Date of Award

2021

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Rycyk, Athena

Area of Concentration

Marine Biology

Abstract

Cetaceans are often found far offshore and require continuous observation, making them difficult to study using traditional methods. To combat these difficulties, we used a passive acoustic monitoring dataset from a bottom-mounted hydrophone (average depth: 391.67 m) deployed by Ocean Networks Canada near Barkley Canyon off the West Coast of Vancouver Island, Canada, to determine when various cetacean species were present. Each cetacean’s presence was based on the detection of their vocalizations in time-stamped recordings from the first four days of each month in 2014, though additional data from 2013-2014 was used for killer whales. The main call types detected were tonal calls from humpback whales (Megaptera novaeangliae), B calls from blue whales (Balaenoptera musculus), 20 Hz calls from fin whales (Balaenoptera physalus), and pulsed calls from killer whales (Orcinus orca). Humpback whales were present (heard) year-round, with a peak vocal presence in December. Blue whales were present in February and from September-December, with a peak presence in October. Fin whales were present from January-May and August-December, with a peak presence in January. In 2013, killer whales were present from May-August with a peak presence in August. In 2014, killer whales were present from January-April, July, September, and December with a peak presence in September. Sperm whales (Physeter macrocephalus) were present from February-October with a peak presence in May. Sperm whales were also found to vocalize most often between 00:00-13:00. We discuss factors that may influence the seasonal patterns in presence for each species, such as seasonal migration, peaks in productivity or prey movement, and the differences between each stock/ecotype. Understanding when cetaceans are present near Barkley Canyon aids conservation efforts by identifying habitats that are important and adds to our understanding of each species phenology and vocal behavior. We also discuss the sampling volumes this study encompassed.

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