Fish Bulletin No. 55. Report on returns of drift bottles released off southern California, 1937
- Author(s): Tibby, Richard B
- et al.
The use of drift bottles as a means of charting ocean currents is an old one, and their use in fisheries research is not without precedent. In the North Sea, particularly, investigations of the oceanic circulation have been carried on over a number of years by this means and have shed light on a great variety of fisheries problems. The circulation of the waters off the coast of southern California was, at the beginning of the present survey, very incompletely charted. It was felt that a more detailed knowledge of hydrographic conditions would materially assist in the interpretation of some of the problems relating to the life-history of the sardine (Sardinops caerulea) and some of the other commercial fishes. The present survey was designed to chart surface circulation throughout the region of maximum spawning of the sardine. As the California State Fisheries Laboratory possessed neither the equipment nor the personnel for a detailed hydrographic survey of the region, it was decided that drift bottles should be used as the most convenient method of obtaining data on the surface circulation. Drift methods have two distinct advantages: the bottles are inexpensive to prepare and no special training or equipment is necessary to carry out their release. After Dr. H. U. Sverdrup, Director of the Scripps Institution of Oceanography, was consulted concerning the plans for the drift bottle investigation, it was proposed that the Scripps Institution, which was then seriously handicapped by the loss of their research vessel, carry on a program of water sampling concurrently with the drift bottle releases as an additional means of obtaining data on the circulation of the region in question. This arrangement proved to be most satisfactory as the information obtained by dynamic methods was more detailed and provided a much better picture of conditions than would have been possible by the drift bottles alone. As it turned out, the main value of the drift bottles lay in confirming the results of the dynamic computations. As the Scripps Institution of Oceanography is now in a position to continue their hydrographic work and as the information they obtain will be available to the California Division of Fish and Game, the drift bottle work need not be continued.