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■ February 



■ March 



June 



July 



October 



Navember 



December 



-21 22-23 24-25 26-27 28-29 30-31 32-33 -34 

 LENGTH INTERVALS (Cm ) 



Figure 3. — The relation of the frequency of the HM factor 

 to length in female P^nglish sole in different months, 

 1962-63, Port Orchard, Wash. 



A distinct seasonal change took place between the 

 spawning in December and the resting stage in 

 July; during this period the HM frequency for a 

 given length interval generally decreased. In the 

 October and November samples, as tlie ovaries 

 developed for the ne.xt spawning season, the HM 

 frequencies in the various length intervals again 

 increased. 



Figure 3 does not take into account any growth 

 between the December sample and subsequent col- 

 lections. If seasonal growth increments were con- 

 sidered, most individuals 26 to 29 cm. long in Decem- 

 ber would be 30 to 33 cm. long in July. This state- 

 ment is based on the assumption that El Sayed's 

 (1959) growth estimates for English sole from Holmes 

 Harbor in Northern Puget Sound are applicable to 

 the Port Orchard population. A comparison of the 



— Februory 

 ■Morch 



June 



July 



^=^ October 

 - ■■■ — November 

 oooooo December 



0.5-0.9 1.0-1.4 1.5-1.9 2.0-2.9 3.0-3.9 

 GONAD WEIGHT (G.) 



4.0 



HM frequency in these two length intervals in 

 December with the next higher interval in July 

 still indicates a striking variation of freciuency. 



Ovarian weight and HM frequency are related 

 (fig. 4) . Gonad weight and HM frequency increased 

 simultaneously. A qualitative seasonal variation 

 in the factor's presence is again indicated. All 

 ovaries weighing more than 1 g. that were taken 

 during or immediately following the spawning season 

 were from HM-positive individuals. Even a con- 

 siderable number of the largest ovaries taken during 

 the resting stage were from HM-negative individ- 

 uals; HM frequency decreased as the ovarian mass 

 decreased. 



The relation between gono-somatic ratio (gonad 

 weight expressed as percentage body weight) and 

 HM frequency is generaly similar to that between 

 gonad weight alone and HM frequency (fig. 5). 



0.3 



0.4 



0.5 0.5 0.7 0.8 



GONO-SOMATIC RATIO 



0.9 2|0 



Figure 4. — The relation of HM frequency to gonad weights 

 in female English sole, 1962-63, Port Orchard, Wash. 



Figure 5. — The relation of HIM frequency to gono-somatic 

 ratios in female English sole. 



The gonad weight shows the relation more clearly 

 than the gono-somatic ratio, however, suggesting 

 that the qualitative seasonal variations of the HM 

 frequency are dependent more on the absolute weight 

 of the gonad than on its mass relative to body weight. 



ANALYSIS OF DATA ON HALIBUT 



The HM frequencj^ of the various halibut samples 

 is given according to length in table 7. Fish of 

 various ages were combined in the length intervals 

 because of the small samples. The criterion for 

 maturity of halibut ovaries was the presence of 

 macroscopic ova. Personnel of the International 

 Pacific Halibut Commission made all maturity esti- 

 mates. The HM factor was detected in the serum 

 from all female halibut that were estimated to be 

 mature. 



SERUM FACTOR IX MATURITY 



53 



