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Evaluating the size at sexual maturity for 20 fish species (Actinopterygii) in wetland (Gajner Beel) ecosystem, north-western Bangladesh through multi-model approach: A key for sound management
expand article infoMd. Rabiul Hasan, Md. Yeamin Hossain, Zannatul Mawa, Sumaya Tanjin, Md. Ashekur Rahman, Uttam Kumar Sarkar§, Jun Ohtomi|
‡ University of Rajshahi, Rajshahi, Bangladesh
§ Central Inland Fisheries Research Institute, Barrackpore, India
| Kagoshima University, Shimoarata, Japan
Open Access

Abstract

Effective fisheries management depend on having an exact assessment of biological parameters, including growth parameters, reproduction, size at sexual maturity (Lm), and stock assessment. The purpose of this research was to estimate the size at sexual maturity (Lm) for 20 fish species belongs to 14 families from a wetland (Gajner Beel) ecosystem in the north-western (NW) Bangladesh through multi-models such as length (Lmax) based empirical model, gonadosomatic index (GSI)-based model, and logistic model using commercial catches from January to December 2018. Also, we assessed the Lm in other water-bodies worldwide. Specimens’ total length (TL) was noted up to 0.1 cm using measuring board body weight (BW) and gonad weight (GW) weighed by digital electronic balance with 0.01 g accuracy. To assess the Lm, maximum body length (Lmax) based empirical model; the relation between TL (total length in cm) vs. GSI (gonadosomatic index in %); and a logistic model were considered. The minimum Lm was 4.64, 3.90, and 4.15 cm for Chanda nama Hamilton, 1822 and the maximum was 25.33, 24.50, and 24.70 cm for Channa striata (Bloch, 1793) through Lmax, GSI, and logistic-based models, respectively. From these three models, the minimum mean Lm was 4.23 cm for C. nama and the maximum was 24.84 cm for C. striata. The Lm with 50.0% species was in 8.80 cm TL. We also calculated the Lm from different bodies of water based on Lmax. This study was generated data of 17 new Lm among 20 species, which are globally absent. Therefore, the study will help develop sustainable management strategies, conservation through the implementation of mesh size based on the size at sexual maturity (Lm).

Keywords

Bangladesh, logistic models, fish species, size at first sexual maturity, Gajner Beel

Introduction

In Bangladesh, fishes are the most affluent organisms, which secure livelihood, contribute food, generate employment, and are used to develop the nation’s economy (Hamilton 1971; Godfray et al. 2010; Costello et al. 2012; FAO 2012). The fisheries sector plays a key role in the national economy, contributing 3.50% to the GDP (Gross Domestic Product) of the country and 25.71% in agricultural GDP (DoF 2019). A large variety of aquatic animals is found in the inland, estuarine, and marine waters of Bangladesh (Rahman 1989).

Bangladesh is fortunate to have vast aquatic resources and rich fish genetic diversity. It has a lot of inland water bodies that host 267 freshwater fish species. Biodiversity of fishes is very essential for nutrition and livelihoods for the rural people in Bangladesh (Thilsted 2013). Fishes, which spend their life in freshwater, (rivers and lakes), where the salinity is below 1.05‰ are considered freshwater fishes. Fishes require a range of physiological modification to live in the freshwater environment (Rohalin et al. 2019).

A land, which is inundated by water, annually or seasonally, permanently or temporarily that is called a wetland (Keddy 2010). Water purification, processing of carbon and other nutrients, maintenance of shorelines, water storage, and assistance of animals and plants are the important functions of a wetland (Butler 2010). Marsh, swamp, pen, and bog are the main types of wetlands (Keddy 2010). The wetlands can be freshwater, brackish, or saltwater (Ramsar Conservation 1971). The Pantanal in South America, the Amazon River basin, the West Siberian Plain (Fraser and Keddy 2005), and the Sundarbans in the Ganges–Brahmaputra delta (Giri et al. 2007) are the largest wetlands on the Earth. Rivers and streams, Hoars, Baors, Beels, lakes and marshes, reservoirs, ponds, cultivated fields flooded by water, and estuarine systems are considered wetlands in Bangladesh (See Table 1). The freshwater wetlands are Haors, Baors, Beels, and Jheels. The man-made wetlands are dighis, lakes, ponds, and borrow pits (Banglapedia 2004).

Table 1.

Types and area of wetlands in Bangladesh.

Types Wetland Area [km2]
Open waters Rivers 7497
Estuaries and mangrove swamps 6102
Beels and haors 1142
Inundable floodplains 54 866
Kaptai Lake 688
Closed water Ponds 1469
Baors (Oxbow Lakes) 55
Brackish-water farms 1080
Total 72 899

Gajner Beel is situated at Sujanagar, Pabna in north-western (NW) Bangladesh. This Beel is used as an imperative feeding and spawning ground by many freshwater fish species. Near about 0.5 million people of surrounding villages of this Beel are directly or indirectly reliant on this wetland for their livelihood (Mazid et al. 2005; Hasan et al. 2020).

Effective fisheries management depends on having an exact assessment of biological parameters, including growth parameters, reproduction, size at sexual maturity (Lm), and stock assessment (Tracey et al. 2007). The Lm in fish species is a fundamental requirement to find out the reasons on behalf of modifications of the length of maturity (Templeman 1987). Subsequently, it is habitually castoff as a sign of least-acceptable capture dimensions (Lucifora et al. 1999).

Scanning of the literature shows non-availability of species-specific data on size at sexual maturity (Lm) of these 20 species except Channa striata (Bloch, 1793) (see Herre 1924; Makmur et al. 2003), Gudusia chapra (Hamilton, 1822) (see Hossain et al. 2010), and Puntius sophore (Hamilton, 1822) (see Hossain et al. 2012a) from the Gajner Beel, Bangladesh. The objective of our research is to estimate the Lm for 20 species from the Gajner Beel in Bangladesh that will be helpful for the management strategies of these species in Gajner Beel in Bangladesh and adjacent aquatic ecosystems.

Materials and methods

The presently reported study was conducted in Gajner Beel (23°55′N, 89°33′E), which is located at Sujanagar, Pabna, NW Bangladesh (Fig. 1). Sampling was done from January to December 2018. Fishes were caught by several types of net (gill nets, long seine) and then preserved in 10% formalin for the further process. Species identification was done by observation of morphometric characters and reviews the various pieces of literature. Each individual was measured by measuring board (0.1 cm) and weighed by digital weight balance (0.01 g). After dissection the fishes, gonads have been removed and weighed. Sexing was determined under the microscopic view, and then only female specimens were used for this analysis. The gonadosomatic index was estimated based on Nikolsky (1963)

GSI (%) = GW/BW*100

where, GW referred to the gonad weight (g) and BW were body weight (g). The length of 50% maturity (50% Lm) of the 20 fish species was estimated using three models, which were shown in Table 2.

Figure 1. 

Sampling sites in a wetland ecosystem (Gajner Beel) (indicated by red circle), northwestern Bangladesh.

Table 2.

Size at sexual maturity of 20 fish species was calculated by these three models.

Model name Equations Reference
Empirical model log (Lm) = –0.1189 + 0.9157* log (Lmax) Binohlan and Froese 2009
GSI based model L m = TL vs. GSI Hossain et al. 2010
Logistic model PMI = 100/[1 + exp{–f (TLmTL50)}] King 2007

Results

Altogether 3040 specimens of 20 fish species were considered in the presently reported study and a list of fish species is given in Table 3. The minimum length was 2.40 cm in TL for C. nama and the maximum length was 46.00 cm for C. striata. The estimated minimum Lm was 4.64, 3.90, and 4.15 cm for C. nama and the maximum was 25.33, 24.50, and 24.70 cm for C. striata through Lmax, TL vs. GSI, and logistic-based models, respectively, and the mean value was 10.04 cm for the 20 species of Gajner Beel, Bangladesh. The maximum length, minimum length, and Lm with 95% CL are given in Table 4. We also calculated the Lm from the different water bodies (Table 5) based on Lmax which are collected from the previous works on these species by previous workers. As an example of TL vs. GSI and logistic models and figures are presented in Fig. 2. Lm shows that 50% of mature fishes are below 8.80 cm, so the selection of this net-mesh size would protect half the adults in the Gajner Beel ecosystem. On the other hand, 80% of mature fishes are below 12.10 cm, so such a larger, more-conservative mesh size might play a vital role for sustainable fish production in wetland ecosystems (Fig. 3).

Figure 2. 

An example figure of size at sexual maturity which produced by TL vs. GSI (A) and logistic model (B) for the 20 species in wetland ecosystem (Gajner Beel) northwestern Bangladesh.

Figure 3. 

Relation between the maximum total length attained by a species and the number of species attaining that length in a wetland ecosystem (Gajner Beel) northwestern Bangladesh.

Table 3.

List of total 20 fish species in a wetland ecosystem (Gajner Beel), NW Bangladesh.

Sl. No Family Scientific name Common name
01 Ambassidae Chanda nama Chanda
02 Anabantidae Anabas testudineus Koi
03 Bagridae Mystus cavasius Gulsa
04 Mystus tengara Tengra
05 Belonidae Xenentodon cancila Kakila
06 Channidae Channa orientalis Cheng
07 Channa punctata Taki
08 Channa striata Shol
09 Clupeidae Gudusia chapra Chapila
10 Cobitidae Lepidocephalichthys guntea Gutum
11 Cyprinidae Amblypharyngodon mola Moa
12 Puntius sophore Jat punti
13 Salmostoma bacaila Chela
14 Gobiidae Glossogobius giuris Bele
15 Heteropneustidae Heteropneustes fossilis Shingi
16 Mastacembelidae Macrognathus aculeatus Shal baim
17 Macrognathus pancalus Guchi
18 Nandidae Nandus nandus Bheda
19 Osphronemidae Trichogaster fasciata Kholisa
20 Siluridae Ompok pabo Pabda
Table 4.

Size at first sexual maturity (Lm) of 20 fish species in a wetland ecosystem (Gajner Beel), NW Bangladesh.

Scientific name n Minimum length [cm] Maximum length [cm] Size at sexual maturity (Lm)
Maximum length based GSI based Logistic-based models Mean
Chanda nama 196 2.40 7.20 4.64 (3.81–5.68) 3.90 4.15 4.23
Anabas testudineus 130 7.50 16.40 9.85 (7.84–12.39) 10.20 9.10 9.72
Mystus cavasius 124 5.30 16.90 10.13 (8.05–12.75) 9.80 9.70 9.88
Mystus tengara 139 4.80 12.60 7.74 (6.23–9.65) 7.00 7.10 7.28
Xenentodon cancila 118 8.50 24.00 13.96 (10.95–17.77) 12.98 13.45 13.46
Channa orientalis 152 8.10 19.00 11.27 (8.92–14.24) 12.48 11.00 11.58
Channa punctata 178 5.30 19.40 11.49 (9.09–14.53) 12.20 11.25 11.65
Channa striata 128 9.50 46.00 25.33 (19.35–32.89) 24.50 24.70 24.84
Gudusia chapra 126 4.40 14.60 7.18 (5.79–8.93) 6.90 6.95 7.00
Lepidocephalichthys guntea 117 5.00 10.30 6.44 (5.22–7.98) 6.50 6.20 6.38
Amblypharyngodon mola 193 3.90 7.80 4.99 (4.09–6.13) 4.90 4.85 4.91
Puntius sophore 191 4.20 11.00 6.83 (5.53–8.49) 7.00 6.50 6.78
Salmostoma bacaila 114 4.20 10.00 6.26 (5.09–7.76) 6.50 5.90 6.22
Glossogobius giuris 189 3.90 14.70 8.91(7.13–11.17) 8.10 8.45 8.49
Heteropneustes fossilis 180 6.30 24.10 14.02 (10.99–17.84) 12.20 13.96 13.39
Macrognathus aculeatus 115 8.70 27.00 15.55 (12.14–19.86) 16.18 15.00 15.58
Macrognathus pancalus 190 6.90 15.70 9.47 (7.55–11.89) 9.80 9.00 9.42
Nandus nandus 168 6.50 17.20 10.29 (8.18–12.96) 10.40 9.95 10.21
Trichogaster fasciata 170 3.30 9.30 5.86 (4.77–7.24) 6.00 5.00 5.62
Ompok pabo 122 4.80 17.80 10.62 (8.43–13.39) 9.85 10.20 10.22
Table 5.

Calculate the size at sexual maturity based on maximum length from the different water bodies in world wide.

Species name Sex Habitat L max [cm] L m (95% CL)
Chanda nama C Brahmaputra River tributary, Bangladesh 6.40 4.16 (3.44–5.08)
C Deepor beel, Assam, India 7.00 4.52 (3.72–5.53)
C Hirakud Reservoir, India 10.10 6.32 (5.13–7.83)
C Brahmaputra River, Bangladesh 7.40 4.75 (3.91–5.83)
C Ganges River, Rajshahi, Bangladesh 7.20 4.64 (3.81–5.68)
C 11.00 6.83 (5.53–8.49)
Anabas testudineus C Chi River, Thailand 16.50 9.91 (7.89–12.46)
C Pampanga River, Candaba, Philippines 11.70 (SL) 7.23 (5.84–9.00)
C Agusan Marsh, Philippines 17.00 10.18 (8.09–12.82)
C Tetulia River, Bangladseh 16.10 9.69 (7.72–12.18)
C India 25.00 14.49 (11.35–18.47)
Mystus cavasius C Betwa River, India 27.40 15.76 (12.30–20.14)
C Ganges River, Bangladesh 15.00 9.08 (7.25–11.39)
C Brahmaputra River tributary, Bangladesh 11.30 7.00 (5.66–7.71)
C Qadirabad barrage, Chenab River, Pakistan 17.80 10.62 (8.43–13.39)
C 40.0 22.29 (17.12–28.81)
Mystus tengara C Brahmaputra River, Bangladesh 11.20 6.95 (5.62–8.64)
C Ganges River, Bangladesh 11.60 7.18 (5.79–8.93)
C India 18.00 10.73 (8.51–13.53)
Xenentodon cancila C Atrai River, Bangladesh 18.10 10.78 (8.55–13.60)
C Hirakud reservoir, India 18.60 11.06 (8.76–13.96)
C Chi River, Thailand 23.00 13.43 (10.55–17.07)
C India 40.00 22.29 (17.12–28.81)
Channa orientalis C Basantar River, India 19.60 11.60 (9.17–14.67)
C Gajner beel floodplain, Pabna, Bangladesh 18.40 10.95 (8.68–13.82)
C 33.00 18.69 (14.47–24.02)
Channa punctata F Siruvani River, Tamil Nadu, India 24.40 14.18 (11.11–18.05)
M 25.00 14.49 (11.35–18.47)
F Vellar River, Tamil Nadu, India 24.50 14.23 (11.15–18.12)
M 27.90 16.03 (12.49–20.49)
F Cauvery River, Tamil Nadu, India 25.90 14.97 (11.70–19.10)
M 25.40 14.71 (11.51–18.75)
F Tamirabrani River, Tamil Nadu, India 27.40 15.76 (12.30–20.14)
M 26.80 15.45 (12.06–19.72)
C Hirakud Reservior, India 19.20 11.38 (9.01–14.38)
C Mathabhanga River, Bangladesh 18.90 11.22 (8.88–14.17)
C 31.00 17.65 (13.70–22.64)
Channa striata F North Kerian rice agoecosystem, Malaysia 54.00 29.34 (22.27–38.28)
M 45.20 24.93 (19.06–32.35)
C Agusan Marsh, Philippines 61.0 32.80 (24.78–42.96)
C Chi River, Thailand 51.00 277.84 (21.18–36.26)
C Pampanga River, Candaba, Philippines 41.40 (SL) 23.0 (17.65–29.77)
Channa striata C Pearl River, China 39.30 21.93 (16.86–28.34)
C 100.00 51.58 (38.20–68.60)
Gudusia chapra F Lake, Mymensingh, Bangladesh 13.70 (SL) 8.36 (6.70–10.45)
M 12.60 (SL) 7.74 (6.23–9.65)
C Lower Brahmaputra, India 13.80 8.41 (6.74–10.52)
C Betwa River, India 15.00 9.08 (7.25–11.39)
C Hirakud Reservoir, India 11.60 7.18 (5.79–8.93)
C Ganges Lower region, Bangladesh 13.40 8.19 (6.57–10.23)
C 20.00 11.82 (9.33–14.95)
Lepidocephalichthys guntea C Atrai River, Bangladesh 8.70 5.51 (4.50–6.80)
C Ganges Lower region, Bangladesh 9.60 (SL) 6.03 (4.91–7.46)
C 15.00 9.08 (7.25–11.39)
Amblypharyngodon mola F Wetlands of Dishoi and Neamatighat, Assam, India 9.00 5.69 (4.64–7.02)
M 6.60 4.28 (3.53–5.23)
C Hirakud Reservoir, India 7.20 4.64 (3.81–5.68)
F Payra River, Bangladesh 5.80 (SL) 3.80 (3.16–4.63)
M 5.40 (SL) 3.56 (2.97–4.33)
C Atrai River, Bangladesh 6.20 4.04 (3.35–4.93)
C Ganges River, Bangladesh 8.10 5.16 (4.23–6.35)
F Garjan beel, India 8.30 5.28 (4.32–6.50)
M 7.60 4.73 (4.00–5.98)
C Ganges lower region, Bangladesh 5.9 (SL) 3.86 (3.20–4.71)
C Mathabhanga River, Bangladesh 7.00 4.52 (3.72–5.53)
U South 24 Parganas, India 8.70 5.51 (4.50–6.80)
C India 20.00 11.82 (9.33–14.95)
Puntius sophore C Ganga basin tributaries, India 18.50 11.00 (8.72–13.89)
C Mathabhanga River, Bangladesh 10.20 6.38 (5.18–7.90)
C Hirakud Reservoir, India 10.80 6.72 (5.44–8.34)
C Brahmaputra River basin, India 7.40 (SL) 4.75 (3.91–5.83)
C 20.00 11.82 (9.33–14.95)
Salmostoma bacaila C Atrai River, Bangladesh 10.50 6.55 (5.31–8.12)
C Hirakud Reservoir, India 14.70 8.91 (7.13–11.17)
C 18.00 10.73 (8.51–13.53)
Glossogobius giuris C Brahmaputra River, Bangladesh 9.70 6.09 (4.95–7.54)
C Hirakud Reservoir, India 22.50 13.16 (10.35–16.71)
C Hongshui River, China 17.50 10.46 (8.30–13.18)
C Agusan Marsh, Philippines 19.50 11.54 (9.13–14.60)
C Ganges lower region, Bangladesh 23.60 13.75 (14.79–17.49)
F 22.80 13.32 (10.47–16.92)
M 23.60 13.75 (14.79–17.49)
C 17.90 (SL) 10.67 (8.47–13.46)
C Estuaries, South Africa 11.90 (SL) 7.34 (5.92–9.15)
C 50.00 (SL) 27.34 (20.82–35.59)
Heteropneustes fossilis C Atrai River, Bangladesh 13.70 8.36 (6.70–10.45)
C Gajner beel floodplain, Pabna, Bangladesh 16.50 9.91 (7.89–12.46)
C Ganga River, India 31.00 17.65 (13.70–22.64)
C Gajner beel floodplain, Pabna, Bangladesh 26.80 15.45 (12.06–19.72)
C 24.10 14.02 (10.99–17.84)
Macrognathus aculeatus C Ganges River, NW Bangladesh 23.40 13.64 (10.71–17.35)
C Thailand 38.00 21.27 (16.37–27.45)
Macrognathus pancalus C Atrai River, Bangladesh 12.60 7.74 (6.23–9.65)
C Mathabhanga River, Bangladesh 16.20 9.74 (7.76–12.25)
C Gajner beel floodplain, Pabna, Bangladesh 14.40 8.75 (7.00–10.95)
C Hirakud Reservoir, India 16.60 9.96 (7.93–12.53)
C 18.00 10.73 (8.51–13.53)
Nandus nandus F Ganges River, NW Bangladesh 13.60 8.30 (6.66–10.38)
M 12.60 7.74 (6.23–9.65)
C Brahmaputra River, Bangladesh 14.00 8.52 (6.83–10.67)
C Mathabhanga River, Bangladesh 14.20 8.63 (6.91–10.81)
C Gajner beel floodplain, Pabna, Bangladesh 14.10 8.58 (6.87–10.74)
C 20.00 11.82 (9.33–14.95)
Trichogaster fasciata C Deepor beel, Assam, India 8.10 5.16 (4.23–6.35)
C Gajner beel floodplain, Pabna, Bangladesh 9.40 5.92 (4.82–7.32)
C 12.50 7.68 (6.18–9.58)
Ompok pabo C 25.00 14.49 (11.35–18.47)
F Feni and Gomati River, Tripura, India 19.00 11.27 (8.92–14.24)
M 20.70 12.19 (9.62–15.45)
C Payra River, southern Bangladesh 22.30 13.05 (10.27–16.57)

Discussion

This study referred to the first strive to evaluate the size at sexual maturity of 20 fishes through multiple models in the Gajner Beel wetland ecosystem. The selection of permissible capture size at first maturity is broadly used and it is also used as an important tool in fisheries management (Lucifora et al. 1999; Hossain et al. 2012b) in open waters. Available information on size at sexual maturity of fishes from plots of percentage occurrence of mature females against length class can be obtained from the resulting logistic equation (King 2007). Some studies have narrated low exactness in the estimation of Lm of fishes using this logistic equation (Hossain and Ohtomi 2008; Hossain et al. 2013) but its accuracy for short life cycle organisms is addressed. Garcia (1985) also reported that using the proportion of mature females as an index of population reproduction was highly biased.

Nevertheless, the Lm was estimated by several models including brooding of eggs over time (especially for crustaceans), the appearance of the ovary and maturation stages over time (King 2007), the relative weight of gonad (TL vs. gonadosomatic index, modified gonadosomatic index, and Dobriyal index) over time (Hossain et al. 2017; Ahamed et al. 2018; Khatun et al. 2019), and histological studies (Chelemal et al. 2009; Jan and Ahmed 2019; Lucano-Ramirez et al. 2019). These methods differ with processing time, precision, accuracy, or suitability when we used these singly (De Martini and Lau 1999). To prevent this problem, we used three models (Lmax, TL vs. GSI, and logistic-based models) and their mean value was used to calculate their size at sexual maturity.

Among the 20 fishes, C. nama was the smallest and C. striata the largest in TL. Information on Lm was available only for three species (Channa striata, Gudusia chapra, and Puntius sophore) in FishBase (Froese and Pauly 2020). In our study Lm (mean Lm) was 24.84 cm for C. striata whereas Makmur et al. (2003) recorded 15.40 and 18.00 cm in the Musi River, south Sumatera, and 25.00 cm was found in Indonesia (Herre 1924). For the G. chapra Lm was 7.00 cm in this study. Hossain et al. (2010) narrated 8.00 cm in the Ganges River. We found 6.78 cm Lm for P. sophore. Halls et al. (1999), Halls (2005), and Hossain et al. (2012a) reported that Lm was 6.10, 4.50, and 5.00 for the P. sophore in the Talimnagar sluicegate, Lohajang River, and Padma River, respectively. The Lm of fish specimens might differ due to several factors like feeding rate, sex and gonadal development, behavior, season, the flow of water, populations density, water temperature, and food (Hossain et al. 2006, 2012a, b; Tarkan et al. 2006; Muchlisin et al. 2010). Most importantly it was the first attempt on Lm for 20 species in Gajner Beel wetland ecosystem so it can be used as baseline information for the future studies and essential for the selection of the permissible mesh size of nets which will be helpful for the sustainable management strategies of these 20 fish species from Gajner Beel in Bangladesh and contiguous ecosystems. Optimum catchable length (Lopt) is the length where the biomass of an unexploited cohort would be maximum (Froese et al. 2016). We also observed the Lopt which is essential for the management of these 20 fish species (Table 6).

Table 6.

Optimum catchable length (Lopt) of 20 fish species in a wetland ecosystem (Gajner Beel), NW Bangladesh.

Scientific name n Minimum length [cm] Maximum length [cm] Optimum catchable length of individuals (Lopt)
Chanda nama 196 2.40 7.20 4.80
Anabas testudineus 130 7.50 16.40 10.93
Mystus cavasius 124 5.30 16.90 11.27
Mystus tengara 139 4.80 12.60 8.40
Xenentodon cancila 118 8.50 24.00 16.00
Channa orientalis 152 8.10 19.00 12.67
Channa punctata 178 5.30 19.40 12.93
Channa striata 128 9.50 46.00 30.67
Gudusia chapra 126 4.40 14.60 9.73
Lepidocephalichthys guntea 117 5.00 10.30 6.87
Amblypharyngodon mola 193 3.90 7.80 5.20
Puntius sophore 191 4.20 11.00 7.33
Salmostoma bacaila 114 4.20 10.00 6.67
Glossogobius giuris 189 3.90 14.70 9.80
Heteropneustes fossilis 180 6.30 24.10 16.07
Macrognathus aculeatus 115 8.70 27.00 18.00
Macrognathus pancalus 190 6.90 15.70 10.47
Nandus nandus 168 6.50 17.20 11.47
Trichogaster fasciata 170 3.30 9.30 6.20
Ompok pabo 122 4.80 17.80 11.87

Fish diversity of Gajner Beel wetland ecosystem is declining at a faster rate because of many factors; damage of habitat, aquatic pollution, fishing pressure, natural disaster, extreme floodplain siltation, and reclamation of wetland (Dudgeon 1992; Hossain et al. 2014; Rahman et al. 2016). Therefore, to conserve the wild stock of wetlands, more population surveys and stock assessments are urgently needed. Identification of the causative factors for declining of the species, the establishment of suitable sanctuaries, conservation of habitats, and protection of adult species during the spawning – and/ or peak spawning season is highly recommended. Besides this, the mesh size of harvesting nets based on size at sexual maturity should be confirmed throughout the year for sustainable conservation and management. Furthermore, public awareness is most important for the conservation of this species.

The presently reported study concludes that around 50.0% of species were sexually matured in 8.80 cm TL. So, we strongly suggest that ≤ 8.80 cm TL fishes cannot be recommended for harvesting. As a result, at least 50% of species survive in the wetland ecosystem.

Acknowledgments

We are very much thankful to the Bangladesh Agriculture Research Council, NATP-2, ID: 484 for the financial support to complete this research.

References

  • Ahamed F, Saha N, Ahmed ZF, Hossain MY, Ohtom J (2018) Reproductive biology of Apocryptes bato (Gobiidae) in the Payra River, southern Bangladesh. Journal of Applied Ichthyology 34(5): 1169–1175. https://doi.org/10.1111/jai.13781
  • Butler S (2010) Macquarie Concise Dictionary (5th edn.). Macquarie Dictionary Publishers, Sydney.
  • Chelemal M, Jamili S, Sharifpour I (2009) Reproductive biology and histological studies in Abu Mullet, Liza abu in the water of the Khozestan province. Su Ürünleri Dergisi 4(1): 1–11. https://doi.org/10.3923/jfas.2009.1.11
  • Costello C, Ovando D, Hilborn R, Steven GD, Olivier D, Lester SE (2012) Status and solutions for the world’s unassessed fisheries. Science 338(6106): 517–520. https://doi.org/10.1126/science.1223389
  • DeMartini EE, Lau BB (1999) Morphometric criteria for estimating sexual maturity in two snappers, Etelis carbunculus and Pristipomoides sieboldii. Fish Bulletin 97(3): 449–458.
  • DoF (2019) National fish week, compendium (In Bengali). Dhaka: Department of fisheries, ministry of fisheries and livestock, government of Bangladesh. 150–151.
  • Dudgeon D (1992) Endangered ecosystems: A review of the conservation status of tropical Asian rivers. Hydrobiologia 248(3): 167–191. https://doi.org/10.1007/BF00006146
  • FAO (2012) The state of world fisheries and aquaculture, food and agriculture organization of the United Nations. Fisheries and aquaculture department. Policy and support branch office of knowledge exchange. Research and Extension 00153.
  • Froese R, Pauly D [Eds] (2020) Fishbase (2020) World wide web electronic publication. http://www.fishbase.org [accessed on 02 January 2020]
  • Garcia S (1985) Reproduction, stock assessment models and population parameters in exploited penaeid shrimp populations. In: Rothlisberg PC, Hill BJ (Eds) Proceedings of 2nd Australian National Prawn Seminar. NSP-2, Cleveland, Australia, 139–158.
  • Giri C, Pengra B, Zhu Z, Singh A, Tieszen LL (2007) Monitoring mangrove forest dynamics of the Sundarbans in Bangladesh and India using multi-temporal satellite data from 1973 to 2000. Estuarine, Coastal and Shelf Science 73(1–2): 91–100. https://doi.org/10.1016/j.ecss.2006.12.019
  • Halls AS (2005) The use of sluice gates for stock enhancement and diversification of livelihoods (R8210). Fisheries Assessment Report. MRAG, London, 75 pp.
  • Halls AS, Hoggarth DD, Debnath D (1999) Impacts of hydraulic engineering on the dynamics and production potential of floodplain fish populations in Bangladesh. Fisheries Management and Ecology 6(4): 261–285. https://doi.org/10.1111/j.1365-2400.1999.tb00080.x
  • Hasan MR, Mawa Z, Ul-Hassan H, Rahman MA, Tanjin S, Ahmed Abro N, Gabol K, Bashar MA, Jasmine S, Ohtomi J, Hossain MY (2020) Impact of eco-hydrological factors on growth of the Asian stinging catfish Heteropneustus fossilis (Bloch, 1794) in a Wetland Ecosystem. Egyptian Journal of Aquatic Biology and Fisheries 24(5): 77–94. https://doi.org/10.21608/ejabf.2020.105438
  • Herre AWCT (1924) Distribution of the true freshwater fishes in the Philippines. II. Philippine Labyrinthici, Clariidae, and Siluridae. Philippine Journal of Science 24(6): 683–709.
  • Hossain MY, Ohtomi J (2008) Reproductive biology of the southern rough shrimp Trachysalambria curvirostris (Penaeidae) in Kagoshima Bay, southern Japan. Journal of Crustacean Biology 28(4): 607–612. https://doi.org/10.1651/07-2970.1
  • Hossain MY, Ahmed ZF, Leunda PM, Jasmine S, Oscoz J, Miranda R, Ohtomi J (2006) Condition, length–weight and length–length relationships of the Asian striped catfish Mystus vittatus (Bloch, 1794) (Siluriformes: Bagridae) in the Mathabhanga River, southwestern Bangladesh. Journal of Applied Ichthyology 22(4): 304–307. https://doi.org/10.1111/j.1439-0426.2006.00803.x
  • Hossain MY, Ahmed ZF, Islam ABMS, Jasmine S, Ohtomi J (2010) Gonadosomatic index-based size at first sexual maturity and fecundity indices of the Indian River shad Gudusia chapra (Clupeidae) in the Ganges River (NW Bangladesh). Journal of Applied Ichthyology 26(4): 550–553. https://doi.org/10.1111/j.1439-0426.2010.01454.x
  • Hossain MY, Rahman MM, Miranda R, Leunda PM, Oscoz J, Jewel MAS, Naif A, Ohtomi J (2012a) Size at first sexual maturity, fecundity, length–weight and length–length relationships of Puntius sophore (Cyprinidae) in Bangladeshi waters. Journal of Applied Ichthyology 28(5): 818–822. https://doi.org/10.1111/j.1439-0426.2012.02020.x
  • Hossain MY, Jewel MAS, Nahar L, Rahman MM, Naif A, Ohtomi J (2012b) Gonadosomatic index-based size at first sexual maturity of the catfish Eutropiichthys vacha (Hamilton, 1822) in the Ganges River (NW Bangladesh). Journal of Applied Ichthyology 28(4): 601–605. https://doi.org/10.1111/j.1439-0426.2012.01954.x
  • Hossain MY, Arefin MS, Mohmud MS, Hossain MI, Jewel MAS, Rahman MM, Ahamed F, Ahmed ZF, Ohtomi J (2013) Length–weight relationships, condition factor, gonadosomatic index‐based size at first sexual maturity, spawning season and fecundity of Aspidoparia morar (Cyprinidae) in the Jamuna River (Brahmaputra River distributary), northern Bangladesh. Journal of Applied Ichthyology 29(5): 1166–1169. https://doi.org/10.1111/jai.12127
  • Hossain MY, Rahman MM, Ahamed F, Ahmed ZF, Ohtomi J (2014) Length–weight and length–length relationships and form factor of three threatened fishes from the Ganges River (NW Bangladesh). Journal of Applied Ichthyology 30(1): 221–224. https://doi.org/10.1111/jai.12251
  • Hossain MY, Hossen MA, Islam MS, Jasmine S, Nawer F, Rahman MM (2017) Reproductive biology of Pethia ticto (Cyprinidae) from the Gorai River (SW Bangladesh). Journal of Applied Ichthyology 33(5): 1007–1014. https://doi.org/10.1111/jai.13427
  • Jan M, Ahmed I (2019) Reproductive biology and histological studies of ovarian development of Schizothorax plagiostomus in river Lidder from Kashmir Himalaya. Journal of Applied Ichthyology 35(2): 512–519. https://doi.org/10.1111/jai.13858
  • Khatun D, Hossain MY, Nawer F, Mostafa AA, Al-Askar AA (2019) Reproduction of Eutropiichthys vacha (Schilbeidae) in the Ganges River (NW Bangladesh) with special reference to potential influence of climate variability. Environmental Science and Pollution Research International 26(11): 10800–10815. https://doi.org/10.1007/s11356-019-04523-5
  • Lucano-Ramírez G, Gómez-García MDJ, Ruiz-Ramírez S, González-Sansón G, Aguilar Betancourt C, Flores-Ortega JR (2019) Reproductive characteristics of the sole Achirus mazatlanus (Pleuronectiformes: Achiridae) in the Barra de Navidad coastal lagoon, Jalisco, Mexico. Ciencias Marinas 45(2): 47–58. https://doi.org/10.7773/cm.v45i2.2952
  • Lucifora LO, Valero JL, Garcia VB (1999) Length at maturity of the green-eye spurdog shark, Squalus mitsukuii (Elasmobranchii. Squalidae) from the sw Atlantic, with comparisons with other regions. Marine & Freshwater Research 50(7): 629–632. https://doi.org/10.1071/MF98167
  • Makmur S, Rahardjo MF, Sukimin S (2003) Biologi reproduksi ikan gabus (Channa striata) di daerah banjiran sungai Musi Sumatera Selatan. Jurnel of Iktiologi Indonesia 3(2): 57–62.
  • Mazid MA, Rahman MJ, Mustafa MG (2005) Abundance, migration and management of Jatka (juvenile hilsa, Tenualosa ilisha) in the Gajner Beel, Pabna, Bangladesh. Bangladesh Journal of Fisheries Research 9(2): 191–202.
  • Muchlisin ZA, Musman M, Azizah MNS (2010) Length–weight relationships and condition factors of two threatened fishes, Rasbora tawarensis and Poropuntius tawarensis, endemic to Lake Laut Tawar, Aceh Province, Indonesia. Journal of Applied Ichthyology 26(6): 949–953. https://doi.org/10.1111/j.1439-0426.2010.01524.x
  • Nikolsky GV (1963) The ecology of fishes. Academic press Inc., London.
  • Rahman AKA (1989) Freshwater fishes of Bangladesh, 1st edn. , zoological society of Bangladesh, department of zoology, University of Dhaka, Dhaka-1000, 123 pp.
  • Rahman MM, Hossain MY, Parvin S, Rahman MS, Ahmed ZF, Ohtomi J, Abd Allah EF (2016) Fecundity of the Threatened Fish, Mystus vittatus (Siluriformes: Bagridae) in the Padma River, Bangladesh. Sains Malaysiana 45(6): 899–907.
  • Ramsar Conservation (1971) Official page of the Ramsar Convention. [retrieved 2011–09–25]
  • Rohalin WM, Yaakub N, Fazdil NM (2019) Level of zinc and lead in freshwater fishes in Balok River, Pahang, Malaysia. United International Journal of Research and Technology 1(1): 44–48.
  • Templeman W (1987) Differences in sexual maturity and related characteristics between populations of Thorny skate (Raja radiate) from the northwest Atlantic. Journal of Northwest Atlantic Fishery Science 7(2): 155–167. https://doi.org/10.2960/J.v7.a18
  • Thilsted SH (2013) Diversifying food and diets: using agricultural biodiversity to improve nutrition and health. Earthscan, London, 270–282.
  • Tracey SR, Lyle J, Haddon M (2007) Reproductive biology and per-recruit analyses of striped trumpeter (Latris lineata) from Tasmania, Australia: Implications for management. Fisheries Research 84(3): 358–368. https://doi.org/10.1016/j.fishres.2006.11.025