Large quantities of herring, plaice and halibut are also taken.
Plaice, like other flat-fishes, prefer a sandy flat bottom to a rocky ground, and occur in suitable localities in great abundance; they spawn early in spring, and are in finest condition in the month of May.
The fishermen of the district consequently combined to defray the expenses of transplanting large numbers of small plaice from the outer waters to the inner lagoons, where they were found to thrive far better than in their natural habitat.
Experiments with labelled plaice, carried out in 1904 by the Marine Biological Association, showed that small plaice transplanted to the Dogger Bank in spring grew three times as rapidly as those on the inshore grounds, and the same result, with insignificant variations, has been obtained by similar experiments in each succeeding year.
Garstang's "Reports on the Natural History of the Plaice" (Rapports et proces-verbaux du conseil international pour l'exploration de la mer, 1905 seq.).
In this case the deep water round the Dogger Bank acts as a barrier to the emigration of the small plaice from the shores.
It has consequently been proposed that the small plaice should be transplanted in millions to the Bank by well vessels every spring.
As a single female plaice produces about 200,000 eggs per annum, this output does not exceed the natural produce of a few hundred fish.
The plaice fry hatched in the Scottish establishment have been distributed for many years in the waters of Loch Fyne.
Yet in this area, according to the investigations of Mr Williamson (Report of the Scottish Fishery Board for 1898), nearly 500 millions of plaice eggs are naturally produced in one spawning season.
Evidence is still lacking as to whether the 20 to 30 million fry annually added from the hatchery have appreciably increased the quantities of young plaice on the surrounding shores.
Garstang, Experiments on the Transplantation of Marked Plaice (First Report of the North Sea Fisheries Investigation Committee, 1905).
The next in order are haddock, cod and plaice, and the east coast fisheries return the greatest bulk of these also.
But whereas the south coast has the advantage over the west in the herring and plaice fisheries, the reverse is the case in the haddock and cod fisheries, haddock, in particular, being landed in very small quantities at the south coast ports.
The entrances to the inner lagoons of the Limfjord are naturally blocked against the immigration of flatfish by dense growths of sea-grass (Zostera), although the outer lagoons are annually invaded by large numbers of small plaice from the North Sea.
This transplantation of plaice in Denmark has been annually repeated for several years with the most successful results, and a suitable subvention to the cost is now an annual charge upon the government funds.
PLAICE (Pleuronectes platessa), a species of flat-fish, common on the coasts of northern Europe from Iceland to the Bay of Biscay.