IMECOCAL - Investigaciones Mexicanas de la Corriente de California

IMECOCAL Investigaciones Mexicanas de la Corriente de California

A programme of ocean monitoring in the Southern Region of the
California Current - off Baja California, Mexico - has been underway
since autumn, 1997. It is modeled after the CalCOFI programme
covering the region off southern and central California to the north.
Establishing a programme 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 programme has been conducting ocean monitoring cruises
every 3 months since October, 1997. The IMECOCAL observations are
scheduled in collaboration with the CalCOFI programme. 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 programme 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