The Reproduction of the Flat-Fishes

Abstract

“The spawning periods of the food-fishes have been fully ascertained for the east coast of Scotland by Dr. Fulton and other Scottish workers, and the present occasion afforded a good opportunity of determining the spawning time of the plaice on the south-west coast of England. Mr. Cunningham's work, published in previous numbers of this Journal, and in more compendious form in his book on Marketable Marine Fishes, covers the whole field of fishery investigation, and forms therefore an excellent basis for more definite and detailed research. The spawning period of the plaice, for example, is given as January, February, and March for the North Sea and English Channel, and in a general way this is quite correct, but it is somewhat vague. The plaice of the Bristol Channel also spawn during the months mentioned, but on the whole later than those of the English Channel. It is evident, therefore, that we must ascertain the periods at which most plaice are spawning or have spawned, in other words the maximum spawning period as it is generally called. The difficulties in the way of ascertaining this accurately arise from the facts that all fish do not spawn exactly at the same time, and that one fish may take two or more weeks in getting rid of all its spawn. We cannot, therefore, delimit the maximum spawning period to less than two to three weeks, and if we allow for fluctuations in different years, one month is the nearest approximation we can make.