Sea Turtle Foraging and Resting Areas off Maui

 Project Name:
 Sea Turtle Foraging and Resting Areas off Maui 

Project Dates: 
Pending

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

Project Aims:
1.  Monitor trends in abundance and distribution of green sea turtles at resting/feeding areas in Maui County waters starting with two sites: Makena Landing and Olowalu, well known green sea turtle aggregation areas and a known feeding area along the Kaanapali coastline

2.   Determine availability of preferred forage (seaweeds primarily) in the study areas and relationships with turtle abundance and distribution pattern

3.   Monitor daytime habitat use patterns by sea turtles in the study areas.
 
Goals at Resting Sites:
1.   Estimate trends in abundance and distribution patterns of green sea turtles at two resting sites in Maui County: Makena Landing and Olowalu

2. Assess boat and swimmer traffic in the study area at different times of year and times of day and the potential effects on sea turtle abundance and distribution

3.  Determine the difference in green sea turtle abundance patterns between breeding and non-breeding season, daytime versus nighttime and at different tidal cycles

4.   Determine distribution patterns related to sex or size-class.
We expect that sex of the turtle will not affect distribution on the reef as this area is not related to reproduction. However, we do expect distribution to be affected by the size-class of the turtle (which is an imperfect proxy for age).

5.   Evaluate habitat preferences at resting sites.
These questions are important from a management perspective as both the Makena Landing and the Olowalu site are used intensively by eco-tours as snorkeling destinations featuring sea turtle viewing as a primary activity. Monitoring long-term abundance and distribution trends year-round and understanding what natural factors determine their fluctuation will help separate natural cycles from potential impacts of eco-tourism on sea turtles.

6.   Test for differences in site fidelity to resting sites between males and females and different size-classes

7.    Measure resting area size and nearest-neighbor distance to better understand green sea turtle social networks at resting sites.

These questions addresses an area of sea turtle biology that has been only partially explored and hypothesizes that the area selected by sea turtles at resting sites  is not independent of the choices of other turtles nearby and that there is an underlying ‘social organization’ to these areas.

Goals at Feeding Sites:
1.   Evaluate the quality of a feeding area based on the nutritional value of food resources available to green sea turtles

2.   Determine how many turtles on average use specific feeding sites and if there is a preference by sex or size-class to particular feeding areas

3.   Determine daily, seasonal, and long-term sea turtle use patterns for specific feeding areas

4.   Monitor grazing rates and habitat recovery from turtle foraging
 

Project Justification:
Green sea turtle populations in Hawaiian waters have been on the increase. Habitat degradation, availability of forage and social dynamics are at play and it is important to understand the long-term impacts of all these factors on the sea turtle population. In addition, the geographic areas under study are heavily used snorkel destinations and interactions with boats and tourists should also play a role in these dynamics. A better understanding of how all these factors interact is critical to management of sea turtles in Maui County waters.

Project Methodology:
Specific methodologies to meet the goals of the project are currently being designed and tested.

Project Permits and/or Collaborators:
A federal and state permit is be required for portions of this project and is under submission. We are collaborating with the Universitá degli Studi, Milano, Italy for portions of this study.

Management Outcomes:
TBD

Publications/Presentations:
See Pacific Whale Foundation Publication/Presentation Summary