Reducing the speeds of large vessels decreases fuel consumption, leading to a decrease in harmful air emissions and greenhouse gases.

• Lindstad et al. (2011) analyzed global historical data and created a model to calculate costs and emissions associated with large ships traveling at different speeds. The authors’ results show that there is a substantial potential for reducing CO2 emissions in shipping by slowing large vessels down. The authors also note that since these emissions reductions calculations are based solely on decreases in speeds of these vessels, they can be implemented and start achieving benefits in the short-term.

• SBCAPCD (2023) analyzed AIS data to quantify air emissions reductions associated with the 2022 Protecting Blue Whales and Blue Skies Vessel Speed Reduction Program, which encourages container and car carrier lines to enroll and slow their vessels to 10 knots or less in VSR zones off of San Francisco Bay and southern California. They found that the combined efforts of all enrolled companies in 2019 across over 266,148 nautical miles helped to reduce approximately 921 tons of smog-forming nitrogen oxides (NOx) and more than 32,600 metric tons of regional greenhouse gases.

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Reducing vessel speeds to 10 knots has minimal to no economic impact on the shipping industry.

• Using AIS data from 2015 for the Santa Barbara Channel region, Gonyo et al. (2019) estimated the economic impact of a variety of ship strike risk reduction strategies, including a 10 knot and 12 knot VSR request, on the shipping industry and estimated that shipping travel costs would increase minimally by 1.3-2.0% (+$880,765-$1,360,034 to a 2015 travel cost estimate of $66,658,476) across the study area as a result of changes in vessel speed impacting vessel transportation costs and inventory carrying costs across industry.

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Targeted analyses have shown that cooperation with the NOAA voluntary Vessel Speed Reduction (VSR) in southern California - and other, similar voluntary VSR requests - has been low.

• Wiley et al. (2008) determined the levels of compliance in 2003 and 2004 with a voluntary VSR program in the northeast U.S. focused on reducing speeds of whale watch vessels to reduce the risk of ship strikes on endangered whales. The authors found that the level of noncompliance was high and that the voluntary conservation program did not achieve the goal of substantially limiting vessel speed near whales. Their findings suggest the importance of establishing quantifiable metrics and frequent evaluations of compliance to ensure efficacy of voluntary conservation efforts like VSR.

• McKenna et al. (2012) analyzed Automatic Identification System (AIS) data for a total of 405 large commercial vessels to monitor changes in their speeds before and after voluntary VSR requests in the Santa Barbara Channel across 2007-2009. The study found that there was no change in average daily vessel speed related to the VSR requests, that few ships reduced their speeds significantly on an individual basis, and none fully cooperated with the voluntary VSR request in any of the three years studied. The authors recommended that future VSR efforts pursue mandatory regulations or incentives to motivate higher levels of compliance and lower speeds of large vessels in these areas.

• Freedman et al. (2016) examined AIS data across 2015 to quantify cooperation levels with the 2015 NOAA voluntary VSR requests in the Santa Barbara Channel region and compare it with cooperation levels of vessels participating in the 2014 incentive-based VSR program. They found that cooperation levels with the NOAA voluntary VSR requests were low - with only 13% of daily average ship speeds traveling at the requested 10 knots or less - and were significantly lower than vessels enrolled in the incentive-based program in 2014.

 

An increase in cooperation with NOAA voluntary VSR requests is estimated to significantly reduce ship strike risk to endangered whales in southern California

• Rockwood et al. (2017) estimated ship strike mortality risk to blue, fin, and humpback whales off of the U.S. west coast using a naval encounter model to quantify risk as the likelihood of co occurrence. They found that the majority of mortalities were occurring within 10% of the EEZ in areas where whale distribution and density data overlaps at a high frequency with shipping data and that significant mortality risk reductions can be achieved by implementing VSR requests in these areas. 

• Redfern et al. 2019 found that a large decrease in ship strike risk can be achieved by higher cooperation levels with speed reduction requests in the southern California Bight. Using AIS data and whale habitat and tagging data, the authors created a model to estimate ship strike risk and fatal ship strike risk for blue, fin, and humpback whales within the study area associated with three proposed mitigation strategies. They found that reducing 100% of ship speeds to 10 knots or less in the Santa Barbara Channel would result in a 22-24% decrease in fatal ship strike risk to endangered whales.

• Using a naval encounter model, Rockwood and Jahncke (2019) found that increasing cooperation with NOAA voluntary VSR requests in the Santa Barbara Channel to 80% or above would decrease blue, fin, and humpback whale mortality in the region by 20-30% - which would be roughly a ten-fold improvement compared to the current VSR cooperation levels and effectiveness. 

 

Mandatory east coast NOAA VSR requests see higher levels of compliance than west coast voluntary VSR requests.

• Using AIS data, Silber, Adams, and Fonnesbeck (2014) quantified vessel operator compliance with a December 2008 regulation aimed at reducing collisions with the endangered North Atlantic right whale that requires vessels 65 feet or greater in length to travel at speeds of 10 knots or less at prescribed times and locations along the U.S. eastern seaboard. The researchers found that compliance with these mandatory VSR requests increased over the 5 year study period - particularly for companies that receive notices of violations and accompanying fines - from 40-45% of all vessel mileage in these areas traveled at speeds of 10 knots or less in 2008 to 70-75% in 2013. 

 

Regulatory changes - particularly related to emissions rules and standards - have been proven to have a significant impact on vessel behavior.

• Moore et al. (2018) examined AIS data from 2008-2015 in waters off of southern California to evaluate the role of vessel emission regulations and economic events on vessel routes and speeds within the study time period and area. They found that the establishment of emissions-related regulations had a profound influence on behavior and resulted in significant changes in vessel routes and speeds. They also found that ship speeds became progressively slower in the Southern California Bight from 2008-2015.

 

Incentive-based voluntary VSR programs have been proven to be effective in achieving vessel behavior change

• Freedman et al. (2016) examined AIS data across 2015 to quantify cooperation levels with the 2015 NOAA voluntary VSR requests in the Santa Barbara Channel region and compare it with cooperation levels of vessels participating in the 2014 incentive-based VSR program.

• The Port of Long Beach operates a year round Green Flag Incentive Program - and publishes annual results online - to reward vessel operators for slowing cargo ships down to 12 knots or less within 40 nautical miles of the harbor. Companies that cooperate at a 90% level or higher can earn up to a 25% reduction in port dockage rates. Port of Long Beach Green Flag Incentive Program (2020) shows a 92% cooperation level across all operators with these slow speed requests in 2019.