FISHERY BULLETIN: VOL. 81, NO. 2 



relaxation from a pre-event index peak to a projected 

 index trough determines to a large extent how far in 

 advance of event occurrence the outlook can be given 

 (Quinn 1978). Nevertheless, we did find the indices 

 useful in predicting the very minor 1975 event and 

 moderate 1976 event. And, when we look at Figure 1, 

 we can see that even the very small changes in index 

 anomaly trends are reflected in the trends of other 

 variables over various parts of the tropical Pacific. 

 Additional Southern Oscillation-related changes in 

 other variables over the tropical and subtropical 

 region are shown in more detail in Quinn (1980a, b) 

 and Quinn et al. (1978, 1981). Since Berlage (1957, 

 1966) and Troup (1965) indicated that the Southern 

 Oscillation was not only involved with the South 

 Pacific subtropical high, but also to some extent with 

 the North Pacific subtropical high region, we monitor 

 a Ship N-Darwin index (Quinn 1979). (With the 

 demise of Ship N, we started using data obtained for 

 its former coordinates: lat. 30°N, long. 140 o W.) The 

 northeast trades can contribute significantly to the 

 equatorial easterly flow. 



When one considers the nature of the short-term 

 climatic changes and the time leads/lags in the in- 

 volved variable changes, as shown in the articles 

 referenced in the previous paragraph, one realizes 

 that the significant changes in the atmospheric cen- 

 ters of action (the semipermanent highs and lows that 

 appear on mean charts of sea level pressure; e.g., the 

 South Pacific subtropical high, the Indonesian 

 equatorial low, the North Pacific subtropical high) 

 take place more nearly on the time scale of the 

 oceanic circulation and thermal pattern changes. 

 Therefore, the centers of action are more likely to re- 

 spond measurably to significant oceanic changes and 

 vice versa; it is through monitoring and projecting 

 these involved large-scale, long-term changes that we 

 are most likely to have a suitable basis for our short- 

 term climatic outlooks. Results will be reflected in 

 the influence these slower changing, large-scale 

 features exert on the developments and trajectories 

 of the rapidly moving transient storms that affect our 

 day-to-day weather and sea conditions. 



Significant changes in fishery populations also take 

 place on the time scales of the large changes in at- 

 mospheric centers of action, oceanic circulation, and 

 oceanic thermal anomaly patterns. In our opinion, 

 through the monitoring and projection of appro- 

 priate pressure and circulation indices and other 

 related variables such as sea level, SST, etc., a suit- 

 able basis for outlooks on fishery environmental 

 changes and fishery catches could be provided. For 

 the north Chilean fishery, in addition to the Southern 

 Oscillation indices, we would also recommend use of 



the E aster- Quintero and E aster- Antofagasta 850 

 mbar height difference indices of Quinn (1980b). 

 They can be used to represent interannual changes in 

 strength of the low level flow (south to north com- 

 ponents) over that part of the southeast Pacific with 

 which we would be concerned. In the case of fisheries 

 we will not only be concerned with interannual 

 changes, but also the longer term changes such as 

 those noted in the previous section. 



CONCLUDING REMARKS 



After seeing what has been happening to the Peru- 

 vian and north Chilean fisheries over the past decade 

 or more, and how they are similarly affected by large- 

 scale ocean/atmosphere changes, the need for a well- 

 coordinated study of this west coast South American 

 fishery region as a whole becomes apparent. In the 

 past, investigations have been limited by the areas 

 covered and the objectives of scientists involved. 

 Most of the studies have been concentrated on the 

 Peruvian coastal region. Investigations should cover 

 an area extending in length from near the Equator to 

 lat. 30°-35°S, and in width from the coast out to about 

 600 km seaward. Participants should include fish- 

 eries biologists, marine ecologists, physical oceano- 

 graphers, meteorologists, and chemical oceano- 

 graphers. 



We will be interested in monitoring the current 

 climatic situation to see what brings about an emer- 

 gence from the extended period of abnormally low 

 Southern Oscillation indices and the greatly reduced 

 amplitudes in fluctuations of these indices. 



We will also be interested in further investigation of 

 the very long-term climatic changes that have been 

 occurring over western South America between the 

 coast and the westernmost ranges of the Andes. This 

 will include further study of the following noted 

 changes in rainfall characteristics over subtropical 

 Chile: 1) The decrease in frequency of abnormally 

 heavy El Nino-related rainfall after 1930, and 2) the 

 sizeable decrease in average annual rainfall after 

 1944. 



ACKNOWLEDGMENTS 



We thank the Chief of the Naval Weather Service 

 and the Director of the Hydrographic Institute of the 

 Armada de Chile; the Director of the Civil Aviation 

 Service and Chief of the Meteorological Service of 

 French Polynesia; the President of the Instituto del 

 Mar del Peru; the Director of the Australian Bureau 

 of Meteorology; and the National Climatic Center, 

 Environmental Data Service, NOAA, for their sup- 



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