Armstrong et al.: Age. growth, and reproduction of Lophius amencanus 



221 



O 'o 



Figure 3 



Seasonal progression of gonad condition in mature male 

 and female Lophius americanus, based on macroscopic 

 examination. 



classes (immature, resting, developing, ripe and spent) 

 were included. 



Oogenesis proceeds through six distinguishable mor- 

 phological stages similar to other fishes, such as black 

 sea bass Centropristis striata (Mercer 1978): 



Oogonia (4.5-1 l/.im) Densely packed, granular, deep- 

 ly basophilic cells. 



Stage 1 Small (15-50 /jm) oocytes with a large nucle- 

 us, single nucleolus, and small amount of basophilic 

 cytoplasm. 



Stage 2 (30-200 f.(m) Previtellogenic oocytes with 

 strongly basophilic cytoplasm and multiple nucleoli 

 around the nucleus margin. 



Stage 3 (1 10-390f/m) Vitellogenesis begins with the 

 deposition of yolk vesicles in the less darkly-staining 

 cytoplasm. A thin zona radiata can be seen in late 

 stage-3. 



Stage 4 (270-970Hm) Cytoplasm filled with yolk vesi- 

 cles and globules, lightly staining. Zona radiata well 

 developed and strongly acidophilic. 



Stage 5 ( > 600 /.(m) Mature or nearly mature oocytes, 

 uniform in appearance due to the coalescence of yolk 

 globules. Often fractured or irregular in outline due 

 to fixation and sectioning. 



o 

 o 



Jon-Feb Mor-April Moy-June July-Auq Sept-Oct Nov-Dei 



Month 



Figure 4 



Seasonal progression of mean gonasomatic index values for 

 male and female Lophius americanus. Numbers of mature in- 

 dividuals examined on each date are indicated. 



Based on the occurrence of these oocyte stages, the 

 ovaries were placed in the following developmental 

 classes: 



Immature Stage 1 and 2 oocytes present, atretic 

 bodies absent. The ovarian lamellae are pressed tight- 

 ly together and lumen is small. 



Resting Stage 1, 2, and 3 oocytes are present with 

 stage 2 dominating. 



