122 THE ESSEX NATURALIST
maximum depth of water in which it was possible to use these nets was
about 80 cm.
The area fished was upstream of Decoy Point and indicated on Figure 1.
Figure 1 The Upper Blackwater Estuary showing:
'A' Decoy Point and 'B' the area fished.
'............' indicates the channel at low-water.
Soft mud extended for about 150 m from the sea-wall to a pebble ridge
which provided a firm foreshore from which to fish. Fishing was carried
out at low-water during springtides when the fish were concentrated in
the channel. Since July 1973, the trawl-net has been used in preference to
the push-net as work at that time showed it to be the more efficient for
catching gobies while not greatly affecting the numbers of flatfish caught
(Table 1). Macer (1967) found a similar situation when working in Red
Wharf Bay, N. Wales. His data are not strictly comparable, however,
since he used the push-net and beam-trawl over different areas of the bay.
Table 1
Record of fish caught on 1.7.73
Identification of Gobies
Gobies are small fish with scaly bodies and two dorsal fins. The feature
used to distinguish gobies as a family is the fusion of the pelvic fins
beneath the abdomen to form a weak sucker (Bagenal, 1972), as shown in
Figure 2. Identification of individual species, however, is more difficult