98 



Fishery Bulletin 102(1) 



Table 1 



Description of histological and macroscopic features (after fixation in a formaldehyde, acetic acid, calcium chloride solution I of 

 ovarian developmental stages of Lutjanus carponotatus. Stage definitions and descriptions are largely a modification of the scheme 

 proposed by Samoilys and Roelofs (2000). Mean ovary weight (GW) and gonosomatic index (GSI) for the larger Palm Island group 

 sample are provided. 



Stage 



Histological features 



Macroscopic features 



Inactive I Immature 



II Resting 



Active III Ripening 



IVa Ripe 



IVb Running ripe 



Relatively thin ovarian wall; lamellae well 

 packed; only darkly purple staining previ- 

 tellogenic oocyte stages (oogonia and peri- 

 nucleolar stages) present. 



Relatively thick ovarian wall; spaces be- 

 tween lamellae common; only previtellogenic 

 oocyte stages and possibly brown bodies and 

 few atretic vitellogenic oocytes present. 



Most advanced oocytes are at yolk globule or 

 migratory nucleus stage; atretic oocytes or 

 brown bodies possibly present. 



Most advanced oocytes at yolk vesicle stage; 

 atretic oocytes or brown bodies possibly 

 present. 



Similar to stage IVa but large, irregularly 

 shaped, clear to lightly coloured hydrated 

 oocytes are present. 



Always even white color over entire surface; 

 smooth surface texture; lobes quite small (typi- 

 cally <2 cm long) and thin (mean GW=0.33 g; 

 meanGSI=0.24^). 



Even white to cream or tan color over gonad sur- 

 face; surface may be smooth or somewhat convo- 

 luted; small white stage II ovaries are difficult to 

 distinguish from stage I without histology I mean 

 GW=1.01 g; mean GSI=0.43%). 



Color sometimes white but more often cream to 

 tan; surface is commonly convoluted; difficult to 

 distinguish from stage II without histology (mean 

 GW=1.18 g; mean GSI=0.53% I. 



Color tan to brown or mustard with opaque speck- 

 les that become larger and more dense as late 

 stage oocytes become more numerous; convoluted 

 surface sometimes with prominent vasculariza- 

 tion (mean GW=4.04 g; mean GSI=1.399S \. 



External appearance identical to stage IVa and 

 can only be differentiated histologically (no sam- 

 ples found at Palm Island group). 



classes compared with the distribution of body sizes offish 

 at stage II (Fig. 2). 



Stage-Ill (ripening) ovaries contain oocytes at the yolk 

 vesicle vesicle stage, which some authors classify as vitel- 

 logenic (e.g. Samoilys and Roelofs, 2000) and others classify 

 as previtellogenic (e.g. West 1990). Like stage-II ovaries, 

 stage-Ill ovaries can, but do not necessarily, contain brown 

 bodies or atretic oocytes as evidence of probable prior 

 spawning. Although the fish might not have spawned pre- 

 viously, stage III is considered to be a mature stage in the 

 present study because the appearance of yolk vesicles is 

 associated with the initial development of the yolk globule 

 and represents advanced development of the oocyte beyond 

 perinucleolar stages (West, 1990). Therefore, the fish is pre- 

 paring for spawning and will soon be part of the mature 

 population if it is not already. Mean age and size of stage-II 

 (4.4. years and 219 mm FL), stage-Ill (5.0 years and 222 

 mm FL), and stage-IV (6.5 years and 261 mm FL) females 

 were much more similar to one another than they were 

 to stage-I females (1.9 years and 119 mm FL). Moreover, 

 size-frequency distributions of fish at stages II, III, and 

 IV showed considerable overlap and similarity with one 

 another and were all quite distinct from the size-frequency 

 distribution for stage-I females (Fig. 2). This suggests a 

 division between immature fish and those that are spawn- 

 ing or are nearly ready to do so. The pronounced difference 



in GW and GSI between stage-I and stage-Ill ovaries and 

 similarity in these metrics between stage-II and stage-Ill 

 fish (Table 1) further support this division. 



Most immature ovaries and all ripe ovaries could be 

 identified macroscopically. Because certain macroscopic fea- 

 tures were common to multiple ovarian stages, additional 

 histological features was required to separate the largest 

 immature from the smallest resting ovaries and all ripening 

 from resting ovaries among the samples remaining after 

 the initial comparison betw-een histological and macroscopic 

 features. Only one ovary with fully hydrated oocytes, col- 

 lected at the Lizard Island group, was found among the 

 samples prepared for histological analysis; therefore stages 

 IVa and IVb were treated as a single stage. Stage IV suf- 

 ficiently represents final development toward spawning on 

 the broad seasonal time scale adopted in this study but 

 encompasses a wide range of ovarian characteristics and 

 would need to be divided into more detailed stages for finer 

 temporal scale studies of lunar or diel spawning patterns. 

 No samples exhibited features of truly "spent" ovaries. 



Sex-specific demography 



Differences were not apparent in early growth of L. car- 

 ponotatus between the island groups (ANCOVA: df=l, 

 46; F=1.07; P=0.301); therefore the data were pooled to 



