Erratum to: Characterizing the Relative Contributions of Large Vessels to Total Ocean Noise Fields: A Case Study Using the Gerry E. Studds Stellwagen Bank National Marine Sanctuary (original) (raw)
Related papers
Environmental Management, 2008
In 2006, we used the U.S. Coast Guard’s Automatic Identification System (AIS) to describe patterns of large commercial ship traffic within a U.S. National Marine Sanctuary located off the coast of Massachusetts. We found that 541 large commercial vessels transited the greater sanctuary 3413 times during the year. Cargo ships, tankers, and tug/tows constituted 78% of the vessels and 82% of the total transits. Cargo ships, tankers, and cruise ships predominantly used the designated Boston Traffic Separation Scheme, while tug/tow traffic was concentrated in the western and northern portions of the sanctuary. We combined AIS data with low-frequency acoustic data from an array of nine autonomous recording units analyzed for 2 months in 2006. Analysis of received sound levels (10–1000 Hz, root-mean-square pressure re 1 μPa ± SE) averaged 119.5 ± 0.3 dB at high-traffic locations. High-traffic locations experienced double the acoustic power of less trafficked locations for the majority of the time period analyzed. Average source level estimates (71–141 Hz, root-mean-square pressure re 1 μPa ± SE) for individual vessels ranged from 158 ± 2 dB (research vessel) to 186 ± 2 dB (oil tanker). Tankers were estimated to contribute 2 times more acoustic power to the region than cargo ships, and more than 100 times more than research vessels. Our results indicate that noise produced by large commercial vessels was at levels and within frequencies that warrant concern among managers regarding the ability of endangered whales to maintain acoustic contact within greater sanctuary waters.
Ship-Induced Noise Predictions in the Atlantic and the Pacific: A Comparison of Two Noise Models
2006
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Relationship between ship type and underwater noise emissions
Concerns that shipping noise could affect marine mammals were raised as early as the 1970s. This was based on the observation that there was a considerable band overlap between the spectra of frequencies used by large Baleen Whales and the major components of noise from the propellers of commercial vessels. This is a very serious threat to the species, since they rely almost entirely on sound waves for communication and hunting. Baleen Whales aren’t the only species affected by shipping noise either, the noise has been observed to cause avoidance behaviours and stress in many other species of fish, in addition to interfering with communication. Out of all the frequencies, elevated noise levels that lie in the 10-300 Hz range have the ability to mask biologically generated sounds. With the increase in global shipping over the last few decades, oceanic ambient noise levels have been rising correspondingly. The NOAA has found evidence that underwater sound has been doubling every 10 years with most of the sound being anthropogenic. These increases amount to 20 dB from the pre-industrial era to the modern age. In the vicinity of major shipping routes, increases in noise can be much larger. Propeller cavitation seems to be the predominant noise source on-board maritime vessels and propeller singing can potentially cause emissions of high-pitched noise. Improved propeller design e.g. anti-singing trailing edge, and efficient wake flow may serve to reduce acoustic emissions. For merchant vessels, it is necessary to accept a certain amount of cavitation in the propeller, at present, because designs that eliminate cavitation reduce efficiency drastically. It is probable that, statistically, one-tenth of the noisiest ships generate a major portion of the net impactful noise undersea. In recent times, international policy making bodies have begun taking environmental concerns very seriously, and although there is no internationally accepted standardization document that guides shipbuilders on crafting less noisy vessels yet, there are two important standards that aid underwater noise measurement.
The Journal of the Acoustical Society of America, 2006
Recent measurement at a previously studied location illustrates the magnitude of increases in ocean ambient noise in the Northeast Pacific over the past four decades. Continuous measurements west of San Nicolas Island, California, over 138 days, spanning 2003-2004 are compared to measurements made during the 1960s at the same site. Ambient noise levels at 30-50 Hz were 10-12 dB higher (95% CI=2.6 dB) in 2003-2004 than in 1964-1966, suggesting an average noise increase rate of 2.5-3 dB per decade. Above 50 Hz the noise level differences between recording periods gradually diminished to only 1-3 dB at 100-300 Hz. Above 300 Hz the 1964-1966 ambient noise levels were higher than in 2003-2004, owing to a diel component which was absent in the more recent data. Low frequency (10-50 Hz) ocean ambient noise levels are closely related to shipping vessel traffic. The number of commercial vessels plying the world's oceans approximately doubled between 1965 and 2003 and the gross tonnage quadrupled, with a corresponding increase in horsepower. Increases in commercial shipping are believed to account for the observed low-frequency ambient noise increase. (Recent measurement at a previously studied location illustrates the magnitude of increases in ocean ambient noise in the Northeast Pacific over the past four decades. Continuous measurements west of San Nicolas Island, California, over 138 days, spanning 2003-2004 are compared to measurements made during the 1960s at the same site. Ambient noise levels at 30-50 Hz were 10-12 dB higher ͑95% CI= 2.6 dB͒ in 2003-2004 than in 1964-1966, suggesting an average noise increase rate of 2.5-3 dB per decade. Above 50 Hz the noise level differences between recording periods gradually diminished to only 1 -3 dB at 100-300 Hz. Above 300 Hz the 1964-1966 ambient noise levels were higher than in 2003-2004, owing to a diel component which was absent in the more recent data. Low frequency ͑10-50 Hz͒ ocean ambient noise levels are closely related to shipping vessel traffic. The number of commercial vessels plying the world's oceans approximately doubled between 1965 and 2003 and the gross tonnage quadrupled, with a corresponding increase in horsepower. Increases in commercial shipping are believed to account for the observed low-frequency ambient noise increase.
Understanding vessel noise across a network of marine protected areas
Research Square (Research Square), 2023
Protected areas are typically managed as a network of sites exposed to varying anthropogenic conditions. Managing these networks bene ts from monitoring of conditions across sites to help prioritize coordinated efforts. Monitoring marine vessel activity and related underwater 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 detection of vessels to quantify vessel noise at 25 locations within eight marine sanctuaries including the Hawaiian Archipelago and the U.S. east and west coasts. Vessel noise metrics were paired with Automatic Identi cation 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 tra c composition. Shifts in vessel noise were correlated with the decrease in vessel activity in early COVID-19 pandemic and vessel speed reduction 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 e ciency, engaging with regional and international vessel quieting initiatives, and leveraging co-bene ts of management actions for reducing ocean noise.
Marine Noise Budgets in Practice
Many countries have made statutory commitments to ensure that underwater noise pollution is at levels which do not harm marine ecosystems. Nevertheless , coordinated action to manage cumulative noise levels is lacking, despite broad recognition of the risks to ecosystem health. We attribute this impasse to a lack of quantitative management targets—or " noise budgets " —which regulatory decision-makers can work toward, and propose a framework of risk-based noise exposure indicators which make such targets possible. These indicators employ novel noise exposure curves to quantify the proportion of a population or habitat exposed, and the associated exposure duration. This methodology facilitates both place-based and ecosystem-based approaches, enabling the integration of noise management into marine spatial planning, risk assessment of population-level consequences, and cumulative effects assessment. Using data from the first international assessment of impulsive noise activity, we apply this approach to herring spawning and harbor porpoise in the North Sea.
Management Measures to Reduce Continuous Underwater Noise from Shipping
Swedish Institute for the Marine Environment Report No. 2023:3, 2023
Underwater radiated noise (URN) from commercial ships is a significant source of elevated noise levels in the oceans and can have a negative impact on marine wildlife. Noise from commercial shipping places additional stress on the oceans, but is one of the least studied environmental pollutants, and there is an urgent need to reduce the aggregate stress levels. Until recently, reduction of underwater noise has not been prioritised by ship designers, shipowners, or crews. Even within the field of marine management, noise has received limited interest. However, the International Maritime organization (IMO) has adopted global guidelines on URN reduction, which are currently being updated. Within the EU, the Marine Strategy Framework Directive (MSFD 2008/56/EC) Descriptor 11 criteria 11.2, now provides a framework for marine administrators to manage noise by establishing threshold values. Marine management focuses on the total noise load on the marine environment. Management entails several considerations before recommendations can be made. As a first step, interdisciplinary teams need to assess the aggregated noise levels and determine acceptable thresholds based on the local ecosystem, then assess which existing mandates and management tools can be used, and finally assess how effective these mandates have been in improving the environment. These activities must also be managed in a way that is acceptable to various relevant stakeholders, who would need to follow the decisions. The URN from a ship can be affected by the vessel’s design, either during its construction or during upgrades, and balances a trade-off against fuel efficiency. However, the URN can also depend on how the ship is operated. Regulating ship speed is one potential management tool, and its effectiveness needs to be assessed. Other management measures include how shipping lanes are drawn, areas to avoid, financial support, information, etc. This report focuses on possible policy measures that the Swedish authorities could adopt to lower URN by regulating the speed of ships. The report presents an interdisciplinary analysis, using a case study of an area in the southern Kattegat that covered several maritime zones, different national jurisdictions, intensive traffic, and high natural values. An important part of the work was to assess whether existing source models for ship noise could be used for the type of ships that are common in waters around Sweden. In this study, the JOMOPANS-ECHO (J-E) model was used. The J-E model was validated by comparing measurement data from a hydrophone station at Vinga on the Swedish coast that collected data from ships (254 passages) that used the port of Gothenburg. The analysis showed some deviation between the J-E model and measurement data, which could be due to differences in the length and speed of ships in waters around Sweden compared to the ships used in the development of the J-E model. However, this was likely to have negligible impact on the outcome of the case study. Analyses of ship traffic in 2021 showed that 4,511 unique vessels visited the study area at least once. Most ships followed the main routes, but no part of the study area was completely free from ship traffic. About 68% of the ships visited the study area for 1-4 days, while about 32% visited the area more regularly. The most common ship types were General Cargo Ships, Dry Bulk Ships, and Tankers. The ships that on average travelled at highest speeds were RoPax Ships, RoRo Ships, Vehicle Carriers, and Container Ships. The ships were registered in 64 countries. About two percent of the ships were registered in Sweden and about four percent in Denmark. Legal analysis showed that Sweden has the right and the responsibility to take measures to reduce underwater noise from ships to the extent that the noise can be deemed to pollute the marine environment. However, this mainly applies to Sweden’s territorial seas, which cover roughly half the area being studied for this report. In the portion that constitutes Danish territorial sea, Denmark has comparable opportunities for managing URN. In areas that are Swedish or Danish exclusive economic zones (EEZs), the ability to introduce mandatory speed limits is significantly limited. There, the most realistic option would be to request the IMO to establish speed limits, or alternatively to issue a recommendation to navigate at lower speeds, although such guidance could not be enforced on ships that do not voluntarily reduce their speed. It was estimated that lowering the ships' speeds to a hypothetical limit of 11 kn would reduce the average URN levels by 4.4 ± 2 dB, as registered by local receivers in the study area. This speed limit would affect approximately 44% of the ships in the area. A maximum speed of 13 kn would instead reduce the level by 1.9 ± 0.5 dB and would affect 11% of the ships on average. The reduction in noise levels may temporarily be much higher in the immediate vicinity of individual fast ships, and there might be a high degree of variation between different ships. The study and report make it clear that it is a complex task to assess the feasibility and benefit of introducing a specific marine management tool, in this case an enforceable local speed limit. But it is also clear that there are reliable methods to make the preliminary assessments, and that it requires interdisciplinary analyses and competence.
A Review and Meta-Analysis of Underwater Noise Radiated by Small (25 m Length) Vessels
Journal of Marine Science and Engineering
Managing the impacts of vessel noise on marine fauna requires identifying vessel numbers, movement, behaviour, and acoustic signatures. However, coastal and inland waters are predominantly used by ‘small’ (<25 m-long) vessels, for which there is a paucity of data on acoustic output. We reviewed published literature to construct a dataset (1719 datapoints) of broadband source levels (SLs) from 17 studies, for 11 ‘Vessel Types’. After consolidating recordings that had associated information on factors that may affect SL estimates, data from seven studies remained (1355 datapoints) for statistical modelling. We applied a Generalized Additive Mixed Model to assess factors (six continuous and five categorical predictor variables) contributing to reported SLs for four Vessel Types. Estimated SLs increased through ‘Electric’, ‘Skiff’, ‘Sailing’, ‘Monohull’, ‘RHIB’, ‘Catamaran’, ‘Fishing’, ‘Landing Craft’,’ Tug’, ‘Military’ to ‘Cargo’ Vessel Types, ranging between 130 and 195 dB re 1µPa ...