Brown-Peterson et al.: Reproductive biology of Brevoortia patronus in the Gulf of Mexico 
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Figure 7 
Estimates of (A) annual egg production of the stock and (B) the 
maximum proportion of spawners-per-recruit of Gulf menhaden 
( Brevoortia patronus) based on collections from the northern Gulf 
of Mexico during 2014 through 2016. For each panel, fecundity from 
Lewis and Roithmayr (1981, lines 1 and 2) and the low (lines 3 and 
4) and high (lines 5 and 6) estimates of fecundity derived in this 
study are displayed with 2 different age-specific maturity patterns 
(dashed and solid lines). Lines 1, 3, and 5 display the expected tem- 
poral patterns when the age at first maturity is 2 years. Lines 2, 
4, and 6 display the expected temporal pattern in maximum pro- 
portion of spawners-per-recruit when maturity is modeled with 
the logistic relationship described in this work (proportion of age-1 
spawners is 0.68). 
leosts typically have notably lower GSI values than 
females (Wootton, 1998). The high male GSI values of 
Gulf menhaden and other clupeids may be related to 
increased sperm competition in the pelagic environ- 
ment (Stockley et al., 1997), which is common with spe- 
cies that spawn in groups (Erisman and Allen, 2006) 
such as Gulf menhaden. 
Lack of concordance between macroscopic and histo- 
logical assessment of reproductive phase in Gulf men- 
haden was unexpected. Although histological assess- 
ment remains the best method to accurately identify 
specific reproductive phases (West, 1990; Brown-Peter- 
son et al., 2011), we found that broadly assessing fish 
as reproductively active or inactive by macroscopic in- 
spection is sufficiently accurate, as did Klibansky and 
Scharf (2015). Thus, macroscopic assessments could 
allow biologists, managers, and industry personnel to 
determine reproductive seasonality of Gulf 
menhaden. 
The fecundity pattern of Gulf menhaden 
has not previously been reported, although 
Combs (1969) documented asynchronous 
oocyte development and suggested Gulf 
menhaden are batch spawners. Fish with 
determinate fecundity recruit all oocytes 
to be spawned during the year into vitello- 
genesis at the beginning of the reproductive 
season before the first spawing and can be 
either batch or total spawners, whereas fish 
with indeterminate fecundity continually 
recruit oocytes into vitellogenesis through- 
out the reproductive season and are batch 
spawners (Murua and Saborido-Rey, 2003). 
Marine clupeids exhibit both types of fecun- 
dity patterns; cold water species, such as 
Atlantic and Pacific herring ( Clupea haren- 
gus and C. pallasii), show determinate fe- 
cundity and total spawning, whereas many 
temperate and subtropical batch spawning 
clupeids (such as species of Sardinella and 
Sardinops ) tend to have indeterminate fe- 
cundity (Ganias, 2013). However, American 
shad ( Alosa sapidissima ) have recently been 
shown to have determinate fecundity in 
northern populations and indeterminate fe- 
cundity in southern populations (McBride et 
al., 2016), as predicted for species with wide 
geographic ranges by Ganias et al. (2015). 
The subtropical/tropical clupeid Spanish 
sardine ( Sardinella aurita) has been shown 
to have determinate fecundity but is likely 
to be a batch spawner (Tsikliras and Anto- 
nopoulou, 2006) while the Brazilian menha- 
den ( Brevoortia aurea ) is a batch spawner 
reported to have indeterminate fecundity 
(Macchi and Acha, 2000; Lajud et al., 2016). 
Our data indicate that Gulf menhaden are 
likely to have indeterminate fecundity, but 
have some traits more typical of fish with 
determinate fecundity, such as high GSI val- 
ues at the beginning of the spawning season, a reduc- 
tion in secondary growth oocytes as the spawning sea- 
son progresses, and the lack of massive atresia at the 
end of the spawning period in at least some individu- 
als. Indeed, Ganias et al. (2017) showed that some spe- 
cies with indeterminate fecundity can cease recruiting 
new oocytes during the spawning season; this is likely 
the case for Gulf menhaden. The variations in fecun- 
dity patterns among clupeids show the importance of 
assessing determinate or indeterminate fecundity for 
each species and of not relying solely on geographic 
location or spawning strategy. Understanding fecundity 
patterns, as well as spawning dynamics, is also impor- 
tant for estimating total annual fecundity. 
Our mean BF estimates of 15,367 eggs (SE 3260) 
are much lower than the previous fecundity estimates 
for age-2 Gulf menhaden of 47,900 eggs (SE 5038) 
