CHANGES IN SALINITY AND LANDINGS OF SIX FISH SPECIES

BULL. INST. OCEAN. & FISH., A.R.E. VOL. 4 1974

CHANGES IN SALINITY AND LANDINGS OF SIX FISH SPECIES

IN THE SHELF, NORTH TO THE NILE DELTA

By
M. L. E. EL-HEHYAWI
fnst1’tufe o( Oceanography and Fisheries, Alexandria~ A. R.E.

Abstract
The substantially decreased water discharge of the Xile River
into the Mediterranean :=:ea in the recent years resulted, a marked
increase of the salt content in the upper layers of water (the range
of sa.linity 38.86-:39.40%) over the shelf areas close to the aelta. The
upperO-iJOm waterlayers attained valuesofat(~igma.t)which Changed
from 20.00-25.00 in the years 1l)lll)-1971. lSimultane usly, profound
changes were obscL’ved, based on the commercia! fish land ngs, in
the al>undance of’ fish species in the same area. While the species
like Sciaena aquilla. J:jolea t:ulgaris and 1:JJpinephelu8 gigas Were
negative affected in tneir abundace, other species, belongmg to the
families .111 ullidae, Pagridae and 2’riglzdae, became more numerous.
It is probable th[tt these changes are associated, above aU, with
the tolerance or aifiinity of the young life stages of !isnes towards
the new salilllty values.