Survival Enhancement Research and Activities Initiative

Two mom and pup pairs wary of nearby Galapagos shark.
Two mom and pup pairs wary of nearby Galapagos shark.

Survival Enhancement Research and Activities Initiative focuses on science-based conservation by developing effective tools and activities to mitigate threats which are impeding monk seal survival. Identification of the threats and implementation of enhancement studies and activities are typically undertaken by the Hawaiian monk seal Population Assessment and Health and Disease Research and Emergency Response teams.

The Hawaiian Monk Seal Survival Enhancement Research and Activities Initiative is led by Stacie Robinson, PhD.

In the Northwestern Hawaiian Islands (NWHI) where high juvenile seal mortality is the primary recovery impediment, multiple strategies are employed to reduce these losses, including mitigation of shark predation, captive rehabilitation, translocation of immature seals to sites where there is a greater probability of survival, and addressing injuries and mortalities caused by aggressive adult male seals. Conversely, in the main Hawaiian Islands (MHI), most of the threats are anthropogenic (human related) in nature, including direct human-seal and fisheries interactions and increased disease and toxin exposure. Addressing these MHI threats requires proactive and innovative measures along with public support to continue the positive growth of this subpopulation.

An analysis of opportunistic interventions activities from 1980-2012 determined that a minimum of 32% of the seals alive in 2012 were either individuals or offspring of individuals that had received a survival enhancing intervention activity. This highlights that the cumulative impact of many, small scale and even seemingly insignificant interventions can over time have a profound positive effect at a population level.

Click here to view NOAA's activities impacting seal survival myths.

Further Reading:

Harting AL, Johanos TC, Littnan CL
2014. Benefits derived from opportunistic survival-enhancing interventions for the Hawaiian monk seal: the silver BB paradigm. Endangered Species Research 25:89-96. DOI: 10.3354/esr00612

Shark Predation and Mitigation

At French Frigate Shoals (FFS), pup survival has been lower than any other NWHI location for more than a decade, primarily attributed to Galapagos shark (Carcharhinus galapagensis) predation on nursing and recently weaned pups in nearshore waters. It is estimated that up to 30% of all pups at FFS are lost annually to shark predation. Galapagos sharks are found throughout the Hawaiian Archipelago, yet shark predation on young seal pups at other subpopulations is exceedingly rare. It is hypothesized that a relatively small group of sharks are involved in this source of monk seal mortality, penetrating the shallow, nearshore waters where young pups reside. Dedicated efforts to reduce or eliminate Galapagos shark predation on monk seal pups at FFS are ongoing.

Historically, the small islands within the atoll of FFS were home to the largest subpopulation of Hawaiian monk seals. This population actually increased from the early 1960s through the late 1980s. However, from 1989-2010, the population decreased by over 75%, largely driven by high juvenile mortality. The demographic structure of the FFS population is now skewed, with relatively few reproductive age individuals leading to concerns that this subpopulation is likely to further collapse.

Beginning in the late 1990s, dedicated effort to characterize and mitigate shark predation through intensive observation (direct and via a remote camera system) of both Galapagos shark and monk seal mother and pup behavior led to the identification of high shark use areas, frequency and time of day of shark activity, and identification of individual sharks likely responsible for seal mortality. In addition, Carl Meyer, PhD. from the Hawaii Institute of Marine Biology (HIMB) has tagged Galapagos sharks to allow for a more detailed analysis of their movement behavior.

Mitigation efforts which began in 1997 include translocation of weaned pups from areas with high Galapagos shark predation risk to relatively safer islets within FFS and have been ongoing. Nursing pups are at the greatest risk of shark predation, but cannot be moved until they wean as they need to stay with their mothers to nurse. Thus, while translocation of weaned pups to low shark use areas within FFS may alleviate predation pressure, alternative methods of protection from shark predation are required to protect nursing pups.

In 2008 and 2009, visual deterrents and electromagnetic and auditory instruments were deployed to reduce shark predation. While such non-lethal deterrents are preferable to shark removal, their effectiveness was inconclusive; however other deterrents may be tested as they become available.

Lethal removal of limited number of Galapagos sharks from the FFS atoll has the potential to alleviate this source of seal mortality. The Galapagos shark is a top predator at this atoll and the removal of a limited number of sharks is not decided upon without intensive evaluation. The removal of a select, limited number of sharks known to prey on endangered Hawaiian monk seal pups, also a valuable part of the system, will likely maintain the overall biodiversity of the atoll.

Further Reading:

Dale JJ, Meyer CG, Clark CE
2011. The ecology of coral reef top predators in the Papahānaumokuākea Marine National Monument. Journal of Marine Biology. 2011:1-14. DOI: 10.1155/2011/725602
Dale JJ, Stankus AM, Burns MS, Meyer CG
2011. The Shark Assemblage at French Frigate Shoals Atoll, Hawaiʻi: Species Composition, Abundance and Habitat Use. PLoS ONE 6(2): e16962. DOI: 10.1371/journal.pone.0016962
Gobush KS
2010. Shark Predation on Hawaiian Monk Seals: Workshop II and Post-Workshop Developments, November 5-6, 2008. U. S. Dep. Commer., NOAA Tech. Memo. NMFS-PIFSC-21
Gobush KS, Farry SC
2012. Non-lethal efforts to deter shark predation of Hawaiian monk seal pups. Aquatic Conservation: Marine and Freshwater Ecosystems. Early View. DOI: 10.1002/aqc.2272
Harting AL
2010. Shark Predation on Hawaiian Monk Seals Workshop Honolulu, Hawaii January 8-9, 2008. National Oceanic Atmospheric Agency Administrative Report H-10-02C 36 p.
Lowe CG, Wetherbee BM, Meyer CG
2006. Using acoustic telemetry monitoring techniques to quantify movement patterns and site fidelity of sharks and giant trevally around French Frigate Shoals and Midway Atoll. Atoll Res Bull 543:281–303.
Meyer CG, Papastamatiou YP, Holland KN
2010. A multiple instrument approach to quantifying the movement patterns and habitat use of Tiger (Galeocerdo cuvier) and Galapagos sharks (Carcharhinus galapagensis) at French Frigate Shoals, Hawaii. Marine Biology. 157:1857–1868. DOI: 10.1007/s00227-010-1457-x

Translocation and Captive Care to Enhance Seal Survival

Translocations have been undertaken for over 3 decades to improve the survival of individual seals by moving them either directly or after captive rehabilitation to more favorable locations (e.g., with lower predation or disease risk and/or better foraging conditions), to improve the survival of other seals by removing aggressive male seals that pose a survival threat to the population, or to remove seals that have developed behaviors which pose a risk to human safety.

To address the ongoing poor juvenile survival in the NWHI, survival trends for the subpopulations are assessed to identify appropriate islands and atolls for collection and release of immature seals to take advantage of favorable conditions elsewhere. Additionally, the most successful tool being implemented to mitigate shark predation on pups at French Frigate Shoals is the translocation of weaned pups to other islets within the atoll with lower shark predation risk.

Genetic studies have determined that the entire monk seal population is not genetically differentiated between the subpopulations and is considered a single "stock" (a group of potentially interbreeding individuals) across its entire range. Because seals naturally travel among the islands, translocations of seals are not likely to result in genetic or adaptive incompatibilities. Also, prior to a translocation, candidate seals must pass a health screening to minimize the potential of introducing diseases to another site.

Captive Rehabilitation

From 1984-1995, captive rehabilitation of undersized immature seals, primarily females from French Frigate Shoals, was undertaken and seals were later released at Kure and Midway Atolls to augment those smaller populations. Various captive facilities on Oʻahu and shore pens in the NWHI were used during these efforts. Notably, these earlier rehabilitation efforts bolstered the wild population at the western end of the Northwestern Hawaiian Island chain by 12-14%.

There were some limited rehabilitation of nutritionally compromised immature seals in later years, but these efforts were hampered because there wasn't an adequate, quarantine facility available for rehabilitation. Recognizing this gap, The Marine Mammal Center (TMMC), a California based non-profit organization specializing in rescue and rehabilitation of pinnipeds, partnered with NOAA Fisheries to fill this void. During the summer of 2014, the newly built TMMC monk seal hospital, Ke Kai Ola (The Healing Sea), opened its doors in Kailua-Kona on Hawaiʻi Island to receive its first patients, all malnourished immature seals from the NWHI. This partnership with TMMC provides a pivotal opportunity to reverse the trend of poor juvenile survival in the NWHI and marks the first time in 8 years that seals from the NWHI have been brought in for rehabilitation. This has major significance, as over the years there have been numerous candidates for rehabilitation, but no appropriate facilities available. In addition, a dedicated monk seal treatment and temporary holding facility at NOAA's Inouye Regional Center on Oʻahu also opened in February 2014.

Further Reading:

Health Screening and Quarantine Protocols for HMS translocation between Subpopulations
Baker JD, Becker BL, Wurth TA, Johanos TC, Littnan CL, Henderson JR
2011. Translocation as a tool for conservation of the Hawaiian monk seal. Biological Conservation, 144(11), 2692-2701. DOI: 10.1016/j.biocon.2011.07.030
Baker JD, Harting AL, Littnan CL
2013. A two-stage translocation strategy for improving juvenile survival of Hawaiian monk seals. Endangered Species Research 21: 33-44. DOI: 10.3354/esr00506
Gilmartin W, Sloan AC, Harting AL, Johanos TC, Baker JD, Breese M, Ragen TJ
2011. Rehabilitation and relocation of young Hawaiian monk seals (Monachus schauinslandi) Aquatic Mammals 37(3): 332-341. DOI: 10.1578/am.37.3.2011.332
Johanos TC, Becker BL, Baker JD, Ragen TJ, Gilmartin WG, Gerrodette T.
2010. Impacts of sex ratio reduction on male aggression in the Critically Endangered Hawaiian monk seal Monachus schauinslandi. Endangered Species Research [Endang. Species Res.] 11: 123-132. DOI: 10.3354/esr00259
Norris TA, Littnan CL, Gulland FMD
2011. Evaluation of the captive care and post-release behavior and survival of seven juvenile female Hawaiian monk seals (Monachus schauinslandi) Aquatic Mammals 37(3): 342-353. DOI: 10.1578/am.37.3.2011.342
Schofield TD, Levine G, Gulland FMD, Littnan CL, Colitz CMH
2011. Short Note: The first successful hand-rearing of a neonate Hawaiian monk seal (Monachus schauinslandi) and post-release management challenges Aquatic Mammals 37(3): 354-359. DOI: 10.1578/am.37.3.2011.354

Adult Male Aggression Mitigation

Multiple male seal aggression.
Multiple male seal aggression.
Injury from multiple male aggressions.
Injury from multiple male aggressions.

Male aggression is typically categorized as either involving multiple or single males. These appear to be two distinct phenomena in terms of the male behavior and the age/sex of the subject seals. Multiple male aggression involves several adult males simultaneously competing to mate with a single seal, typically an adult female (although younger animals and males can be targeted in some cases). This can lead to severe traumatic wounds and death. Single male aggression involves one male harassing, mounting and biting a young seal, typically a recently weaned pup of either sex. In the process, the young seal may be drowned or sustain bite wounds that subsequently become infected and lead to debilitation or death.

Aggressive interactions between male seals and smaller animals (of a variety of species, not just monk seals) are normal, and often lead to scratches and relatively minor bite wounds. However, single male aggression in seals becomes a particular concern when an adult male displays an aberrant focus on young animals, with frequent, repeated and severe aggressive behavior that threatens their survival. This is highly unusual behavior amongst monk seals in Hawaii and cannot be well explained, but previous experience shows that the impact of such aggression on smaller seals can be considerable.

Events involving multiple and single adult male Hawaiian monk seals exhibiting aggression towards adult females and immature seals has led to a significant number of severe injuries and deaths. Unfortunately, the loss of even a single female, and the loss of her lifetime reproductive potential, represents a significant setback to population recovery of this endangered species.

The mechanism that triggers male aggression in monk seals is not clear. It is hypothesized that a major contributing factor is an unbalanced sex ratio that is skewed towards males. At islands with the greatest sex ratio imbalance, multiple male aggression is most severe. Although multiple male aggression has been observed at most of the primary breeding sites, this behavior has been most notable at Laysan and Lisianski Islands.

Over an 11 year period from 1984-1994, 37 male seals were selectively removed from Laysan Island to restore a balanced sex ratio. These seals were translocated to Johnston Atoll (n=9) or the main Hawaiian Islands (n=21), placed into captivity (n=5), or died (n=2). Following removal, instances of injury or death from multiple male aggression events drastically declined. The removal of these males from the Laysan Island population has contributed to the restoration of a balanced sex ratio and has proven a valuable mitigation strategy.

Single male aggression events have most notably occurred at French Frigate Shoals and more recently at Kure Atoll. Intervention efforts include hazing of identified aggressors, translocating pups from areas where aggressive males frequent, treating injured seals when appropriate and removal of the adult male. The 3 adult males at French Frigate Shoals observed to repeatedly target pups, were translocated to Johnston Atoll (n=2 in 1998) or euthanized (n=1 in 1991). One adult male was brought into permanent captivity in 2013 after he had been observed injuring pups at Kure atoll. This mitigation strategy effectively reduced pup deaths as a result of adult male aggression at this site.

A possible tool to reduce aggressive behavior may include the administration of a testosterone suppressant drug to individual aggressive males. However, this technique has not been evaluated in affecting aggressive behavior and is not available at this time.

Further Reading:

Atkinson S, Ragen TJ, Gilmartin WG, Becker BL, Johanos TC
1998. Use of a GnRH agonist to suppress testosterone in wild male Hawaiian monk seals (Monachus schauinslandi). General Comparative Endocrinology 112: 178-182.
Hiruki LM, Stirling I, Gilmartin WG, Johanos TC, Becker BL
1993. Significance of wounding to female reproductive success in Hawaiian monk seals (Monachus schauinslandi) at Laysan Island. Canadian Journal of Zoology 71: 469-47
Johanos TC, Becker BL, Baker JD, Ragen TJ, Gilmartin WG, Gerrodette T
2010. Impacts of sex ratio reduction on male aggression in the Critically Endangered Hawaiian monk seal Monachus schauinslandi. Endangered Species Research [Endang. Species Res.] 11: 123-132. DOI: 10.3354/esr00259

Mitigating Fisheries and Human-Seal Interactions in the MHI

Despite the population level benefits of an expanding MHI subpopulation, there are unique concerns and management challenges associated with growth in the region. The number of fishery-related injuries and mortalities (from hooking or entanglement) has been increasing and additional vessel traffic around the MHI increases the potential for collision. Also, there have been serious human-seal interactions, where a small number of habituated seals have become a human safety risk or incurred injuries as a result of interacting with people. Other potentially harmful interactions include human and dog disturbances to seals on beaches and intentional killing. Addressing these increasing threats requires proactive and innovative measures along with public support to continue the positive growth of this subpopulation.

Human-Seal Interactions

There have been a few notable events in the MHI where a pup born in an area where few other seals occur, then seeks out humans for socialization after weaning. These human-seal interactions typically occur in the water, and as the seal matures and grows in size, the behaviors often become more threatening towards people, including biting, holding under water, and preventing exit from the water.

Other harmful human interactions may arise when seals have been provisioned (fed), either accidentally or intentionally, from fishing gear or fish discards from boats and docks. As a seal becomes focused on this source of food, begging behavior may become increasingly aggressive. Additionally, seals may sustain injury from boat propellers or ingestion of hooks as they attempt to access this seemingly easily available food source.

Decreasing human-seal interactions via translocation of seals from high density human areas to the more remote areas in the MHI, has been successful when pups were moved shortly after weaning, but not for older animals. In most cases, once human-seal socialization behaviors have been established, there are few options available to extinguish this behavior which had developed as a direct result of human actions. Therefore, efforts are focused towards early detection, including careful review of seal sighting reports and public-generated images and videos of monk seals posted on the internet. The application of aversive conditioning (using an unpleasant experience to modify an undesired behavior) to MHI seals may be a possible tool to address human-seal interactions.

It is hypothesized, that the MHI seal population will reach a minimum density where pups won't be born in isolation from other seals and the undesired human socialization behaviors may subsequently diminish.

Further Reading:

Baker JD, Becker BL, Wurth TA, Johanos TC, Littnan CL, Henderson JR
2011. Translocation as a tool for conservation of the Hawaiian monk seal. Biological Conservation, 144(11), 2692-2701. DOI: 10.1016/j.biocon.2011.07.030.
Gobush KS, Wurth TA, Henderson JR, Becker BL, Littnan CL
2016. Prevalence of interactions between Hawaiian monk seals (Nemonachus schauinslandi) and nearshore fisheries in the main Hawaiian Islands. Pacific Conservation Biology. doi:10.1071/PC15029
Jenkinson EM
2011. Aversive conditioning and monk seal-human interactions in the Main Hawaiian Islands: Aversive Conditioning Workshop, Honolulu, Hawaii, November 10-11, 2009. U.S. Dept. of Commerce, NOAA Technical Memorandum NOAA-TM-NMFS-PIFSC-25, 28 p.