The Food of Pike, Esox lucius L., in Windermere

Abstract

and deals with the food and feeding habits of the pike and the relationship of these to other fish in the lake. The pike were taken from both north and south basins of Windermere. The lake has an area of 51 square miles (14 sq.km.) and a mean depth of 70 ft. (22 m.) and the water is essentially soft. The fish in Windermere, in addition to the pike, are salmon (Salmo salar L.), brown trout (S. trutta L.), char (Salvelinus willughbii (Gunther)), perch (Perca fluviatilis L.), eel (Anguilla anguilla L.), Stickleback (Gasterosteus aculeatus L.), bullhead (Cottusgobio L.) and minnow (Phoxinusphoxinus (L.)). Formerly the association of species was mainly trout and char, but since the eighteenth century environmental conditions have been more favourable to pike and perch, although the former are still important species in the lake. The experiment carried out by the Freshwater Biological Association, and still in progress, to reduce the perch and pike populations of Windermere (Worthington 1949) produced much of the material on which the present study of the food of pike is based. MATERIAL The pike examined were caught by standard seine, minnow seine, gill-nets and handnet. Each year from April to September a seine is fished monthly in the north basin of the lake. The standard seine used is 50 yd. (46 m.) long and 12-15 ft. (3.7-4.6 m.) deep. The mesh is graded from 1 in. (2.5 cm.) knot to knot on the wings to 3 in. (0.9 cm.) at the bag. A minnow seine of 30 yd. (27.5 cm.) long was used specifically to catch smaller pike (particularly those of less than 20 cm.) which had a mesh of 4 in. (0.6 cm.) knot to knot. This was used, particularly in weedy localities, from June to October, at various times during 1943 to 1951. The removal of the pike in Windermere, in connexion with the experiment with fish populations being carried out in this lake, was done by means of gill-nets set during the winter and spring (October to March) from 1944 to the present day. The gill-net used consisted of a sheet of netting of 5 in. mesh (21 in. knot to knot) of fine