130 



Fishery Bulletin 93(1). 1995 



Table 3 



Oocyte developmental stages based on histological criteria. 



Stage 



Description 



Chromatin nucleolar 

 Perinucleolar 



Cortical alveoli formation 

 Vitellogenic (yolk) 



Hydrated 

 o atresia 



I atresia 



Postovulatory follicle 



The oocyte is surrounded by a few squamous follicle cells, and scant cytoplasm surrounds a large 

 nucleus containing a single, large basophilic nucleolus. 



The oocyte grows, the nucleus increases in size and multiple basophilic nucleoli appear. These arrange 

 themselves towards the periphery of the nucleus; a single dark dot or "Balbiani body" may be visible 

 in the outer surface of the cytoplasm. 



Spherical vesicles appear in the cytoplasm. Zona radiata present. 



Oocytes are greatly increased in size and ooplasm is filled with yolk globules. Nucleus may be toward 

 the periphery; there is a rapid thickening of the zona radiata. 



Yolk globules fuse to form a continuous mass of fluid and the nucleus is not apparent. Postovulatory 

 follicle may be visible. 



Oocyte is resorbed. Oocyte characterized by an irregular shape and granular, dark basophilic staining. 

 When resorption is complete all that remains is the follicle. 



Follicle degenerates and is resorbed. Follicle compact, composed of several granulosa cells surounded 

 by a thecal and blood vessel layer. Yellow-brown pigment may be present. 



Collapsing follicle is irregularly shaped; cell layers form loose folds or loops. Degenerating follicle 

 shows fewer loops and is reduced in size. 



licles (POF) were identified except in later stages of 

 degeneration when they could not be differentiated 

 from ji atresia (Hunter and Macewicz, 1985). Ova- 

 ries were staged on the basis of the most develop- 

 mentally advanced oocyte observed. Proportions of 

 oocyte stages, atretic structures, and POF's were 

 calculated from counts of structures passing under 

 a line horizontally bisecting the tissue slide. Because 

 oocytes at different stages of development differ 

 greatly in size, counts may be biased against smaller, 

 less-developed stages. Average oocyte diameter was 

 determined from the first 10 oocytes encountered at 

 the most advanced developmental stage and sec- 

 tioned through the nucleus, except hydrated oocytes 

 which were measured as encountered. 



Washington commercial bottom trawl logbook data 

 from July 1991 to July 1992 were examined for trends 

 in fishing depth and arrowtooth flounder catch rates. 

 Information on the target fish and estimates of the 

 amount of fish discarded at sea were unavailable. 

 Catch rates were calculated from the set of 14,559 

 bottom trawl tows in which reported hours fished 

 were greater than 0. Depth of each tow was defined 

 as the shallowest (minimum) depth recorded for ei- 

 ther start or end position. Catch rate or catch per 

 unit of effort (CPUE) was computed as the average 

 of the tow-by-tow arrowtooth flounder catch divided 

 by hours fished; catch data were not adjusted to re- 

 flect actual fish ticket landings. 



Results 



Arrowtooth flounder larger than 53 cm FL were all 

 female and the size ranges in each of the sample cat- 

 egories differed (Fig. 2). Females accounted for 85% 

 (by number) of market, 42% of discard, and 67% of 

 survey samples. Males were not well represented and 

 did not show grossly apparent developmental 

 changes over time; therefore, males were categorized 

 only as mature or immature and were not consid- 

 ered further. However, males appeared most developed 

 in July when the testes were largest, brown to whitish 

 and folded. No spawning males were seen. 



The average length of males was less than that of 

 females in every month that market and survey 

 samples were taken (Table 1; 1-tailed Student's t- 

 test, oc=0.05). Fish size (Table 1) and catch rates 

 (Table 4) were highest in spring and summer. In win- 

 ter, average length of market-sample fish decreased 

 by approximately 9.0 cm for males and 16.0 cm for 

 females. CPUE peaked (>200 kg/hr) in spring and 

 fall at depths of 183-365 m and decreased in winter, 

 while above 183 m CPUE was highest (about 50- 

 150 kg/hr) in July-August but dropped to at or near 

 0.0 kg/hr in November-March. There was no appar- 

 ent seasonal trend in CPUE at depths >366 m. 



The proportion of mature females at each macro- 

 scopic maturity stage varied seasonally (Fig. 3). Be- 

 cause spring discards included fish that were the 



