PROGRESS IN BIOLOGICAL INQUIRIES, 1925 ' 



By Willis H. Rich, Assistant in Charge of Scientific Inquiry 



CONTENTS 



Page 



Introduction 1 



Investigations of fish and fisheries 3 



Atlantic coast 3 



Life histories and migrations of cod, pol- 

 lock, and haddock 3 



Mackerel investigations 7 



Fishes of the South Atlantic and Gulf 



coasts 8 



Smelts and Salmonidae 11 



Larval fishes 13 



Chesapeake Bay 14 



North American Committee on Fishery 



Investigations 14 



Interior waters 15 



Coregoninse of the Great Lakes 15 



Pacific coast and Alaska 16 



Alaska Salmon 17 



Salmon of the Pacific Coast States 17 



Herring of Alaska 18 



Marine fishes of the Gulf of Venezuela 19 



Investigations of shellfish and terrapin 19 



Oysters 19 



Clams of the Pacific coast 23 



Scallops 24 



Fresh-water mussels 25 



Terrapins 26 



Ecological and oceanographic studies 27 



Control of mosquitoes by means of fish... 27 



Oceanography 27 



Ecology of fresh-water lakes... 28 



Fouling of ships' bottoms 30 



Investigations pertaining to fish-cultural 



operations 30 



Physiology and nutrition of fishes 30 



Holden experiment station 32 



Pathology 33 



Pollution 33 



Experimental work in fish culture 34 



Inspection of the sponge fisheries 34 



Biological laboratories 34 



INTRODUCTION 



The work of the division of scientific inquiry during 1925 gave 

 unusually encouraging and satisfactory results. Each major inves- 

 tigation distinctly contributed to our knowledge of fish and the fish- 

 eries, and both the volume and the quality of such contributions were 

 unusual. 



The policy of stressing the study of the immediate rather than the 

 ultimate causes of fluctuations in the abundance of fish of each species 

 was continued. The practical value of the information resulting from 

 such studies is being recognized more and more, and solicitations for 

 further investigations of this nature are increasing; but in spite of 

 larger appropriations for such work, it has been impossible to respond 

 to all of these requests. While appreciation and support of the work 

 of the division is distinctly gratifying, it is realized that such interest 

 entails increased responsibility in addition to the greater opportunity 

 for public service. Every effort has been and will continue to be 

 made to meet this responsibility as ably as possible. 



There has been no change in the policies of the division, as outlined 

 in the reports for the past few years. The division of the work into 

 major investigations has been continued, emphasis having been 

 placed on those giving the greatest promise 01 results of practical 

 importance in the conservation and development of our fishery 

 resources. 



1 Appendix I to the Report of the United States Commissioner of Fisheries for 1926. 

 No. 1003. 



B. F. Doc. 



