BIOLOGY OF THE ATLANTIC MACKEREL (SCOMBER 



SCOMBRUS) OF NORTH AMERICA. PART 1: EARLY 



LIFE HISTORY, INCLUDING GROWTH, DRIFT, 



AND MORTALITY OF THE EGG AND 



LARVAL POPULATIONS 



By Oscar Elton Sette, United Stales Fish and Wildlife Service 



J- 

 CONTENTS 



Face 



Introduction 149 



Account of field work 151 



Synopsis of results 152 



Significance of results 155 



Life history 156 



Reproductive age 156 



Fecundity 156 



Spawning grounds and spawning sea- 

 sons 158 



Coast of southern New England 



and Middle Atlantic Statrs___ 158 



Gulf of Maine 159 



Coast of Nova Scotia 1 (10 



Gulf of St. Lawrence 160 



Relative importance of the var- 

 ious spawning grounds 161 



Numbers of eggs spawned and size of 



spawning stock 164 



l'aKe 

 Life history — Continued. 



Spawning habits 165 



The egg 166 



The larva 170 



Growth 173 



Drift and migration 183 



Mortality 191 



Appendix 208 



Methods of determining size at 



maturity 208 



Methods of collecting eggs and larvae. 209 



Enumeration of eggs and larvae 211 



Computations of catch per station . . 213 

 Records of tow netting and catches 



of 1932 219 



Sizes of youngest post-planktonic 



mackerel 235 



Literature cited 230 



INTRODUCTION 



The common mackerel, Scomber scombnis, is found on both sides of the Atlantic 

 Ocean, approximately between the 30th and 50th parallels of north latitude. Although 

 American and European representatives are very much alike in appearance, life 

 history, and habits, their ranges are discontinuous, so that the two populations may 

 be regarded as separate races with no intermigration. Consistent with this view is the 

 observation (Garstang, 1898, p. 284) that the two stocks differ in morphological 

 characters. 



The American race has from colonial times been caught and marketed in large 

 volume. 1 In the nineteenth century the annual yield occasionally reached 200,000,000 

 pounds. The present yield is about 60,000,000 to 80,000,000 pounds annually, of 

 which the United States fishery takes about tliree-quarters and the Canadian fishery 

 the remainder (Sette and Needier, 1934, p. 43). 



1 The European race, too, is the object of an important commercial fishery, but appears never to have been held as high in esteem 

 or occupied so high a rank among the commercial fishes of Europe as has Its American relative among the fishes of tills side of the 

 Atlantic. Fishery Bulletin 38. Approved for publication May 15, 1939. 



149 



