192 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



the season, and also prevented their continuation into August. Thus, there was less 

 opportunity for taking large larvae corresponding to the eggs and small larvae of the 

 earlier cruises. However, the cruises did thoroughly cover the major portion of the 

 season of maximal spawning and subsequent larval development; so there need be 

 only a treatment which excludes from comparison the large larvae early in the season 

 and the eggs and young larvae late in the season which were not proportionately 

 represented in the other stages of their planktonic existence. 



This was done by taking the average numbers of eggs and larvae per cruise for 

 the several cruises that spanned the period of maximal numbers of each stage of egg 

 and larva. 19 The selection of cruises for these averages was as follows: for egg stages 

 A to C, cruises I to IV; 3-mm. larvae, cruises II to V; 4- to 7-mm. larvae, cruises III 

 to VI; 8- to 9-mm. larvae, cruises IV to VII; 10- to 12-mm. larvae, cruises V to VIII; 

 13- to 15-mm. larvae, cruises VI to IX; 16- to 22-mm. larvae, cruises VII to IX; and 

 23- to 50-mm. larvae, cruise IX. 



1 The categories of egg stages are defined on p. 178, the categories of larval lengths are the midpoints of the class interval. 



> See text p. 179. 



' See text p. 192. 



* Items in the third column divided by the items in the first column. 



« Logarithms of the items in the fourth column plus the constant 2.041. 



• These are the values represented by the heavy lines of fig. 17. 



This selection provides a series that approximately follows the eggs of cruises I 

 to IV through their subsequent stages. Since by far the largest numbers of eggs were 



18 Before theaverages were drawn an adjustment was made in the numbers of larvae from cruise IV on which a group of stations, 

 Fcnwick I, Winternuarter I, II, and III, and Chesapeake I and III had been omitted. These stations were located in the area where 

 only 2 days previously there had been found most of the 5- to 11-mm. larvae and the omission of these stations caused a marked, 

 deficiency of these sizes in the totals of cruise IV (note in table 5, column 4, the abrupt drop in numbers from the 3- to the 5-mm. 

 class). Since these particular stations were occupied at the very end of cruise III, growth and mortality in the few intervening days 

 before cruise IV would have only slightly altered the catches at these stations by the time of the latter cruise. Therefore, to restore 

 the deficiency, the catches of cruise III at these stations were added to the cruise IV totals, giving new values of 5381, 1998, 682, 150, 

 67, 31, 6, and 3 for the 4- to 11-mm. classes in the 4th column of table 6. 



