Establishing a program of ... regular observations for the Mexican sector provided the extended coverage needed to match the scales of scientific sampling and analysis to the natural scales of variability in the California Current. It will also provide information relevant to understanding the behaviour of transboundary pelagic resources inhabiting both the waters off Mexico and the United States. The long term goal of IMECOCAL is to improve the capability to predict the response of the pelagic ecosystem to regional and global climate change, as well as to the combined effects of harvesting practices by Mexico and the United States.
The IMECOCAL program has been conducting ocean monitoring cruises every 3 months since October, 1997. The IMECOCAL observations are scheduled in collaboration with the CalCOFI program. The IMECOCAL survey design is based on the original CalCOFI Basic Station Plan. The cruises cover a subset of the original CalCOFI grid, with station spaced 20 nautical miles apart extending a maximum distance of 220 nautical miles offshore on the two long central lines and roughly 120 nautical miles on the other lines. The distance between the lines is 40 nautical miles.
The core sampling activities of IMECOCAL cruises include routine CTD casts to 1000m. There are also sensors to measure dissolved oxygen and fluorescence profiles to complement the CTD data. Water samples are taken from the surface to 150m at standard depths, using 5 litre Niskin bottles mounted ont he CTD sampling rosette system. The water is used to analyse the concentrations of dissolved oxygen, inorganic nutrients and chlorophyll. At each station, standard oblique bongo tows are made to capture macrozooplankton, including the icthyoplankton (fish eggs and larvae). Vertical Calvet tows are also made at each station for qualitative collection of fish eggs through a depth of 70m. Casts for in situ measurements of primary productivity, as well as measurements profiling photosynthetic radiation, are carried out daily at the the mid-day stations. Continuous underway sampling of surface temperature and salinity, as well as continuous ADCP profiling for mapping the currents in the upper 200m is also done. A CUFES system (Continuous Underway Fish Egg Sampling) was installed on the R/V Francisco de Ulloa and has been operational since January 2000.
In addition to the monitoring cruises, IMECOCAL maintains sea level pressure gauges at Guadalupe Island, about 280km offshore at 29 degrees N, and at a coastal location at San Quintin (about 31 degrees N). The location of Guadalupe Island provides a unique opportunity to continuously measure the mean flow of the California Current, in a way not available at any
other place along the West Coast of North America. These paired instruments permit us to monitor the sea surface pressure gradient between the island and the coastal stations to provide a measure of the mean flow in the upper ocean associated with the California Current. They have been operating since January 1999 and it is hoped that they will be maintained for at least 10 years to provide continuous measurements from which to develop a long-term climatology of the flow across the main axis of the California Current in this region.
The IMECOCAL research program also includes the retrospective analyses of available palaeo-ecological records from near coastal sites off southern Baja California. These provide a regional historical context of interdecadal to centennial variability as seen over the past 500-1500 years to compare to records collected off southern California.
A public database is for the IMECOCAL data is being developed at CICESE.
This information was provided by Dr. Tim Baumgartner of CICESE