Presence Of Marine Mammals Research Articles

Process-based balance of system cost modeling for offshore wind power plants in the United States

This paper describes the development of a process-based and open-source balance of system cost model that provides the capability to evaluate both existing and novel offshore wind technologies. Individual design and installation steps are represented with bottom-up engineering models that compute times and costs associated with the process; furthermore, operational constraints are assigned to each process so that delays caused by weather and presence of marine mammals may be accounted for in the overall project timeline. The model structure, assumptions, inputs, and results are vetted with industry partners and compared against actual projects for validation. Installation times show reasonable agreement with real data. Project cost sensitivities are investigated to compute the system-level impact of different design choices. First, individual vessel efficiencies are computed for varying numbers of installation vessels and weather time series to show the diminishing returns of more than two feeder barges. Then, array cable capital costs and installation times are determined for a representative project with different turbine sizes. These values quantify the cost-benefit tradeoffs and show a net-cost savings of decreasing numbers of turbines, increased turbine spacing, and fewer turbine terminations. These results demonstrate that the balance of system model features the accuracy, functionality, and accessibility to serve as the foundation for a wide range of analyses to identify cost reduction potentials for offshore wind energy in the United States.

Distribución potencial de mamíferos marinos durante el verano austral en el Golfo San Jorge, Argentina

El Golfo San Jorge (GSJ) es una región oceanográfica importante debido a la influencia de dos frentes de marea, siendo uno de los sectores más productivos y con alta biodiversidad marina del Mar Argentino. El objetivo de este estudio fue identificar cuáles variables oceanográficas explican la presencia de mamíferos marinos y explorar el solapamiento de la riqueza predicha con las áreas frontales del GSJ durante el verano austral. La distribución potencial de las 9 especies (Balaenoptera sp., Cephalorhynchus commersonii, Globicephala melas, Grampus griseus, Lagenorhynchus australis, L. obscurus, Mirounga leonina, Orcinus orca, Otaria flavescens) fue modelada con Maxent utilizando 6 variables ambientales (batimetría, pendiente del fondo marino, distancia a la costa, distancia al frente de marea, temperatura superficial y concentración de clorofila). Los mamíferos marinos se encontraron más cerca de las áreas frontales que al azar (9,48 km y 13,34 km, respectivamente). La profundidad, la distancia a la costa y la pendiente fueron las variables más importantes en la distribución de todas las especies. Balaenoptera sp., G. melas, G. griseus, L. australis y O. orca mostraron una distribución costera (< 10 km), principalmente al noroeste del golfo. M. leonina, O. flavescens y C. commersonii siguieron la isobata de los 80 m, mientras que L. obscurus se distribuyó en todo el golfo. Las áreas de mayor riqueza predicha se solaparon un 75% con las áreas frontales localizadas al noroeste y sudeste del golfo. Este trabajo provee información de base para el diseño de futuros muestreos que pueden explicar la influencia de los procesos y variación estacional de la distribución de los mamíferos marinos del GSJ.

Bowhead whale acoustic detection probability and spatial density of calls in ice-free and ice-covered Arctic waters

Estimation of Arctic marine mammal presence and acoustic density from passive acoustic monitoring is complicated by effects of the environment and noise levels on sound propagation and the detection of calls. We used acoustic modeling and detection simulations to estimate site-specific transmission loss for sounds produced by bowhead whales in the northeast Chukchi Sea at two sites, outer shelf and continental slope, with and without sea ice cover at various ocean noise levels. A time series of hourly acoustic detection probability was produced for the two recording sites between 2012 and 2013 from modeled transmission loss for daily sea ice state and hourly average noise levels. We applied the detection probability to recorded bowhead whale call detections to correct for effects of ice cover and noise level. Corrected acoustic presence suggests a decrease in detectable calls within a 40 km radius of the recording sites with arrival of open water while the uncorrected detections increase or change little. When sea ice state is constant, substantial variability in acoustic presence tracks closely with changing noise levels. These results highlight the importance of incorporating effects of the environment and changing noise levels when interpreting results of passive acoustic monitoring.

Acoustic detections of Arctic marine mammals near Ulukhaktok, Northwest Territories, Canada

The Arctic marine environment is changing rapidly through a combination of sea ice loss and increased anthropogenic activity. Given these changes can affect marine animals in a variety of ways, understanding the spatial and temporal distributions of Arctic marine animals is imperative. We use passive acoustic monitoring to examine the presence of marine mammals near Ulukhaktok, Northwest Territories, Canada, from October 2016 to April 2017. We documented bowhead whale (Balaena mysticetus Linnaeus, 1758) and beluga whale (Delphinapterus leucas (Pallas, 1776)) vocalizations later into the autumn than expected, and we recorded bowhead whales in early April. We recorded ringed seal (Pusa hispida (Schreber, 1775)) vocalizations throughout our deployment, with higher vocal activity than in other studies and with peak vocal activity in January. We recorded bearded seals (Erignathus barbatus (Erxleben, 1777)) throughout the deployment, with peak vocal activity in February. We recorded lower bearded seal vocal activity than other studies, and almost no vocal activity near the beginning of the spring breeding season. Both seal species vocalized more when ice concentration was high. These patterns in vocal activity document the presence of each species at this site over autumn and winter and are a useful comparison for future monitoring.

The feasibility of a multipurpose acoustic network in Baffin Bay

Operating autonomous underwater vehicles at high latitudes is a challenge because ice cover prevents the use of GPS or data communications. As a result, our scientific observations are biased towards late spring, summer, and early autumn when ships can navigate and autonomous platforms can safely surface. To address this problem, we studied the feasibility of a basin-scale multipurpose acoustic network called the “Baffin Bay Acoustic Navigation and Communication System” (BBANC). BBANC would deploy broadband low frequency sources and receivers, offering one-way communication, acoustic positioning, and acoustic thermometry services. Passive acoustic listening elements would support the study of marine mammal communication and ambient noise from ships, ocean-based resource exploitation, and ice dynamics, as well as gate acoustic source operation in the presence of marine mammals. We describe the challenges and design parameters for such a system, as well as define additional acoustic and remote sensing measurements required to complete a system design. Drawing from a large database of Baffin Bay hydrography, we present simulations of under-ice sound speed conditions, ice properties derived from satellite remote sensing and upward looking sonar data, and modelled acoustic propagation paths in an ice-covered Baffin Bay. We also assess the feasibility of non-coherent and coherent communication.

Seasonal patterns in marine mammal vocalizations in the western Canadian Arctic

The Arctic marine environment is changing rapidly through a combination of sea ice loss and increased anthropogenic activity. Given that these changes can affect marine animals in a variety of ways, understanding the spatial and temporal distributions of Arctic marine animals is imperative. Here, we use passive acoustic monitoring to examine the presence of marine mammals in the western Canadian Arctic, where we have had recorders deployed near the communities of Sachs Harbour and Ulukhaktok, Northwest Territories, Canada. At both sites, we documented bowhead and beluga whales during the ice-free season, bearded seals throughout the ice-covered season and during their mating season, and ringed seals throughout the year. The sites also had different patterns in marine mammal presence, where we found whales later into the year at Ulukhaktok than at Sachs Harbour, and ringed seals vocalized much more at Ulukhaktok than at Sachs Harbour. These patterns in vocal activity at both sites help to document the presence of each species in the western Canadian Arctic, and serve as a baseline for future monitoring in the region. Next steps in this project involve deploying at more sites throughout the region to more comprehensively monitor marine mammals in the region.

Italy introduces pre and post operation monitoring phases for offshore seismic exploration activities

Concern is growing that marine fauna can be affected by noise such as naval sonar, pile driving or geophysical surveys, among others. Literature reports a variety of animal reactions to human noise (from apparently null or negligible to strong). However, conclusive results on its effects on marine mammals at individual and population level are still lacking. In 2015, the Italian Environmental Impact Assessment Commission mandated seismic operators apply a standard scientific protocol comparing marine mammal presence before, during, and after offshore seismic survey. For 60days before and after the survey, marine mammals are monitored using visual and acoustic methods. One or more acoustic autonomous recorders, depending on area size, must also be deployed throughout the three phases for continuous monitoring. Consistent data gathered from many surveys will enable robust statistical analysis of results. Diffusion of this monitoring method internationally would improve the study of far-reaching, intense, low frequency noise.

Seasonal Trends in Acoustic Detection of Marine Mammals in Baffin Bay and Melville Bay, Northwest Greenland + Supplementary Appendix 1 (See Article Tools)

The expansion of hydrocarbon exploration in northwest Greenland has made it increasingly important to understand the occurrence of marine mammals in the region. We describe the seasonal occurrence of marine mammals and the spatial distribution of their calls in Baffin Bay and Melville Bay. Four Autonomous Multichannel Acoustic Recorders (AMARs) were deployed during summer 2012 (late July to early October), five recorders during September 2013, and two recorders from late September 2013 to early September 2014. The call presence of several species was analyzed using automatic call detection and manual verification analysis methods. A novel approach to discern narwhal (Monodon monoceros) clicks from beluga (Delphinapterus leucas) clicks was implemented during the verification process. Narwhal calls were detected in spring and fall, showing a south-to-north migration pattern in spring and a north-to-south migration pattern in fall. Few beluga whales were detected during fall 2013 and spring 2014. Bearded seal (Erignathus barbatus) calls were detected mainly during spring (mating period). A small number of bowhead whale calls (Balaena mysticetus) were detected during fall 2013 and spring and summer 2014. For the first time at this latitude in Baffin Bay, long-finned pilot whales (Globicephala melas) and sperm whales (Physeter macrocephalus) were detected during summer and fall. Our results suggest that the presence of marine mammals in Baffin Bay and Melville Bay is governed mainly by the annual cycle of sea ice formation and decay.

Seasonal marine mammal occurrence detected from passive acoustic monitoring in Scott Inlet, Nunavut, Canada

Monitoring Arctic wildlife is important due to the increasing potential impact of environmental and industrial changes. Passive acoustic monitoring (PAM) can be an important tool for wildlife management through observations of several species simultaneously along with abiotic elements such as industrial activity. Here, we use PAM methods to monitor the occurrence of marine mammals over an 8-month period (Oct 2012–May 2013) in Scott Inlet, Nunavut. When marine mammals were present, we investigated possible environmental correlates. Sea ice coverage strongly influenced detections of marine mammal sounds: narwhals and bowhead whales were only present before full ice cover occurred in the fall, while bearded seals and walruses could only be detected after ice formation. Tidal phase, time of the day, water temperature at 300 m depth, and air temperature all influenced detections of narwhal clicks. This PAM study provides a baseline measure for the presence of marine mammals over the fall to spring in Scott Inlet. Long-term PAM in the same location would allow us to document changes in the phenology of marine mammals at this site in relation to environmental changes.

Relative abundance of sound scattering organisms in the Northwestern Hawaiian Islands is a driver for some odontocete foragers

Previous studies in the Northwestern Hawaiian Islands (NWHI) focused on shallower communities in and near reefs and did not investigate the organisms living in deeper waters that some apex predators rely on for food, e.g., some odontocetes forage at depths greater than 400 m. To examine the relationship between deep-diving odontocete predators and prey, a Simrad EK60 echosounder operating at 70 kHz collected acoustic abundance throughout the NWHI from May 7 to June 4, 2013. Visual and passive acoustic surveys for marine mammal presence were conducted concurrently with the echosounder. Two broad scattering layers were found, a deep layer from 325 to 670 m and a shallow layer from 0 to 195 m. The highest densities of both deep and shallow scattering organisms were associated with deep slopes of banks and atolls. Beaked and short-finned pilot whale sightings occurred in locations of high scattering density associated with slopes of atolls and banks. It is hypothesized that the high scattering organisms associated with these features are similar to the mesopelagic boundary community found in the Main Hawaiian Islands and support a food web representing the prey of the cetaceans.

Monitoring and impact mitigation during a 4D seismic survey near a population of gray whales off Sakhalin Island, Russia

A 4D seismic survey was conducted in 2010 near the feeding grounds of gray whales off Sakhalin Island, Russia. To minimize disruptions to the whales’ feeding activity and enhance understanding of the potential impacts of seismic surveys on gray whales Eschrichtius robustus, an extensive monitoring and mitigation plan (MMP) was developed. Typically, mitigation plans involve observers on seismic vessels to monitor for the presence of marine mammals in an exclusion zone so as to prevent physical injury to the animals. Due to the protected status of western gray whales, an additional protection zone based on a behavioural disturbance threshold of exposure of 156 dB re μPa2-s per pulse was applied for whales within their feeding habitat defined by the estimated 95% abundance contour. Real-time radio-transmitting acoustic recorders were deployed along this contour to verify modelled acoustic footprints within the feeding grounds. Shore- and vessel-based observation teams monitored for the presence and activity of whales. A real-time GIS workflow tracking procedure was developed that integrated acoustic and whale positioning data to determine if sound levels at a whales’ position within the feeding area exceeded the behavioural threshold, in which case a shut-down of the seismic source was implemented. Additionally, behaviour and distribution surveys were conducted before, during and after the seismic survey to evaluate the effectiveness of the MMP. No large changes in whale movement, respiration, or distribution patterns were observed during the seismic survey. This could be interpreted to mean that the MMP was effective in reducing the sound exposure and behavioural responses of gray whales to seismic sounds. KEY WORDS: Seismic · Mitigation · Western gray whale · Eschrichtius robustus · Sakhalin · Piltun · Sea of Okhotsk · Anthropogenic disturbance

Passive acoustic monitoring and ambient noise in the high Arctic: Resolute Bay, Nunavut

Resolute Bay, a remote bay in the Canadian High Arctic to the north of Parry Channel, hosts diverse populations of marine mammals that migrate through the bay each year following food availability and/or oceanographic conditions. The changing climate combined with increasing anthropogenic activity in the Arctic make it important to create an ecosystem baseline from which to predict, understand, and monitor future changes. Passive underwater acoustic observations provide a non-invasive way to monitor marine mammal presence. Broadband noise (10 Hz to 48 kHz) was recorded by an Autonomous Marine Acoustic Recorder (AMAR) and marine mammal click detections were logged by two CPODs over a 5 month period from August to December 2013. Acoustic data were processed with click and tonal call detectors to determine marine mammal presence. Resolute Bay is ice-covered 10 months a year, leading to increased broadband ambient noise levels due to ice movement. During the short open-water period, vessel activity is common in the bay. The aim is to compare these two different ambient noise regimes and how they affect the effectiveness of passive acoustic marine mammal detections and tracking.

Marine mammal acoustic detections in the northeastern Chukchi Sea, September 2007–July 2011

Several cetacean and pinniped species use the northeastern Chukchi Sea as seasonal or year-round habitat. This area has experienced pronounced reduction in the extent of summer sea ice over the last decade, as well as increased anthropogenic activity, particularly in the form of oil and gas exploration. The effects of these changes on marine mammal species are presently unknown. Autonomous passive acoustic recorders were deployed over a wide area of the northeastern Chukchi Sea off the coast of Alaska from Cape Lisburne to Barrow, at distances from 8km to 200km from shore: up to 44 each summer and up to 8 each winter. Acoustic data were acquired at 16kHz continuously during summer and on a duty cycle of 40 or 48min within each 4-h period during winter. Recordings were analyzed manually and using automated detection and classification systems to identify calls.Bowhead (Balaena mysticetus) and beluga (Delphinapterus leucas) whale calls were detected primarily from April through June and from September to December during their migrations between the Bering and Beaufort seas. Summer detections were rare and usually concentrated off Wainwright and Barrow, Alaska. Gray (Eschrichtius robustus) whale calls were detected between July and October, their occurrence decreasing with increasing distance from shore. Fin (Balaenoptera physalus), killer (Orcinus orca), minke (Balaenoptera acutorostrata), and humpback (Megaptera novaeangliae) whales were detected sporadically in summer and early fall. Walrus (Odobenus rosmarus) was the most commonly detected species between June and October, primarily occupying the southern edge of Hanna Shoal and haul-outs near coastal recording stations off Wainwright and Point Lay. Ringed (Pusa hispida) and bearded (Erignathus barbatus) seals occur year-round in the Chukchi Sea. Ringed seal acoustic detections occurred throughout the year but detection numbers were low, likely due to low vocalization rates. Bearded seal acoustic detections peaked in April and May during their breeding season, with much lower detection numbers in July and August, likely as a result of reduced calling rates after breeding season. Ribbon seals (Histriophoca fasciata) were only detected in the fall as they migrated south through the study area toward the Bering Sea. These results suggest a regular presence of marine mammals in the Chukchi Sea year-round, with species-dependent seasonal and spatial density variations.

Challenges of using passive acoustic monitoring for marine mammals during anthropogenic activities.

Monitoring the presence of marine mammals in the vicinity of an anthropogenic activity using passive sonar can greatly improve detection rates by visual monitoring, and it is the only way to detect marine mammals at large distances during nighttime monitoring. Therefore, passive acoustic monitoring (PAM) is sometimes required by regulatory agencies as a mean to supplement visual monitoring during anthropogenic activities that may potentially adversely affect marine mammals. However, there are many critical aspects that need to be taken into consideration when prescribing PAM to support mitigation measures. These challenges include (1) training for shipboard observers to operate and maintain sophisticated PAM hardware and software; (2) proper design of PAM system that works well during industrial operations (such as seismic vessels); (3) reliable bearing and ranging of calling of animals, thus providing basis for mitigation measures; and (4) the affordability of PAM system to small businesses. This presentation provides a comprehensive analysis on the above aspects that are essential for marine mammal passive acoustic monitoring during anthropogenic activities, and highlights future needs to improve and expands PAM as a standard technique to support mitigation measures to reduce anthropogenic impacts.

North Atlantic right whale seasonal presence off the coast of New Jersey: Confirmation by passive acoustic monitoring and ship survey data.

North Atlantic right whales (NARW) are one of the most critically endangered marine mammals with abundance estimates for the North Atlantic population at about 438 individuals cataloged in 2008. Data presented here were part of a larger, long-term study to assess presence of marine mammals, sea turtles, and birds along the New Jersey coast in advance of wind farm development. Seasonal presence of NARW off New Jersey was characterized using static passive acoustic monitoring (PAM) and line-transect shipboard surveys. NARW upcalls were detected on 115 days over 21 months of deployment (March 2008 to December 2009) with a significant difference in number of upcalls detected between PAM stations by month (F-ratio = 3.1292, df = 22, p = 0.000). NARW upcalls were detected from March to June and September to December 2008 and from January to March and in June 2009, with the greatest number of calls detected during spring months annually. Presence of NARW was confirmed by sighting data, with sightings all seasons except summer. Four sightings were recorded: three during November, December, and January when right whales are on calving grounds farther south or in the Gulf of Maine and the fourth sighting was a cow-calf pair in May.

Factors influencing biodiversity and marine animal habitat use in the Bering Sea.

A combination of active and passive acoustic technology was integrated into NOAA oceanographic moorings at two locations on the eastern Bering Sea shelf. Physical, biological, and acoustical oceanographic instruments made synoptic measurements of marine mammal presence, zooplankton/fish concentrations, physical oceanographic processes, primary production, and sound levels from 2008–2009. Synergistic factors influencing biodiversity and marine animal habitat use were investigated. Observed patterns in the central Bering Sea indicate that ecosystem dynamics and the acoustic environment are strongly driven by sea ice. Marine mammal presence and diversity were tightly coupled to sea ice presence. Bowhead whales and ice seals dominated the acoustic soundscape during the winter and spring, whereas geophysical signals dominated during the fall and summer months. Zooplankton abundance was also tightly linked to ice coverage. Time series of acoustic backscattering strength during the winter months indicated that the zooplankton community rapidly responds to short period of open water at a level that equals or exceeds maximum volume backscatter values at other times of the year. Integrated data such as these will be vital in understanding the relationship between marine mammals, zooplankton, and the physical environment. [Work supported by ONR.]

The Removal of Feral Cats from San Nicolas Island: Methodology

Feral cats are considered one of the most detrimental invasive species within island ecosystems. Non-native feral cats have been on San Nicolas Island (5,896 ha, or 14,562 acres) since at least 1952. In an effort to counter the negative impacts of feral cats on marine and terrestrial birds, the San Nicolas seabird restoration project, with the goal of eradicating cats, was initiated in June 2009. Although aimed at seabird restoration, feral cat eradication is expected to aid in the protection of endemic terrestrial species, including the federally threatened island night lizard, federally threatened western snowy plover, a subspecies of deer mouse, and the state threatened island fox. Methods including the use of altered padded leg-hold live traps, detection dogs, and hunting are being utilized to deliver a successful eradication within a short window of opportunity. In addition, a trap monitoring system, operated in tandem with field PCs and GIS, has proven effective in managing large numbers of traps. Since initiation, a rotation of staff has provided an average of 6 field personnel on-island at any one time to staff the project continuously over 10 months. Eradication was complicated by the similarly sized island fox, rugged topography, restricted access to parts of the island by Navy activities, marine mammal presence on the beaches, and sea and shore birds nesting and roosting. Island eradications require multiple methods to effectively remove all cats, and operations on larger islands benefit from the intensive use of management tools such as GIS. The systems developed on the San Nicolas Seabird Restoration Project will advance the global effort to reduce the threats of invasive species, particularly feral cats.

Qualitative correlation of marine mammals with physical and biological parameters in the ligurian sea

In support of its acoustic risk mitigation policy, NATO SACLANT Undersea Research Centre (SACLANTCEN) is sponsoring a series of sea trials, entitled to collect a multiyear integrated oceanographic, biological, and hydrographic data set, the goal being to explain, based on these parameters, the distribution of marine mammals found in specific locations. By understanding how ocean dynamics affects the distribution and behavior of whales and the organisms forming the food web upon which the whales feed, it may be possible to conduct acoustic exercises in areas of low cetacean density. The first two Sirena multidisciplinary cruises were conducted in the Ligurian Sea in late summer time frame during 1999 and 2000. The focus of this analysis is to determine whether remotely sensed satellite data can indicate nutrient-rich regions in areas where the oceanography is known and to determine if these regions of higher productivity, coupled with knowledge of cetacean presence from all available sources, could be used as an indicator of marine mammal presence for acoustic risk mitigation purposes. For the two years of data examined, cooler sea-surface temperature data correlated with high levels of chlorophyll production as seen by remotely sensed images. This remotely sensed data correlated well with measured subsurface values of the same parameters. Coincident sightings of three species of marine mammals indicated that fin and sperm whales generally preferred the deep, nutrient-rich portion of the basin while Cuvier's beaked whales preferred a submarine canyon where there is a frontal influence, as indicated from satellite data and historical oceanography. This paper is intended as a contribution to the longer term objective of developing the means to accurately predict cetacean presence from physical oceanographic characteristics.