Posted on 8th Oct 2024 08:54:50 PM Fisheries
INTRODUCTION
Bangladesh is a riverine country. There are 260 indigenous freshwater bony fish species, suitable for human consumption, belonging to 145 genera and 55 families, constitute a very rich aquatic bio-diversity in Bangladesh (Craig et al. 2004). Fish alone supplies about 60% of animal protein intake (Ahmed et al. 1997). Moreover, the fisheries sector provides full-time employment to an estimated 2 million fishermen, small fish traders, fish transporters and packers, etc. (World Bank 1989), and another 10 million people are partly dependent on fishing, e.g. part-time fishing for family subsistence (BFRSS 1986).
The Tank gobi, Glossogobius giuris (Hamilton 1822) belongs to the family Gobiidae of the order Perciformes commonly known as Nyaguna, Ngagulnun, Luthu in Australia, Bele in Bangladesh (Talwar and Jhingran 1991), Trey ksan in Cambodia, Flachkopfgrundel in Germany, Lam go ue in Hongkong, Kurudan, Pooan, Poolan, Kharbi, Gulah in India, Gel-ye Mahi Chshm Noarye in Iran, Jumburu, Kijumburu in Kenya, Pa boo in Laos, Gobie giurus in Madagaskar, Bekukor, Bekulor, Bekut trisau, Belodok, Belodok ubi in Malaysia, Bulla in Nepal, Bakla, Batung, Sagunayon in Philippines, Tenk dikkop in South Africa, Khane, Weligouva in Sri lanka, Cá Bống cát, Cá bong cat in Viet Nam (Froese & Pauly 2012). G. giuris is found in Africa to Oceania: Red Sea and East Africa and most inland freshwater bodies over the Indian Ocean and western Pacific. Moreover, the tank gobi is common in coastal and estuarine waters from austral Africa and Madagascar to India and south of China (Riede 2004; Froese & Pauly 2012). Nonetheless, it is common in inland freshwater bodies in several Asian countries, where it occurs in streams, canals, ditches and ponds with rock, gravel or sand bottoms, feeding on small insects, crustaceans and small fishes (Allen 1991). The tank gobi grows to a much larger size in brackish water than in fresh water. As G. giuris is one of the dominant fish species in the Ganges (northwestern Bangladesh), it is an important target species for small-scale fishermen, who use a variety of traditional fishing gears (Craig et al. 2004; Kibria and Ahmed 2005).
Le Cren (1951) defined the length–weight relationship as describing mathematically the relationship between length and weight, primarily so that one may be converted into the other. However, length–weight relationships are important for the estimation of weight from length for individual fish and for length classes of fish, estimation of standing-crop biomass when the length–frequency distribution is known, and for calculation of condition indices (Anderson & Gutreuter, 1983; Petrakis & Stergiou 1995), conversion of growth-in-length equations to growth-in-weight for prediction of weight-at-age and use in stock assessment models (Pauly 1993) and life history and morphological comparisons of populations from different locations (Petrakis & Stergiou 1995). Furthermore, length–weight (L-W) and length–length (L-L) relationships have applied and basic uses for assessment of fish stocks and populations (Ricker 1968). Again, length-length relationships are also important in fisheries management for comparative growth studies (Moutopoulos & Stergiou 2002).
Morphometric relationships including length-length (L-L) and length-weight (L-W) relationships and relative Kn and Fulton's condition factors KF are important biological parameters for fishes, from which the condition of stocks health of fish populations can be deduced (Bagenal & Tesch 1978). Moreover, relative weight (Wr) is one of the most popular indexes for assessing condition of fishes in the USA since last two decades (Rypel & Richter 2008).
Information on the biological parameters including LWRs, LLRs, condition and form factor of G. giuris are quit inadequate in Bangladeshi waters especially in the Padma River (except Hossain et al. 2009a & 2009b). However, a number of studies have been conducted on G. giuris including reproduction (Allen 1991), length-weight and length relationships in Ganges (Hossain et al., 2009a & Hossain et al. 2009b), length weight relationships in Pampanga River, Candaba, Philipplines (Garcia 2010), length weight relationships in the estuaries of South Africa (Harrison 2001). However, detailed studies on life history traits are still scarce for most sub-tropical fish species (Hossain et al. 2006a; 2006b) including G.giuris and to the best of the authors’ knowledge, there is no previous information on the length-weight relationships, length-length relationships, condition factors and form factor from the Padma River in Bangladesh of this species (except Hossain et al. 2009a & 2009b). Therefore, detailed knowledge on the population structure of G. giuris is needed immediately for proper management and initiate conservation measures for this important fish of the Padma River.
Objectives
This study is the first complete and comprehensive description of the following aspects of G. giuris in the Padma River, NW Bangladesh.
1. Sex ratio;
2. Length-frequency distribution;
3. Length-weight relationships;
4. Length-length relationships;
5. Condition factors (KF, KR, KA, WR); and
6. Form factor (a3.0).
ABSTRACT
The Tank Gobi Glossogobius giuris is an important indigenous small fish species of Bangladesh. The present study describes some biological parameters, including sex ratio, length-frequency distributions (LFD), length-weight relationships (LWR), length-length relationships (LLR), condition factors (Allometric, KA; Fulton’s, KF; Relative condition, KR; Relative weight, WR) and form factor (a3.0) of G. giuris in the Padma River, NW Bangladesh. Sampling was done using traditional fishing gears including Bewshi jal, Khepla jal, Ber jal, Feri jal, Dohair, Bittii and Kholson during April 2011 to March 2012. Total length (TL), head length (HL) and standard length (SL) were measured to the nearest 0.01 cm using digital slide calipers, and total body weight (BW) was measured using an electronic balance with 0.01 g accuracy. The length-weight relationship was calculated using the expression: W= a Lb, where W is the BW, L the TL. A sum of 219 specimens ranging from 5.70 cm - 22.00 cm TL (total length) and 1.62 g – 73.93 g BW (body weight) were analyzed in this study. ). However, the Mann-Whitney U-test showed significant differences in the TL-frequency distributions between males and females (Two tailed, P = 0.001). Again, the results showed that BW of females was significantly higher (Mann-Whitney U-test, Two tailed, P < 0.001) than that for males. The overall sex ratio was statistically differences from the expected value of 1:1 (df = 1, χ2 = 26.14, P > 0.001). Moreover, The calculated b for the LWR indicated negative allometric growth (< 3.00) in males and females (< 3.00) and there was significant differences in the intercepts (F = 19.43, df = 216, P < 0.001), but not in the slopes (F = 3.59, df = 215, P = 0.059) between the sexes of G. giuris in the Padma River. Moreover, the regression models show that there were no significant differences between observation and prediction growth patterns in both sexes (ANCOVA, P < 0.05). All the LLRs between males and females revealed no significant differences for slopes and intercepts (ancova, P > 0.05) during this study. Furthermore, the Mann-Whitney U-test showed significantly differences in the allometric condition factor between males and females (Two tailed, P < 0.001). The WR (actual median = 98.97) showed no significant differences from 100 for males (P = 0.519) and females (Wilcoxon rank test, Two tailed, P = 0.854) in this study, indicating the habitat was still in good condition for G. giuris. Furthermore, the results showed that WR was not significantly differences between males and females (Mann-Whitney U-test, Two tailed, P = 0.663) in the Padma River. To the best of author’s knowledge, this study reports the first complete and inclusive description of life-history traits for G. giuris from Bangladeshi waters. The results of this study would be useful for the sustainable conservation of this Tank Gobi fishery in Bangladesh and neighboring countries.
CONTENTS
Acknowledgements
Abstract
Contents
List of Tables
List of Figures
List of Plates
Chapter One: Introduction
Chapter Two: Review of Literature
Chapter Three: Materials and Methods
3.1. Study area and sampling
3.2 Fishing Methods
3.3. Length-weight and length-length relationships
3.4. Condition factors
3.5. Form factor
3.6. Gonadosomatic index
3.7. Statistical analyses
Chapter Four: Results
4.1. Sex ratio
4.2. Length-frequency distributions
4.3. Length-weight relationships
4.4. Length-length relationships
4.5. Fulton’s condition factor (KF)
4.6. Relative condition factor (KR)
4.7 Allometric condition factor (KA)
4.8. Relative weight (WR)
4.9. Form factor (a3.0)
Chapter Five: Discussion
Chapter Six: Conclusion
Chapter Seven: References
LIST OF TABLES
1. The sex ratio (male: female = 1:1) of the total length dependent for Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
2. Descriptive statistics on the length (cm) measurements of the male Glossogobius giuris (Hamilton, 1822) (sample, n = 163) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh.
3. Descriptive statistics on the length (cm) measurements of the female Glossogobius giuris (Hamilton, 1822) (sample, n = 56) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh.
4. Descriptive statistics on the length (cm) measurements of the combined gender Glossogobius giuris (Hamilton, 1822) (sample, n = 219) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh.
5. Descriptive statistics on the weight (g) measurements of the Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh.
6. Descriptive statistics and estimated parameters of the length-weight relationships (BW = a × TLb) of the Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh.
7. Gonado-somatic index, mean gonado-somatic index, condition factors and form factor of the Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh.
LIST OF FIGURES
1. Study sites in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
2. The length-frequency distribution of the male Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh. Here, n indicates the number of sample.
3. The length-frequency distribution of the female Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh. Here, n indicates the number of sample
4. Relationships between ln total length (ln TL) and ln body weight (ln BW) of the male Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
5. Relationships between total length (TL) and body weight (BW) of the male Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
6. Relationships between ln total length (ln TL) and ln body weight (ln BW) of the female Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
7. Relationships between total length (TL) and body weight (BW) of the female Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Banglades
8. Relationships between ln total length (ln TL) and ln body weight (ln BW) of the combined gender Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
9. Relationships between total length (TL) and body weight (BW) of the combined gender Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
10. Comparison of observed and predicted growth for the male Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
11. Comparison of observed and predicted growth for the female Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
12. Comparison of observed and predicted growth for the combined gender Glossogobius giuris (Hamilton, 1822) in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
13. Relationships between total length (TL) and standard length (SL) of the male Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
14. Relationships between total length (TL) and standard length (SL) of the female Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
15. Relationships between total length (TL) and standard length (SL) of the common gender Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
16. Relationships between total length (TL) and head length (HL) of the male Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
17. Relationships between total length (TL) and head length (HL) of the female Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
18. Relationships between total length (TL) and head length (HL) of the common gender Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
19. Relationships between standard length (SL) and head length (HL) of the male Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
20. Relationships between standard length (SL) and head length (HL) of the female Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
21. Relationships between standard length (SL) and head length (HL) of the common gender Glossogobius giuris in the Padma (main distributary of the Ganges) River, northwestern Bangladesh
LIST OF PLATES
1. Length measurement of Glossobius giuris (Hamilton, 1822) in Padma River, Northwestern Bangladesh
2. Weight measurement of Glossobius giuris (Hamilton, 1822) in Padma River, Northwestern Bangladesh
3. Bewshi jal
4. Khepla jal
5. Ber jal
6. Feri jal
7. Dohair
8. Bittii
9. Kholson
Morphometric, Tank, Goby, Glossogobius, Giuris, Hamilton, Perciformes, Gobiidae, Padma, River, Northwestern, Bangladesh, Bewshi, Khepla, Ber, Feri, Jal, Dohair, Bittii, Kholson
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