Leila T. Hatch

Many fish species are suspected to produce sound, but the variety of sounds they produce is still largely undocumented. This study investigated the presence and diversity of fish sounds in the Channel Islands National Marine Sanctuary. Besides regular sounds from three known species—bocaccio (Sebastes paucispinis), plainfin midshipman (Porichthys notatus), and white seabass (Atractoscion nobilis)—two unusual sound types were observed that require further analyses and for which the species is still unknown: Unidentified Fish or UF200 and UF450. Sound types had distinct acoustic signatures and varied in diel presence. Monitoring fish sounds is a promising technique for non-invasive monitoring of fish presence with conservation applications.

Marine vessels are mandated or requested to reduce speed to meet operational, economic, and conservation goals. Vessel speed reduction (VSR) is a key strategy in global efforts to reduce ocean noise. Many regional VSR programs incorporate underwater acoustic monitoring to assess reductions in underwater radiated noise (URN) from vessels. Drawing from North American VSR programs, approaches to measuring URN reduction are assessed and progress toward robust metrics, scalable methods, and integrative measures are documented. Improved alignment across programs is recommended across programs to achieve measurement comparability to advance VSR evaluation and contribute to global underwater noise reduction and sustainable shipping goals.

Models of the underwater acoustic soundscape are important for evaluating the effects of human generated sounds on marine life. The performance of models can be validated against measurements or verified against each other for consistency. A verification workshop was held to compare models that predict the soundscape from wind and vessels and estimate detection ranges for a submerged target. Eight modeling groups participated in the workshop which predicted sound levels with observation windows of 1 min and 1 km2. Substantial differences were found in how modelers computed the propagation losses for decidecade bands and estimated the source level of wind. Further investigations resulted in recommendations on best practices. Choices of temporal and spatial modeling resolution affected the estimates of metrics proportional to total sound energy more than distributions of sound pressure level. Deeper receivers were less sensitive to these parameters than shallow ones. A temporal resolution of 1 min and spatial resolution of 100 m is recommended. Models that follow the recommendations will yield similar results. The detection range of underwater targets is highly variable when the ambient noise depends on moving noise sources. Future work to verify models against data and understand model uncertainty is recommended.

Protected areas are typically managed as a network of sites exposed to varying anthropogenic conditions. Managing these networks benefits from monitoring of conditions across sites to help prioritize coordinated efforts. Monitoring marine vessel activity and related underwater radiated noise impacts across a network of protected areas, like the U.S. National Marine Sanctuary system, helps managers ensure the quality of habitats used by a wide range of marine species. Here, we use underwater acoustic detections of vessels to quantify different characteristics of vessel noise at 25 locations within eight marine sanctuaries including the Hawaiian Archipelago and the U.S. east and west coasts. Vessel noise metrics, including temporal presence and sound levels, were paired with Automatic Identification System (AIS) vessel tracking data to derive a suite of robust vessel noise indicators for use across the network of marine protected areas. Network-wide comparisons revealed a spectrum of vessel noise conditions that closely matched AIS vessel traffic composition. Shifts in vessel noise were correlated with the decrease in vessel activity early in the COVID-19 pandemic, and vessel speed reduction management initiatives. Improving our understanding of vessel noise conditions in these protected areas can help direct opportunities for reducing vessel noise, such as establishing and maintaining noise-free periods, enhancing port efficiency, engaging with regional and international vessel quieting initiatives, and leveraging co-benefits of management actions for reducing ocean noise.

Chorusing is widespread across the animal kingdom. Animal calling behavior is often driven by phenological and environmental factors such as seasonality, lunar period, and temperature. Now, in the Anthropocene, factors such as increased anthropogenic noise levels are also affecting calling behavior. Many fish call in choruses to attract mates, but the dynamics that drive fish calling behavior have rarely been studied in the field. We investigated how seasonality, lunar period, ambient noise, and temperature influenced the calling behavior of two species of toadfish, the plainfin midshipman ( Porichthys notatus ) and putatively, the Atlantic midshipman ( Porichthys plectrodon ). Acoustic recordings from a two-year period in twelve different locations, spanning two ocean basins showed that midshipman chorus presence was driven by seasonality and lunar period. Furthermore, chorus frequency increased with increasing temperature. Chorus levels were strongly influenced by seasonality and increased somewhat with increasing noise levels. Taken together, these results indicate that midshipman calling behavior was strongly influenced by interacting environmental conditions. Understanding the various impacts of each driver will facilitate predictions of changes in midshipman calling due to future changes in environmental conditions.

Effective fishery management measures to protect fish spawning aggregations require reliable information on the spatio-temporal distribution of spawning. Spawning closures have been part of a suite of fishery management actions to rebuild the Gulf of Maine stock of Atlantic cod (Gadus morhua), but difficulties remain with managing rebuilding. The objective of this study was to identify the spatial and temporal distribution of cod spawning during winter in Massachusetts Bay to improve our understanding of cod spawning dynamics and inform fisheries management. Spawning was investigated in collaboration with commercial fishermen during three winter spawning seasons (October 2013–March 2016) using acoustic telemetry and passive acoustic monitoring equipment deployed in fixed-station arrays and mounted on mobile autonomous gliders. Tagged cod exhibited spawning site fidelity and spawning primarily occurred from early November through January with a mid-December peak and some inter-annual variability. The spatial distribution of spawning was generally consistent among years with multiple hotspots in areas >50 m depth. Current closures encompass most of spawning, but important areas are recommended for potential modifications. Utilizing multiple complementary technologies and deployment strategies in collaboration with commercial fishermen enabled a comprehensive description of spawning and provides a valuable model for future studies.

The effects of prolonged exposure to increasing levels of anthropogenic noise on populations of acoustic signalers are a topic of considerable scientific concern and research focus. Although there is mounting literature on the topic, studies to date have largely focused on terrestrial animals and marine mammals. Low-frequency ocean noise has dramatically increased in the past few decades in certain ocean areas, some of which are important habitats for a number of threatened or endangered marine organisms. One of these areas is Stellwagen Bank National Marine Sanctuary (SBNMS), located off the northeast coast of the US and in close proximity to a densely populated coastal zone. Using autonomous acoustic recorders, we investigated the extent and patterns of acoustic behavior in a number of soniferous fishes in several different bottom types within SBNMS. Our results showed significant daily, lunar and spatial patterns in the total number of fish vocalizations and vocalization types. These results were then used to take the first steps in assessing the effective calling radius for Atlantic cod. Identifying and better understanding the implications of anthropogenic noise at lower trophic levels is important to advancing the management of this pollutant both within the sanctuary, and globally.

To increase understanding of the potential effects of chronic underwater noise in US waters, the National Oceanic and Atmospheric Administration (NOAA) organized two working groups in 2011, collectively called “CetSound,” to develop tools to map the density and distribution of cetaceans (CetMap) and predict the contribution of human activities to underwater noise (SoundMap). The SoundMap effort utilized data on density, distribution, acoustic signatures of dominant noise sources, and environmental descriptors to map estimated temporal, spatial, and spectral contributions to background noise. These predicted soundscapes are an initial step toward assessing chronic anthropogenic noise impacts on the ocean’s varied acoustic habitats and the animals utilizing them.