Morphometry characters comparison of the painted spiny lobster, Panulirus versicolor , from three locations in Simeulue Island

. The painted spiny lobster, Panulirus versicolor , is an economically spiny lobster species on Simeulue Island. Fishing pressure on this species is suspected of experiencing overfishing, with indications that its size is getting smaller during the fishing season. Therefore, it is necessary to manage existing lobster resources. Several aspects that need to be considered in the sustainability of fisheries management are related to biological aspects, including the study of morphometry characters. This study aims to compare the morphometric characteristics of P. versicolor from three locations in Simeulue Island. The research was conducted from March to May 2023 with three sampling locations, including East Simeulue, Teluk Dalam, and South Teupah. A total of 90 samples were sampled using the random sampling method. To differentiate or classify the population, 15 parameters of spiny lobster morphometry were studied using discriminant function analysis. The results led to the assertion that P. versicolor from three separate places belonged to the same population but had distinct subpopulations. This condition is affected by the lobster samples collected from nearby areas. The investigation of the relationship between length and weight revealed that the growth pattern of P. versicolor in three locations were negative allometric, with length increasing faster than weight increasing.


Introduction
Indonesia has vast marine resources, including six types of Panulirus spp.lobsters with significant economic potential.The habitat conditions of each lobster vary depending on the type [1].The spiny lobsters found in Indonesian waters are scalloped spiny lobster (P.homarus), ornate spiny lobster (P.ornatus), pronghorn spiny lobster (P.penicillatus), mud spiny lobster (P.polyphagus), longlegged spiny lobster (P.longipes), and painted spiny lobster (P.versicolor).This six types of lobster are evenly distributed and are found almost in all coral waters in Indonesia [2].The six lobster species found in Indonesian waters are also found in Aceh waters, especially the southwest coast and P. versicolor is one of the fishing targets of local fishermen, because of its dominance [3].
The painted spiny lobster, scientifically known as P. versicolor, is a species of lobster that can be found in coral or rocky reef areas at depths of 5 to 20 meters [4].Unfortunately, this type of lobster is being overfished, leading to a reduction in size during the fishing season.To protect this valuable resource, it is important to manage it sustainably.In order to do so, various aspects must be taken into consideration, including biological factors such as the study of morphometric characters and condition factors [5].
Morphometric studies play a crucial role in lobster resource management efforts as they aid in determining the diversity of a species by examining general morphological characteristics.The marine and fisheries sector heavily relies on morphometric research.particularly in aquaculture, to ensure that a species genetics are suitable for domestication.This information is also crucial in the initial steps of cultivators.Domestication is possible through the collection of broodstock from various locations as different lobster parents have varying genetic diversity.Genetic diversity can occur between geographically separated populations and even within a single population [6].This diversity can be reflected in the lobster's phenotype and genotype.Morphometric measurements of the lobster's body structure aid in phenotypic observations.Morphometric studies help in understanding lobster taxonomy and also provide insights into the variations that occur in measurements, which are related to the habits and habitat of different variants of the species [7].

Data collection
The research was conducted between March to May of 2023 in three locations in Simeulue Island: East Simeulue, Teluk Dalam, and South Teupah.The simple random sampling method was used to collect samples, with lobster sampling stations being determined based on fishing areas and landing sites for P. versicolor in the three locations above.Thirty samples were taken at each station.

Morphometric measurements
The body of P. versicolor was measured using a measuring instrument and weighed using a digital scale to determine its body mass.In total, 15 morphometric characters were measured in lobsters, including several commonly used ones as described by [8].

Phenotypic diversity
The diversity value is a percentage of the standard deviation of fish length.To see phenotypic diversity in P. versicolor, the following formula is used [9]: The equation involves three variables: kk, which is the diversity coefficient, S, which is the standard deviation, and Y, which is the median.

Discriminant Function Analysis (DFA)
The study conducted data analysis using Discriminant Function Analysis (DFA).This involved obtaining eigenvalues, total variance, canonical correlation, matrix structure and morphological analysis.The aim of DFA was to group each population in a canonical correlation graph of function 1 and function 2. All data were analyzed using IBM SPSS Statistics software version 26, according to [10].

Length-weight relationship
To analyze the relationship between the length and weight of P. versicolor, [11] used the following formula: Given weight (W), length (L), and the intercept (a) of the length and weight relationship curve with the y-axis, as well as the regression coefficient (b).
To test the value of b = 3 or b ≠ 3, a t-test (partial test) is carried out, with a hypothesis [9].
H0 : b = 3, the relationship between length and weight is isometric H1 : b ≠ 3, the relationship between length and weight is allometric, namely: 1. Positive allometric, if b>3 (weight increase is faster than length increase), and 2. Negative allometric, if b<3 (length increase is faster than weight increase), tcount= With b1 representing the b value obtained from the relationship between length and weight, b0 set at 3, and Sb1 indicating the deviation coefficient of b.
It is important to compare the tcount value with the ttable value at the 95% confidence interval.To determine the growth pattern of lobsters, the decision rule taken is: tcount > ttable : reject the null hypothesis (H0) tcount < ttable : fails to reject the null hypothesis

Phenotypic diversity
Each character in the phenotypic diversity table displays the highest value for the body weight (BW) variable, which is 0.44.On the other hand, the lowest value of phenotypic variation can be observed in the variables of abdominal width (AL), chest width (ChW), and antennule peduncular length (APL), which have a value of 0.11.Table 1 presents the phenotypic diversity of painted spiny lobsters (P.versicolor) found in East Simeulue, Teluk Dalam, and South Teupah.Phenotypic characteristics of the painted spiny lobster (P.versicolor) can be identified through morphometric measurements of its body structure [7].Each morphometric character has several phenotypic variations.The extent of diversity of a phenotypic character indicates the genetic diversity of the population.Based on the phenotypic diversity values obtained for P. versicolor, it can be concluded that the level of genetic diversity is relatively low, less than 20%.

Discriminant Function Analysis (DFA)
Discriminant Function Analysis (DFA) was conducted on 15 morphometric characteristics of P. versicolor, with total length as the comparison feature, The analysis produced two functions, with the first function having Eigenvalues greater than the second.This means that the first function plays a significant role in distinguishing the three stations.The first function accounts for 91.2% of the total variance with Eigenvalues of 3.549, while the second function with Eigenvalues of 0.344 accounts for the remaining 8.8% of the total variance.The results of the analysis are shown in Table 2. Based on morphometric analysis using Discriminant Function Analysis (DFA) in East Simeulue, Teluk Dalam, and South Teupah, several characters are found to be different.The first function has the character with the highest value, namely the length of the antennula (AnL) with a value of 0.403, while the second function has the character with the highest value, namely the length of the abdominal segment (ASL) with a value of 0.690.
The results of morphological analysis indicate that the three measured stations of P. versicolor can be classified into 2 distinct groups, Teluk Dalam, and Teupah Selatan have similar discriminant functions, which are different from East Simeulue.The morphological analysis was conducted using Discriminant Function Analysis (DFA) to analyze morphometric characters and the results can be seen in Figure 1.The Discriminant Function Analysis (DFA) results indicate the distinguishing characteristics of each location.The highest value for character function 1 is the length of the antennula (PAn) with a value of 0.4.This suggests that the antennula length (PAn) is a key characteristic that sets it apart from other locations.On the other hand, the highest value for character function 2 is abdominal segment length (PSA) with a value of 0.69.Therefore, it can be inferred that the character of abdominal segment length (PSA) is another key characteristic that differentiates from other locations.These differences in characteristics are likely due to physical isolation, ecological barriers, geographic distance or behavioral influences [12].
According to morphological analysis, the three locations can be classified into two groups, Teluk Dalam station, and South Teupah station belong to the same group, while East Simeulue station belongs to a different group.The analysis of morphometric data suggests that P. versicolor found in all three locations belong to the same population but consist of different sub-populations, likely due to the nearby locations.The differences in their morphology and species can be attributed to their overall body shape.Quantitative differences are expressed through statistical values such as average, range, variance, and correlation, obtained by taking various measurements from individual lobsters [13].

Length-weight relationship
Panulirus versicolor's length and weight are related by the equation y = 2.3914x -3.0355.with a of determination (R 2 ) of 0.82.The b value of the equation is 2.39.indicating a negative allometric growth pattern in length and weight.This means that the increase in length is faster than the increase in weight.In the East Simeulue, the relationship between length and weight was analyzed.resulting in the equation y = 2.9862x -4.4941 with an R 2 value of 0.80.The b value of 2.98 indicates that the growth pattern in length and weight is negative allometric, meaning that the increase in length is faster than the increase in weight.In Teluk Dalam, the equation for the relationship between length and weight was determined to be y = 2.671x -3.6831, with a coefficient of determination (R 2 ) of 0.82.The b value of the equation for the relationship between length and weight is 2.67.This indicates that the pattern of growth in length and allometric is negative, meaning that the increase in length is faster than the increase in weight.The relationship between the length and weight of painted spiny lobsters (P.versicolor) has been studied at different stations.At the overall station.the equation for the relationship is y = 1.5956x -1.1447 with a coefficient of determination (R 2 ) of 0.81, that the model can explain the estimated values by 81%.This suggests a strong correlation between the length and weight of P. versicolor at all stations.In East Simeulue, the equation for the relationship between length and weight is y = 2.9862x -4.4941 with an R 2 of 0.79.This model can explain the estimated values by 79%.suggesting a close relationship between the length and weight of P. versicolor in this.Similarly, Teluk Dalam found an equation for the relationship between length and weight, which is y = 2.671x -3.6831 with an R 2 of 0.81.This model can explain the estimated values by 81%.indicating a strong correlation between the length and weight of P. versicolor in this location as well.Finally, Teupah Selatan found the equation for the relationship between length and weight to be y = 1.5956x -1.1447 with an R 2 of 0.64.This model can explain the estimated values by 63%, suggesting a moderate relationship between the length and weight of P. versicolor in this location.
According to [14], painted spiny lobsters (P.versicolor) in East Simeulue, Teluk Dalam, and South Teupah exhibit negative allometric growth patterns (b<3).This means that their length increases faster than their body weight.The b value.which represents this growth pattern, is mainly influenced by environmental factors.Similar research findings were also observed for the same species in several other regions including West Aceh, Cilacap, Pangandaran, Ekas Bay, and Thoothukudi-India [15,16].

Conclusions
The results led to the assertion that P. versicolor from three separate places belonged to the same population but had distinct subpopulations.This condition is affected by the lobster samples collected from nearby areas.The investigation of the relationship between length and weight revealed that the growth pattern of P. versicolor in three locations were negative allometric, with length increasing faster than weight increasing.

Fig. 2 .
Fig. 2. Graph of the relationship between length and weight of P. versicolor at all stations.

Fig. 3 .
Fig. 3. Graph of the relationship between length and weight of P. versicolor in East Simeulue.

Fig. 4 .
Fig. 4. Graph of the relationship between length and weight of P. versicolor in Teluk Dalam.The study carried out in South Teupah found that the equation representing the relationship between length and weight is y = 1.5956x -1.1447.The coefficient of determination (R 2 ) was calculated as 0.64.The b value of the equation is 1.59, indicating a negative allometric growth pattern.This means that the increase in length is faster than the increase in weight.

,Fig. 4 .
Fig. 4. Graph of the relationship between length and weight of P. versicolor in South Teupah.
* The largest real correlation between each variable and the discriminant functionThere are certain characteristics of a creature that perform different functions.These include Antenula Length (AnL), Head Width (HW), Chest Width (ChW), Telson Width (TW), Telson Length (TL), and Antenula Peduncular Length (APL).Another set of https