18 
1 
NOAA 
Spencer F Baird 
National Marine 
Fisheries Service 
Fishery Bulletin 
ft*- established 1881 
First U S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
m 
Age, growth, and recruitment of larval and 
early juvenile Atlantic croaker iMicropogonias 
undulatus), determined from analysis of otolith 
microstructure 
Matthew J. Kupchik (contact author ) 1 
Richard F. Shaw 2 
Email address for contact author: mkupch1@lsu.edu 
1 Department of Oceanography and Coastal Sciences 
School 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 
School of the Coast and Environment 
Louisiana State University 
002Q Energy, Coast, and Environment Building 
Baton Rouge, Louisiana 70803 
Abstract— The Atlantic croaker (Mi- 
cropogonias undulatus) is an im- 
portant commercial species in the 
Gulf of Mexico, but this stock has 
been reduced historically as bycatch 
in other fisheries. Sagittal otoliths 
(1V=190) were removed from larval 
and early juvenile Atlantic croaker 
collected within a Louisiana tidal 
pass over a 2-year period, from Oc- 
tober 2006 through March 2007 and 
from September 2007 through March 
2008. Standard length (SL) at age 
in days after hatching (dah), over 
both years, was fitted with a Laird- 
Gompertz growth model, and simi- 
lar models were fitted separately to 
year and season to determine wheth- 
er different spawning subgroups ex- 
isted. In both years, the maximum 
growth rate occurred 20 days ear- 
lier in spring than in fall. Otolith 
microstructure measurements were 
used to determine the age (~40 dph) 
at which larvae encountered differ- 
ing water mass characteristics of 
the coastal boundary zone (the off- 
shore to inshore recruitment corri- 
dor). Growth rates increased after 
fish encountered lower-salinity (<20) 
waters of the coastal boundary zone 
and estuary of Bayou Tartellan, LA. 
Temporal variability in spawning of 
Atlantic croaker, determined with 
age-length keys, revealed that the 
highest frequency of hatch dates oc- 
curred during November in 2006 and 
2007. 
Manuscript submitted 28 July 2014. 
Manuscript accepted 13 October 2015. 
Fish. Bull. 114:18-33 (2016). 
Online publication date: 5 November 2015. 
doi. 10.7755/FB.114.1.2 
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. 
The Atlantic croaker (Micropogonias 
undulatus) in the western Atlantic 
range from the Gulf of Maine to the 
northern Gulf of Mexico (GOM). That 
range potentially may extend into 
the southern GOM, the Lesser An- 
tilles, and southern Caribbean and 
from Brazil through southern Argen- 
tina (Smith, 1997). The status of the 
Atlantic croaker stock is unknown 
(NMFS, 2009), although it is expect- 
ed to be below maximum sustainable 
yield. The amount of Atlantic croaker 
harvested commercially has been cy- 
clic, ranging from 1100 metric tons 
(t) per year to more than 15,000 t 
per year; annual levels recently were 
estimated at approximately 9000 
t, with a value of approximately $8 
million (NMFS, 2012). These fluctua- 
tions reflect the high variability in 
recruitment patterns driven by both 
small and large spatial and temporal 
scales of environmental conditions, 
such as wind field patterns, storm 
frequency, salinity, temperature, hy- 
poxic zones, and local hydrographic 
features (Norcross, 1983; Norcross 
and Austin, 1988; Able, 2005; Eby et 
al., 2005; Montane and Austin, 2005). 
The commercial stock is further 
affected by the amount of Atlantic 
croaker that is caught as bycatch, 
principally through shrimp trawl- 
ing — an amount that is calculated 
to be 60-80% of the catch by weight 
(NMFS, 2012). The amount of Atlantic 
croaker caught annually as bycatch 
can total from 100,000 to 400,000 t, 
and data from the 1990s indicated 
that Atlantic croaker may have made 
up almost 73% of the total bycatch of 
short-lived demersal species (NMFS, 
2009, 2012). The results of analysis of 
samples collected during 1986-2006 
by Southeast Area Monitoring and 
Assessment Program crews show that 
the Atlantic croaker, which was clas- 
sified as a bycatch species, to be the 
dominant species by weight at depths 
less than 30 m off the Louisiana coast 
(Helies and Jamison 1 ). At depths 
1 Helies, F. C., and J. L. Jamison. 2009. 
Reduction rates, species composition, 
and effort: assessing bycatch within the 
Gulf of Mexico shrimp trawl fishery. 
NOAA/NMFS Cooperative Agreement 
Number NA07NMF4330125 (#101). Fi- 
nal Report, 182 p. Gulf and South At- 
lantic Fisheries Foundation Inc., Tampa, 
FL. [Available at website.] 
