Bulletin Of The United States Bureau Of Fisheries Vol 33 Classic Reprint PDF Download

Excerpt from Bulletin of the United States Bureau of Fisheries, Vol. 33 The present paper embodies the results of observations made on the eggs and larvae of two species of teleosts, Bairdiella chrysura and Anchovia mitchilli. The work was carried on at the United States Fisheries Laboratory at Beaufort, N. C., during the summer of 1913. It is not the purpose of this paper to discuss at length any of the merely technically-interesting points in the development of pelagic fish eggs. Nor does it contribute anything essentially new to our knowledge of the embryology of teleosts. The work was undertaken for the purpose of securing a record as complete as possible of the time of spawning and of the embryological and larval development of fishes with pelagic eggs breeding in these waters during the summer, one of the primary objects being to afford a ready means of identifying either eggs or larval fishes at any time during embryological and larval life. Observations were made as far as possible on living material. The eggs wen-collected in the tow net. The larval fishes were taken primarily in the stow net, the bunt of which was provided with a hood of cheesecloth terminating at its apex in a large collecting bottle. A small per cent of the larval fishes taken in this manner were brought into the laboratory alive. The large majority of them, however, were dead before being taken from the net. Eggs collected at the same hour on successive days were found to be in approximately the same phase of development. Obviously, spawning occurs regularly each day at approximately the same hour. Observations show that both species under consideration spawn regularly in the early evening, probably before 8 o'clock. The eggs of these species are relatively small and contain but little yolk material. Embryological development, therefore, proceeds very regularly and requires a relatively short time. The eggs of Anchovia mitchilli require approximately 24 hours for hatching. Those of Bairdiella chrysura hatch in approximately 18 hours. The time required for hatching, doubtless, varies somewhat with the temperature of the water. The height of the spawning season of Bairdiella chrysura occurs during the last week of June and the lira week of July. Anchovia mitchilli spawns freely during June, July, and August. The height of the spawning season of this species, doubtless, occurs in July. The average temperature of the water in the vicinity of the laboratory for the latter half of June was 27.15 C. The average temperature for the entire month of July was 27.77 C. These averages are based on daily readings taken at 5 o'clock p. m. About the Publisher Forgotten Books publishes hundreds of thousands of rare and classic books. Find more at www.forgottenbooks.com This book is a reproduction of an important historical work. Forgotten Books uses state-of-the-art technology to digitally reconstruct the work, preserving the original format whilst repairing imperfections present in the aged copy. In rare cases, an imperfection in the original, such as a blemish or missing page, may be replicated in our edition. We do, however, repair the vast majority of imperfections successfully; any imperfections that remain are intentionally left to preserve the state of such historical works."