Coastal upwelling in the eastern Gulf of California

Understanding and quantifying upwelling is of great importance for marine r esource management. Direct measurement of this process is extremely difficu lt and observed time-series do not exist. However, proxies are commonly der ived from different data; most commonly wind-derived. A local wind-derived coastal upwelling index (CUI) is reported for the period 1970-1996 and is c onsidered representative for the eastern central Gulf of California, an imp ortant fishing area where no proxies exist. The index is well related to pi gment concentration distribution, surface water temperature, and population dynamics of important fish resources over the seasonal time-scale. There i s a biological response to ENSO activity not reflected by this index, indic ating that improvement of biological enrichment forecasting also requires w ater column structure input. A clearly increasing seasonal amplitude signal is detected in the coastal upwelling index and sea surface temperature sin ce the mid 1970s. Understanding the nature of these long-term trends, the i ncorporation of remote tropical ocean signals into the enrichment proxy, th e dynamics of atmosphere and ocean, and the biological responses are major challenges to the proper management of fish resources in the Gulf of Califo rnia.