Researchers have found that tuna spawn within the boundaries of the Palau National Marine Sanctuary, suggesting that the secured area potentially provides protection for tuna during key life stages.
“This finding is in line with past research on tropical tuna larvae and spawning activity, which are widely distributed in the Pacific Ocean and have been previously observed within other large-scale marine protected areas,” states a report based on the research project led by the Palau International Coral Reef Centre.
The study highlights the importance of research in large-scale marine-protected areas and aimed to develop a useful platform to conduct large-scale ocean research within small-islands-large-ocean states.
PICRC researchers began the project in 2022, using plankton nets to look at the top 50 meters in the protected area. Photo courtesy of PICRC
“This platform can support the ever-increasing demand for offshore research in small island, large ocean states with limited resources and expertise,” said Dr Louw Claassens, first author and former PICRC researcher.
Palau’s marine sanctuary is an offshore large-scale marine protected area covering almost 500,000km of its exclusive economic zone.
Established in 2015 and fully implemented in January 2020, the marine sanctuary closed 80 percent of Palau’s exclusive economic zone to any extractive activities, with the remaining 20 percent open to commercial longline and free-school purse seine fishing as well as community artisanal fishing.
The marine sanctuary was established to protect against the overexploitation of important fishery species such as tunas to support and promote the development of a domestic pelagic fishery as well as a cultural aspiration to protect pelagic resources for Palauans.
PICRC said researchers began the project in 2022, using plankton nets to look at the top 50 meters in the protected area.
The nets were towed across different sites at night to investigate the diversity, abundance and distribution of tuna larvae.
“Twenty-two tuna larvae were collected from five of the sites and modeling results suggest that the larvae originated at these sites. The researchers have also analyzed the gonads of sampled tunas collected by the Belau Offshore Fisheries Inc.,” PICRC said.
Most of the tuna were found to be mature, with three of the 59 sampled fish actively spawning.
“The findings suggest that tuna spawn, to some extent, within the PNMS, and the PNMS provides local protection to tuna populations during this time,” the reef centre said.
“Using this research project as an example, the researchers then designed a platform with five steps for developing, undertaking and understanding offshore research in small-island-large-ocean states, like Palau, which includes advice on challenges and tips,” the reef centre said.
Large-scale marine protected areas larger than 100,000 km2 or 150,000 km2 are increasingly used to provide ocean protection across vast seascapes.
Researchers said large-scale ocean protection may support species conservation by encompassing entire species’ home ranges and ecosystems as well as removing or limiting direct human impacts, which in turn can support increased resilience against impacts such as climate change
PICRC said large-scale sanctuaries have increased in popularity in recent years and are considered by some to be the most practical solution in achieving 30 percent ocean conservation and management by 2030.
