Hawaii FEP - Western Pacific Fishery Council

southern boundary of the Subartic Frontal Zone (SAFZ) and the northern boundary of theSubtropical Frontal Zone (STFZ; see Figure 7). Individual temperature and salinity gradients areobserved within each front, but generally the SAFZ is colder (~8° C) and less salty (~33.0 ppm)than the STFZ (18° C, ~35.0 ppm, respectively). The North Pacific Transition Zone (NPTZ)supports a marine food chain that experiences variation in productivity in localized areas due tochanges in nutrient levels brought on, for example, by storms or eddies. A common characteristicamong some of the most abundant animals found in the Transition Zone such as flying squid,blue sharks, Pacific pomfret, and Pacific saury is that they undergo seasonal migrations fromsummer feeding grounds in subartic waters to winter spawning grounds in the subtropical waters.Other animals found in the NPTZ include swordfish, tuna, albatross, whales, and sea turtles(Polovina et al. 2001).3.2.9 EddiesEddies are generally short to medium term water movements that spin off of surface currents andcan play important roles in regional climate (e.g., heat exchange) as well as the distribution ofmarine organisms. Large-scale eddies spun off of the major surface currents often blend coldwater with warm water, the nutrient rich with the nutrient poor, and the salt laden with fresherwaters (Bigg 2003). The edges of eddies, where the mixing is greatest, are often targeted byfishermen as these are areas of high biological productivity.Figure 7: North Pacific Transition ZoneSource: http://www.pices.int/publications/special_publications/NPESR/2005/File_12_pp_201_210.pdf(accessed July 2005).42