Brown-Peterson et al.: Reproductive biology of Brevoortia patronus in the Gulf of Mexico 
291 
Table 1 
Bimonthly percentages of (A) female and (B) male Gulf menhaden ( Brevoortia patronus), collected from 
Mississippi and Louisiana coastal waters of the northern Gulf of Mexico during 2014-2016, in re- 
productive phases determined by histological examination. The phases include immature (Imm), early 
developing subphase (EDev), developing (Dev), spawning capable (SC), early germinal epithelium (GE) 
subphase (EGE), mid GE subphase (MGE), late GE subphase (LGE), actively spawning subphase (AS), 
regressing (Rgs), and regenerating (Rgn). 
(A) Females 
Date 
n 
Imm 
EDev 
Dev 
SC 
AS 
Rgs 
Rgn 
16-31 Aug 
46 
0 
0 
0 
0 
0 
0 
100 
16-30 Sep 
80 
5 
6 
3 
0 
0 
0 
86 
1-15 Oct 
56 
2 
11 
20 
57 
3 
0 
7 
16-31 Oct 
64 
1 
0 
0 
58 
41 
0 
0 
1-15 Nov 
14 
0 
0 
0 
100 
0 
0 
0 
16-31 Jan 
17 
0 
6 
0 
59 
35 
0 
0 
1-15 Feb 
4 
100 
0 
0 
0 
0 
0 
0 
16-28 Feb 
6 
0 
0 
0 
100 
0 
0 
0 
1-15 Mar 
1 
0 
0 
0 
0 
0 
100 
100 
16-31 Mar 
7 
14 
0 
0 
14 
29 
0 
43 
16-30 Apr 
5 
0 
0 
0 
0 
0 
0 
100 
1-15 May 
15 
7 
0 
0 
0 
0 
0 
93 
1—15 Jun 
23 
4 
0 
0 
0 
0 
0 
96 
(B) Males 
SC subphase 
Date 
n 
Imm 
EDev 
Dev 
SC 
EGE ] 
MGE 
LGE 
Rgs 
Rgn 
16-31 Aug 
50 
4 
41 
8 
0 
0 
0 
0 
0 
47 
16-30 Sep 
54 
6 
37 
36 
4 
0 
0 
0 
0 
17 
1-15 Oct 
50 
0 
0 
28 
72 
83 
17 
0 
0 
0 
16-31 Oct 
56 
0 
0 
0 
100 
59 
37 
4 
0 
0 
1-15 Nov 
14 
0 
0 
0 
100 
60 
30 
10 
0 
0 
16-31 Jan 
16 
0 
6 
0 
94 
31 
69 
0 
0 
0 
1-15 Feb 
3 
0 
0 
0 
100 
0 
100 
0 
0 
0 
16-28 Feb 
2 
0 
0 
0 
100 
0 
0 
0 
0 
0 
1-15 Mar 
4 
0 
25 
0 
25 
0 
0 
100 
25 
25 
16-31 Mar 
4 
0 
0 
0 
75 
0 
0 
100 
25 
0 
16-30 Apr 
12 
0 
0 
0 
0 
0 
0 
0 
33 
67 
1-15 May 
16 
6 
6 
0 
0 
0 
0 
0 
6 
82 
1-15 Jun 
13 
0 
8 
0 
0 
0 
0 
0 
15 
77 
Batch fecundity was not significantly related to age 
(P=0.698) nor K (P= 0.768). Additionally, RBF was 
not significantly related to length (P=0.282), weight 
(P=0.615), or K (P= 0.546), suggesting the RBF calcula- 
tion removes the effects of fish size and can therefore 
be used to accurately compare fecundity of different- 
size fishes. Thus, based on RBF and spawning frequen- 
cy, an average size female of 150 g may produce as 
many as 614,460-1,277,430 eggs during the 5.5-month 
reproductive season. 
The oocyte dynamics of Gulf menhaden offer an un- 
clear picture as to whether this species has determi- 
nate or indeterminate fecundity. Oocyte size-frequency 
distributions of secondary growth oocytes in Gulf men- 
haden from October and March show a dramatic re- 
duction in the number of small vitellogenic oocytes in 
March than in October (Fig. 6), suggesting that new 
oocytes are not recruited into vitellogenesis at the end 
of the spawning season — a pattern typical of determi- 
nate fecundity but also seen in some species with inde- 
terminate fecundity. The gap in oocyte distribution be- 
tween primary and secondary growth oocytes typically 
seen in species with determinate fecundity is not seen 
in Gulf menhaden, although that is not unexpected in 
this instance because only secondary growth oocytes 
were counted. Histological observations of females from 
February and March showed a lower percentage of pri- 
mary and secondary vitellogenic oocytes in the ovary 
than from October and November, suggestive of deter- 
minate fecundity. However, the percentage of atresia in 
