Association patterns and social dynamics of killer whales (Orcinus orca) in Greater Puget Sound

Killer whales were observed in the inland marine waters of Washington and British Columbia from March to November 1982 and January to November 1983. The majority of the research occurred in Haro Strait in the San Juan Islands. All whales were individually identifiable from naturally occurring marks and scars on the dorsal fin and back. Many whales were identified visually in the field with the aid of a photographic guide to individuals (Biggs et al. 1987). Seventy-two whales comprised the study population. Data collection concentrated on group composition and spacing, identification and associations of all whales present, and the recording of the dominant behavior occurring at that time. Behaviors were categorized from combinations of quantifiable parameters of group composition, spacing of individuals, speed and direction of travel, and the occurrence of specific behaviors such as leaps, tail slaps, penile erections, etc. (Osborne 1986). Behaviors were pooled into four major groups: feeding, travel, rest and social/sexual behaviors. The results suggest the following hypothesis about the social organization of the killer whales resident to Greater Puget Sound. As a whale ages, it moves from an integrated position within the community, based on its relationship with its mother to a less integrated period during adolescence in which social ties remain primarily through the older female generation. With full adulthood, dependency upon these “allo-mothers” (N.J. Haenel 1986) declines and direct affiliation with the mothers are re-established. Adult whales remain with the maternal sub-group. Close associations between adult whales appear to be based on relationship between direct kin. Fission from the main material sub-group and the establishment of separate subgroups may be the result of several factors including the age of the older female and the number, ages, and sex of her offspring, including adult sons. When older females die out, siblings or cousins may separate more permanently, forming new lineages or pods

Marine Mammal Tracks from Two-Hydrophone Acoustic Recordings Made with a Glider

A multinational oceanographic and acoustic sea experiment was carried out in the summer of 2014 off the western coast of the island of Sardinia, Mediterranean Sea. During this experiment, an underwater glider fitted with two hydrophones was evaluated as a potential tool for marine mammal population density estimation studies. An acoustic recording system was also tested, comprising an inexpensive, off-the-shelf digital recorder installed inside the glider. Detection and classification of sounds produced by whales and dolphins, and sometimes tracking and localization, are inherent components of population density estimation from passive acoustics recordings. In this work we discuss the equipment used as well as analysis of the data obtained, including detection and estimation of bearing angles. A human analyst identified the presence of sperm whale (Physeter macrocephalus) regular clicks as well as dolphin clicks and whistles. Cross-correlating clicks recorded on both data channels allowed for the estimation of the direction (bearing) of clicks, and realization of animal tracks. Insights from this bearing tracking analysis can aid in population density estimation studies by providing further information (bearings), which can improve estimates

The distribution and abundance of harbour porpoises and other small cetaceans in the North Sea and adjacent waters

To provide accurate and precise estimates of abundance for harbour porpoises and other small cetaceans throughout the North Sea and adjacent waters, an intensive shipboard and aerial sightings survey was conducted in July 1994 as part of project SCANS - Small Cetacean Abundance in the North Sea. New methods of data collection and analysis were developed as part of the project. These methods included estimating g(0) and accounting for animal movement in response to survey ships using data collected from a primary and a tracker platform on each ship, and estimating g(0) for the aerial survey using data collected from two aircraft flying in tandem (one behind the other). The survey area included the North Sea (including waters north to 62°N), Skagerrak, Kattegat, western Baltic Sea, Channel and Celtic Shelf Good weather enabled most of the area to receive excellent survey coverage, but too few data for analysis were collected in the Western Baltic. The three most commonly sighted species were harbour porpoises, whitebeaked dolphins and minke whales. Harbour porpoises were distributed throughout most of the North Sea, Skagerrak, Kattegat and Celtic Shelf. None were seen in the southern tip of the North Sea or the Channel. Whitebeaked dolphins were concentrated between 55° and 60°N, particularly in the western North Sea. Minke whales were seen mostly north of 55°N, particularly in the western North Sea, and on the Celtic Shelf. Common dolphins were seen almost exclusively on the Celtic Shelf. Other small cetacean species encountered in small numbers included whitesided dolphins, bottlenose dolphins, striped dolphins, Risso's dolphins, killer whales and pilot whales. Estimates of abundance for the entire survey area using the new methodology are 352,523 (CV=0.14) [95% Cl: 267,000- 465,000] harbour porpoises, 7,856 (CV=0.30) [95% Cl: 4,000- 13,300] whitebeaked dolphins, and 8,445 (CV=0.24) [95% Cl: 5,000- 13,500] minke whales

Application of Density Estimation Methods to Datasets Collected from a Glider

Ocean gliders can provide an inexpensive alternative for marine mammal population density studies. Gliders can monitor bigger spatial areas than fixed passive acoustic recorders. It is a low-noise, low-speed platform, easy to set up, maneuver, and transport on land, deploy, and recover. They can be deployed for long periods and report near real-time results through Iridium modem. Furthermore, gliders can sense the environmental conditions of the survey area, which are important for estimating detection distances. The main objective of this work is to evaluate the use of ocean gliders for population density estimation. Current methodologies developed for fixed sensors will be extended to these platforms by employing both simulations and real experimental data. An opportunistic preliminary sea trial conducted in June 2014 allowed for testing of a Slocum glider fitted with an inexpensive acoustic recording system comprising of two hydrophones connected to an off-the-shelf voice recorder installed inside the glider. Acoustic data recorded in deep waters (\u3e1500 m) off the western coast of Sardinia, Mediterranean Sea, showed the presence of sperm whale echolocation clicks. An improved experiment is planned for the summer 2015. Preliminary results of both campaigns will be presented with an emphasis on population density estimation