26 U. S. BUREAU OF FISHERIES. 



oy,er, '' and the production of food fish would probably have been 

 somewhat greater had the larger fisli been removed at intervals 

 during the summers of those years. 



The ett'ort in manipulating the stock of this pond has been to so 

 control the number of fish of different ages in it that an association 

 might result that would give continual maximum production of fish 

 of edible size year after year. The tendency of the manipulation 

 for the last three years has been to decrease the number of fish con- 

 stituting the spring plant, so that the small fish produced by them 

 during the current year might not make up an undue proportion of 

 the total annual production of fish flesh. It has been observed that 

 too great a production of young fish in a given year prevents many 

 of the half-grown fish from attaining edible size through too serious 

 competition for the available food. 



THE BIOLOGICAL LABORATORIES. 



Tlie biological laboratory at Woods Hole, Mass., was reopened 

 during the summer of 1922 under the direction of Dr. R. E. Coker, 

 then assistant in charge of the division of scientific inquiry. The 

 laboratory was again opened in June, 1923, and was made available 

 during the summer for investigators working on fishery problems. 

 Doctor Coker was secured as director for the season. The policy 

 of extending the use of the laboratory to the Marine Biological Lab- 

 oratory of Woods Hole with the understanding that no charge be 

 made by that institution for the use of the facilities providecl the 

 bureau has been continued. The laboratory has been used through- 

 out the year by Dr. P. S. Galtsoff, naturalist of thp Albatross, who 

 has conducted here the laboratory work connected with the hydro- 

 graphic and biological survey of Long Island Sound. Dr. Charles J. 

 Fish and Marie D. P. Fish have also made use of the laboratory facil- 

 ities in the work they have been doing on the study of the plankton 

 and larval fishes of the Woods Hole region. 



On account of the inadequate salary provision, the Beaufort 

 Biological Laboratory has continued without a scientific director, 

 and, wdth the exception of the diamond-back terrapin experiments, 

 has remained inactive so far as the investigation of fishery problems 

 is concerned. The facilities of the laboratory were used by several 

 investigators during the season, among whom were Dr. L, F. 

 Shackell, of the University of Utah ; Dr. H. V. Wilson, of the LTni- 

 versity of North Carolina ; and Dr. Bert Cunningham, of Trinity 

 College, Durham, N. C. The Navy Department also made use of 

 , the laboratory in continuing its investigations on the fouling of ships' 

 bottoms, and in October a conference was held there by the naval 

 officers and investigators concerned. This bureau was represented at 

 the conference l^y J. Paul Visscher, whose work on the fouling of 

 ships' bottoms is referred to elsewhere in this report. The acting 

 director has supervised the necessary repairs to buildings, sea wall, 

 and grounds, and has carried out instructions for the conduct of the 

 terrapin experiments, which have been intrusted largely to his care 

 for several years past. 



The work at the Key West biological station for the fiscal year has 

 been, for the most part, of a preliminary nature. Owing to the lack 

 of equipment and a laboratory building, together with an insufficient 



