D'Alessandro, E.K.

Sponaugle, S.

Aquatic Commons

Larval Growth, Duration, and Supply Patterns of Sphyraena barracuda 
 
EVAN K. D’ALESSANDRO and SUSAN SPONAUGLE 
Rosenstiel School of Marine and Atmospheric Science, University of Miam 
 4600 Rickenbacker Causeway 
 Miami, Florida 33149 USA 
 
ABSTRACT 
The great barracuda (Sphyraena barracuda) is an important predator in mangrove, seagrass, and reef environments of 
south Florida and the Caribbean. Despite this very little is known about their early life history or population replenishment. 
In order to determine temporal patterns of larval supply to nearshore waters, a series of light traps was deployed over shal-
low coral reefs along the upper Florida Keys every other night for six months from May-October of 2002 and 2003. Traps 
were also deployed monthly during peak settlement times throughout winter and spring (November-April) of 2003 and 
2004. Larval growth rates and the pelagic larval duration (PLD) of barracuda were determined through otolith analysis and 
compared to concurrently collected hydrographic data. Barracuda appeared in the traps only during summer months, with 
two primary lunar-cyclic pulses occurring between the third quarter and new moons in late June-early July and late August-
early September. Water temperature explained most of the variability in early larval growth, however, patterns were unclear 
for later larval growth. Additional data are needed to augment the four seasonal cohorts and verify these preliminary results. 
 
KEY WORDS:  Great Barracuda, Sphyraena barracuda, larval growth, duration 
 
Crecimiento Larval, Duración, y Patrones de Oferta de Sphyraena barracuda 
 
 La barracuda (Sphyraena barracuda) es un predador importante en los manglares, pastos marinos, y arrecifes de coral 
del sur de la Florida y del Caribe. A pesar de esto, se sabe muy poco con respecto a su historia de vida temprana y al repo-
blamiento de sus poblaciones. Con el objeto de determinar patrones temporales de oferta de larvas a las aguas costeras, se 
usaron una serie de trampas de luz en arrecifes someros de los cayos superiores de la Florida cada noche de por medio por 
seis meses desde mayo hasta octubre durante el 2002 y el 2003. También se usaron trampas mensuales durante la época 
pico del reclutamiento durante el invierno y la primavera (noviembre a abril) del 2003 y el 2004. Así mismo, se determinó 
la tasa de crecimiento larval y la duración pelágica larval (DPL) de la barracuda con el análisis de otolitos y se compararon 
con datos hidrográficos recaudados concurrentemente. Solo se encontraron larvas de barracuda en las trampas durante los 
meses de verano, con pulsos relacionados al ciclo lunar, bimodales, y picos de oferta entre el cuarto menguante y la luna 
nueva al final de junio–principios de julio y al final de agosto–principios de septiembre. La mayoría de la variabilidad en el 
crecimiento larval y el DPL se pueden explicar usando la temperatura del agua. Sin embargo, factores hidrográficos tales 
como la presencia temporal de eddies tienen una influencia en el transporte de larvas y también pueden contribuir a varia-
ciones adicionales en las características de la historia de vida temprana. 
 
PALABRAS CLAVES:  La barracuda, Sphyraena barracuda, crecimiento larval, duración 
 
 
INTRODUCTION 
Sphyraena barracuda (Walbaum), or the great 
barracuda, is an apex predator found in most tropical and 
sub-tropical seas.  While juveniles up to ~30 cm standard 
length (SL) and three years of age remain in nearshore 
seagrass and mangrove environments, and older, larger 
adults occur further offshore, they remain almost exclu-
sively piscivorous throughout their lives (de Sylva 1963, 
Blaber 1982, Schmidt 1989).  In south Florida, barracuda 
occur in marine mangrove, seagrass, and coral reef 
environments, as well as estuarine environments of Florida 
Bay.  Although not commercially fished in these areas, the 
barracuda is an important, if not unavoidable, gamefish. 
Despite its widespread occurrence, very little is known 
about the ecology of this species, especially early life 
history traits such as larval growth rate and causes of 
variation in this rate.  Water temperature has been shown to 
be the major cause of variation in the growth rate of 
another species of reef fish (Thallasoma bifasciatum) in 
south Florida (Sponaugle et al. 2006).  The objectives of 
the present study were to: 
i) Identify patterns of larval barracuda ingress to 
nearshore environments,  
ii) Measure the larval growth rate for this species, 
and 
iii) Determine whether water temperature is a major 
cause of larval growth variation. 
 
METHODS 
 
Field Sampling 
 To intercept larval barracuda settling to nearshore 
environments, larval light traps (for design see D'Alessan-
dro 2005) were deployed over French Reef in Key Largo 
Page 217  58th Gulf and Caribbean Fisheries Institute  
 
every other night from May – October in 2002 and 2003. 
Traps were also deployed twice monthly (during third 
quarter and new moons) from November – April in 2003 
and 2004.  Deployment occurred at sunset and retrieval at 
dawn, upon which samples were immediately preserved in 
95% ethanol. 
Water temperatures were recorded by a Sontek 
Argonaut-MD acoustic Doppler current meter at 21m depth 
fixed to a subsurface mooring located at 25º04’N and 
80º19’W at the shelf break.  Data were recorded every 5 
min and were made available by Dr. Tom Lee, RSMAS, 
University of Miami. 
 
Otolith Analysis 
Prior to dissection, the standard length (SL) of all 
larvae were measured to the nearest 0.01mm.  All otoliths 
(saggite, lapillis, and asterisciis) were removed from each 
larva and placed on a microscope slide in a drop of 
medium viscosity immersion oil.  After clearing for 
approximately one week, the clearest lapilli from each 
individual was photographed at 400X oil-immersion 
magnification through a Leica DMLB microscope and 
accompanied Dage MTI video camera and frame grabber. 
Images were sharpened and read using Image Pro Plus 4.5 
image analysis software.  Daily increments were enumer-
ated and measured along the longest axis of the otolith 
twice by the same individual (E.D.) and the larva was 
omitted from analysis if the age differed by more than two 
days between reads.  All increments were considered larval 
because larvae were intercepted during ingress to juvenile 
habitat.  Because it was assumed that increment formation 
began at the onset of exogenous feeding (Jones 1986), 
three days were added to the age of each larvae based on 
yolk absorption times of the closely related species S. 
borealis and S. argentea (Orton 1955, Houde 1972). 
 
Data Analysis 
To examine temporal patterns of larval barracuda 
ingress, the total number of barracuda larvae collected 
were collapsed into a single lunar cycle with day 29 
corresponding to a new moon and day 15 corresponding to 
a full moon. A Rayleigh test (Zar 1999) was then used to 
determine whether catches were distributed randomly 
about the lunar cycle. 
An approximate larval growth rate was obtained from 
the slope of a regression between larval SL and larval age. 
Barracuda larvae were classified into early summer (May - 
July) and late summer (August - October) cohorts in 2002 
and 2003.  The effect of water temperature on larval 
barracuda growth was examined by regression of the 
average water temperature a cohort encountered while in 
the plankton (estimated by back-calculation of the hatch 
date) with the average otolith increment width over 
different periods of larval growth. 
 
 
RESULTS AND DISCUSSION 
In total, 108 barracuda larvae were captured during the 
two years of light trapping over French Reef.  The near-
continuous time series of larval barracuda ingress from 
May-October in 2002 and 2003 indicated that in both years 
there was peak larval ingress in late June-early July and 
late August - early September.  No barracuda were 
captured in light traps during monthly sampling from 
November-April in either year.  A Rayleigh test (Z = 9.54; 
p < 0.01) revealed that most supply occurred between the 
third quarter and new moons in each month (lunar day = 
27).  This suggests that barracuda spawn in spring and 
summer which agrees with previous work examining 
barracuda gonads (de Sylva 1963).  Of the 108 barracuda 
larvae captured over the reef, measurement of SL was 
possible for 48 larvae (many larvae were damaged by the 
time of preservation), and only these were included in 
otolith analyses.  The SL of barracuda larvae ranged from 
5.98 to 23.3 mm, with a mean SL of 15.69 mm.  The age of 
these larvae ranged from 9 to 22 days, with a mean age of 
16.46 days. Regression of SL on age (r2  = 0.84; p < 0.01) 
revealed a larval growth rate of 1.2 mm/day over this 
period. Significant regressions between mean water 
temperature and average increment widths by cohort 
existed for increments 1 - 5 but not for overall average 
increment width or for any other part of the otolith.  Thus, 
water temperature explains a major portion (99%) of 
variability in growth rate early in the barracuda larval life 
but other factors such as prey availability may be equally 
or more important for the majority of the pelagic larval 
duration (PLD).  Caution must be used in the interpretation 
of these regressions, however, due to the low sample size 
of only four cohorts.  Further, if the vertical positions of 
larvae change over time, the effective water temperature is 
likely to vary and a single location at the shelf break may 
not be reflective of the water in which the larvae spent their 
PLD. Additional data are needed to verify these prelimi-
nary results. 
 
LITERATURE CITED 
Blaber S.J.M.  1982.  The ecology of Sphyraena barracuda 
(Osteichthyes: Perciformes) in the Kosi system with 
notes on the Sphyraenidae of other Natal estuaries. 
South African Journal of Zoology 17:171-176. 
D'Alessandro, E.K. [2005].  Patterns and processes of 
larval fish supply to the coral reefs of the Florida 
Keys.  Unpubl. Ms., University of Miami, Miami, 
Florida USA. 
de Sylva, D.P. 1963.  Systematics and life history of the 
great barracuda, Sphyraena barracuda (Walbaum). 
Studies in Tropical Oceanography 1:1-179. 
Houde, E.D. 1972.  Development and early life history of 
the northern sennet, Sphyraena borealis DeKay 
(Pisces: Sphyraenidae), reared in the laboratory. 
Fishery Bulletin 70:185-195. 
 
  D’Alessandro, E. and S. Sponaugle  GCFI:58   (2007) Page 218 
 
Jones, C.  1986.  Determining age of larval fish with the 
otolith increment technique. Fishery Bulletin 84:91-
104. 
Orton, G.L. 1955.  Early developmental stages of the 
California barracuda, Sphyraena argentea Girard. 
California Fish and Game 41:167-176 
Schmidt, T.W.  1989.  Food habits, length-weight relation-
ship and condition factor of young great barracuda, 
Sphyraena barracuda (Walbaum), from Florida Bay, 
Everglades National Park, Florida. Bulletin of Marine 
Science 44:163-170 
Sponaugle S., K. Grorud-Colvert, and D. Pinkard.  2006.  
Temperature-mediated variation in early life history 
traits and recruitment success of the coral reef fish 
Thalassoma bifasciatum in the Florida Keys. Marine 
Ecology Progress Series 308:1-15 
Zar, J.H.  1999.  Biostatistical Analysis: Fourth Edition. 
Prentice Hall, Upper Saddle River, New Jersey USA. 


Larval growth, duration, and supply patterns of Sphyraena barracuda

http://aquaticcommons.org/12998/1/gcfi_58-27.pdf

Larval growth, duration, and supply patterns of Sphyraena barracuda

Abstract

Similar works

Full text

Available Versions

Aquatic Commons