14 THE MAMMALS, REPTILES, AND FISHES OF ESSEX.
ports nearest to their trawling grounds. Others,
again, of late years, have embarked largely on White-
bait fishing. This tiny fish is taken either by means
of a small stow-boat net or a ground-seine. The shores
of the estuaries of the Thames, Crouch, and Roach
are favourite localities for this trade, because they are
within easy reach of the great market of London ; for
Whitebait is a fish that bears carriage badly, and soon
loses its freshness.
The town of Barking was, at one time, the port
from which the North Sea trawlers started ; but, since
railways have enabled fish to be sent in a fresh
condition from almost any port, the importance of
Barking as a trawling centre has materially declined.
Harwich has always had a large number of boats
engaged in the North Sea fishery, and their number
is not decreasing. Here, in 1712, was first invented
the well-boat, which, in pre-railway clays, enabled
fish to be delivered in London in a good and some-
times almost in a living condition. The well-boat
has a portion of its bottom perforated by a large
number of small holes, thus letting the sea-water
freely into its interior. This part is called the "well,"
and it is divided from the spaces at both ends, by
which the boat floats, by water-tight bulk-heads. The
fish, when caught, are placed in this well, where they will
keep alive for a long time, as the movements of the boat