OCEAN TEMPEEATUEES. 159 



ing water temperatures conjointly with the migrations of fishes can be readily established, and 

 excellent opportunities for good work in this direction are afforded by all the larger rivers of our 

 country. 



The practical value as weHas scientific importance of investigations of this character, in their 

 bearing upon many of our most extensive sea and inland fisheries, has been fully recognized bj 

 the U. S. Fish Commissioner, and in all the explorations carried on under his direction the 

 observation of water temperatures has been made a conspicuous feature. Unfortunately, the 

 field work of the Fish Commission is, necessarily, limited to a comparatively short season in each 

 year, during which operations have, for the most part, been confined within narrow areas, chang- 

 ing more or less from year to year, or have been extended irregularly from place to place, depend- 

 ent upon the movements of the steiamers. The temperature observations made by the Commission 

 do not, therefore, form continuous series suflflciently complete in themselves for detailed compari- 

 son with the movements of fishes during an entire season of their migrations. In order to supple- 

 ment and extend this class of investigations with reference to the surface waters and surface 

 schooling fishes, the co-operation of the U. S. Light-House Board and U. S. Signal Service was 

 obtained, and for a number of years past continuous series of observations have been taken at 

 some sixty stations belonging to these two services, distributed along the entire Atlantic and 

 Gulf coasts of the United States from Eastern Maine to Southern Texas. 



In this report we have given the temperature results of the light-house stations only, reserv- 

 ing those of the Fish Commission and Signal Service for a future one. Most of the light-house 

 stations form a series which can well be considered apart from the others, all of the stations here 

 included being located on exposed portions of the coast, while those of the Signal Service are 

 mostly situated in inclosed bays or harbors. A few of the light stations are, however, in similar 

 situations to those of the Signal Service and will be considered with them. Before describing the 

 positions and relations of the stations, it may be best to note briefly the character of observations 

 required for application to the problem of fish migrations. 



While general temperature results are of much interest, it is evident that they are totally 

 inadequate to explain the varying movements of fishes. The changes in temperature from day 

 to day and from season to season must be studied in great detail in order to ascertain their pre- 

 cise influence in regulating the arrival, progress, and departure of the schools. If mackerel 

 appear at an earlier date in one year than in another, is that earlier appearance accompanied by 

 a more rapid rise in temperature ? If more abundant or more widely distributed during one season 

 than another, is it due to warmer temperatures covering a wider area than usual, or to other 

 causes ? Answers to these questions are to be sought in a better understanding of the conditions 

 of temperature along our coast, although it cannot be denied that other subjects, such as the dis- 

 tribution and abundance of food, and the influence of the winds and currents, need to be con- 

 sidered in the same connection. In order to make this precise study of the temperatures it is 

 necessary to establish numerous stations at successive points along the course followed by the 

 fishes in their migrations. These stations should be located at a sufiacient distance from the coast 

 to be beyond the influence of local conditions, and at such an ideal series of observing posts the 

 determination of the relations of temperature to fish migrations would be simply a question of 

 time, but unfortunately it is impossible to locate many such stations, and inferior ones have to be 

 selected to complete the series. Observations should be made continuously throughout each 

 season of migrations for several successive years, and by this means many parallel series of 

 records would be obtained suitable for the work of comparison. 



In this report we have to do only with the surface temperature of the waters immediately 



