1
ABSTRACT.
Sardinella mbriata
S. mbriata
Key words:
Biología reproductiva del tunsoy (Sardinella mbriata Valenciennes, 1847) del Estrecho de
Malampaya, Palawan, Filipinas
RESUMEN.
Sardinella
mbriata
S. mbriata
Reproductive biology of fringescale sardinella (Sardinella mbriata
Valenciennes, 1847) from Malampaya Sound, Palawan, Philippines
*
Jesusito A. Vicente Herminie P. Palla
Marine and
Fishery Sciences
MAFIS
Marine and Fishery Sciences 38 (1): xxx-xxx (2025)
Sardinella
mbriata
Sardinella auritaS. maderensis
S. longiceps
Palabras clave:
Vicente and Palla: Reproductive biology of fringescale sardinella
Marine and Fishery Sciences 38 (1): xxx-xxx (2025)
4
specimen were carefully set aside, weighed and
sampled. Maturity stages were assessed based on
morphological characteristics of gonads (Brown-Pe-
terson et al. 2011). Random samples were subjected
to histological evaluation to conrm correct staging
and documentation. Ovaries in spawning capable
stage were placed in plastic vials and immediately
xed in 10% buered formalin for 24 h, and then
they were transferred in 70% ethanol for storage.
Total lengths (TL) were measured at the nearest
0.1 cm, from the tip of the snout to the end of the
tail. Whole body weight and gonad weight were
measured to the nearest 0.01 g. Resulting values
were used to compute for the Fulton’s condition
factor (K) (Froese 2006) and gonadosomatic index
(GSI) (Gaikwad et al. 2009) with the following
formulas:
K = 100 * Weight/length3
GSI (%) =
Weight of gonad × 100
Total weight of sh
Gonadosomatic index of all the sh samples
were computed throughout the sampling period
and was used as a tool to identify the spawning
season. The GSI of small (= mean length – stan-
dard deviation) and large (= mean length + stan-
dard deviation) females were also determined. The
proportion of mature individuals in each size class
were determined and calculated. Fish was consid-
ered matured when they were in spawning capable,
regressing and, regenerating stages (Brown-Peter-
son et al. 2011). The length at maturity (Lm50) was
the size where 50% of sh are already sexually
mature (Willoughby and Tweddle 1978). Fish were
clustered into 1.0 cm size class. The Lm50 was cal-
culated using the following formula (Fontoura et
al. 2009):
P = A + e(-r(L-Lm50))
1
where P is the proportion of reproductive females,
A is the curve asymptote, r is the slope and L is the
length of the sh.
Fecundity determination was done using the vol-
umetric method described by Bagenal and Braum
(1978). A gonad was placed in a container with a
known volume of water. Clumps of adhering eggs
were broken up and eggs were carefully separated
using a dissecting needle. The bottle was homog-
enized before a subsample was taken for analysis.
Three subsamples were taken from each gonad for
counting. The number of hydrated oocytes in the
subsample were counted under a stereo microscope.
Note that the ovaries with postovulatory follicles
were not included as it is an indication that the sh
has already spawned. Fecundity (F) was calculated
using the formula (Murua et al. 2003):
F =
Total volume S
× no. of hydrated ova Ss
Volume Ss
where S is the sample and Ss is the subsample.
The relationship between fecundity and mor-
phometric variables such as length, weight, evis-
cerated weight and gonad weight were determined
using the General Linear Model and Regression
Analysis.
RESULTS
Sex ratio and gonadal development
A total of 1,238 sh samples were examined
throughout the study period, where 50.6% and
52.9% were identied as male (n = 626) and fe-
male (n = 612), respectively (Table 1). Monthly
proportion between sexes varied. Despite this, no
signicant dierence was observed except during
the month of May. This was veried by the chi-
squared (x2) values computed which revealed no
signicant dierence between the two.
Vicente and Palla: Reproductive biology of fringescale sardinella 5
Gonadal examination of sh revealed presence
of spawning capable individuals throughout the
study period (Figures 2-4). However, very few
mature sh were observed during the months of
June and January. The minimum size of matured
sh measured were 11.0 and 11.1 cm for male and
female fringescale sardinella, respectively.
Spawning season determination
The gonadosomatic index of all the samples for
the entire period of study showed that males had
relatively lower GSI than females (Figure 5). It
was further revealed that male GSI was relatively
more stable uctuating slightly between 1.19%
and 3.93%, whereas for females, it started at the
highest of 7.62% in April 2023 and then abruptly
decreased to 2.47% the following month. From
May 2023 onwards, it was observed that the GSI
was almost constant between 1.98% to 4.2%. Gen-
erally, larger females have higher GSI than small
females except in the months of April, June and
October (Figure 6).
Length at maturity (Lm50)
Gonads classied as spawning capable, re-
gressing, and regenerating were considered ma-
tured. High frequencies of sexually matured sh
were observed in all size classes between 10.7 to
15.8 cm. The length at maturity, where 50% of the
sh already reached sexual maturity, was estimat-
ed to be 11.4 and 8.8 cm for males and females,
respectively. The smallest mature sh sample that
was collected for this study was 11.0 cm for males
and 11.1 cm for females.
Table 1. Monthly sex ratio with the corresponding chi-square (x2) values, percentage of mature individuals, and Fulton’s condition
factor (K) of fringescale sardinella from Malampaya Sound, Palawan from April 2023 to March 2024, n = 1,238. Note:
the asterisk indicates signicant dierence observed between the number of sexes based on the computed p-values at 0.05
level of signicance.
Male Female
Month n % %Mature K n % %Mature K Sex ratio x2
male:female
April 2023 49 49.0 71.4 0.929 51 51.0 84.3 0.985 1:1 0.04
May 39 38.2 51.3 1.025 63 61.8 76.2 1.015 1:1.6 5.65*
June 57 55.9 33.3 0.927 45 44.1 68.9 0.930 1:0.8 1.41
July 54 52.4 63.0 0.938 49 47.6 87.8 0.955 1:0.9 0.24
August 46 44.2 52.2 1.028 58 55.8 86.2 1.009 1:1.3 1.38
September 57 54.8 56.1 0.981 47 45.2 87.2 0.992 1:0.8 0.96
October 48 46.2 85.4 0.968 56 53.8 96.4 0.947 1:1.2 0.62
November 59 56.7 59.3 0.926 45 43.3 88.9 0.914 1:0.8 1.88
December 56 53.8 66.1 0.932 48 46.2 87.5 0.911 1:0.9 0.62
January 2024 53 51.5 49.1 0.940 50 48.5 66.0 0.955 1:0.9 0.09
February 59 56.7 61.0 0.969 45 43.3 93.3 0.971 1:0.8 1.88
March 49 47.1 65.3 0.906 55 52.9 89.1 0.905 1:1.1 0.35
Total 626 50.6 59.3 0.956 612 49.4 84.3 0.958 1:1 0.16
Marine and Fishery Sciences 38 (1): xxx-xxx (2025)
Fecundity
Vicente and Palla: Reproductive biology of fringescale sardinella
Marine and Fishery Sciences 38 (1): xxx-xxx (2025)
Vicente and Palla: Reproductive biology of fringescale sardinella
Marine and Fishery Sciences 38 (1): xxx-xxx (2025)
Vicente and Palla: Reproductive biology of fringescale sardinella 11
Sardinella mbri-
ata
Author contributions
Sardinella
Sardinella aurita Sardinella maderensis
Marine and Fishery Sciences 38 (1): xxx-xxx (2025)
Sardina pilchardus
Engraulis encrasicolusSardina
pilchardus
Sar-
dinella mbriata
Epinephelus
guttatusE. striatus
Mycteroperca venenosa
Sardinella brasiliensis
Vicente and Palla: Reproductive biology of fringescale sardinella
Channa gachua
Sardina pilchar-
dus
Sardina
pilchardus sardina
Sardinella gib-
bosaSardinella mbriata
Epi-
nephelus coioides
Pleuronectes platessa
Salmo trutta fario
Gadus morhua
Marine and Fishery Sciences 38 (1): xxx-xxx (2025)
Sardinella longiceps
Seriola lalandi
Mystus nemurus
Sardinella mbriata
Encrasicholina
devisiSardinella mbriata
Sar-
dinella mbriata
Vicente and Palla: Reproductive biology of fringescale sardinella
Euastacus armatus
Pleuronectes platessa
Sardinella gib-
bosaSardinella mbriata
Sardinel-
la aurita
Marine and Fishery Sciences 38 (1): xxx-xxx (2025)
Solea solea
