MadSci Network: Environment & Ecology

Re: What is the cause of fewer fish and birds in california's coastal waters?

Date: Sat Nov 25 13:06:29 2000
Posted By: Kai Bester, Post-doc/Fellow, Environmental Science, Institute for Reference Materials and Measurements
Area of science: Environment & Ecology
ID: 972956219.En

Dear William!

Now essentially what time are You referring to?

I guess You are referring to the El Nino events, of the last years, aren't 
Well at first generally there are ocean currents. They do have a favourite
direction due to main wind
directions, the rotation of the earth and the tidal waves.
In the Case of the American West Coast (South as well as North) the main
current on the ocean surface goes
west, i.e. away from th coast. This means waters from the depth of the 
which are nutrient rich come
to the surface at the coastline. This means plankton finds good conditions 
grow, an thus  a rich food
chain may start.
The Nina effect means the currents are reversed for several months and the
upwelling does not take place,
thus the nutrients are much reduced and there is little food for 
macroorganims such as fish. This is what
happens very drastically in the waters of Southern America and I think as 
in waters of California.
The effects in South America mean that in some years these waters are the 

the fish richest in the
world and in others among the poorest.

In general terms this means the fishery on the West Coast is very much
dependent on the currents of the
ocean and thus the winds.
Some people think there may be changes in the winds and ocean currents due 
to  the greenhouse effect as
ocean currents are very much dependent on temperature and temperature
distribution on the globe. Anyway it
seems the Nino effect, which is occuring naturally has been occuring more 

in the last decades,
possibly dues to the greenhouse effect.
You will find more on the Nino and Nina effect on the following pages:
(by the way effects are largest around christmas and the name refers to the
spanish christmas scenery El
Nino is the Jesus child)  

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