Surprise Encounters With Humpback Whales

Project Name:
Surprise Encounters With Humpback Whales

Project Dates:
Winter of 2010 - ongoing 

Project Site(s):
Maui Four-Island Region, Hawaiian Islands Humpback Whale National Marine Sanctuary

Project Aims:
To determine the rate and location of vessel-whale interactions, along with the frequency of “Surprise” and “Near Miss” encounters.  

To model the probability of ship collisions by using surprise encounters and near misses.

To correct models obtained from platforms of opportunity and systematic transect surveys from research vessel.

To test the effects of environmental variables, vessel specific variables and boat speed on probability of collision.

To test hypothesis that susceptibility to collisions may differ between age classes and group composition.

Project Justification: 
Vessel collisions between whales and vessels are a matter of concern in the Hawaiian Islands Humpback Whale National Marine Sanctuary given that both whale and boat numbers are on the increase. Data collected on this issue will be useful to determine where and how frequent vessel whale interactions may be occurring in Maui waters and how probable are vessel collisions. Information gathered will help determine if additional precautions need to be taken by boat captains at specific times of day or in specific areas to further prevent collisions with whales in Maui waters. 

Project Methodology:
Research On Board Program

Using Pacific Whale Foundation’s whale-watching ecotours’ fleet as a Platform of Opportunity, one member of our research team is deployed on board of whalewatching vessels departing from Maalaea and Lahaina as an observer and to collect data. PWF eco-tour vessels abide to all federal and state whalewatching regulations during operation and data collection.

Data collected include environmental variables such as sea state, wind speed, cloud cover, and glare to determine sighting conditions on the water.  Using a handheld GPS device, we record the vessel’s track and, at regular intervals, the number of humpback whales found within a mile radius from the boat. 

Staff also record “surprise encounters”, which are encounters with a humpback whale that occur closer than 300 yards from the boat without having previously being detected by the captain and crew.  When a “surprise encounter” occurs, the time, location, number of whales involved, the distance from the boat at first detection, sex and age class of the whale(s) are recorded.  

Line-transect surveys

Similar data are also collected from the research vessel. Rather than following random routes, systematic line-transect surveys are run at varying speed- increased ever 15 min in 5 mph increments from 5 to 20 mph maximum. Scans are also conducted to allow comparison with data collected from Platforms of Opportunity (whalewatching vessels). Random surveys will then be used to provide a correction factor for density estimates from whalewatching vessels. Photo-identification is undertaken to determine whether certain individuals, size classes, or specific group composition are more prone to be involved in surprise encounters.

Project Permits and/or Collaborators:
The Research On Board Program is conducted during regular whalewatching operations by research and naturalist staff. sightings are collected opportunistically. No permit is required given that the cetaceans are not actively approached or ‘taken’ by our vessels. PWF eco tour vessels abide by all federal and state regulations and guidelines in effect for Hawaiian and National Marine Sanctuary waters.

Line-transect surveys rely on data collected under NOAA/NMFS permitted research permit (NOAA/NMFS 16479). 

Management Outcomes:
During 2011, 2,464 humpback whale sightings including 133 (3%) surprise encounters were recorded. Findings suggest vessel speed is important and that the probability of incurring in a near miss increases by approximately 8% with an increase in one knot of boat speed. Therefore, regulation of boat speed during whale season is critical. The study also suggests there are differences by vessel type in the probability of having close encounters with whales and that weather also affects this probability. 

See Pacific Whale Foundation Publication/Presentation Summary

2014: Currie, J.J., Stack, S.H., Davidson, E.H., Kaufman, G.D. and Martinez, E. Results from two years of line transect surveys utilizing surprise encounters and near-misses and proxies of vessel collisions with humpback whales (Megaptera novaeangliae) in the four-island region of Maui, Hawai'i, USA. Document SC/65b/HIM01 presented to the IWC Scientific Committee, Bled, Slovenia: 12-24 May. Download this paper.

2013: Stack, S.H., Currie, J.J., Davidson, E.H., Frey, D, Maldini, D., Martinez, E. and Kaufman, G.D. Preliminary results from line transect surveys utilizing surprise encounters and near misses as proxies of vessel collisions with humpback whales (Megaptera novaeangliae) in Maui County waters, Hawai'i, USA. Document SC/65a/WW04 presented to the IWC Scientific Committee, Jeju, Korea: 3 June-15 June.  Download this paper.