The Impact of Swim with Dolphin Tours on Spinner Dolphins

Lessons from a Citizens Science Project

The information collected by the community volunteers in this Citizen Science Project shows that: a) the spinner dolphin resting areas in both Kealakekua and Honaunau Bays are only used by people when dolphins are present, and the people are there to target the dolphins, and; b) people approaching and trying to interact with the dolphins, prevent the dolphins from descending into a resting pattern. Instead the dolphins became much more active when people were within 100m of them, thus loosing valuable resting time.


Long-term data on occupancy rates suggest that Honokohau Bay is the only traditional spinner dolphin resting bay where the occupancy rate increased after swim-with tours began on the Kona coast. Observations suggest that this may be because the boat traffic in and out of the harbor discourages dolphin-oriented activities, especially by swimmers and kayakers.


It is not known how lack of rest during the day impacts the dolphins’ ability to feed, avoid predators and protect their young at night, but it is likely to impact all these activities negatively. To allow the dolphins to get undisturbed rest, human exclusion zones around the core resting areas have been suggested, and have been embraced by all but one of the resident stakeholder groups using Kealakekua Bay, the swim-with-dolphin tour operators. The data from this monitoring effort also suggest that the current viewing distance set by NOAA Fisheries in Hawaii be extended from 50 to 100 yards.

See the links below for more information from the Citizen Science Study in the Spinner Dolphin Resting Bays.

The resulting Final Report, was submitted to:

National Marine Fisheries Service,

Pacific Island Regional Office in 2009.


Kealakekua Bay was the bay that had the most coverage. It was where the Citizen Science monitoring began and it is where a serendipitous natural experiment took place, where the bay was closed off from human use for 18 days, leaving the dolphins to themselves in their Core Resting Area.

As a result the observations in this bay showed us both how much the spinner dolphins were affected by certain human activities, but also how fast they could recover if the repeated disturbances ceased.

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Results from Honaunau and Kauhako Bays.
To be activated soon

The observations in these additional bays corroborated many of the findings from Kealakekua Bay, not only showing how the spinner dolphin population along the Kona Coast was disturbed in many of their traditional resting areas, but that their reaction to this disturbance also was consistent. 

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Impact on the Spinner Dolphin Population
To be activated soon

Comparing the occupancy rates in the various bays along the Kona Coast shows how the spinner dolphin population adjusted their movement patterns to get away from the consistent harassment in the other bays. It also indicate which human activities were most disturbing.

Image from Marinas. com