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. 2022 Oct 18;8(10):e11124. doi: 10.1016/j.heliyon.2022.e11124

First biometrics record of bartail flathead, Platycephalus indicus (Linnaeus, 1758) from the Bay of Bengal, Bangladesh

Md Rahamat Ullah a,∗, Md Mahamudul Hasan Mredul b
PMCID: PMC9593288  PMID: 36303928

Abstract

For the very first time the sex ratio, length-weight relationships (LWRs), length-length relationships (LLRs), form factor, as well as condition factor were calculated for bartail flathead, Platycephalus indicus, captured with gill nets (mesh size: 2.0–6.0 cm) from the Bay of Bengal, Bangladesh, from August 2021 to January 2022. A digital caliper was used to measure the length to 0.1 cm accuracy, and an electronic balance was used to quantify weight to the accuracy of 0.01 g. The sex ratio for the sample was 1: 0.76 (Male: Female). The estimates of slope in the fitted linear regressions relating logarithms of weights to logarithms of the total, standard, and fork lengths varied from 2.978 to 3.297, and the coefficient of determination from 0.89 to 0.97. Moreover, the three-length measures were also strongly associated (r2 > 0.996; P < 0.05). For the males, females, and combined sexes, the computed form factors were 0.0111, 0.0112, and 0.0107, correspondingly. For both males and females, individuals in the 33–36 cm and 27–30 cm length classes exhibited the highest and lowest in all the four condition factors, respectively. The size at first sexual maturity for combined sex of P. indicus was 30.2 cm in total length in the Bay of Bengal, Bangladesh. These results of the study will help with the conservation and long-term management of this species in the Bay of Bengal, Bangladesh, and other nearby nations.

Keywords: Length-weight relationships, Length-length relationships, Condition factor, Form factor, Sex ratio

Length-weight relationships; Length-length relationships; Condition factor; Form factor; Sex ratio.

1. Introduction

Platycephalus indicus (Linnaeus, 1758), commonly known as bartail flathead, a member of the family Platycephalidae (Flatheads) and the order Scorpaeniformes, is native to the Indian Ocean (Imamura, 2015) but found in the Indo-West Pacific, Red Sea, and East Africa, as well as in the Philippines, northern Japan, and Australia (Talwar and Jhingran, 1991; Riede, 2004; Froese and Pauly, 2007). Their bodies are lengthy, with flattened heads, long tail, as well as their large mouths, with the bottom jaw considerably larger than the top (Kuiter and Tonozuka, 2001; Nelson, 2006). This sedimentary fish may be encountered on the continental shelf’s muddy or sandy grounds, at depths of less than 100 m and up to 300 m (Imamura, 2015; Froese and Pauly, 2007). It is employed by conventional healers. It possesses high energy (310 kJ/100 g), protein (18.8 g/100 g), low-fat content (0.3 g/100 g), high mineral composition (Iron, Zinc, and Calcium content 1.7 mg, 0.79 mg, and 150 mg, respectively) and has economic value (Bogard et al., 2015; Chen et al., 2020). However, there is relatively little knowledge about the physiology of this species in the Bay of Bengal, Bangladesh.

A fish’s weight is related to its length however, knowledge of these parameters would aid the estimation of productivity. The length-weight relationships (LWRs) are also widely acknowledged as the most effective framework for evaluating fish stocks inside the environment (Andrade and Camos, 2002; Saha et al., 2019, 2021), and it is of considerable relevance in species population assessments (Oscoz et al., 2005; Ogunola and Onada, 2017). The research on LWRs has grown popular, and fish scientists are now doing it on a regular basis (Froese, 2006; Saha et al., 2019; Rahman et al., 2020). Fish longevity is typically assessed by determining the ages of fish sampled from the population and growth is typically assessed by analysis of the lengths of fish at their ages at capture, tracking the progression over time of modes in length compositions, or analysis of data from recaptured fish that were tagged and released (Ogunola and Onada, 2017; Huang et al., 2018). LWRs assessment is helpful for estimating the condition of fish or plumpness score, which is an influential factor for assessing the wellbeing of fish stocks or individuals (Muchlisin et al., 2017; Batubara et al., 2019; Rahman et al., 2020), and for comparing individual life history of a species across regions (Bagenal and Tesch, 1978; Muchlisin and Siti-Azizah, 2009; Oluwatoyin et al., 2013).

Fish condition factors (K) may be used as an indicator of a fish’s overall well-being and condition in regard to its surroundings, reflecting how strong or fairly deep-bodied the fish are (Froese, 2006) and physiological status (Rahman et al., 2020; Parvin et al., 2021). This value is derived from the relationship between the length and weight of a fish in order to ascertain the condition of that organism (Nash et al., 2006; Bolarinwa, 2017). The ratio of females and males in a stock is an important phenotypic metric as well as a good indication of stock characteristics and fertility, as well as a basic principle in biological evolution (Clutton-Brock, 2007). Changes in the environment that affect the sex ratio of fish that recruit to the population, mortality that is related to sex, differential sexual habits, development rate, and lifespan expectations might all contribute to a sex ratio imbalance (Badcock and Merrett, 1976; Clarke, 1983).

Some studies (Hashemi and Taghavimotlagh, 2013; Mousavi-Sabet et al., 2015; Kassem et al., 2021) have demonstrated the morphometric traits and biology of P. indicus from the Persian Gulf coastal waters in Iran and Bardawil lagoon in Egypt. However, there are no published data available with accurate biological status such as sex ratio, fish size distribution, length-weight dynamics, form factor (a3.0) as well as condition factor (K) of P. indicus from Bangladeshi waters to the best of our knowledge. The aims of the present study, therefore, are to collect and report, for the first time, fundamental data on the sex ratio, fish size distribution, length-weight relationships (LWRs), length-length relationships (LLRs), form factor (a3.0), condition factor, size at first sexual maturity as well as natural mortality of P. indicus from the Bay of Bengal, Bangladesh.

2. Materials and methods

From August 2021 to January 2022, the research was carried out in the Bay of Bengal, on Bangladesh’s mid-southern coast (Figure 1). This sampling location belongs to a major fishing zone of the Bay of Bengal named ‘swatch of no ground’. Local fishermen captured fish employing gill nets (mesh size: 2.0–6.0 cm), and 197 individuals of P. indicus were pooled over these five months. Following Cheng and Zheng (1987), all collected fish were instantaneously placed on ice and brought to the laboratory for verification and measurement. Individuals of P. indicus were identified using the characteristics that distinguished different species of Platycephalus from Chinese seas, as described by Chen et al. (2020). The gonads of all individuals were visually inspected and sexed (Mohammadikia et al., 2014). A digital caliper was used to measure each specimen’s total length (TL), standard length (SL), and fork length (FL) were measured and recorded in cm to the nearest 0.1 cm and weight (W) was measured in g using an electronic balance and recorded to the nearest 0.01 g. The research was conducted in accordance with the ethical standards of the Bangladesh Fisheries Research Institute. The experimental protocol and guidelines were maintained according to the animal welfare and ethical committee of Bangladesh Fisheries Research Institute, Bangladesh. The research and use of animals for the experiment have been authorized by the ethical committee.

Figure 1.

Figure 1

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Sampling locations of bartail flathead, Platycephalus indicus across the Bay of Bengal, Bangladesh.

The total lengths of P. indicus were classified into 2 cm intervals with the total number of fish of each sex in the different intervals providing the length distribution for that sex. The relationship between weight and length of fish was assumed to be a power function of the form described by Le Cren (1951):

W = aLb

where L was the standard length (cm), fork length (cm), or total length (cm), and W was the total weight (g).

Estimates of the intercept (a) and slope (b), were obtained by fitting LWRs using the method described by Froese (2006) method of linear regression following logarithmic conversion, log (W) = log (a) + b log (L) where a and b represent coefficient related to body form and growth type respectively, with Length (L) and Weight (W). Just before linear regression investigation, anomalies were removed using log-log plots of length and weight (Froese, 2006). For parameters, a and b, the coefficient of determination (r2) and 95% confidence limits (95% CL) were also determined. Furthermore, linear regressions were employed to estimate the parameters and coefficients of determination of the fitted linear relationships between TL vs SL, TL vs FL, as well as SL vs FL. Form factor (a3.0) was calculated by the formula: a3.0 = 10log a-s(b−3) (Froese, 2006). As recommended by Froese (2006), an average slope of S = −1.358 was used to estimate the form factor for the analyzed species using weight and total length. Fulton’s condition factor (KF) was calculated by the formula of Fulton (1904): KF = 100 × (W/L3). The allometric condition factor (KA) was calculated by the equation of Tesch (1971): KA = W/Lb. The relative condition factor (KR) was calculated following the equation of Le Cren (1951): KR = W/(aLb); where W and L represent the weight of the body (g) and total length (cm) respectively, a and b are the LWR parameters. The relative weight (WR) was calculated with the formula (Froese, 2006): WR = (W/Ws) × 100; where W is the weight of a particular individual, Ws is the predicted standard weight for the same individual, Ws is calculated by Ws = aLb. The size at first sexual maturity (Lm) of P. indicus was measured through the empirical formula proposed by Binohlan and Froese (2009): log (Lm) = ˗0.1189 + 0.9157 × log (Lmax); where Lm is the size at first sexual maturity in total length, Lmax is the maximum observed total length of P. indicus in the present study. The Natural mortality (Mw) of P. indicus was assessed through the model proposed by Peterson and Wroblewski (1984): Mw = 1.92 year−1 × (W) (−0.25); where Mw is natural mortality at mass weight; and W = aLb, a and b are the regression variables of LWR. Statistical software R (R Core Team, 2020) and GraphPad Prism 9 were used to conduct all analyses. The Spearman rank correlation test was applied to evaluate the association of condition factors with total length and body weight.

3. Results

3.1. Fish size distribution and sex ratio

There were 112 males (57%) and 85 females (43%) among the 197 sampled fish, the data for which were subjected to morphometric analysis. According to the sex ratio for the entire sample was 1: 0.76 (M: F), males were much more abundant than females throughout all TL categories between 20 and 40 cm, while females are dominating from 40 to 56 cm (Figure 2). The greatest numbers of males and females were reported in the 38–40 cm (Male = 22, Female = 09) and 40–42 cm size groups (Male = 19, Female = 24), respectively.

Figure 2.

Figure 2

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Length size distribution of bartail flathead, Platycephalus indicus across the Bay of Bengal, Bangladesh, X-axis represent the total length (TL) with 2 cm bar interval, Y-axis represents the number of total species count, two-color for two sexes respectively.

3.2. Length-weight relationships (LWRs)

A descriptive analysis of length-weight assessment is depicted in Table 1. A high correlation of determination value was observed between weight and length variables ranging from 0.89 to 0.97 (Figure 3). The “b” value was between 2.978 and 3.297.

Table 1.

Length-weight relationships parameters and form factor of bartail flathead, Platycephalus indices from the Bay of Bengal, Bangladesh.

Sex n a 95% Cl of a b 95% Cl of b GP Length type a3.0
Male 112 0.011 0.008–0.015 3.004 2.912–3.094 I SL 0.0111
0.002 0.001–0.003 3.295 3.200–3.389 A+ TL
0.008 0.005–0.011 3.043 2.947–3.139 I FL
Female 85 0.012 0.008–0.017 2.978 2.864–3.091 A- SL 0.0112
0.002 0.001–0.003 3.296 3.173–3.419 A+ TL
0.007 0.005–0.011 3.054 2.935–3.173 I FL
Combined 197 0.011 0.008–0.014 2.994 2.925–3.062 A- SL 0.0107
0.002 0.001–0.003 3.297 3.224–3.369 A+ TL
0.008 0.006–0.010 3.047 2.975–3.119 I FL
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Here, n: sample size, a: intercept, b: slope, TL: Total Length, BW: Body Weight, FL: Fork Length, SL: Standard Length, GP: Growth Pattern, A+: Positive Allometric, A-: Negative Allometric, I: isometric.

Figure 3.

Figure 3

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Scatter plot represents the relationship between weight and length parameters of bartail flathead, Platycephalus indicus across the Bay of Bengal, Bangladesh; Boxes represent a 25th to 75th percentile, solid lines in boxes are median value, error bar represent 5th and 95th percentile of individual parameters; Regression coefficient (r2) values are coded as number for each relationship and ∗∗∗ are constituted for a significant relationship at 0.05 level of significance.

3.3. Length-length relationships (LLRs)

The estimated LLRs for P. indicus in the coastal region of Bangladesh showed that b values were less than 1 in male, female, and combined sex in the relationship between SL and FL but higher than 1 in all the other relationships for male, female, and combined sex (Table 2). With r2 values more than 0.996 and b values varying from 0.960 to 1.075, all LLRs were found statistically significant (P < 0.05). ANOVA shows there is no significant variation among male and female individuals.

Table 2.

Length-length relationships parameters of bartail flathead, Platycephalus indicus from the Bay of Bengal, Bangladesh.

Sex n Equation a 95% Cl of a b 95% Cl of b r2
Male 112 TL = a + bSL 2.959 2.605–3.313 1.075 1.064–1.086 0.996
TL = a + bFL 2.518 2.142–2.894 1.033 1.022–1.044 0.996
SL = a + bFL −0.385 −0.645 to −0.126 0.960 0.952–0.967 0.998
Female 85 TL = a + bSL 3.582 3.190–3.974 1.054 1.043–1.065 0.997
TL = a + bFL 2.598 2.107–3.090 1.029 1.015–1.042 0.996
SL = a + bFL −0.913 −1.286–0.540 0.975 0.965–0.985 0.997
Combined 197 TL = a + bSL 3.229 2.968–3.489 1.065 1.058–1.073 0.997
TL = a + bFL 2.575 2.284–2.865 1.030 1.022–1.0390 0.996
SL = a + bFL −0.590 −0.802–0.378 0.966 0.960–0.972 0.998
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Here, n: sample size, a: intercept, b: slope, r2: coefficient of determination.

3.4. Form factor (a3.0)

The determined form factor (a3.0) value of P. indicus was ranging from 0.0107 to 0.0112, and the maximum difference between the values was only 0.0005 (Table 1).

3.5. Condition factors

The KF value ranged from 0.73 to 1.69 and the maximum KF value was observed in the 33–36 cm TL groups in both males and females and the minimum KF value was found in the 27–30 cm TL group (Table 3). According to Spearman rank correlation test, there were highly significant relationships between TL vs. KF (rs = −0.467 and p < 0.0001) and BW vs. KF (rs = −0.382 and p < 0.0001) (Table 4).

Table 3.

Condition factors (KF and KA) of bartail flathead, Platycephalus indicus in relation to size classes from the Bay of Bengal, Bangladesh.

TL Total individuals Fulton’s condition factor range Mean ± SD Allometric condition factor range Mean ± SD
<21-23 14 0.91–1.26 1.10 ± 0.10 0.032–0.059 0.041 ± 0.011
24–27 31 0.81–1.69 1.09 ± 0.21 0.025–0.061 0.047 ± 0.014
27–30 9 0.73–1.54 1.05 ± 0.34 0.018–0.062 0.034 ± 0.023
30–33 6 1.17–1.49 1.37 ± 0.11 0.039–0.061 0.052 ± 0.012
33–36 6 1.35–1.66 1.48 ± 0.14 0.041–0.078 0.057 ± 0.009
36–39 9 1.14–1.50 1.29 ± 0.13 0.026–0.061 0.045 ± 0.005
39–42 54 0.98–1.34 1.14 ± 0.08 0.011–0.050 0.031 ± 0.016
42–45 32 0.98–1.37 1.08 ± 0.11 0.016–0.058 0.038 ± 0.012
45–48 19 1.00–1.21 1.10 ± 0.08 0.022–0.047 0.032 ± 0.001
>48 17 0.99–1.15 1.04 ± 0.04 0.021–0.049 0.035 ± 0.001
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Table 4.

Relationships of condition factors with total length and body weight of bartail flathead, Platycephalus indicus from the Bay of Bengal, Bangladesh.

Relationship rs value rs range P value Significance
TL vs. KF −0.467 −0.834–0.047 <0.0001 ∗∗∗
TL vs. KA 0.684 0.461–0.827 0.852 ns
TL vs. KR 0.073 0.058–0.092 0.035 ∗
TL vs. WR 0.073 0.058–0.092 0.035 ∗
BW vs. KF −0.382 −0.972–0.278 0.0001 ∗∗∗
BW vs. KA 0.728 0.502–0.981 0.529 ns
BW vs. KR 0.165 0.048–0.307 0.011 ∗
BW vs. WR 0.165 0.048–0.307 0.011 ∗
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Here, TL: total length, BW: body weight, KF: Fulton′s condition factor, KA: allometric condition factor, KR: relative condition factor, WR: relative weight, rS: Spearman rank-correlation values, ns: not significant, ∗: significant, ∗∗∗: highly significant.

The KA value ranged from 0.011 to 0.078 and the maximum KA value was observed in the 33–36 cm TL groups in both males and females and the minimum KA value was found in the 39–42 cm TL group (Table 3). According to Spearman rank correlation test, there were no significant relationships between TL vs. KA (rs = 0.684 and p = 0.852) and BW vs. KA (rs = 0.728 and p = 0.529) (Table 4).

The KR value ranged from 0.76 to 1.73 and the maximum KR value was observed in the 33–36 cm TL groups in both males and females and the minimum KR value was found in the 27–30 cm TL group (Table 5). According to Spearman rank correlation test, there were significant relationships between TL vs. KR (rs = 0.073 and p = 0.035) and BW vs. KR (rs = 0.165 and p = 0.011) (Table 4).

Table 5.

Condition factors (KR and WR) of bartail flathead, Platycephalus indicus in relation to size classes from the Bay of Bengal, Bangladesh.

TL Total individuals Relative condition factor range Mean ± SD Relative weight range Mean ± SD
<21–23 14 1.00–1.33 1.16 ± 0.11 100.09–132.81 115.76 ± 10.99
24–27 31 0.89–1.73 1.17 ± 0.21 88.85–173.04 116.60 ± 21.31
27–30 9 0.76–1.72 1.15 ± 0.40 76.28–172.13 115.27 ± 40.48
30–33 6 1.29–1.65 1.46 ± 0.11 128.99–165.02 145.67 ± 11.52
33–36 6 1.40–1.66 1.53 ± 0.11 139.88–165.59 153.07 ± 10.84
36–39 9 1.20–1.52 1.36 ± 0.10 120.20–152.43 136.33 ± 10.89
39–42 54 1.06–1.40 1.20 ± 0.08 106.14–139.91 120.38 ± 7.78
42–45 32 1.05–1.38 1.18 ± 0.09 104.51–137.63 118.60 ± 8.89
45–48 19 1.08–1.29 1.17 ± 0.08 108.11–128.87 117.21 ± 8.57
>48 17 1.09–1.26 1.16 ± 0.03 109.51–126.13 116.49 ± 3.27
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The WR value ranged from 76.28 to 173.04 and the maximum WR value was observed in the 33–36 cm TL groups in both males and females and the minimum WR value was found in the 27–30 cm TL group (Table 5). According to Spearman rank correlation test, there were significant relationships between TL vs. WR (rs = 0.073 and p = 0.035) and BW vs. WR (rs = 0.165 and p = 0.011) (Table 4).

3.6. Size at first sexual maturity (Lm)

The Lm for combined sex of P. indicus was calculated in the present study as 30.2 cm total length in the Bay of Bengal, Bangladesh.

3.7. Natural mortality (Mw)

In the present study, the mean natural mortality (Mw) for the P. indicus population was calculated as 0.46 year−1 in the Bay of Bengal, Bangladesh and it is shown in Figure 4.

Figure 4.

Figure 4

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Natural mortality (Mw) of P. indicus from the Bay of Bengal, Bangladesh.

4. Discussion

The sex ratio is important in population demographics, and it may be influenced by anthropogenic pressures like selective fishing (Mredul et al., 2021). Our study revealed that gender-biased fishing was not conducted during the study period, however dominant male population was reported due to high fishing pressure. The sex ratio can fluctuate from population to population, or even within the same population at various times, depending on a variety of factors such as population adaptability, reproductive function, food sources, and characteristics of the environment (Vandeputte et al., 2012). Female reproductive success is typically linked to resource availability and environmental conditions, rather than the number of mating partners, as it is for males. As a result, the successful reproductive performance of males is restricted by the availability of females, whilst the efficiency of female reproduction is unaffected by access to males, resulting in an imbalance in the population’s number of each sex (Forsgren et al., 2008).

Estimates of the parameter b (2.978 and 3.297) obtained from linear regressions of the relationship between log weight and total length demonstrate that the patterns of growth of females, males, and the combination of females and males of P. indicus from the Bay of Bengal all exhibit positive allometry. A similar outcome (b = 3.2299) was also reported by Mohammadikia et al. (2014) for the combined data for females and males of this species from the Persian Gulf. Isometric growth means that the body expands in all aspects at the same rate, whereas positive allometry means that the body gets fatter as it grows longer, and negative allometry means that the body gets slimmer (Jobling, 2002). If b is greater than 3, the pattern of growth exhibits positive allometry; if b is less than 3, the pattern of growth exhibits negative allometry; and if b is equal to 3, the growth pattern is isometric (Bagenal and Tesch, 1978). Although values of the allometric coefficient (b) of LWRs can vary from 2.0 to 4.0, they normally lie between 2.5 and 3.5 (Carlander, 1969; Froese, 2006). Environmental variables, gonad development stages, sex, stomach fullness, functional health state, season, population, and variation among species all influence the parameters of L-W interactions in fish (Nieto-Navarro et al., 2010).

The lack of P. indicus with total lengths less than 21 cm in samples collected for the current study is attributed to the selectivity of the fishing gear (Hossain et al., 2012). In addition, the greatest length of P. indicus inside the sampling sites was 55.9 cm TL, somewhat less than the largest documented value of 58 cm TL (Mohammadikia et al., 2014). Hashemi et al. (2012) reported the minimum size group of this species was 5.7 cm. In principle, maximum size is recognized as a valuable tool for fisheries resource utilization and conservation, and it is essential for determining asymptotic growth and length coefficient (Khatun et al., 2019; Saha et al., 2021). LLR involves the relation between TL and the other three-length parameters such as Fork length (FL), Standard length (SL) & Body width (BWth); the equation is Y = bx + a, and the regression equation is shown in Figure 3. At a 95% level of significance, all correlation coefficient (r2) findings are highly correlated. The slope (b) of LLRs is close to 1.0, indicating that the three-length parameters expand simultaneously as the total length (TL). The relationship between total length, standard length, and fork length with body width is closely connected, which reflects a homogenous growth pattern. These variables are critical in determining the maximum permissible catch and mesh size to utilize. The assessed form factor (a3.0) score in this investigation ranged from 0.0107 to 0.0112. This number is commonly used to determine whether an individual’s body shape in a certain fish population or species differs from that of other species (Froese, 2006). However, no form factor reference value has been identified in the literature for this species. So, the current form factor results will serve as a valuable baseline for future comparisons.

Several condition factors (KF, KA, KR, and WR) were calculated in the present study to assess the well-being and health status of P. indicus from the Bay of Bengal, Bangladesh though most of the investigations address only a single condition factor. Condition factors based on the LWRs are a good indicator of general fish condition and food reserves (Offem et al., 2007). The Spearman correlation values (rs) showed a positive value between total length (TL) and condition factors (KA, KR, WR) as also did so between weight (BW) and condition factors (KA, KR, WR) (Table 4). But within those four condition factors, only Fulton’s condition factor (KF) showed different correlation values between TL vs. KF (rs = −0.467) and BW vs. KF (rs = −0.382). Fulton’s condition factor (KF) may thus be the best method for evaluating the condition of this population in Bangladesh’s Bay of Bengal as well as the surrounding environment. Fluctuation in condition factors indicates the gonad weight increase or decrease during the reproduction cycle. According to Ali et al. (2014) many elements, including sex, seasonality, environmental conditions, stress, gonadal maturation, and the availability of prey items, govern the condition factor overall. Moreover, food supply, floods, heat, temperature variations, pH, water pollution, and other factors might cause a rise or reduction in the condition factor (Osman et al., 2019).

An important predictor of the minimum allowable catch size is the size at first sexual maturity, or Lm, which is particularly significant for fish stock assessment (Hossain et al., 2019). According to this study, the size at first sexual maturity for P. indicus in Bangladesh’s Bay of Bengal was 30.2 cm. This study is the first to attempt to determine the size at first sexual maturity for P. indicus in both Bay of Bengal and global waters. Moreover, the natural mortality of the P. indicus in the Bay of Bengal, Bangladesh for the entire population was expected to be 0.46 year−1, allowing it the first worldwide evaluation. However, it is the fundamental data for future fisheries biology studies.

5. Conclusion

In closing, our study is the first one to give specific information on P. indicus biometric traits in Bangladesh’s large coastal habitat. The length-length relationships have a strong correlation. Almost all LWRs had positive allometric fish growth, which might be attributed to environmental conditions. The results of this study provide valuable benchmark data for coastal and marine fisheries management of P. indicus in the Bay of Bengal against which to assess future deleterious changes in sex ratio or conditions arising from anthropogenic pressures or environmental change. For example, knowing the species' growth rate will aid in the protection of this valuable fishery resource and the implementation of appropriate fishing laws to lessen fishing pressure. However, in order to effectively preserve and conserve this species, more detailed research on recruitment pattern, reproductive physiology, and gonad development is required.

Declarations

Author contribution statement

Md. Rahamat Ullah: Conceptualization; Methodology, Investigation, Data collection and analysis; Fund acquisition; Writing – original draft, Finalising the manuscript.

Md Mahamudul Hasan Mredul: Data analysis; Validation; Writing – review & editing; Finalising the manuscript.

Funding statement

Md. Rahamat, Ullah was supported by National Science and Technology Fellowship (NST-2019-20).

Data availability statement

Data will be made available on request.

Declaration of interests statement

The authors declare no conflict of interest.

Additional information

No additional information is available for this paper.

Acknowledgements

The authors are grateful for partial financial support from the National Science and Technology Fellowship (NST-2019-20) from the Ministry of Science and Technology, The Government People’s Republic of Bangladesh.

References

  1. Ali S., Barat A., Kumar P., Sati J., Kumar R., Haldar R.S. Study of length-weight relationship and condition factor of the Golden mahseer, Tor putitora from Himalayan rivers of India. J. Environ. Biol. 2014;35:225–228. [Google Scholar]
  2. Andrade H.A., Camos R.O. Allometry coefficient variations of the length-weight relationship skipjack tuna (Katsuwonus pelamis) caught in the southwest South Atlantic. Fish. Res. 2002;55:307–312. [Google Scholar]
  3. Badcock J., Merrett N.R. Midwater fishes in the eastern North Atlantic. I. Vertical distribution and associated biology in 30°N, 23°W, with developmental notes on certain myctophids. Prog. Oceanogr. 1976;7:3–58. [Google Scholar]
  4. Bagenal T.B., Tesch F.W. In: Methods of Assessment of Fish Production in Fresh Waters. Bagenal T., editor. Oxford Blackwell Scientific Publication; Oxford: 1978. Age and growth; pp. 101–136. [Google Scholar]
  5. Batubara A.S., Muchlisin Z.A., Efizon D., Elvyra R., Irham M. Length-weight relationships and condition factors of the Naleh fish, Barbonymus gonionotus (Pisces, Cyprinidae) harvested from Nagan Raya waters, Indonesia. Vestn. Zool. 2019;53(1):75–82. [Google Scholar]
  6. Binohlan C., Froese R. Empirical equations for estimating maximum length from length at first maturity. J. Appl. Ichthyol. 2009;25:611–613. [Google Scholar]
  7. Bogard J.R., Thilsted S.H., Marks G.C., Wahab M.A., Hossain M.A.R., Jakobsen J., Stangoulis J. Nutrient composition of important fish species in Bangladesh and potential contribution to recommended nutrient intakes. J. Food Compos. Anal. 2015;42:120–133. [Google Scholar]
  8. Bolarinwa J.B. Length-weight relationships and condition factors of Cynoglossus Cynoglossus and Caranx hippos in Epe Lagoon, Nigeria. Int. J. Res. Agric. For. 2017;4(3):1–5. [Google Scholar]
  9. Carlander K.D. vol. 1. The Iowa State University Press; Ames, USA: 1969. Handbook of Freshwater Fishery Biology. [Google Scholar]
  10. Chen Z., Song N., Zou J., Qin Y., Ma L., Gao T. Identification of species in genus Platycephalus from seas of China. J. Ocean Univ. China. 2020;19(2):417–427. [Google Scholar]
  11. Cheng Q., Zheng B., editors. Systematic Synopsis of Chinese Fishes. Science Press; Beijing: 1987. pp. 460–463. [Google Scholar]
  12. Clarke T.A. Sex ratios and sexual differences in size among mesopelagic fishes from the central Pacific Ocean. Mar. Biol. 1983;73:203–209. [Google Scholar]
  13. Clutton-Brock T. Sexual selection in males and females. Science. 2007;318:1882–1885. doi: 10.1126/science.1133311. [DOI] [PubMed] [Google Scholar]
  14. Forsgren E., Reynolds J.D., Berglund A., Mooi R.D. Behavioural ecology of reproduction in fish. Handb. Fish Biol. Fish. 2008;1:225–247. [Google Scholar]
  15. Froese R. Cube law condition factor and weight-length relationships: history, meta-analysis and recommendations. J. Appl. Ichthyol. 2006;22(4):241–253. [Google Scholar]
  16. Froese R., Pauly D. In: Day F., editor. vol. 2. Barnard Quaritch; London: 2007. Platycephalidae; pp. 274–278. (The fishes of India). [Google Scholar]
  17. Fulton T.W. Fisheries Board of Scotland; Edinburgh: 1904. The Rate of Growth of Fishes; pp. 141–241. Twenty-second Annual Report, Part III. [Google Scholar]
  18. Hashemi S.A., Taghavimotlagh S.A. Population parameters and length-weight relationship of bartail flathead (Platycephalus indicus Linnaeus, 1758) in Northwest Persian Gulf (Khuzestan coastal waters, Iran) World J. Fish Mar. Sci. 2013;5(1):20–25. [Google Scholar]
  19. Hashemi S.A., Taghavimotlagh S.A., Eskandary G. Some biological aspect of bartail flathead (Platycephalus indicus, Linnaeus, 1758) in Northwest of Persian Gulf (Khuzestan coastal waters, Iran) World J. Fish Mar. Sci. 2012;4(2):185–190. [Google Scholar]
  20. Hossain M.Y., Rahman M.M., Miranda R., Leunda P.M., Oscoz J., Jewel M.A.S., Naif A., Ohtomi J. Size at first sexual maturity, fecundity, length-weight and length-length relationships of Puntius sophore (Cyprinidae) in Bangladeshi waters. J. Appl. Ichthyol. 2012;28:818–822. [Google Scholar]
  21. Hossain M.A., Hossain M.Y., Hossen M.A., Rahman M.A., Islam M.A., Khatun D., Nawer F., Ohtomi J. Temporal variations of sex ratio and growth pattern of critically endangered catfish Clupisoma garua from the Ganges River of north-western Bangladesh. Indian J. Geo-Mar. Sci. 2019;48(5):647–653. [Google Scholar]
  22. Huang L.M., Wang J., Li J., Zhang Y.Z., Shen S.C. Length-weight relationships of 15 fish species in the Amoy Bay, East China sea. J. Appl. Ichthyol. 2018;34:1381–1383. [Google Scholar]
  23. Imamura H. Taxonomic revision of the flathead fish genus Platycephalus Bloch, 1785 (Teleostei: Platycephalidae) from Australia, with description of a new species. Zootaxa. 2015;3904(2):151–207. doi: 10.11646/zootaxa.3904.2.1. [DOI] [PubMed] [Google Scholar]
  24. Jobling M. Environmental factors and rates of development and growth. Handb. Fish Biol. Fish. 2002;1:97–122. [Google Scholar]
  25. Kassem S., Ibrahim G., Mousa M., Ahmed M. Length-weight relationship and condition factor of the bartail flathead (Platycephalus indicus) in Bardawil lagoon, north Sinai, Egypt. Sinai J. Appl. Sci. 2021;10(2):137–148. [Google Scholar]
  26. Khatun D., Hossain M.Y., Rahman M.A., Islam M.A., Rahman O., Azad M.A.K., Sarmin M.S., Parvin M.F., Haque A.T.U., Mawa Z., Hossain M.A. Life-history traits of the climbing perch Anabas testudineus (Bloch, 1792) in a wetland ecosystem. Jordan J. Biol. Sci. 2019;12:175–182. [Google Scholar]
  27. Kuiter R.H., Tonozuka T. Eels- Snappers, Muraenidae - Lutjanidae; Zoonetics, Australia: 2001. Pictorial Guide to Indonesian Reef Fishes. Part 1; pp. 1–302. [Google Scholar]
  28. Le Cren E.D. The length-weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis) J. Anim. Ecol. 1951;20(2):201–219. [Google Scholar]
  29. Linnaeus C. Systema Naturae, Ed. X. (Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata.) Holmiae. Syst. Nat. 1758;X(1):1–824. [Google Scholar]
  30. Mohammadikia D., Kamrani E., Reza-Taherizadeh M., Soleymani A., Farokhi E., Momeni M. Age and growth of flathead, Platycephalus indicus from the Persian Gulf (Bandar Abbas, Iran) J. Mar. Biol. Assoc. U. K. 2014;94(5):1063–1071. [Google Scholar]
  31. Mousavi-Sabet H., Heidari A., Fekrandish H. Population structure, length-weight and length-length relationships of six populations of the Bartail Flathead Platycephalus indicus (Scorpaeniformes: Platycephalidae) along the Persian Gulf coastal waters. J. Threat. Taxa. 2015;7:6810–6814. [Google Scholar]
  32. Mredul M.M.H., Alam M.R., Akkas A.B., Sharmin S., Pattadar S.N., Ali M.L. Some reproductive and biometric features of the endangered Gangetic Leaf Fish, Nandus nandus (Hamilton, 1822): implication to the baor fisheries management in Bangladesh. Aquac. Fish. 2021;6(6):634–641. [Google Scholar]
  33. Muchlisin Z.A., Fransiska V., Muhammadar A.A., Fauzi M., Batubara A.S. Length-weight relationships and condition factors of the three dominant species of marine fishes caught by traditional beach trawl in Ulelhee Bay Banda Aceh City, Indonesia. Croat. J. Fish. 2017;75(4):104–112. [Google Scholar]
  34. Muchlisin Z.A., Siti-Azizah M.N. Diversity and distribution of freshwater fishes in Aceh waters, northern Sumatera, Indonesia. Int. J. Zool. Res. 2009;5(2):62–79. [Google Scholar]
  35. Nash R.D., Valencia A.H., Geffen A.J. The origin of Fulton’s condition factor-setting the record straight. Fisheries. 2006;31(5):236–238. [Google Scholar]
  36. Nelson J.S. fourth ed. John Wiley & Sons; New York: 2006. Fishes of the World; p. 601. [Google Scholar]
  37. Nieto-Navarro J.T., Zetina- Rejon M., Arreguin- Sanchez F., Arcos- Huitron N.E., Pena- Messina E. Length-weight relationship of demersal fish from the Eastern coast of the mouth of the Gulf of California. J. Fish. Aquat. Sci. 2010;5:494–502. [Google Scholar]
  38. Offem B.O., Akegbejo-Samsons Y., Omoniyi I.T. Biological assessment of Oreochromis niloticus (Pisces: Cichlidae: Linne, 1958) in a tropical floodplain river. Afr. J. Biotechnol. 2007;6:1966–1971. [Google Scholar]
  39. Ogunola O.S., Onada O.A. Preliminary investigation of length-weight relationships and condition factors of two commercially important fish species (Mullet, Mugil cephalus (Linnaeus 1758) and Sardine, Sardinella maderensis. (Lowe 1838)) in Okrika creeks (Niger-Delta) of Nigeria. Reg. Stud. Mar. Sci. 2017;13:54–58. [Google Scholar]
  40. Oluwatoyin A., Akintade A., Edwin C., Victor K. A study of length weight relationship and condition factor of west African blue crab (Callinectes pallidus) from Ojo Creek, Lagos, Nigeria. Am. J. Res. Commun. 2013;1(3):102–114. [Google Scholar]
  41. Oscoz J., Campos F., Escala M.C. Weight–length relationships of some fish species of the Iberian Peninsula. J. Appl. Ichthyol. 2005;21(1):73–74. [Google Scholar]
  42. Osman H.M., Saber M.A., El Ganainy A.A. Population structure of the striped piggy Pomadasys stridens in the Gulf of Suez. Egypt. J. Aquat. Res. 2019;45:53–58. [Google Scholar]
  43. Parvin M.F., Hossain M.Y., Rahman M.A., Khatun D., Sarmin M.S., Rahman O., Islam M.A., Azad M.A.K., Samad M.A., Sabbir W., Kamruzzanan S., Hosneara U., Ul-Hassan H. Growth, maturity, condition, size at sexual maturity and mortality of the Banded gourami Trichogaster fasciata from the Ganges River, Northwestern Bangladesh. Egypt. J. Aquat. Biol. Fish. 2021;25(4):285–299. [Google Scholar]
  44. Peterson I., Wroblewski J.S. Mortality rates of Fishes in the pelagic ecosystem. Can. J. Fish. Aquat. Sci. 1984;41:1117–1120. [Google Scholar]
  45. R Core Team R: A Language and Environment for Statistical Computing. 2020. http://www.R-project.org Retrieved from.
  46. Rahman M.A., Hossain M.A., Ullah M.R., Iqbal M.M. Reproductive biology of Gagora catfish (Arius gagora) at Meghna river system, Kushiara river, Bangladesh. Int. J. Aquat. Biol. 2020;8(6):383–395. [Google Scholar]
  47. Riede K. Federal Agency for Nature Conservation; Bonn, Germany: 2004. Global register of migratory species - from global to regional scales; p. 329. (Final Report of the R&D-Project 808 05 081). [Google Scholar]
  48. Saha N., Rakib M.H., Mredul M.M.H., Rahman M.A., Ahamed F. Life history traits of the Gangetic scissortail rasbora, Rasbora rasbora (Hamilton, 1822) in the Payra River, southern Bangladesh. Jordan J. Biol. Sci. 2021;14:129–135. [Google Scholar]
  49. Saha N., Ullah M.R., Islam M.S., Hossain M.B. Morphometric relationships between length-weight and length-length and condition factor of four small indigenous fishes from the Payra River, southern Bangladesh. Arch. Agric. Environ. Sci. 2019;4(2):230–234. [Google Scholar]
  50. Talwar P.K., Jhingran A.G. vol. 2. Oxford & IBH Publishing Co. Pvt. Ltd.; New Delhi-Calcutta: 1991. Inland Fishes of India and Adjacent Countries; pp. 782–783. [Google Scholar]
  51. Tesch F.W. In: Methods for Assessment of Fish Production in Fresh Waters. Ricker W.E., editor. Blackwell Scientific Publications; Oxford: 1971. Age and growth; pp. 99–130. [Google Scholar]
  52. Vandeputte M., Quillet E., Chatain B. Are sex ratios in wild European sea bass (Dicentrarchus labrax) populations biased? Aquat. Living Resour. 2012;25(1):77–81. [Google Scholar]

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