48 U. S. BUREAU OF FISHERIES 



* 



of the coastal waters. They must await a rise in temperature in 

 the suirace waters over the continental shelf in order that they may 

 lose the boundaries of the Gulf Stream and follow the Sargassum 

 as it is l)lown into the area outside. No doubt the immediate waters 

 about Woods Hole are prepared to receive the visitors long before 

 the outer waters permit their passage through. For that reason, 

 although api)roximately 12.5° C. may be taken as their minimum 

 t(MU|)eiatuie for existence in local waters, the date when the inshore 

 waters rise to 12.5° C. far precedes the same rise in surface water 

 otl' the coast and also the actual arrival of tlie first summer forms. 

 In the fall, however, reverse conditions exist. The date when the 

 surface water locally reaches the minimum temperature for these 

 forms is then of great importance, because this drop directly affects 

 those which are already here and they disappear at once. During 

 1924 the first sunnuer visitors aj)peared on July 12 and the last on 

 October 22. The comi>lete absence of southern fish after that date 

 would seem to be a result of a sudden drop in temperature that 

 occurred on October 20, when the temi)erature of tlie air fell 1(> 

 degrees overnight and a really cold spell set in. A trip was made 

 to Katama liay on November 7, when the sui'face teni})erature was 

 12.5° C, but diligent seining brought in nothing except young 

 (•unners, tautog, sculpins, winter fiounders, and other typically resi- 

 dent fauna. 



To date 92 truly tropical species, which are undoubtedly mere 

 " accidents " of the (lulf Stream, and TO species Avith a predomi- 

 nantly southern range, whose northern limit of migration is Woods 

 Hole, have be(>n taken in local waters. A general account of their 

 ai)i)earance, distribution, and disapi)earance in this region, together 

 with descriptions and illustrations of the various tropical species, 

 is nearly complete. 



CIIIOSAI'KAKK HAY 



The work of preparing for publication the data beaiing on the 

 fish and fisheries of Chesapeake Ba}^, which were secured in connec- 

 tion with the hydrographic and biological survey of this region 

 undertaken several years ago, has gone forward. The work has 

 been delayed fiecpiently, owing to the more pressing need of other 

 investigations, but satisfactory jirogress can be reported. This 

 Avork has been carried out under the direction of Sauuiel F. Hilde- 

 bi'and aided l)y William C. Schroeder and Isaac Ginsburg. 



NOin'll AMKKU'AX COM M 1 TTKK ON FISIIKUV INVESTIGATIONS 



Only one meeting of the committee was held during the period 

 covered by this report. This occurred at Montreal, Canada, on 

 November 7 and was attended by W. A. Found and Dr. A. {}. Hunts- 

 man, rei^resentatives for Canada, and Henry O'jMalley, Dr. H. B. 

 Bigelow, and Dr. W. H. liich, representatives for the I'nited States. 

 No cliange in the personnel of the committee has taken ])lace since 

 the last re[K)rt. 



Oceanograi)hic work and cod-tagging operations received particu- 

 lar attention, and plans were made for an extension of both of these 

 lines of investigation. Further steps were taken to coordinate more 



