206 
National Marine 
Fisheries Service 
NOAA 
Abstract —Sagittal otoliths (/i=208) 
were removed from larval Gulf men¬ 
haden (Brevoortia patronus) col¬ 
lected in a Louisiana tidal pass over 
a 2-year period, from October 2006 
to March 2007 and from September 
2007 to March 2008, and analyzed 
with digital imaging and fast Fourier 
transformations to estimate age and 
growth. Length at age was estimated 
by using a 2-cycle Laird-Gompertz 
growth model and the growth rates 
were found to be relatively consis¬ 
tent with rates from previous re¬ 
search in the northern Gulf of Mex¬ 
ico, and the estimated timing of an 
ontogenetic shift in feeding strategy 
occurred at approximately 33 days 
after spawning. Laird-Gompertz 
growth models fitted separately to 
age and length groupings revealed 
that the ontogenetic shift was cor¬ 
related more with larval age than 
with length. Measurements taken 
from digital images were used to 
conduct fine-scale analyses of otolith 
microstructure and confirmed that a 
change in otolith structure coincided 
with the ontogenetic shift in feed¬ 
ing at approximately 33 days after 
spawning. Keys of length frequencies 
at age were used to assess temporal 
variability in Gulf menhaden spawn¬ 
ing and they revealed earlier (i.e., 
September) recruitment to spawning 
and estuarine areas and shorter re¬ 
cruitment corridors than those pre¬ 
viously reported. 
Manuscript submitted 28 June 2016. 
Manuscript accepted 7 February 2017. 
Fish. Bull. 115:206-218 (2017). 
Online publication date: 9 March 2017. 
doi: 10.7755/FB.115.2.8 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Fishery Bulletin 
established in 1881 
Spencer F. Baird 
First U.S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Effects of recruitment through a coastal 
hydrodynamic boundary layer on growth 
and otolith microstructure of larval Gulf 
menhaden iBtewoortia patronus} 
Matthew J. Kupchik (contact author)' 
Richard F. Shaw^ 
Email for contact author: mkupch1@lsu.edu 
' Department of Oceanography and Coastal Sciences 
College of the Coast and Environment 
Louisiana State University 
2143 Energy, Coast, and Environment Building 
Baton Rouge, Louisiana 70803 
2 Department of Oceanography and Coastal Sciences 
College of the Coast and Environment 
Louisiana State University 
1002Q Energy, Coast, and Environment Building 
Baton Rouge, Louisiana 70803 
The Gulf menhaden {Brevoortia pa¬ 
tronus) is both the target of a com¬ 
mercially important fishery in the 
Gulf of Mexico (GOM; Pritchard, 
2005; Vaughan et al.'; McCrea-Strub 
et al., 2011) and is an ecologically 
important prey item for commercially 
and recreationally valuable species 
(Del Rio et al., 2010; Nelson et al., 
2012; Simonsen and Cowan, 2013). 
Gulf menhaden have an established 
distributional range from the west¬ 
ern central Atlantic to the GOM, and 
specifically within the GOM from 
Florida Bay to the Bay of Campeche 
(Whitehead, 1985). The Gulf men¬ 
haden fishery is the second largest 
United States fishery by both weight 
and value (Pritchard, 2005), and this 
reduction fishery harvests an aver¬ 
age of 400-600 kilotons annually. In 
' Vaughan, D. S., J. W. Smith, and A. M. 
Schueller. 2010. Age, growth and re¬ 
production of gulf menhaden. Southeast 
Data, Assessment, and Review SEDAR 
27-DW02, 34 p. [Available from web¬ 
site.] 
recent years, 92% of the annual land¬ 
ings occurred in Louisiana (Vaughan 
et al.^). There is also a second, and 
minor component of annual landings 
collected by the small bait fishery in 
the GOM (VanderKooy and Smith^). 
Although the stock is relatively 
healthy with a lower fishing-induced 
mortality rate than that reported for 
target fishing over the long term, in 
recent years fishing mortality has 
increased above the target level, 
but below the mortality limit, and 
population fecundity has decreased 
(Vaughan et al., 2007). Possible limi¬ 
tations to population growth for Gulf 
menhaden include food availability, 
habitat limitations, and successful 
recruitment of larvae into estuarine 
nursery areas, but with declining re¬ 
cruitment being more of a concern 
2 VanderKooy, S. J., and J. W. Smith (eds.). 
2015. The menhaden fishery of the 
Gulf of Mexico, United States: a regional 
management plan, 2015 Revision, 201 p. 
Gulf States Mar. Fish. Comm., Ocean 
Springs, MS. [Available from website.] 
