Tests of an unmanned airborne system (UAS) for surveys of marine mammals were conducted near Port Townsend, Washington. Sixteen surveys were conducted over a 10-d period to find 128 simulated whale targets (4 to 9 per survey). Various weather conditions were encountered, and searchwidths and altitudes were varied to establish optimal search parameters for future surveys. Logistic regression models were applied to estimate how detection rates were influenced by target color, degree of target inflation, shutter speed, searchwidth, and Beaufort wind force. Beaufort wind force was the strongest predictor of detection rates with color and degree of target inflation also included in the model that best fit these data. Overall detection rates of simulated large whale profiles using UASs were similar to published estimates of detection rates during manned aerial surveys for marine mammals, except the search area was much smaller (narrow strip width) when using the UAS. The best detection rates were obtained when Beaufort wind force was lowest (~ 2). The UAS tested showed promise for replacing manned aerial surveys for monitoring distribution and abundance of large marine mammals; however, improvements are required before the UAS would be an efficient tool for detection of all species. Side-by-side comparisons are needed between the UAS and manned aircraft to evaluate any differences in detection rates from the two platforms.

Traditional methods of acquiring mass data limit the ability to collect large samples from across populations of some pinnipeds, or to sample without great disturbance to the animals. In order to collect substantial samples of mass data from the Weddell seal (Leptonychotes weddellii) population in Erebus Bay, Antarctica, we developed the equipment and methods for estimating the mass of Weddell seals using digital photographs. Resulting regression models predict the mass of adult female seals to within ±13.8% of estimated mass, and ±25.9% of estimated mass for pups. We show the protocols developed are repeatable and efficient enough to be applied to a large number of animals in a relatively short period of time and may be useful for studies of other marine mammals. We caution that prediction intervals exist around mass estimates and must be accounted for when estimates are applied to biological questions. In a limited application of the method, differences in mass transfer between experienced and inexperienced maternal females and their pups were detected when prediction error variance around mass estimates was explicitly included. Similar mass-estimation methods may therefore be useful in consideration of biological questions requiring large samples of mass previously unattainable.

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Concerns about the potential environmental impacts of geophysical surveys using air gun sources, coupled with advances in geophysical surveying technology and data processing, are driving research and development of commercially viable alternative technologies such as marine vibroseis (MV). MV systems produce controllable acoustic signals through volume displacement of water using a vibrating plate or shell. MV sources generally produce lower acoustic pressure and reduced bandwidth (spectral content) compared to air gun sources, but to be effective sources for geophysical surveys they typically produce longer duration signals with short inter-signal periods. Few studies have evaluated the potential effects of MV system use on marine fauna. In this desktop study, potential acoustic exposure of marine mammals was estimated for MV and air gun arrays by modeling the source signal, sound propagation, and animal movement in representative survey scenarios. In the scenarios, few marine mammals could be expected to be exposed to potentially injurious sound levels for either source type, but fewer were predicted for MV arrays than air gun arrays. The estimated number of marine mammals exposed to sound levels associated with behavioral disturbance depended on the selection of evaluation criteria. More behavioral disturbance was predicted for MV arrays compared to air gun arrays using a single threshold sound pressure level (SPL), while the opposite result was found when using frequency-weighted sound fields and a multiple-step, probabilistic, threshold function.

The fin whale (Balaenoptera physalus), humpback whale (Megaptera novaeangliae), and minke whale (Balaenoptera acutorostrata) are known to occur in the New York Bight (NYB). The primary North Atlantic feeding grounds for these large whale species are commonly recognized to be further north in waters of the Gulf of Maine, eastern Canada, West Greenland, and the eastern North Atlantic (e.g., Iceland, Norway, Ireland, Scotland). Although much is known about their feeding activities in the North Atlantic, relatively little is known about their occurrence and foraging behaviors in mid-Atlantic regions such as the NYB. Understanding how large whales utilize NYB waters is important to evaluate potential impacts from direct (e.g., offshore development, vessel strikes, entanglements) and indirect (e.g., rising ocean temperatures) anthropogenic sources. The New York State Department of Environmental Conservation funded a 3-year baseline monitoring program (2017-2020) which conducted monthly line-transect aerial surveys focused on large whales. Over 3 years, 36 surveys comprised of 263 flights and totaling 688.3 hours of observation time along 140,370 km of over-water flight path were completed. Aerial survey observers documented foraging events for the fin, humpback, and minke whales, including mixed-species aggregations, and analyzed other parameters such as distance from shore, distribution zones, and presence of fish schools. Foraging behavior was observed for 27% of the recorded fin whale sightings, 40% of the recorded humpback whale sightings, and 18% of the recorded minke whale sightings. Sighting rates of foraging whales were highest for humpback whales (4.4 whales/1,000 km of effort), followed by fin whales (0.6 whales/1,000 km effort) and minke whales (0.1 whales/1,000 km of effort), and varied by season, year, and distribution zone. In addition, nearly 5,700 fish schools were recorded with fish presence highest during summer and fall.