Transitional areas (TAs) are characterized by strong gradients in the physical environment that challenge biological communities, many of which are already exposed to their physiological limits. Because of their nature, TAs are expected to reflect the impacts of climate variability and change more dramatically and sooner than other more homogeneous areas, making them regions of particular concern. There is also great interest in the potential of TAs as regions of early detection of these changes.
Within the Pacific, large TAs include the convergence between the Oyashio and Kuroshio currents in the western North Pacific; the divergence of the North Pacific Current into the Alaska and California Currents in the eastern North Pacific; the convergences between the Equatorial Countercurrent and the California and Peru Currents in the eastern Central Pacific; the divergence of the North and South Equatorial Currents into the Equatorial, Kuroshio, and East Australia Currents in the western Central Pacific; and also the basin-wide borders between the North and South Pacific Gyres with equatorial and subpolar systems. At the meso- and local scales, the number of regions that can be considered TAs is much higher, and some of them are of great regional relevance.
In April 2002, the international PICES symposium on “North Pacific Transitional Areas” was held in La Paz, Mexico. After that meeting, the study of these systems became part of the scientific agenda of many research groups. However, there has been no integrative symposium for the last 15 years. The goal of the 2018 symposium is to update and expand our understanding of Pacific TAs. The symposium will focus on questions surrounding natural and anthropogenic climate variability and change in Pacific TAs and discuss evidence of climate-driven changes in the position and physical structure of TAs and their biological communities. The symposium will examine the impacts changing TAs have or may have on fisheries, including examples from individual systems and projections for the future. Effective monitoring is essential for detecting changes in TAs. Therefore, the symposium will discuss the major challenges in adequately observing these highly dynamic and heterogeneous systems as well as what should be monitored. We expect to tackle questions on whether current observations and models are informative enough to predict future changes, and whether we can design simple and inexpensive ways to maintain basin-scale observational systems in TAs. The symposium will also address socioeconomic questions related to the challenges of managing the highly migratory and transboundary resources in TAs.