Hawaiian Monk Seal | NOAA Fisheries

NOAA Fisheries uses innovative science to explore monk seal biology and interactions with humans and the environment, and apply the best available science to guide our management and recovery plans for monk seals. Our Hawaiian Monk Seal Research Program leads these efforts.

The Hawaiian Monk Seal Research Program

Our overarching goal is to achieve an optimal and sustainable monk seal population. This program works together with outside collaborators on two key research and conservation initiatives designed to address the recovery strategies outlined in the Hawaiian Monk Seal Recovery Plan.

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Research and Conservation Initiatives

Key research and conservation initiatives are undertaken by integrated teams of Hawaiian Monk Seal Research Program personnel and collaborators to further identify impediments to survival and respond with appropriate science-based conservation measures.

Population Assessment and Enhancement Research

The work performed under this initiative provides annual high-resolution information from each monk seal subpopulation required to assess the species status, population trends, and current threats. Survival enhancement activities are implemented and tracked to evaluate their effectiveness. NOAA field teams are deployed to field camps in Papahānaumokuākea Marine National Monument to monitor the subpopulations and perform recovery activities in these remote islands. Main Hawaiian Islands activities are performed by a collaboration of NOAA and other federal and state agencies, nonprofits, and volunteers.

Health and Disease Research, Mitigation and Emergency Response

Our scientists and collaborators investigate the role infectious diseases, parasites, and other health threats play in the recovery of monk seals and develop effective tools and activities to mitigate these threats. Other activities include critical response for compromised seals (e.g., hooked, entangled, sick, and/or injured).

Genetics Research

Our scientists use molecular techniques to advance knowledge of Hawaiian monk seal health, population dynamics, and diet.

Population Status/Stock Assessment

The prolonged and steep decline of Hawaiian monk seal populations had occurred more or less continuously since the 1950s. However, there have been some relatively recent encouraging developments, including:

• The population has been trending upward since 2013
• Promising advances in juvenile seal survival enhancement research and local community engagement

The best estimate of the current total Hawaiian monk seal population is 1,600 seals—about 1,200 in Papahānaumokuākea (from Nihoa to Hōlanikū (Kure Atoll)), and about 400 in the main Hawaiian Islands (from Ni'ihau to Hawai'i Island).

Recent Research Highlights

Four Decades of Hawaiian Monk Seal Entanglement Data Reveal the Benefits of Plastic Debris Removal

Large-scale and sustained removal of abandoned, lost, or otherwise discarded fishing gear meaningfully benefits marine ecosystems and has the potential to be transformational in restoration efforts.

Leading threats to seals in the Main Hawaiian Islands

Researchers categorized the causes of seal deaths since 1992 to determine which are most harmful to the recovery of this endangered population. This study, conducted by NOAA scientists and colleagues, summarized the causes of monk seal deaths in the main Hawaiian Islands from 1992 to 2019 (114 seals). It found that more than half of the deaths were caused by humans.

Conservation Translocations of Hawaiian Monk Seals: Accounting for Variability in Body Condition Improves Evaluation of Translocation Efficacy

Hawaiian monk seal pup translocations conducted during 2012–2014 had a statistically significant positive effect on the survival of the pups.

Vaccinating highly connected seals

Vaccinating highly connected animals can help decrease disease risks.

Hawaiian Monk Seal Population Saw Signs of Recovery in 2019

Latest update looks at the Hawaiian monk seal population, pups and juveniles, and threat mitigation from the 2019 field season; highlighting the need for continued conservation.

Hawaiian Monk Seal Movements Among Islands and Atolls - It was once assumed that monk seals did not travel between the Northwestern Hawaiian Islands and the main Hawaiian Islands, but research now shows that in rare cases they do, and even make it down to Johnston Atoll.

The Role of Diet as a Driver of Divergent Population Trends - Monk seals in the Northwestern Hawaiian Islands and main Hawaiian Islands eat a similar diet, but seals in the main Hawaiian Islands may experience less competition for food. In addition, prey that may be more bountiful and better quality, allowing the main Hawaiian Islands population to increase while the Northwestern Hawaiian Islands population continues to decrease.

Non-Lethal Efforts to Deter Shark Predation of Monk Seal Pups - Monk seal pups at French Frigate Shoals are heavily preyed upon by Galapagos sharks, but it’s unclear if non-lethal efforts to deter this behavior are effective. However, translocating newly weaned pups to areas with less shark predation has proven beneficial to pup survival.