Blue (Balaenoptera musculus) and fin whales (B. physalus) in the Southern Ocean were subjects of extensive whaling industry during the twentieth century. Their current population numbers remain low, making population monitoring using traditional visual surveys difficult. Both blue and fin whales produce low frequency, regularly repeated calls and are suitable for acoustic monitoring. Eight, continuously recording acoustic recorders were deployed off the Western Antarctic Peninsula (WAP) between March 2001 and February 2003. Ranges to calling blue and fin whales were calculated using hyperbolic localization and multipath arrivals up to the distances of 200 and 56km, respectively. Calls of both species had high intensity, blue whales calls had the average source level 189±3dB re: 1µPa at 1m and the average fin whale call source level was 189±4dB re: 1µPa at 1m. Automatic call detection methods were used for analysis of calling blue and fin whale seasonal presence and habitat preferences. Blue whale calls were detected year round, on average 177 days/year, with peak calling in March and April, and a secondary peak in October and November. Fin whale calling rates were seasonal with calls detected between February and June (on average 51 days/year), and a peak in May. During the entire deployment period, detected calls from both species showed negative correlation with sea ice concentrations. Also, baleen whale sounds were recorded during multiple cruises off the Antarctic Peninsula using sonobuoys. Recordings from two fall cruises off the WAP were used for analyses of habitat preferences of calling blue and fin whales. The presence of calling blue whales was positively correlated with bottom depth and sea surface temperature, and negatively correlated with krill biomass in the top 100m and abundance of the rest of the zooplankton at depth (101–300m). Locations of fin whale calls were associated with a deep trough area and high Chl-a concentrations. Distribution of baleen whale calls recorded in the Scotia Sea (east of the Antarctic Peninsula) indicated that fin whales occur in open water, and blue, southern right (Eubalaena australis), minke (B. bonaerensis), and humpback whales (Megaptera novaeangliae) occur near islands or close to the ice edge.

Marine fish are a valuable nutritional and economic resource for many communities world- wide. However, many populations have declined due to excessive exploitation and limited regulations. More than 800 species of fish produce sound which enables the use passive acoustic methods to monitor these species. Epinephelids, commonly known as groupers, are a family of fishes that account for a significant percentage of the commercial and artisanal fisheries worldwide but have experienced population declines due to high fishing pressure. Their life-history features, such as long life and formation of spawning aggregations, make them vulnerable to fishing pressure. A number of species within this family produce sound including Nassau grouper (Epinephelus striatus), red hind (E. guttatus), black grouper (Mycteroperca bonaci), and yellowfin grouper (M. venonosa). These four species are common throughout the Caribbean and targeted by fishing. I used passive acoustic data collected in Little Cayman, Cayman Islands from 2013 to 2017 to study the calling and spawning behavior and acoustic communication of these fishes. I applied signal processing and machine learning techniques and passive acoustic localization to reveal information about the calls of these species and their presence at a known Nassau grouper spawning site. I found that Nassau grouper, red hind, and black grouper calls were present all or the majority of the year with peak calling during the spawning season at this location. However, yellowfin grouper calls were scarce. Calling was correlated with lunar phase and, for most species, significantly different between tidal stages. These fishes likely use a combination of time, space, and frequency to partition their acoustic space. Localization enabled observations of small-scale movements during the spawning aggregations of Nassau grouper and red hind at night, a period previously unobserved, and showed that calling ceased for Nassau grouper after sunset and for red hind near sunrise. The first direct source level measurements for these species ranged from 144 to 155 dB re : 1μPa at 1 m. The methods and results that I present can be used to further study, monitor, and manage these species and other sound-producing fishes and may lead to improved or adaptive management strategies.

The acoustic repertoire of the Northeast Pacific population of blue whales (Balaenoptera musculus) consists of three different sounds: A, B, and D calls. The pulsed A and tonal B calls can be produced singularly or in phrases or songs, while downswept D calls are only produced as singular calls. Although these sounds have been well described, the behavioral context of sound production is poorly understood. To investigate spatial and temporal variability in blue whale call and song usage off southern California, passive acoustic data collected from four High-Frequency Acoustic Recording Packages (HARPs) were analyzed. The acoustic and dive profile data collected through tags deployed on blue whales were also analyzed to describe the behavioral context of sound production. Singular call and phrase production rates were calculated to assess variability in sound type abundances on different spatial, temporal and behavioral scales. Distinct differences in song type preference were apparent, with offshore sites featuring songs comprised of multiple sequential B units following a single A, while inshore, A and B units alternated. Most blue whale sounds were produced during the summer and fall. The majority of all sounds produced by tagged blue whales occurred during non-lunging dives at shallow depths (less than 30 m). Song production was associated with shallow, non-lunging dives, while singular calls often occurred during lunging dives or bouts of surface behavior. The observed differences in blue whale acoustic behavior off southern California will aid in the development of context specific rates for future models of density estimation.

Different species of baleen whales display distinct spatial distribution patterns in the Scotia Sea during the austral summer. Passive acoustic and visual surveys for baleen whales were conducted aboard the RRS James Clark Ross in the Scotia Sea and around South Georgia in January and February 2003. Identified calls from four species were recorded during the acoustic survey including southern right (Eubalaena australis), blue (Balaenoptera musculus), fin (B. physalus) and humpback whales (Megaptera novaeangliae). These acoustic data included up calls made by southern right whales, downswept D and tonal calls by blue whales, two possible types of fin whale downswept calls and humpback whale moans and grunts. Visual detections included southern right, fin, humpback and Antarctic minke whales (B. bonaerensis sp.). Most acoustic and visual detections occurred either around South Georgia (southern right and humpback whales) or south of the southern boundary of the Antarctic Circumpolar Current (ACC) and along the outer edge of the ice pack (southern right, blue, humpback and Antarctic minke whales). Fin whales were the exception, being the only species acoustically and visually detected primarily in the central Scotia Sea, along the southern ACC front. In addition to identifiable calls from these species, two types of probable baleen whale calls were detected: 50Hz upswept and pulsing calls. It is proposed that minke whales may produce the pulsing calls, based on their similarities with minke whale calls recorded in the North Atlantic Ocean. There was an overlap between locations of fin whale sightings and recordings and locations of 50Hz upswept calls in the central Scotia Sea, but these calls were most similar to calls attributed to blue whales in other parts of Antarctica. More study is required to determine if baleen whales produce these two call types, and if so, which species. The efficiency of acoustics and visual surveys varied by species, with blue whales being easier to detect using acoustics, Antarctic minke whales being best detected during visual surveys and other species falling in between these two extremes.