Human Interactions

Two juvenile monk seals draw a crowd of beach-goers at Poipu Beach on Kauaʻi.
Two juvenile monk seals draw a crowd of beach-goers at Poipu Beach on Kauaʻi.

The Hawaiian monk seal population in the main Hawaiian Islands (MHI) has been increasing over the last decade. 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.

Seal-Fisheries Interactions

Because monk seals have such a diverse diet (including many prey items rarely targeted by fishers such as small wrasses, flatfishes, and shrimps), and forage over large areas, including habitats and deeper depths not targeted by fishers, the overlap with fishers is relatively small and seals are not likely to impact fish stocks. However, there could be impacts to individual fishermen when seals interact with their gear or catch. These direct fishing interactions occur when the seals are transiting to and from shore. Though seals are most often seen in shallow, nearshore waters, they are not necessarily foraging or spending most of their time there. This is the "driveway effect" where seals must pass through the shallows to transit between their resting and foraging areas, similar to people using their driveway to get to and from their home.

Fishing guidelines have been developed to minimize seal-fisheries interactions, including using barbless hooks, not feeding seals, and avoiding fishing when seals are in the area. To better track fisheries interactions, NOAA Fisheries is working with fishers to report seal interactions, including interaction types (including type of gear, bait, location, seal information, and other factors), frequencies and trends. Solutions can then be developed so that monk seals and fishermen can both use the marine resources with minimal conflict.

Click here for Guidelines to avoid Monk Seal and Fishery Interactions (0.7 MB PDF)

Further Reading:

Boggs CH, Gonzales DP, Kokubun RM
2015. Marine mammals reported under catch lost to predators on fishermen's commercial catch reports to the State of Hawaii, 2003-2014 Pacific Islands Fisheries Science Center, PIFSC Data Report, DR-15-006, 14 p. DOI: 10.7289/v5pr7szm
Cahoon MK, Littnan CL, Longenecker K, Carpenter JR
2013. Dietary comparison of two Hawaiian monk seal populations: the role of diet as a driver of divergent population trends. Endang Species Res 20: 137–146. DOI: 10.3354/esr00491
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
Iverson S, Piche J, Blanchard W
2011. Hawaiian monk seals and their prey: assessing characteristics of prey species fatty acid signatures and consequences for estimating monk seal diets using fatty acid signature analysis. U.S. Dept. of Commerce, NOAA Technical Memorandum NOAA-TM-NMFS-PIFSC-23, 114 p. + Appendices
Sprague R, Littnan C, Walters J
2013. Estimation of Hawaiian monk seal consumption in relation to ecosystem biomass and overlap with fisheries in the main Hawaiian Islands. U.S. Dept. of Commerce, NOAA Technical Memorandum NOAA-TM-NMFS-PIFSC-37, 42 p. + Appendices
Williams TM, Richter B, Kendall T, and Dunkin R
2011. Metabolic Demands of a Tropical Marine Carnivore, the Hawaiian Monk Seal (Monachus schauinslandi): Implications for Fisheries Competition. Aquatic Mammals 37(3), 372-376. DOI: 10.1578/AM.37.3.2011.372

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 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 directed 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
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.