1
Population Biology of Squid Loligo
chinensis in The Waters of Barru Regency,
South Sulawesi
Joeharnani Tresnati1), Achmar Mallawa1) dan Nuraeni L. Rapi2)
1)
2)
Faculty of Marine Science and Fisheries, Hasanuddin University
Postgraduate Program, Hasanuddin University
ABSTRACT Squid is an economically important resource. Currently, squid populations,
especially in the waters of Barru Regency, were intensive exploited, that is feared to affect
the population biology parameters. The study was conducted from February to April 2011.
The sampling period was three times a week. The samples were obtained using random
collection from the fishermen catch using large liftnet (“bagan Rambo”). Squid mantle
length was measured to the nearest one mm. The parameters analyzed were age group,
gonad maturity stage, growth, mortality, and exploitation rate. Squid population in Barru
Regency consists of three age groups with the length of each mode of 50 mm, 105 mm,
145 mm for males, and 47 mm, 92 mm, 124 mm for females. The gonad maturity stage
(GMS) ranging from GMS I to IV for males and females, with the largest percentage of
GMS III (47.82% in males and 50.06% in females). The squid first maturity is reached at
94.3827 mm in long coat for males, and 59.6735 mm for females. Growth equation for
males was Lt = 227 {1 - e -0.31 (t + 0.30)} and females are Lt = 196 {1-e-0, 37 (t +0.26)}. The
total mortality rate (Z) is 1.59 for males and 1.63 for females. The natural mortality rate
(M) is 0.20 for males and 0.57 for females. The capture mortality rate (F) is 1.39 for males
and 1.06 for females. The highest CPUE values reached in 1999 was 0.0022 ton per trip,
while the smallest CPUE values reached in 2001 was 0.0001 tons per year. The greatest
catches could be reached with fishing effort of 50 000 trips with catches of 50 tonnes.
Key words : Age group, Gonad maturity stage, Growth, Mortality, MSY, Exploitation Rate
Introduction
In Indonesia, squid (Loligo sp) is one of important economically
valuable fishery commodities, and an export commodity. Due to significant
economic value and very popular, the demand for squid increased. This trend
will urge fishermen to conduct intensive arrest, while it is known that the
production of squid still hanging on the stock in the wild so feared arrest
intensification will somehow threaten the sustainability of resource
commodity.
The squid in Indonesia are almost all surface waters, such as waters
of the west coast of Sumatra (Aceh and North Sumatra), Strait Java (West
Java and Central Java), Bali, NTB, NTT, South and West Kalimantan, South
Sulawesi, Southeast Sulawesi, Northern Sulawesi, Maluku and Irian Jaya
(Pratiwi and Ward, 1996 in Nurcahaya, 2004).
Waters in Barru Ragency that include in Makassar strait in South
Sulawesi are included in the scope of a potential Indonesian waters will
capture squid, cuttlefish whereabouts has long been used by the surrounding
community as income and food ingredients. According to statistics of the
Department of Fisheries and Marine Resources of South Sulawesi, the
production of squid in Barru increase since 2002 amounted to 25.7 tons to
127.1 tonnes in 2008.
If the arrest was made on a continuous basis to meet consumer
demand in the absence of a business setting, the biological resources of
squid in a certain period can have excess catch and result in disruption of
resource sustainability. The results Sriwana (2007) in the waters of Polewali
Mandar, West Sulawesi using large liftnet (bagan rambo) scored exploitation
2
rate of 0.70 per year. Syriac (2007) in the waters of the North Galesong
District, Takalar get the value of exploitation rate of 0.79 per month. The
data indicate that the level of exploitation of the squid is very high.
Statistical data of 1999 - 2008 obtained the catch per trip on the
amount of fishing gear decreased at the end of the year, 0.0013 on purse
seine and 0.0853 on the large liftnet (bagan rambo), while the longline had
increase of 0.3556 (Departemen Kelautan dan Perikanan Sulawesi Selatan,
2009).
A realistic view of the stock in the sustainable management of fishery
resources, is included to take advantage of the existing stock in the optimal,
for example squid stocks. For this purpose it is necessary to analyze the
impact of squid fishing technology, and biological characteristics must be
understood as the dynamic nature of fish resources. One way to know the
size of the squid that first ripe gonads can be used as one indication of the
gear arrangement specifically regarding mesh sizes of large liftnet. It can be
used as a reference in the sustainable management of fisheries resources.
Materials and Methods
The study was conducted in February-April 2011 in the waters of
Barru Regency, South Sulawesi. The sampling period was three times a
week. There are 2090 squids used in this study, which number of males are
1307 individu and females are 783 individu. Each squid mantle length is
measured with a ruler and expressed in millimeters and then calculate the
rate of gonadal maturation, maturation, growth, mortality, MSY, and the
exploitation rate.
Determination of the age group using the method of Bhattacharya
(1967) which divides the squid in batches mantle lenght. To get good results,
the observed frequency is converted into a frequency count (Fc) using the
normal distribution equation (Hassel Blad in Sparre et al. 1989) : Fc =
n.dl
S√2π
−(X− ̅̅̅̅̅
X)2
exp [
2𝑆 2
]wherein Fc is frequency calculated, n is number of squid, dl is
interval of class, sd is standard deviation, x is mean of squid’s mantle length,
π = 3,1415. Estimation of growth parameters using the Von Bertalanffy
growth formula (Sparre et al. 1999) : Lt = L∞(l-e-K(t-to)), wherein Lt is total
mantle length (mm), L∞ is asymptotic mantle length (mm), K is growth
coefficient, t0 is age theoretical squid at zero length (years) and t is age
(years).
To determine the asymptotic length of squid (L∞) and growth
coefficient (K) is used in the method of Ford and Walford in Sparre et al.
(1999), by plotting L (T + Δt) and L (T) : L(t + ∆t) = a + b. L(t), then bring
in to linear equation : Y = a + bX, wherein a = L∞ (1-b) and b = exp(-K. ∆t),
a
−1
thus obtained : L∞ =
and K =
. Furthermore, to determine t0
1−b
∆t Ln b
formula of Pauly (1980) used Log (-to) = -0,3922 – 0,2752 (Log L∞) – 1,038
(Log K).
Natural mortality allegedly using empirical formula Pauly (1980) : Ln
M = -0,0066 – 0,279 Ln L ∞ + 0,6543 Ln K + 0,4634 Ln T, wherein M is the
rate of natural mortality (years), L∞ mantle length asymptote (mm), K is
growth coefficient, T is water temperature (˚C). Total mortality would be
expected with the Beverton and Holt equations presented in the Sparre et al.
(1999) :



L


L

 , wherein Z is the rate of total mortality (years), L is mean
Z  K 
 L  L 


3
of mantle length (mm), L’ is Limit length of the smallest class size squid
caught (mm). Fishing mortality (F) is suspected by the equation: Z = F + M,
then obtain : F = Z – M.
Observations gonad maturity, gonadal morphology done by
macroscopic observation (visual observation by looking at the color and
texture of the gonads) and histology used gonad maturity criteria of
Sepioteuthis lessoniana Lesson, 1830. To determine the size of the first ripe
gonads in fish can be predicted using the Spearman-Karber method as
X
proposed by Udupa (1986) : Log m=Xk+ - (X x ∑pi)
2
If a = 0,05; 95% confidence limit of m : Anti log (m ± 1,96 √X 2
∑(pi x qi)
ni−1
)
wherein m is Log of mantle length while the squid’s gonads are mature, Xk is
Log class midpoint when all the squid (100%) mature gonads, X is log
difference in median, pi is proportion mature squid in the class-i (pi = ri/ni),
qi is the number of mature squid in the class i, ni is the number of squid in
the class i, qi = 1 – pi
Exploitation rate analysis of squid by collecting secondary data from
annual catch statistics obtained from the Dinas Kelautan dan Perikanan
Sulawesi Selatan for 10 years and performed standardized gear, then used
methods of Schaefer and Fox in Ricker(1995) : Y/f = a + bf. To determine
the potential of the squid sustainable use formulas MSY 
optimal amount of fishing gear : F opt 
 a2
(ton) and
4b
a
. To determine the exploitation
2b
rate : (Last Year Production / MSY) x 100%. Standardization of fishing effort
𝐶𝑃𝑈𝐸𝑛
following the equation (Gulland, 1982) : 𝐸𝑠𝑡𝑑 =
𝑥 𝐸𝑛, wherein Estd =
𝐶𝑃𝑈𝐸𝑠𝑡𝑑
total capture effort that has been standardized (trip), CPUEn = CPUE gear to
be standardized (tons / trip), CPUEstd = standard gear CPUE (tons / trip), En
= fishing effort will standardize. To find high-low level of exploitation then
used criteria level of exploitation(Mallawa, 2005):>80-60% very high levels
of exploitation, 80-60% high levels of exploitation, 60-50% moderate of
exploitation, <50% a low rate of exploitation.
Results and Discussion
Size Structure and Age Groups.
The catch of squid for this research in the waters of Barru regency
was 2090 individu. The squid males were 1307 individu and females 783
individu. The male squid that many caught in the class midpoints size 104
mm is 136 individu and the female on the size of the class midpoints of 100
mm is 139 individu. Catches gained at least 164 mm size of the class
midpoints is 10 individu in males and the female on the size of the class
midpoints of 154 mm is 7 individu (Fig.1 and 2).
The number of samples of squid (Loligo chinensis) obtained during the
study in Barru waters is 2090 individu. Based on the analysis of the results of
the mapping method Bhattacharya class midpoint values by accounting for
the difference in the natural logarithm of the frequency obtained three age
groups for males and females with modus of length 50 mm, 105 mm, 145
mm for males and 47 mm, 92 mm, 124 mm for females (Figures 3 and 4).
4
Frequency
150
100
50
0
32 44 56 68 80 92 104 116 128 140 152 164
Class midpoint (mm)
Figure 1. Relation between the Class Midpoint (mm) and the Frequency of
Males Squid (individu)
Frequency
150
100
50
0
34
46
58 Class
70 82midpoint
94 106(mm)
118 130 142 154
Figure 2. Relation between the Class Midpoint (mm) and the Frequency of
Females Squid (individu)
Both image mapping (Figures 3 and 4) showed the presence of three
straight lines indicating that squid caught in the waters of Barru use Large lift
net for each study consisted of three age groups.
1.00
0.50
L1 = 50
L2 = 105
L3 = 145
Δ Ln Fc
0.00
-0.50 32 44 56 68 74 86 98 110 122 134 140 152 164
-1.00
-1.50
-2.00
Class midpoint (mm)
Figure 3. Mapping Between Class Midpoint and the Difference Frequency
Effective Natural logarithm (ln Δ Fc) Males squid (Loligo
chinensis) in waters of Barru Regency.
5
2.00
L2 = 92
Δ Ln Fc
1.50
1.00
0.50
L3 = 124
L1 = 47
0.00
-0.50 34 46 58 64 76 88 100 106 118 130 142 154
-1.00
-1.50
Class Midpoint (mm)
Figure 4. Mapping Between Class Midpoint and the Difference Frequency
Effective Natural logarithm (ln Δ Fc) Females squid (Loligo
chinensis) in waters of Barru Regency.
While the relationship between mantle length range, the relative age and
mode of mantle length of squid (Loligo chinensis) in waters of Barru Regency
can be seen in Table 1.
Table 1. Relation between Range of Mantle Length (mm), Age Group and
Mean Length of Squid (Loligo chinensis) Male and Female in the
waters of Barru Regency.
Range of
Mean Length
Frequency
Sex
Age Group
Length (mm)
(mm)
(individu)
Male
Female
29 – 77
1
50
292
71 – 137
131 – 167
31 – 67
61 – 109
103 – 157
2
3
1
2
3
105
145
47
92
124
877
189
117
424
274
Table 1 shows that at the same relative age, male squid has a mantle length
of the mode is larger than the female squid. Compared with the results of the
study Sriwana (2007) in the waters of Polewali Mandar, West Sulawesi on S.
lessosiana use large lift net, obtained three age groups with a length mantle
is 11.761 cm, 18.603 cm and 23.962 cm as well as research Nurcahaya
(2004) in the waters of Bali on Loligo sp, using purse seine earned four age
groups with length mantle is 66.07 mm, 85.88 mm, 100.03 mm and 115.15
mm. The difference in results is caused by the differences in fishing gear and
species of squid were caught.
Gonad Maturity Stage
During the study used large lift net obtained different levels of
gonadal maturation in the male and female sexes. Gonad maturity range of
each sample squid ranging from GMS I - IV in males and females. Percentage
GMS for squid males and females were caught in the waters of Barru
Regency using large lift net can be seen in Table 2.
6
Table 2. Gonad Maturity Stage of Male and Female Squid were caught in the
waters of Barru Regency
Male
Female
Gonad
Maturity
Stage
Number of
sample
Percentage
Number of
sample
Percentage
I
256
19.59%
109
13.92%
II
211
16.14%
205
26.18%
III
625
47.82%
392
50.06%
IV
215
16.45%
77
9.83%
Total
1307
100%
783
100%
Based on Table 2, the male squid that is 1307 more than the number
of 783 females squid. Greatest percentage of cuttlefish males at GMS III in
the amount of 47.82% (625 individu) and females at GMS III in the amount
of 50.06% (392 individu). Percentage of immature and mature gonads of
squid can be seen in Table 3.
Effendi (2000) stated that fish have a short periode spawning in a
year or as long it spawn, will be marked by an increase in the percentage of
high level of maturity in each would approach the spawning season. For
those who have fish spawning season of the year, will get the maturity
composition of gonad consisting of various levels with unequal percentages.
Table 3. Percentage of squid (Loligo chinensis) Immature (GMS I and II) and
mature (GMS III and IV) caught by large lift net.
Sample
n
(individu)
Male
Immature
Mature
n
(individu)
Percentage
n
(individu)
Percentage
1307
467
22.34%
840
40.19%
Female
783
314
15.02%
469
22.44%
Total
2090
781
37.37%
1309
62.63%
Table 3 shows that immature gonads of male squid obtained 467
individu (22.34%) and 314 individu of female squid (15.02%), while the
squid with mature gonad obtained 840 individu in males (40.19%) and 469
individu in females (22.44%). During the study the large lift net obtained
squid with immature gonad 37.37% and mature gonad 62.63%. The results
showed that squid populations are found in the Barru waters mostly located
in the phase of mature gonads.
Size in First Maturity
Male squid has a mantle length range between 43-163 mm and squid
females between 42-156 mm. There are differences in range size between the
sexes. The results of the calculation male squid for first maturity stage at
94.3827 mm mantle length with a 95% confidence interval ranged from
93.3518 to 95.4248 mm. While the female squid at 59.6735 mm mantle
7
length with a 95% confidence interval ranged from 59.6729 to 59.6742 mm.
Sukramongkol et al. (2005) in the waters of the Andaman Thailand get L.
duvauceli mature sex on mantle length 125-224 mm in males and 103-186
mm in females, while Loligo chinensis mature sex on mantle length 121-286
mm in males and 104-235 mm in females. According to Andy Omar (2002)
that the squid S. lessosiana first mature gonads in mantle length range 100109 mm for males and females at mantle length size range 150-159 mm.
Fate (2004) found the squid S. lessosiana first spawn at mantle length range
from 11.2 to 14.0 cm. Jackson and PECL (2003) in Australian waters get
mature female squid with mantle length 165-358 mm, weighing 210-1700 g
and mature male with mantle length 172-501 mm and weight of 175-2830 g.
Mariani (2007) get the first ripe gonad size L. chinensis were caught on squid
in the waters of Beba, Tamasaju Village, District of North Galesong, Takalar is
94.0 mm mantle length in the range of 88.65 to 99.75 mm in males and 98.1
mm mantle length in females or in the range of 92 , 51 to 104.09 mm.
Growth
Data analysis of the growth of the squid in the waters of Barru Regency used
combined data chart catches rambo and purse seine. The results of the
analysis using the Ford Walford (Sparre et al. 1989), obtained values of each
growth parameter, which can be seen in Table 4.
Table 4. Growth parameters (L∞, K and t0) Each Sex Squid (Loligo chinensis)
in Barru Waters
Growth parameters
Asymptotic Length (mm)
Coefficient Growth Rate
Theoretical age
Sex
Male
227
0,31
-0,30
Female
196
0,37
-0,26
Table 4 shows that asymptotic length (L∞) for squid males larger than
females is 227 mm for males and 196 mm for females. Growth coefficient (K)
squid males and females showed a low value due to under 0.5 per year so it
takes a long time to achieve asymptotic length. This is consistent with the
statement Spare et al. (1989) that the fish has a low coefficient of growth
rate will take a long time to achieve its symptotic length and fish that have a
high growth rate of value takes quickly to achieve its asymptotic length.
Asymptotic length and growth coefficient different from the results of
research conducted by Thomas and Khizhakudan (2006) in Indian waters and
get an asymptotic length coefficient growth in the squid Loligo duvauceli of
303 mm and 0.98 per year. Sriwana (2007) in the waters of Polewali Mandar,
West Sulawesi, where the squid asimptot length S. lessosiana 43.30 cm while
the coefficient of the growth rate of 0.24 cm per year. Charles and
Sivashanthini (2010) in the northern waters of Sri Lanka to get the value of
the coefficient of the growth rate of 0.85 per year with the theoretical age at
first -0.18627 per annum while the maximum length coat (L∞) of 31.13 cm.
The difference in results obtained, presumably due to differences in
environmental conditions are not the same (Indian waters, the waters of the
North Galesong District, Northern Sri Lankan waters and waters Barru), so
the size and growth rate of squid differently. Nontji (1987) states that any
8
water has different properties in the geographical structure of the seasons
and cycles of water, therefore the organisms that live in it will have the
shape and size of different body.
By using equation Von Berthalanffy (Spare et al. 1989) then in theory
get old male squid (t0) is -0.30 (a relative), and -0.26 (relative time) for
females. Based on the obtained values of growth parameters (L∞, K and t0)
then the growth equation squid in waters Barru by Von Berthalanffy : Males
Lt = 227 (1-e-0, 31 (t +0.30)) and Females Lt = 196 (1-e-0, 37 (t +0.26)). Shape of
growth curve referred to specific growth curves where the squid in the early
phase of his life experiencing rapid growth and will be followed by slower
growth in older age. Effendi (1997) stated that the young fish will have a
relatively rapid growth, being adult fish will be slower to reach the
asymptotic. This is because the energy obtained from food is no longer used
for growth, but is used to replace cells damaged body. Furthermore, Aziz
(1989) suggested that the length of the body with respect to time shows a
uniform level with the growth rate at the beginning, then downhill towards
the theoretical maximum length or the asymptotic length.
Mortality
Estimation of the rate of mortality is important in analyzing the dynamics of
fish populations, the rate of mortality can give an idea of the amount of stock
that can be exploited on a population. Based on the value of the growth
parameters obtained from the calculation in getting the value of the rate of
total mortality (Z), natural mortality rate (M), and the rate of fishing
mortality (F) of each sample squid were analyzed as shown in Table 5.
Table 5 shows that fishing mortality (F) squid males and females is
greater than natural mortality (M). This suggests that the death of squid in
the waters Barru generally caused by the arrest. The results of research from
Thomas and Khizhakudan (2006) in the waters of India scored 3.94 per year
total mortality, natural mortality of 1.94 per year and fishing mortality 2.20
per year.
Table 5. Alleged Value mortality (Z, M, F) squid (Loligo chinensis) in Waters
of Barru Regency
Natural mortality
Total Mortality (Z)
Fishing Mortality (F)
Sex
(M)
Male
1,59
0,20
1,39
Female
1,63
0,57
1,06
Syriac (2007) in the District of North Galesong scored 1.53 per month
total mortality in males and 1.53 for females 1.89 per month, natural
mortality 0.14 per month in males and 0.40 females per month, fishing
mortality 1.11 per month in males and 1.49 per year in females. Karnik and
Chakraborty (2002) conducted research in the waters of Mumbai, India to get
the value of the total mortality of 4.29 per year, 1.82 per year of natural
mortality, fishing mortality 2.47 per year. Furthermore Neethiselvan and
Venkataranami (2002) in the South Coast India scored 2.27 per year total
mortality, natural mortality of 0.91 per year, fishing mortality 1.36 per year.
Mortality values different from above by several studies in the waters of
9
Barru Regency presumably because the water conditions are not the same,
so the cause of death would naturally be different, and the amount or
intensity of arrests in each region are different. Mortality values different
from above by several studies in waters of Barru Regency presumably
because the water conditions are not the same, so the cause of death would
naturally be different, and the amount or intensity of arrests in each region
are different.
Exploitation Rate
Maximum Sustainable Yield (MSY) or maximum sustainable capture fisheries
production is the maximum that can be maintained continuously, and is one
of the parameters generated in the management of fisheries resources
assessment. Estimated resource potential of squid is done by analyzing the
data of total catch and fishing effort of fishing gear. By using statistical
Office of Marine and Fisheries in southern Sulawesi Barru exploitation rates
can be calculated using the production model of Schaefer and Fox in Ricker
(1975). To find the catch per unit of arrest can be seen in Table 6.
Table 6. Data Exploitation magnitude estimation results Catch and CPUE
model Schaefer on squid in the waters of Barru Regency
Year
Catch (ton)
Effort Standar (trip)
CPUE
1999
51
23651
0.0022
2000
32
26729
0.0012
2001
12
83983
0.0001
2002
26
19199
0.0013
2003
28
58958
0.0005
2004
31
27396
0.0011
2005
34
25949
0.0013
2006
34
25012
0.0014
2007
125
31088
0.0040
2008
127
69422
0.0018
Table 6 shows that the highest CPUE values obtained in 1999 is 0.0022 tons
per trip, whereas the smallest CPUE in 2001 is 0.0001 tonnes per year. It
indicates that there is always an increase in fishing effort would increase the
catch. This can be seen in 2001, where the attempts to arrest as many as
83,983 trip but production of squid only 12 tons. From the data in Table 6
after the model was analyzed by Schaefer obtained a regression equation as
follows: Y= 0,002 - 0,00000002x or C/F = 0,128 - 0,00000002f
10
60
50
40
30
20
10
0
Yield (ton)
MSY =
50
0
fopt =
50000
20000 40000 60000 80000 100000
Effort (trip)
Figure 5. The relationship of the catch (Y) and attempts (f) for model
Schaefer
Figure 5 shows that the greater the effort to arrest the dwindling
catches. Obtained the greatest catches in fishing effort by 50 000 trip which
catches up to 50 tons. From the analysis of the data according to the model
of Schaefer (Table 13), obtained MSY and maximum fishing effort amounted
to 50 tons / year and 50,000 trip gear. This means that it is not possible to
do additional trip arrests for fishing effort exceeds MSY.
Table 7. Linear Estimation (Model Schaefer) CPUE = a + bf
Parameter
R
a
b
MSY = -a2/4b
f opt = -a/2b
2
Exploitation rate = (127/50) x 100%
Value
0,155
0,002
-0,00000002
50
50000
= 254 %
Theoretically, if the potential maximum sustainable (MSY) compared
with annual catches by comparison MSY = annual catch (catch / year), then
it belongs to the moderate level of exploitation or balanced, MSY is greater
than the annual production of relatively low levels of exploitation and if MSY
less than the annual production, the classified and highly exploitable.
Conclusions
Based on the results of research on the impact of fishing technology on squid
(Loligo chinensis) in Barru waters, it can be concluded that:
1. Large liftnet impact on squid populations, characterized by the size of
squid caught that small and generally not spawn yet (phase I and II).
2. Squid population dynamics in waters of Barru Regency tend to be similar
to other places, where the growth of females larger than males and fishing
mortality is greater than natural mortality.
3. The utilization rate of squid in the waters Barru has exceeded the ability of
the population to recover.
11
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