Burchard et al Maturity indices and field sampling practices for staging Melanogrammus aeglefinus 
95 
70°12'W 
! ! Western Gulf of Maine Closure 
□ Stellwagen Bank National Marine Sanctuary 
Figure 2 
Map of the locations where mature female Haddock (Melanogrammus aeglefinus) were 
sampled in the southwestern region of the Gulf of Maine in the spring of 2006 and 
2007 for for staging reproductive maturity. 
(Humason, 1972) through a graded ethanol series, em- 
bedded in paraffin, and sectioned at 6 p. Tissues were 
stained with Gill’s hematoxylin and counterstained 
with eosin-Y. Ovary samples were classified by the oc- 
currence of specific histological features that represent 
progressive oocyte maturation stages (Brown-Peterson 
et ah, 2011) (Table 2). The most progressive feature ob- 
served in each sample was used to assign the appropri- 
ate stage. Photomicrographs were taken of a random 
subsample of stained tissue for each field index stage. 
Statistical analysis 
A contingency table was used to compare the results 
between the macroscopic staging methods used in the 
field and the histological staging methods used in the 
laboratory (Table 4). The table cell where the 2 equiv- 
alent stages cross shows the number of samples for 
which the data from the 2 methods agreed. Because 
the 2 indices were developed independently, 2 differ- 
ent types of percent agreement were calculated. One 
type was derived by dividing the number of samples 
for which the 2 methods agreed by the field stage 
sample size (last row in Table 4). The second type 
of percent agreement was calculated by dividing the 
number of samples for which the 2 methods agreed 
by the histological stage sample size (last column 
in Table 4). We did not have enough observed frequen- 
cies in each cell to perform a chi-square statistical 
analysis. 
