29 HAYWARD ET AL.: THE CALIFORNIA CURRENT, 1998 -1999 CalCOFI Rep., Vol. 40, 1999 THE STATE OF THE CALIFORNIA CURRENT IN 1998-1999: TRANSITION TO COOL-WATER CONDITIONS THOMAS L. HAYWARD Marine Life Research Group Scripps Institution of Oceanography University of California, San Diego 9500 Gilman Drive La Jolla, California 92093-0227 thayward@ucsd.edu  TIM R. BAUMGARTNER Centro de Investigación Científica y Educación Superior de Ensenada División de Oceanología Km. 107 Carretera Tijuana-Ensenada Ensenada, B.C. México DAVID M. CHECKLEY Marine Life Research Group Scripps Institution of Oceanography University of California, San Diego 9500 Gilman Drive La Jolla, California 92093-0227 REGINALDO DURAZO GILBERTO GAXIOLA-CASTRO  K. DAVID HYRENBACH, UABC-Facultad de Ciencias Marinas Centro de Investigación Científica y ARNOLD W. MANTYLA, MICHAEL M. MULLIN Apartado Postal 453  Educación Superior de Ensenada Marine Life Research Group Ensenada, B.C. División de Oceanología  Scripps Institution of Oceanography México Km. 107 Carretera Tijuana-Ensenada University of California, San Diego Ensenada, B.C. 9500 Gilman Drive México La Jolla, California 92093-0227 TOM MURPHREE  FRANKLIN B. SCHWING  PAUL E. SMITH Department of Meteorology Pacific Fisheries Environmental Laboratory Southwest Fisheries Science Center Naval Postgraduate School National Marine Fisheries Service, NOAA  National Marine Fisheries Service, NOAA Monterey, California 93943  1352 Lighthouse Avenue P.O. Box 271 Pacific Grove, California 93950-2097  La Jolla, California 92038 MIA J. TEGNER Marine Life Research Group Scripps Institution of Oceanography University of California, San Diego 9500 Gilman Drive La Jolla, California 92093-0227 ABSTRACT  This report reviews and provides a preliminary interpretation    of    recent    observations    made    by    CalCOFI (California   Cooperative   Oceanic   Fisheries   Investigations) and   other   programs   sampling   the   coastal   waters   of   the Californias. Since this is a continuation of a series of annual reports, the emphasis here is upon observations made during the   past   18   months,   but   longer-term   trends   must   also   be considered.  The  major  change  in  oceanographic  structure  in the    past    year    was    the    transition    from    strong    El    Niño conditions in early 1998 to cool-water, La Niña conditions in early  1999.  Ecosystem  structure  also  showed  large  changes during this period. Phytoplankton abundance during 1998, as indicated  by  chlorophyll  concentration,  was  typical  of  the values  seen  during  the  last  decade,  but  it  appeared  to  be increasing in early 1999 in association with the transition to cool-water   conditions.   Macrozooplankton   biomass   during 1998   continued   the   long-term  trend  of  low  values  which have  been  seen  since  the  mid -1970s  regime  shift,  and  El Niño-related   changes   were   superimposed   upon   this   trend. The  1999  macrozooplankton  data  are  not  yet  available  to assess  whether  biomass  is  increasing.  Observations  made  at coastal   shore   stations,   in   southern   California   kelp   forest communities, in central and northern California, and in Baja California,   Mexico,  a re  considered  in  order  to  place  the CalCOFI  observations  in  a  larger  regional  context.  Because this year marks the fiftieth   anniversary of the CalCOFI program, we use the discussion to consider future directions for the time -series program and how   the   CalCOFI   data   can   be   put   to   greater   use   at   the regional, state, and national level. INTRODUCTION This is a continuation in a series of reports (e.g., Hayward et  al.  1996;  Schwing  et  al.  1997;  Lynn  et  al.  1998)  which present  and  synthesize  recent  observations  in  the  California Current system. The emphasis is upon data collected during 1998  and  1999.  The  1998-99  period  was  marked  by  rapid and remarkable changes in physical and ecosystem structure in the study region. Winter and spring of 1998 was a period of   strong   El   Niño   conditions   in   physical   and   biological structure. The physical influence of El Niño declined during the  summer  and  fall  of  1998,  and  there  was  a  transition  to cool   water   conditions   during   the   winter   of   1998   and   the spring of 1999. Oceanographic programs     to     the     south -sampling off northern  Baja  California,  Mexico-and  to  the  north  sampling off   Monterey   and   the   central   California   coast   are   making observations  that  help  to  put  the  CalCOFI  time  series  in  a larger  regional  context,  and  that  allow  the  influence  of  El Niño  to  be  examined  on  larger  spatial  scales.  Observations made at coastal shore stations and in kelp forest communities are   being   related   to   CalCOFI   time -series  observations  in order to determine