Tourism, human activity affecting spinner dolphin reproduction in Hawaii, study finds
A new study suggests tourism and human activity off Hawaii Island may be contributing to unexpectedly low calf numbers in spinner dolphins.The study, led by the University of Hawaii’s Marine Mammal Research Program and published in the journal Endangered Species Research, found that only about 9% of the dolphins in the study group were calves, compared with an expected rate closer to 17%.The findings are “raising urgent concerns about the long-term survival of this isolated population,” according to a release from the University of Hawaii.Acrobats of the ocean, spinner dolphins are known for leaping and spinning out of the water, and they fish at night and rest in bays during the day, when many visitors encounter them.“Viewing spinner dolphins is an attraction of the tourism industry in Hawai‘i, however, those activities put pressure on the marine species. Previous research has shown that this population of dolphins experiences the highest levels of disturbance exposure recorded for dolphins worldwide,” the university said.The study’s lead author Fabien Vivier, who was a doctoral student at the Hawai‘i Institute of Marine Biology in the UH Mānoa School of Ocean and Earth Science and Technology at the time of this work, said that the evidence researchers uncovered “suggests chronic human disturbance—especially tourism and recreational-related interactions during critical dolphin resting periods—as a likely contributing factor affecting reproductive success and calf survival.”“The findings support stronger conservation actions, such as time-area closures for human activities, alongside continued long-term monitoring—actions that have long been called for,” Vivier said.To make their conclusion, scientists used drones and photography to measure the body length of the dolphins. They then combined that data with age-length data from stranded spinner dolphins collected by Kristi West, study co-author and researcher with the UH Health and Stranding Lab at the UH Mānoa College of Tropical Agriculture and Human Resilience,That allowed the researchers to create the first age-length growth curve for this specific population of spinner dolphins and allowed them to accurately categorize individuals into calves (under 2 years), juveniles (2–9 years), and adults (over 9 years), the university said.“Age structure is an early indicator of population health and long-term viability. The documented low proportion of calves suggests the spinner dolphin population off Hawaiʻi Island may not be replacing itself fast enough, which could lead to future population decline,” the release states.A federal rule requires boats and people to stay 50 yards away from the dolphins, but the study’s authors said that distance may not be enough to reduce stress.Now, the scientists are calling for stronger protections for the sea creatures.“Understanding these impacts is critical for protecting an isolated local population before declines become irreversible,” Randall Wells, study co-author and director of Brookfield Zoo Chicago’s Sarasota Dolphin Research Program. “We hope this work provides the science-based evidence needed to develop effective protections for spinner dolphins while helping balance marine tourism, cultural stewardship, and long-term ecosystem health in Hawaiʻi.”
A new study suggests tourism and human activity off Hawaii Island may be contributing to unexpectedly low calf numbers in spinner dolphins.
The study, led by the University of Hawaii’s Marine Mammal Research Program and published in the journal Endangered Species Research, found that only about 9% of the dolphins in the study group were calves, compared with an expected rate closer to 17%.
The findings are “raising urgent concerns about the long-term survival of this isolated population,” according to a release from the University of Hawaii.
Acrobats of the ocean, spinner dolphins are known for leaping and spinning out of the water, and they fish at night and rest in bays during the day, when many visitors encounter them.
“Viewing spinner dolphins is an attraction of the tourism industry in Hawai‘i, however, those activities put pressure on the marine species. Previous research has shown that this population of dolphins experiences the highest levels of disturbance exposure recorded for dolphins worldwide,” the university said.
The study’s lead author Fabien Vivier, who was a doctoral student at the Hawai‘i Institute of Marine Biology in the UH Mānoa School of Ocean and Earth Science and Technology at the time of this work, said that the evidence researchers uncovered “suggests chronic human disturbance—especially tourism and recreational-related interactions during critical dolphin resting periods—as a likely contributing factor affecting reproductive success and calf survival.”
“The findings support stronger conservation actions, such as time-area closures for human activities, alongside continued long-term monitoring—actions that have long been called for,” Vivier said.
To make their conclusion, scientists used drones and photography to measure the body length of the dolphins. They then combined that data with age-length data from stranded spinner dolphins collected by Kristi West, study co-author and researcher with the UH Health and Stranding Lab at the UH Mānoa College of Tropical Agriculture and Human Resilience,
That allowed the researchers to create the first age-length growth curve for this specific population of spinner dolphins and allowed them to accurately categorize individuals into calves (under 2 years), juveniles (2–9 years), and adults (over 9 years), the university said.
“Age structure is an early indicator of population health and long-term viability. The documented low proportion of calves suggests the spinner dolphin population off Hawaiʻi Island may not be replacing itself fast enough, which could lead to future population decline,” the release states.
A federal rule requires boats and people to stay 50 yards away from the dolphins, but the study’s authors said that distance may not be enough to reduce stress.
Now, the scientists are calling for stronger protections for the sea creatures.
“Understanding these impacts is critical for protecting an isolated local population before declines become irreversible,” Randall Wells, study co-author and director of Brookfield Zoo Chicago’s Sarasota Dolphin Research Program. “We hope this work provides the science-based evidence needed to develop effective protections for spinner dolphins while helping balance marine tourism, cultural stewardship, and long-term ecosystem health in Hawaiʻi.”
