Field Season Ends for Hawaiian Monk Seal Research and Population Monitoring
The 2011 summer field season has drawn to a close with notable progress made in research to assess the status of Hawaiian monk seals throughout the Hawaiian Archipelago and actions to enhance recovery of the highly endangered species.
In the Northwestern Hawaiian Islands (NWHI), researchers deployed at summer field camps monitored monk seal populations at all 6 major breeding locations within the remote group of islands and atolls, including French Frigate Shoals (FFS), Laysan and Lisianski Islands, Pearl and Hermes Reef, and Midway and Kure Atolls. With the recent deployment of winter field camps at Laysan Island, in addition to the usual summer camps, monitoring of the Laysan population has been carried out almost year-round since May 2009. In September of 2010, a winter camp was also set up at Kure Atoll, enabling year-round monitoring there. Winter field teams at both of these sites were evacuated immediately following the Tōhoku earthquake of March 11, 2011 and resulting tsunami. However, in early April, teams were reestablished at all sites except Midway. Operations at summer field camps ended in August. Periodically between late January and mid-August, short-term surveys were conducted at Midway Atoll, and in August 1-day studies were conducted at Nihoa and Mokumanamana Islands. Winter monk seal field camps are not expected to be deployed this year.
At the 6 major NWHI pupping sites, researchers monitored births of seal pups. Records show that at least 138 monk seal pups were born at these sites during 2011. Field staff also disentangled seals from marine debris and removed entanglement hazards from beaches at all sites. As part of the PIFSC program to mitigate pup losses resulting from predation by Galapagos sharks at French Frigate Shoals (FFS), researchers monitored Galapagos sharks at FFS, lethally removed one of the sharks near a pupping island, and relocated newly weaned pups within FFS to lower their risk of shark predation. Further, field staff helped mitigate effects of adult male seal aggression towards weaned pups by deterring aggressive males and treating abscesses on pups resulting from this aggression. At Laysan Island, researchers tested the efficacy of a topical dewormer in reducing the parasite loads in treated juvenile seals. The purpose of the test is to determine whether this treatment could be a potential tool to increase survival of starving juvenile seals.
At Kure Atoll, two individual male monk seals (KE18 and KO42) were observed this season repeatedly and violently attacking multiple weaned and juvenile seals, causing serious injury (scratches, bites and abscesses) and death (at least 3 injured pups disappeared after being injured). One of the males has displayed aggression towards juveniles for the last 2 years; the severity and frequency of the aggression increased this year. The second male directed aggression towards juveniles on 8 occasions in August. After reviewing the data, NMFS determined that 1 male (KE18) met the agency's conservative criteria for definitive intervention. Because it would be dangerous to translocate individually aggressive males to other locations and there were no captive care facilities available to accommodate additional seal, the only available option was euthanasia. Accordingly, NMFS deployed a team of scientists and a veterinarian with the objective of capturing and euthanizing KE18 in the field. Although the seal was sighted several times, there was no opportunity to capture it. NMFS will continue to monitor the situation and review potential courses of action in the future.
PIFSC field staff also were busy with monk seal research and monitoring in the main Hawaiian Islands (MHI). By late August, scientist in the MHI Population Assessment Program had identified 127 individual seals in the main islands, including 16 pups born this year and had applied flipper tags to 20 of the seals, including 11 pups. Program staff had also disentangled 2 seals from marine debris, removed a fishing hook from 2 seals on Oahu, and conducted medical interventions with 2 seals on Kauai.
The PIFSC Hawaiian Monk Seal Research Program completed a second year of collaborative research with the U.S. Navy by deploying cellphone tags on monk seals to examine the seals' foraging behavior and at-sea movements, and the potential impacts of Navy activities on these behaviors. In 2011, tags were placed on 8 seals for the first time, and on 2 seals that had been previously instrumented in 2010. Data collected by the tags are currently being analyzed to identify monk seal home ranges and core areas of habitat used by the seals, and to examine variation in monk seal diving and foraging behavior. These analyses give insight into how monk seals move and use their available habitat. Determining the amount of time seals spend foraging, the type of foraging occurring, and the amount of time spent foraging in specific areas is an important step in thoroughly understanding monk seal behavior and will provide good baseline data for future comparisons regarding the impact of Navy activities on monk seal behavior.