FISHERY BULLETIN: VOL. 80, NO. 2 



%. 



- ;. f < ' BHAi 









D 



Figure 2.— Sagittae of herring larvae, Clupea harengus. Bar on photographs represents 10 fim; pr - primordium, a = anterior, 

 p = posterior, nc = nuclear check. A. Otolith from laboratory-reared larva, 8.4 mm SL, showing 2 growth increments (1000X). 

 Additional increments are optical artifacts. B. Otolith with 23 increments showing band of thin, poorly defined 4-5 increments 

 around nucleus; 18.6 mm SL; Annandale 76-01, Stn. 38. C. Otolith with 51 increments (630X). Note the first 3-4 thin, poorly 

 defined increments immediately surrounding nuclear check; 19.9 mm SL; Researcher 76-01, Stn. 105. D. Otolith with 54 incre- 

 ments (630X), posterior view. Note pattern of increment thickness from initial thin, poorly defined 7-9 increments encircling a 

 heavy nuclear check increasing to maximum thickness at 10th-35th increments and then decreasing thickness towards the edge; 

 21.6 mm SL; Researcher 76-01, Stn. 35. 



ameter (otolith length); 2) lateral diameter: a line 

 perpendicular to anterior-posterior axis; 3) nu- 

 cleus diameter: whole otolith at hatching without 

 increments or to inner edge of first increment; 4) 

 anterior radius: nucleus center (primordium) to 

 anterior edge; and 5) posterior radius: nucleus 

 center (primordium) to posterior edge. Selected 

 otoliths were photographed, enlargements 

 made, and increment thicknesses were mea- 

 sured across a posterior radius from the nucleus 

 using a Zeiss MOP Digital Image Analyzer Sys- 

 tem. 



All field-collected larvae used in this study for 

 otolith aging were frozen, whereas the labora- 



tory-reared larvae were preserved in 75% ethyl 

 alcohol, and larvae referred to in other corrobo- 

 rative field studies were preserved in Formalin. 

 Theilacker (1980) reported that the amount of 

 shrinkage of northern anchovy larvae, Engraulis 

 mordax, varies with fish size and duration of 

 time larvae are retained within the net. Larvae 

 smaller than 11 mm SL net-treated for 20 min 

 could shrink as much as 19% of their live length 

 prior to preservation. We estimate that nearly all 

 herring larvae collected on ICNAF surveys have 

 been dead at least 20 min prior to preservation. 

 An additional 3% shrinkage due to 5% Formalin 

 preservation was recommended by Theilacker 



190 



