Active Whale Avoidance by Large Ships: Components and Constraints of a Complementary Approach to Reducing Ship Strike Risk

Abstract

The recurrence of lethal ship-whale collisions ('ship strikes') has prompted management entities across the globe to seek effective ways for reducing collision risk. Here we describe 'active whale avoidance' defined as a mariner making operational decisions to reduce the chance of a collision with a sighted whale. We generated a conceptual model of active whale avoidance and, as a proof of concept, apply data to the model based on observations of humpback whales surfacing in the proximity of large cruise ships, and simulations run in a full-mission bridge simulator and commonly used pilotage software. Application of the model demonstrated that (1) the opportunities for detecting a surfacing whale are often limited and temporary, (2) the cumulative probability of detecting one of the available 'cues' of whale's presence (and direction of travel) decreases with increased ship-to-whale distances, and (3) following detection time delays occur related to avoidance operations. These delays were attributed to the mariner evaluating competing risks (e.g., risk of whale collision vs. risk to human life, the ship, or other aspects of the marine environment), deciding upon an appropriate avoidance action, and achieving a new operational state by the ship once a maneuver is commanded. We thus identify several options for enhancing whale avoidance including training Lookouts to focus search efforts on a 'Cone of Concern,' defined here as the area forward of the ship where whales are at risk of collision based on the whale and ship's transit/swimming speed and direction of travel. Standardizing protocols for rapid communication of relevant sighting information among bridge team members can also increase avoidance by sharing information on the whale that is of sufficient quality to be actionable. We also found that, for marine pilots in Alaska, a slight change in course tends to be preferable to slowing the ship in response to a single sighted whale, owing, in part, to the substantial distance required to achieve an effective speed reduction in a safe manner. However, planned, temporary speed reductions in known areas of whale aggregations, particularly in navigationally constrained areas, provide a greater range of options for avoidance, highlighting the value of real-time sharing of whale sighting data by mariners. Development and application of these concepts in modules in full mission ship simulators can be of significant value in training inexperienced mariners

Quantifying behavior and collision risk of humpback whales surfacing near large ships: implications for detection and avoidance

“…whales, slow ships can be involved in lethal collisions (Kelley et al 2021), and adherence to different regulatory efforts is variable (Ebdon et al 2020). Additionally, cruise ship operators demonstrate willingness and ability to change operational state to avoid detected whales (Gende et al 2019). Our work builds on other studies that use data on whale surfacing behavior to quantify risk of ship strikes whereby the time at or near the surface equates to their availability to be struck (Calambokidis et al 2019, Keen et al 2019, Rockwood et al 2021.…”

“…This information guides decisions about whether, or to what degree, risk-reducing changes in vessel operations (e.g. a change in course or speed) are feasible and effective (Gende et al 2019). Additionally, the quantity of cues (e.g.…”

Computing ship strikes and near miss events of fin whales along the main ferry routes in the Pelagos Sanctuary and adjacent west area, in summer

“…Sharing information on almost real-time whale localization can be very useful across a day, but it seems that, in the Mediterranean Sea, even with such information of a nearby whale, the vessels equipped with a system do not take precautionary action such as temporary speed reduction nor alteration of course (Folegot, Gallou & Ody, 2019). Raising awareness or training programmes for vessel crews, within a global pro-active avoidance system (Gende et al, 2019) could improve the efficacy of such mitigation.…”

Estimating effectiveness of speed reduction measures for decreasing whale-strike mortality in a high-risk region

“…Vessel-strike mortality is an established mortality source for large whale populations around the world (Berman-Kowalewski et al 2010, David et al 2011, Redfern et al 2013, McKenna et al 2015, Priyadarshana et al 2016, Nichol et al 2017, Rockwood et al 2017. Researchers continue to explore new technologies such as acoustic and infrared detection and real-time reporting (Couvat & Gambaiani 2013, Horton et al 2017, Baumgartner et al 2019, regulatory approaches (Silber et al 2012b, Sèbe et al 2019, best navigational practices (Williams et al 2016, Gende et al 2019 and new conceptual frameworks (Pirotta et al 2019) to decrease ship strikes. Nonetheless, speed restrictions remain one of the most studied and proven methods to avoid strike deaths (Leaper 2019, Schoeman et al 2020.…”