Kelsie Murchy

Topic

Impacts of marine shipping on the underwater soundscape and Chinook salmon behaviour

Department of Biology

Date & location

• Thursday, February 29, 2024
• 11:00 A.M.
• Clearihue Building, Room B007

Examining Committee

Supervisory Committee

• Dr. Francis Juanes, Department of Biology, University of Victoria (Co-Supervisor)
• Dr. Rodney Rountree, Department of Biology, UVic (Co-Supervisor)
• Dr. Julia Baum, Department of Biology, UVic (Member)
• Dr. Svein Vagle, School of Earth and Ocean Sciences, UVic (Outside Member)

External Examiner

• Dr. Joseph Smith, Northwest Fisheries Science Center, National Oceanic and Atmospheric Administration

Chair of Oral Examination

• Dr. Jason Colby, Department of History, UVic

Abstract

With the persistent growth of the shipping industry, the underwater soundscape across the globe has been changing. The prevalence of low-frequency noise from shipping activities has led to a noticeable increase in ambient underwater noise levels. Research to date has focused on large commercial vessels in motion, but commercial vessels are also anchoring in coastal ecosystems and there is a high presence of small commercial vessel that might be altering the marine soundscape. In this dissertation, these underrepresented anthropogenic noise sources are explored in Cowichan Bay, and Campbell River, British Columbia using underwater hydrophones. Results from these chapters (2 and 3) demonstrated significant changes to the underwater soundscape from anchored commercial bulk carriers and tugboats, highlighting the need to understand these noise sources further. Additionally, the growing body of literature on the impacts of anthropogenic noise on the underwater soundscape has generated concern as to the impacts the elevated noise has on marine species. In the Northeast Pacific Ocean, many ecological important species have been declining since the 1970s, specifically Chinook salmon. Other species of fish have demonstrated behaviour changes and modified calling behaviours in the presence of anthropogenic activities, but little work has been done on the impacts of shipping on Chinook salmon. To date, Chinook salmon vocalizations have only minimally been explored with limited information on frequency or amplitude reported. To better understand the impacts of shipping on their vocal behaviour, further understanding of sound production in salmon is required. Sound production in three species of Pacific salmon (Chinook, pink and coho salmon) were evaluated at Big Qualicum Hatchery (chapter 4). Chinook and coho salmon were found to produce air movement, hydrodynamic and pulse sounds, while pink salmon were shown to likely produce all these sounds, but since they were always found in mixed schools with Chinook salmon, sounds could not be definitively tied to pink salmon. Additionally, the impacts of shipping on Chinook salmon movement and behaviour have never been evaluated, but vessel noise and other anthropogenic sources like pile driving have been shown to produce spatial displacement and behavioural changes in other salmonids. Changes in Chinook salmon behaviour in the presence of shipping noise was evaluated using acoustic tags in Cowichan Bay, British Columbia (chapter 5). Significant changes in depth for tagged salmon were observed with increased sound pressure levels and number of AIS-equipped vessel present, while activity levels were only significant with one AIS-equipped vessel present. This chapter represents the first study demonstrating the impacts of increased underwater noise levels on Chinook salmon. Collectively this dissertation highlights the impacts of anchored commercial vessels and tugboats on the underwater soundscape and the influence of shipping noise on Chinook salmon behaviour, demonstrating the importance of developing mitigation methods to help reduce the noise produced by shipping activities to protect ecologically, and culturally important species.