90 
Staging ovaries of Haddock (Melanogrammus 
aeglefinus ): implications for maturity indices 
and field sampling practices 
Email address for contact author: katie burchard@noaa.gov 
Department of Natural Resources Conservation 
University of Massachusetts-Amherst 
Amherst, Massachusetts 01003 
Present address: Narragansett Laboratory 
Northeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
28 Tarzwell Drive 
Narragansett, Rhode Island 02882 
Department of Biology 
University of Victoria 
Victoria, BC, Canada V8W 3N5 
Marine Ecology and Technology Applications, Inc 
23 Joshua Lane 
Waquoit, Massachusetts 02536 
4 Marine Resources Research Institute 
South Carolina Department of Natural 
Resources 
217 Ft Johnson Rd 
Charleston, South Carolina 29412 
Abstract — We build on recent efforts 
to standardize maturation staging 
methods through the development 
of a field-proof macroscopic ovarian 
maturity index for Haddock (Me- 
lanogrammus aeglefinus) for stud- 
ies on diel spawning periodicity. A 
comparison of field and histological 
observations helped us to improve 
the field index and methods, and 
provided useful insight into the re- 
productive biology of Haddock and 
other boreal determinate fecundity 
species. We found reasonable agree- 
ment between field and histological 
methods, except for the regressing 
and regenerating stages (however, 
differentiation of these 2 stages is 
the least important distinction for 
determination of maturity or repro- 
ductive dynamics). The staging of 
developing ovaries was problematic 
for both methods partly because of 
asynchronous oocyte hydration dur- 
ing the early stage of oocyte matura- 
tion. Although staging on the basis 
of histology in a laboratory is gen- 
erally more accurate than macro- 
scopic staging methods in the field, 
we found that field observations can 
uncover errors in laboratory staging 
that result from bias in sampling 
unrepresentative portions of ovaries. 
For 2 specimens, immature ovaries 
observed during histological exami- 
nation were incorrectly assigned as 
regenerating during macroscopic 
staging. This type of error can lead 
to miscalculation of length at matu- 
rity and of spawning stock biomass, 
metrics that are used to characterize 
the state of a fish population. The 
revised field index includes 3 new 
macroscopic stages that represent 
final oocyte maturation in a batch 
of oocytes and were found to be reli- 
able for staging spawning readiness 
in the field. The index was found to 
be suitable for studies of diel spawn- 
ing periodicity and conforms to re- 
cent standardization guidelines. 
Manuscript submitted 6 February 2012. 
Manuscript accepted 30 November 2012. 
Fish. Bull. 111:90-106 (2013). 
The views and opinions expressed 
or implied in this article are those of the 
author (or authors) and do not necessar- 
ily reflect the position of the National 
Marine Fisheries Service, NOAA. 
Katie A. Burchard (contact author ) 1 
Francis Juanes 2 
Rodney A, Rountree 3 
William A. Roumillat 4 
An important component of the as- 
sessment and management of any 
fish stock is quantification of the 
stock’s productivity, which is a func- 
tion of survival, individual growth, 
and reproductive success of a fish 
population (Wootton, 1998; Morgan, 
2008). There are several factors that 
can be used to estimate the annual 
reproductive potential of a fish stock, 
including but not limited to sex ratio, 
age and size at maturity, spawning 
stock biomass, fecundity, and stock 
recruitment estimates where egg 
and larval viability are taken into 
consideration (Jennings et ah, 2001; 
Morgan, 2008). Regular monitoring 
and data collection on reproduc- 
tive potential, including estimation 
of spawning stock biomass, age and 
size at maturity, and fecundity, are 
dependent upon the use of reproduc- 
tive maturity indices from a sample 
of the population (Tomkiewicz et ah, 
2003). 
Because the ability to accurately 
determine reproductive maturity by 
macroscopic examination of the go- 
nads alone is fallible, the validity of 
field reproductive indices has been 
questioned (Hilge, 1977; Templeman 
et al., 1978; Saborido-Rey and Jun- 
quera, 1998; Vitale et ah, 2006). De- 
termination of maturation stages in 
the field has been criticized as not be- 
ing dependable because different re- 
productive phases may appear simi- 
lar during gross staging of the gonad. 
For example, estimates of spawning 
stock biomass or mean length at ma- 
turity will depend upon an accurate 
distinction between adult fishes with 
regenerating gonads and immature 
fishes (Forberg, 1982; West, 1990). 
Similarly, estimates of fecundity in 
determinate-spawning species, such 
as Atlantic Cod ( Gadus morhua ) and 
Haddock, require accurate identifica- 
tion of ovaries in prespawning stages 
(Murua et al., 2003). Therefore, it is 
important that the system used for 
determination of maturity stage is 
accurate and unambiguous (Brown- 
Peterson et al., 2011; Lowerre-Barb- 
ieri et al., 2011). 
There have been considerable in- 
consistencies in the definitions of 
maturity stages of fishes among the 
existing indices in the literature. For 
example, O’Brien et al. (1993) defined 
