Hawaii FEP - Western Pacific Fishery Council

make poleward feeding migrations in summer and move toward the equator in winter, few actualobservations of fin whales in tropical and subtropical waters have been documented, particularlyin the Pacific Ocean away from continental coasts (Reeves et al. 1999). There have only been afew sightings of fin whales in Hawaii waters.There is insufficient information to accurately determine the population structure of fin whales inthe North Pacific, but there is evidence of multiple stocks. The status of fin whales in Hawaiiwaters relative to the optimum sustainable population is unknown, and there are insufficient datato evaluate trends in abundance (Forney et al. 2000).Sei WhalesSei whales (Balaenoptera borealis) have a worldwide distribution but are found mainly in coldtemperate to subpolar latitudes rather than in the tropics or near the poles (Horwood 1987). Theyare distributed far out to sea and do not appear to be associated with coastal features. Two seiwhales were tagged in the vicinity of the Northern Mariana Islands (Reeves et al. 1999). Seiwhales are rare in Hawaii waters. The International Whaling Commission only considers onestock of sei whales in the North Pacific, but some evidence exists for multiple populations(Forney et al. 2000). In the southern Pacific most observations have been south of 30°(Reeves etal. 1999).There are no data on trends in sei whale abundance in the North Pacific (Forney et al. 2000). It isespecially difficult to estimate their numbers because they are easily confused with Bryde’swhales, which have an overlapping, but more subtropical, distribution (Reeves et al. 1999).Hawaiian Monk SealsThe Hawaiian monk seal (Monachus schauinslandi) is a tropical seal endemic to the HawaiianIslands. Today, the entire population of Hawaiian monk seals is about 1,300 to 1,400 and occursmainly in the NWHI. The six major reproductive sites are French Frigate Shoals, Laysan Island,Lisianski Island, Pearl and Hermes Reef, Midway Atoll, and Kure Atoll. Small populations atNecker Island and Nihoa Island are maintained by both reproduction and immigration, and anincreasing number of seals are distributed throughout the MHI where they are also reproducing.The subpopulation of monk seals on French Frigate Shoals has shown the most change inpopulation, increasing dramatically in the 1960s–70s and declining in the late 1980s–90s. In the1960s–70s, the other five subpopulations experienced declines. However, during the past decade,the number of monk seals increased at Kure Atoll, Midway Atoll, and Pearl and Hermes Reefwhile the subpopulations at Laysan Island and Lisianski Island remained relatively stable. Therecent subpopulation decline at French Frigate Shoals is thought to have been caused by maleaggression, shark attack, entanglement in marine debris, loss of habitat, and decreased preyavailability. The Hawaiian monk seal is assumed to be well below its optimum sustainablepopulation, and, since 1985, the overall population has declined approximately 3 percent per year(Forney et al. 2000).79