102 
Fishery Bulletin 111(1) 
Tabie 5 continued 
Hydration stage 3 (H3) 
Macroscopic: The ovary is well developed, reddish-yellow in color, and approximately 
2/3 the volume of the body cavity. The membrane is opaque with blood vessels conspicu- 
ous. Greater than 50% of the visible surface of the ovary consists of large translucent 
oocytes. 
Microscopic: There is a predominance of oocytes showing germinal vesicle migration and 
germinal vesicle breakdown. Greater than 50% of the advanced oocytes are hydrated. 
Postovulatory follicles may be present (magnification 40x). 
Regressing (S) 
Macroscopic: The ovary is soft and flabby and approximately 1/4 the volume of the 
body cavity. The membrane is thick and tough, purplish in color, and bloodshot. The 
inside of the ovary is almost empty and few oocytes remain, giving the gonad a patchy 
appearance. 
*Note: Toward the end of the spawning season, the ovary loses its rigidness although it 
still has 1-2 batch(es) of oocytes to spawn. Staging should not be based only on the flab- 
biness of the ovary, and the ovary should be inspected internally. The ovary is likely not 
yet spent if any hydrated oocytes remain. 
Microscopic: An abundance of postovulatory follicles are present. Oogonia and primary 
oocytes are evident. The ovary wall is thick, and muscle bundles are visible (magnifica- 
tion 40x). 
vM o A&i&L 
§gr 
Iff! ♦, ' w 
it spawned much earlier that season or skipped that 
year’s spawning season (Fig. 1). One mature regenerat- 
ing female was observed during the peak of the spawn- 
ing season. Skipped spawning is a response to various 
physiological and ecological conditions (Jorgensen et 
al., 2006) and often a trade-off between present re- 
production and survival for future reproduction (Bull 
and Shine, 1979; Rideout et ah, 2005). Because it is 
not possible to determine the existence and frequency 
of skipped spawning and its effect on recruitment, it 
is difficult to determine spawning stock biomass and, 
hence, difficult to conduct stock assessments and man- 
age such species (i.e., stock-recruitment models may 
overestimate recruitment and underestimate survival; 
Rideout et ah, 2005). 
Postovulatory follicles 
POFs were commonly found in ovary samples classified 
as HI, H2, H3, and S in the field, but these POFs of- 
ten were in various phases of atrophy. The observation 
of early and late phases of POFs in the same ovary 
indicated that POFs from the 2 previous batches still 
existed during the OM of the next batch to be spawned 
(Table 2). Evidence indicates that the complete atro- 
phy of a POF in Haddock could take up to 10 days, 
considering that Haddock have an average interval of 
5.4 days between spawned batches (Trippel and Neil, 
2004), and that final oocyte maturation in marine fish- 
es with pelagic eggs generally lasts 1-2 days and ends 
with ovulation (Thorsen and Fyhn, 1996). The atrophy 
