Toole et al Otolith microstructure, mlcrochemistry, and early life history of Microstomas psoficus 



74 



A 



B 



y 



D 



Figure 8 



Stage-3 Dover sole. Microstomas pacificus, otoliths showing variations in accessory primordium formation; anterior to left, dorsal toward 

 top in A-C, dorsal toward bottom in D. AP = accessory primordium, CCA = clear central area, CP = central primordium, OCA = opaque 

 central area. (Al Left otolith of 55.6-mm larva collected 19 January 1989, showing unenclosed central primordium growth (indicated by 

 triangle). Magnification = 100x. (B) Left otolith of 46.9-mm larva collected on 17 March 1990, showing two accessory primordia 

 (anterior and posterior) completely enclosing growth from the central primordium. Magnification = 100*. (C) Left otolith of 64.9-mm 

 larva collected 17 March 1990, showing growth from four accessory primordia (anterior, posterior, dorsal, and ventral) completely 

 enclosing growth from the central primordium. Magnification = 100 • . (D) Right otolith of 55.5-mm larva collected on 17 March 1990. 

 showing growth from four accessory primordia (one anterior, two posterior, and one dorsal) completely enclosing growth from the central 

 primordium. Magnification = 100x. 



with the conical cavity described previously (Fig 8, 

 A-D). This situation also applied to the origin of the 

 most posterior AP in left otoliths (Fig. 8, A-C). The 

 chronology of additional AP formation did not follow a 

 consistent pattern. Dorsal and ventral AP were often 

 associated with dark bands in the opaque central area 

 (Fig. 11). 



Dorsal and ventral AP were formed 196-338 incre- 

 ments distal to the central primordium (Table 4). When 

 increments were counted back from the otolith edge. 



dates of last AP formation varied between fish, rang- 

 ing over a six-month period from October to March 

 (Fig. 12). The number of days between the first-formed 

 and last-formed dorsal and ventral AP averaged 28.8 

 (range 1-75, n-25). This range would be greater if it 

 were possible to make accurate counts to the anterior 

 AP. 



Enclosed peripheral area Growth from accessory 

 primordia completely enclosed growth from the cen- 



