• The idea here is to have some variables describing the variation in recruitment

The regional seas

• The sea_cd => this one is obvious, and will describe varying recruitments into the Baltic, the Mediterranean, North sea, unfortunately sea_cd is repeated and probably needs grouping with other variable
  
  

This will create a new column in ccm21.seoutlets

ALTER TABLE ccm21.seaoutlets ADD COLUMN area_cd character varying(3);
UPDATE ccm21.seaoutlets set area_cd= system_cd||sea_cd;

Now that sounds much better :

Latidunal distance to the maximum density area

The largest densities are found in the vendée région (source wgeel 2009)

Tidal Range

Tidal range