Monk Seal Population News and Updates

August 22, 2014

Northwestern Hawaiian Islands (NWHI)

Monk seal field effort and Survival Enhancement Activities

Derelict net hazard removed from the reef at Kure Atoll.
Derelict net hazard removed from the reef at Kure Atoll.
Photo courtesy of Hawaiʻi Department of Land and Natural Resources.
Photo courtesy of Hawaiʻi Department of Land and Natural Resources.

In June, monk seal field teams began their 3-month deployment at 5 of the 6 main NWHI (French Frigate Shoals (FFS), Laysan and Lisianski Islands, Pearl and Hermes Reef, and Kure Atoll; excluding Midway Atoll). Fortunately, US Fish and Wildlife Service (USFWS) personnel and volunteers at Midway Atoll and State of Hawaiʻi Department of Land and Natural Resources (DLNR) teams at Kure Atoll, maintain a year-round presence and opportunistically fill in some of the monk seal data gaps at these sites. Though the NMFS field teams have been on-site for just five weeks, they have already successfully intervened to improve seal survival by disentangling 3 seals, removing a massive (1,000+ pound) potentially entangling derelict net ball ensnared on the reef, administering deworming medication to a 2-year-old seal in poor body condition, and translocating 11 newly weaned pups at FFS from islands with high shark predation to other safer islands within the atoll. Earlier this spring prior to NMFS field effort, an additional seal was disentangled at Midway by USFWS personnel and DLNR personnel at Kure hazed an aggressive subadult male away from a weaned pup. Finally, 4 undersized and malnourished immature seals were collected for rehabilitation at The Marine Mammal Center's monk seal hospital, Ke Kai Ola, in Kailua-Kona.

Pup Production and Nihoa Remote Camera Seal Monitoring

Photo from Remote Camera System installed at Nihoa Island showing 20 seals hauled out on the only beach on this island.
Photo from Remote Camera System installed at Nihoa Island showing 20 seals hauled out on the only beach on this island.

It is encouraging that this year's NWHI pup production (currently 113) has already surpassed last year's total of 103, the lowest since records began in 1984. The NWHI population size and birth totals exclude Nihoa and Mokumanamana (Necker) Islands, as those sites are visited only a few days each year.

To increase seal monitoring effort on Nihoa, remote cameras were deployed last September. During the recent June NOAA Research Vessel Hiʻialakai cruise, the two cameras were serviced and the 8 months of accumulated images were downloaded. Background information on the fabrication of these remote camera monitoring systems may be found in the April 26, 2013, News and Highlights, A New Remote Camera Seal Monitoring System. These cameras are providing the first year-round seal monitoring of Nihoa. A preliminary review of the overwinter photos shows the beach awash from winter wave action and in other images more than 20 seals can be seen in 1 photo. Also, a previously undocumented late-born pup was photographed in early November. Though there are some limitations with the current camera set-up (e.g., not all seal haul-out areas are being photographed and image resolution could be increased), this system is providing new insights on the Nihoa seal population.

Noteworthy Seal Movement within the NWHI

In efforts to improve immature survival, a total of 12 weaned pups (6 each in 2008 and 2009) had been translocated 300 miles from FFS to Nihoa, where survival was more favorable. In 2014, one of these seals, now a 6-year old adult, swam back to FFS five years after the translocation. This is noteworthy, as this is the first NWHI seal that was directly translocated to another atoll in the NWHI and subsequently returned to its birth island. See below for additional seal movement Main Hawaiian Islands - Noteworthy Seal Movement between the NWHI and MHI.

Main Hawaiian Islands (MHI)

Pup production and Mortality

There are currently 12 monk seal births in the MHI (a record high of 5 for Kauaʻi, 4 on Molokaʻi, and 3 on Oʻahu), suggesting lower pup production after the record high of 21 in 2013 (excludes Niʻihau, which hasn't routinely been surveyed). This is not surprising, as some females will take one or more years off between successive pupping events. It is noteworthy that one of the Molokaʻi mothers was born there in 2010, and is only the second known 4-year old female to give birth anywhere. Most females give birth for the first time between 5-12 years of age.

Eight seals have died in the MHI (3 on Oʻahu, 2 on Kauaʻi, and 1 each on Kahoʻolawe, Molokaʻi, and Hawaiʻi). The yearling male seal from Hawaiʻi Island died shortly after ingesting a fishhook (see News and Highlights, Seal Response Updates-Fisheries interactions), a nursing pup on Kauaʻi died from dog inflicted injuries, and the results are pending on the cause of death for the 6 other seals.

Of special note, the two week old pup, PK5, is the first known monk seal to have died from a dog attack. Additionally, four other seals in the vicinity sustained non-life threatening dog bites at the same time. Though these other bites were not as serious, the potential of infectious disease transmission (such as canine distemper) to these other seals (and seals they may come in contact with) is being monitored because of the potentially catastrophic impact on the immunologically naive endangered seal population.

Noteworthy Seal Movement between NWHI and MHI

Movement of a seal from Nihoa Island to Kahoʻolawe.  The exact track of movement is not known, but the shortest distance is 380 
        miles.
Movement of a seal from Nihoa Island to Kahoʻolawe. The exact track of movement is not known, but the shortest distance is 380 miles.

A 4-year old male seal, RT76, who was born and tagged on Nihoa in 2010, was not resighted anywhere until this year on Kahoʻolawe Island, about 380 miles away. However, the limited survey effort on Nihoa (a few days each year) is likely a key factor in the lack of sightings. This is the seventh confirmed movement of a seal swimming from Nihoa to the MHI, which includes one seal that moved twice. It's exciting to know this "lost" seal is alive and well! A review of monk seal movements can be found in a recent staff publication: Range-wide movement patterns of Hawaiian monk seals (0.5 MB PDF).