.S. Army Corps of Engineers bid for reductions in sizing and pricing for these tags, leading to many advances in the technology. The study is on-going, and research is being conducted on the biological effects of tagging and how the environment is affecting the receivers and their detection capability. This telemetry system has been designed extremely efficiently and should be used as a model for other up and coming acoustic tagging endeavors.

Literature Cited

Grothues, T.M., 2009. A review of acoustic telemetry technology and a perspective on its diversification relative to coastal tracking arrays. In Tagging and tracking of marine animals with electronic devices (pp. 77-90). Springer, Dordrecht.

Heupel, M.R., Semmens, J.M. and Hobday, A.J., 2006. Automated acoustic tracking of aquatic animals: scales, design and deployment of listening station arrays. Marine and Freshwater Research, 57(1), pp.1-13.

McMichael, G.A., Eppard, M.B., Carlson, T.J., Carter, J.A., Ebberts, B.D., Brown, R.S., Weiland, M., Ploskey, G.R., Harnish, R.A. and Deng, Z.D., 2010. The juvenile salmon acoustic telemetry system: a new tool. Fisheries, 35(1), pp.9-22.

Stone, G., Schubel, J. and Tausig, H., 1999. Electronic marine animal tagging: New frontier in ocean science. OCEANOGRAPHY-WASHINGTON DC-OCEANOGRAPHY SOCIETY-, 12, pp.24-27.

Image 1 source:

Image 2: McMichael, G.A., Eppard, M.B., Carlson, T.J., Carter, J.A., Ebberts, B.D., Brown, R.S., Weiland, M., Ploskey, G.R., Harnish, R.A. and Deng, Z.D., 2010. The juvenile salmon acoustic telemetry system: a new tool. Fisheries, 35(1), pp.9-22.

Acoustic Telemetry Analysis of California Gamefish Reveals the Functional Performance of the Wheeler North Artificial Reef

By Chelsea Black, SRC MS Student

Submerged structures such as ships, steel frames, or boulders placed on the seafloor deliberately to mimic attributes of a natural habitat are known as artificial reefs (ARs). Since the development of the National Fishing Enhancement Act of 1984, most AR construction in the United States has been focused on enhancing fishery resources and opportunities (Logan & Lowe 2018). These ARs provide new habitat for both fish and benthic organisms to colonize, which increases food resources and overall fish biomass. However, to establish reef productivity for mobile species it is pertinent to know when and for how long species are resident to a reef, which has historically been overlooked by previous AR studies.

The largest constructed rock reef in the US, the Wheeler North Artificial Reef (WNAR) off the coast of San Clemente in the Southern California Bight, was built by the Southern California Edison Company (SCE) as mitigation for the loss of the San Onofre Kelp Bed after discharged cooling water from a nuclear generating station resulted in restricted giant kelp growth and subsequently the loss of species diversity (Figure 1). For SCE to receive mitigation credit, WNAR must either meet or exceed the abiotic and biotic performance standards relative to community performance from two nearby natural reefs, the San Mateo Kelp Bed (SMK) and the Barn Kelp Bed (BK).

Figure 1. Construction of the WNAR [Source:].

In a recent study, Logan & Lowe (2018) examined the movement patterns of three economically and ecologically important fishes, the kelp bass (Paralabrax clathratus), the barred sand bass (P. nebulifer) and the California sheephead (Semicossyphus pulcher) within WNAR. 195 fish were captured, tagged with acoustic transmitters, released, and monitored by underwater receiver stations for a study period of two years to determine residency indices (Figure 2). When examining these indices, the authors concluded kelp canopy surface area was the single environmental parameter that explained the most variation in residency. This makes sense considering previous research demonstrates that artificial structures with high vertical relief provide important habitat conditions, including refuge from predators, for many species (Martin & Lowe 2010).

Figure 2. Locations of acoustic receivers and neighboring natural reefs [Logan & Lowe 2018].

Figure 3. From top to bottom: California sheephead, kelp bass, and barred sand bass [Source: Wikimedia Commons].














After analyzing movement patterns of the tagged fish across WNAR, SMK and BK, this study suggests that during favorable conditions fish were highly resident to WNAR and demonstrate that it is currently functioning similar to the surrounding natural reef habitats, effectively reaching the set performance standards. In addition, the results reveal that future AR management plans in California would be most successful when implementing structures that are ideal for giant kelp growth to aid in increased species diversity in abundance by providing an ideal habitat for important species.

Works Cited

Logan, R. K., & Lowe, C. G. (2018). Residency and inter-reef connectivity of three gamefishes between natural reefs and a large mitigation artificial reef. Marine Ecology Progress Series, 593, 111-126.

Martin CJ, Lowe CG (2010) Assemblage structure of fish at offshore petroleum platforms on the San Pedro Shelf of southern California. Mar Coast Fish 2:180−194.