Hawaii FEP - Western Pacific Fishery Council

salinity low-nutrient water to the eastern margins of the Pacific Ocean. As the easterly tradewinds are reduced, the normal nutrient-rich upwelling system does not occur, leaving warmsurface water pooled in the eastern Pacific Ocean.The impacts of ENSO events are strongest in the Pacific through disruption of the atmosphericcirculation, generalized weather patterns, and fisheries. ENSO affects the ecosystem dynamics inthe equatorial and subtropical Pacific by considerable warming of the upper ocean layer, risingof the thermocline in the western Pacific and lowering in the east, strong variations in theintensity of ocean currents, low trade winds with frequent westerlies, high precipitation at thedateline, and drought in the western Pacific (Sturman and McGowan 2003). ENSO events havethe ability to significantly influence the abundance and distribution of organisms within marineecosystems. Human communities also experience a wide range of socioeconomic impacts fromENSO such as changes in weather patterns resulting in catastrophic events (e.g., mudslides inCalifornia due to high rainfall amounts) as well as reductions in fisheries harvests (e.g., collapseof anchovy fishery off Peru and Chile; Levington 1995; Polovina 2005).Changes in the Aleutian Low Pressure System are another example of interannual variation in aprominent Pacific Ocean weather feature profoundly affecting the abundance and distribution ofmarine organisms. Polovina et al. (1994) found that between 1977 and 1988 the intensification ofthe Aleutian Low Pressure System in the North Pacific resulted in a deeper mixed-layer depth,which led to higher nutrients levels in the top layer of the euphotic zone. This, in turn, led to anincrease in phytoplankton production, which resulted in higher productivity levels (higherabundance levels for some organisms) in the Northwestern Hawaiian Islands. Changes in theAleutian Low Pressure System and its resulting effects on phytoplankton productivity arethought to occur generally every ten years. The phenomenon is often referred to as the “PacificDecadal Oscillation” (Polovina 2005; Polovina et al. 1994).3.2.12 Pacific Island GeographyThe following sections briefly describe the island areas of the Western Pacific Region to providebackground on the diversity of island nations and the corresponding physical and politicalgeography surrounding the Hawaii Archipelago. The Pacific islands can be generally groupedinto three major areas: (a) Micronesia, (b) Melanesia, and (c) Polynesia. However, the islands ofJapan and the Aleutian Islands in the North Pacific are generally not included in these threeareas, and they are not discussed here as this analysis focuses on the Western Pacific Region andits ecosystems. Information used in this section was obtained from the online version of theU.S.Central Intelligence Agency’s World Fact Book. 113.2.12.1 MicronesiaMicronesia, which is primarily located in the western Pacific Ocean, is made up of hundreds ofhigh and low islands within six archipelagos: (a) Caroline Islands, (b) Marshall Islands, (c)Mariana Islands, (d) Gilbert Islands, (e) Line Islands, and (f) Phoenix Islands.11 http://www.cia.gov/cia/publications/factbook/index.html45