Abstract: Background and Objective: Mystus nigriceps is a consumption fish species and also preferred as ornamental fish. The existence of this species population in Kampar Kanan and Kampar Kiri river continues to decline due to non-selective fishing. While conservation efforts through domestication are currently not done. The purpose of this study was to analyze the relationship between length and weight and relative condition factors of M. nigriceps on Kampar Kanan and Kampar Kiri river. Materials and Methods: A total of 414 fish were collected from both rivers. Fish samples were collected from local fishermen in Kampar Kanan and Kampar Kiri rivers. The fish length measured by using calipers with an accuracy of 0.01 mm and the weight measured with a digital scale with 0.01 g accuracy. Results: The total length of M. nigriceps from Kampar Kanan river ranges from 97.48-160.45 mm and weighs 5.58-59.54 g, while from Kampar Kiri river has a total length ranging from 94.66-198.64 and weight of 6.28-60.44 g. The length and weight relationship of M. negriceps in Kampar Kanan river can be estimated with equation W = 0.0029*L3.393 (R2 = 0.86) with relative condition factor value (Kn) 3.37 and have positive allometric growth pattern. While the length and weight relationship in Kampar Kiri river is W = 0.0034*L3.256 (R2 = 0.91) with relative condition factor value (Kn) 4.62 and also have positive allometric growth. Conclusion: This study provides the first baseline data on the relationship between length and weight and relative condition factors of M. nigriceps from Kampar Kanan and Kampar Kiri rivers in Riau Province, Indonesia. The data is very valuable to build a management system and domestication for the fish species.
INTRODUCTION
Two spot Catfish, Mystus nigriceps (Valenciennes 1840) is group of Bagridae family that exist in slow-flowing waters and muddy substrates1. This species founded in Kampar Kanan river2 also subsist in oxbow lake area around Kampar Kiri river3. M. nigriceps widely spread in Sumatera, Java and Borneo1,4. M. nigriceps is popular consumption fish because of its delicious taste and also popular as ornamental fish5, so the demand for this species at various sizes is very high.
The increase of demand of M. nigriceps, leads to species exploitation of smaller size fish and population in nature is endangered6. Exploitation, industrialization, water pollution that causes habitat degradation is a threat to population sustainability of M. nigriceps7,8,9. IUCN reported that M. nigriceps as a not evaluated species and conservation management are needed for the sustainability of this species2,10.
Information about growth patterns and body shapes required for conservation and domestication of M. nigriceps. This species growth pattern can be analyzed from the length-weight relationship and condition factors. Determining the relationship between length-weight and condition factors is very important to understand and assess stock production and the factors that influence the population growth of M. nigriceps11-13. Several studies on the length-weight relationship and condition factors or relative condition factors of the Mystus genus have been carried out by Hossain et al.8 and Sani et al.9. Until today, there is no report from Kampar Kanan (KKA) and Kampar Kiri (KKI) river except M. nigriceps from Batang river14. The purpose of this study was to analyze the relationship between length-weight, growth patterns and relative condition factors of M. nigriceps in Kampar Kanan (KKA) and Kampar Kiri (KKI) river.
MATERIALS AND METHODS
Sampling area: M. nigriceps sample were collected with the help of local fishermen in accordance with the fishers fishing habits of Kampar Kanan (KKA) (N: 0°21'3.78'' E: 101°61'9.00''), Kampar Kiri (KKI) (N: 0°8'8.40'' E: 101°14'57.60''), Kampar Regency, Riau Province. Sample collected from October 2015 to June 2016. A total of 414 fish were collected using traditional fishing gear (gillnet, bubu and fishing rod). The total length measured using digital calipers with an accuracy of 0.01 mm and weight measured using digital scale Kern: ABS 220-4 Analytical Balance with an accuracy of 0.01 g. Samples grouped according to sex and study location. Fish samples were preserved with 10% formalin and species identification confirmed with relevant guidance1,15.
Length-weight relationship: Length-weight relationships calculated based on population origin and sex16,17. The equation used is:
W = aL
Transformed into logarithm:
Log W = log a+b log L
where, W is the total weight (g), L is total length (mm), a = regression intercept, b = regression slope12,17. Regression analysis and the correlation between length-weight and condition factors by using Microsoft Excel 2007.
Growth pattern. Growth patterns comparing regression coefficients (b) were analyzed according to Froese17 and Okgerman18: 1. if b <3, fish growth is negative allometric (body length growing faster than weight gain); 2. if b> 3, positive allometric (weight gain is faster than body length); 3. if b = 3, isometrik (balanced in body length growth and weight gain).
Relative condition factor. The relative condition factor (Kn) calculated based on population origin and sex. If b≠3, The relative condition factor or Kn is calculated based on population origin and sex19. Kn = W/aLb, where Kn is a relative condition factor; W is fish weight (g); L is fish total length (mm); a = constant and b = coefficient obtained from the length-weight relationship.
RESULTS
Distribution based on body size: Total of 414 M. nigriceps were analyzed in this study, 202 individuals of M. nigriceps from Kampar Kanan (KKA) and 212 individuals from Kampar Kiri (KKI). Male-female ratio is 40.10-59.90%, respectively. The average length and weight of female fish were greater than males. Total length and weight based on population origin and sex indicated on Table 1.
Length-weight Relationship (LWR): Statistic description of Length-weight Relationship (LWR) of M. nigriceps population from KKA and KKI showed on Table 2. The r values of 0.894 and 0.949 are close to 1 which indicates a very strong and positive relationship between weight gain and length growth of M. nigriceps. While based on sex category, the correlation coefficient ranges from 0.723 to 0.949, meaning that origin and sex also have a very strong relationship.
| Table 1: | The total number of male, female M. nigriceps and their total length and body weight observed from population KKA and KKI rivers |
| Table 2: | The length-weight relationship and relative condition factor of M. nigriceps |
N-Number of fish samples; A-intercept; B-slope; R-correlation coefficient; R2-coefficient determination; Kn-condition factor | |
| Fig. 1(a-b): | Length-weight relationship of M. nigriceps in (a) Kampar Kanan river and (b) Kampar Kiri river |
The coefficient of determination (R2) presented in Fig. 1a-b. The R2 values from KKA and KKI in this study were 0.859 and 0.908 respectively, while the value of R2 based on sex, ranges from 0.716 to 0.908. This value indicates the body length affects total body weight. Both population origin and sex categories showed significant value (p<0.01). Calculation of length-weight relationship (LWR) of M. nigriceps shows the value of a (intercept) of 0.0025; b (slope) 3,393 for KKA river population and a (intercept) value of 0.0034; b (slope) of 3,256 for KKI river population (Fig. 1a-b). Based on sex category, the value of a (intercept) ranges from 0.0022 to 0.0031 and; b (slope) ranges from 3,308 to 3,446. All values of b>3 indicate positive allometric growth patterns for M. nigrceps (Table 2).
Relative condition factor (Kn): Table 2 shows the relative condition factors (Kn) of M. nigriceps from KKA and KKI rivers. The average Kn value is 3.36 and 4.56 for the entire population of KKA and KKI population, respectively. The average Kn values for male and female KKA populations are 3.29 and 3.45, respectively. The average Kn values for male and female KKI populations are 4.31 and 4.74, respectively. Based on sex category the average female fish has a larger Kn size than the male. Average Kn value from KKI river population also greater than KKA river. Kn values are highly correlated with length-weight relationships and therefore exponent b is very important for assessing fish species in good condition. This study provides new information of M. nigriceps species from KKA and KKI rivers because there is no previous study conducted about LWR from this location.
DISCUSSION
Size variety of fish caught from KKA and KKI rivers cannot be separated from the use of fishing gear. This condition was previously reported in Cirrhinus reba in Padma river of Bangladesh20 and Hamapala macrolepidota in Singkarak lake, West Sumatra, Indonesia21. The maximum length of M. nigriceps founded in this study is 198.64 mm, longer than M. nigriceps (195 mm) caught in the Batang Martapura river, South Kalimantan14 and M. pancalus (126 mm), M. tengara (112 mm) from Brahmaputra river, Bangladesh22. In contrary, with M. cavasius (274 mm) and M. tengara (330 mm) from Betwa river and Gomti, Uttar Pradesh, India9,23. The difference in size may be due to the use of different sizes and type of
fishing gear. Variations in size most likely caused by the size of fishing gear and the effects of formalin during preservation24. In addition, geographic, ecological and water quality parameters as fish habitat largely determine the morphological differences and size25.
Table 1 showed that the catch number is not balanced between male and female fish. The ratio of male and female fish caught compared to 0.91: 1.1 for KKA river and 0.4: 2.03 for KKI river. According to Mitu et al.26 natural population ratios range from 1:1. This ratio can shift before and during spawning, especially by fish-catching factors. In KKA and KKI rivers, the population of female fish is greater than the male. Many possibilities cause the differences in the sex ratio, including community activities in river banks and along the river2.
On the upstream of KKA river, there are Koto Panjang reservoir and community and plantations floating net cages, while on KKI river there are flooding swamps with plantation activities, rubber plantations and sand mining activities. The difference in activities that occur estimated to have an effect on fish quality, food composition, changes in water levels including sediment travel which ultimately affects fish metabolism and biology. The activities mentioned brought different impacts to the habitat including non-selective fishing. Thus, it becomes necessary to standardize the sampling size, water depth, mating season and fish biology27. Banik et al.28 reported that in the Ompok pabda, the sex ratio of female fish was higher than male fish. Mitu et al.26 also recently reported that M. tengara showed a greater ratio of female than male fish. The difference in sex ratio of male fish can be caused by differences in metabolic strain. Older male fish at spawning have higher possibilities to die than female and can occur in other fish species26.
Table 2 showed the relationship of length-weight of M. nigriceps in KKA and KKI river with value of b> 3 indicating a positive allometric growth pattern. This means that weight gain is faster than body length growth. Differences in growth patterns can be caused by fish length, gonad maturity size and stomach fullness29-31, included differences in habitats32. Other researchers also stated that the level of fish gonad maturation positively correlated with water chemical-physical properties, food availability, age differences17,33-36, including waters conditions for spawning, such as currents, water substrate37. But in this study we did not analyze the relationship between water quality parameters and the level of maturity of M. nigriceps gonads.
Khan and Sabah38 pointed out that fish LWR cannot be separated from spatial and temporal factor, sex and sexual maturity. Variations in the value of b highly dependent on geographical factors, biological conditions, environmental, temporal and sampling time17,39. Thus, isometric or allometric growth patterns can occur in the same or different species40.
In addition to growth patterns, condition factors are part of growth parameters. The condition factor shows if the fish in good condition, in terms of physical capacity for survival and reproduction19. The average value of M. nigriceps relative conditions in KKA is 3.37 and KKI is 4.62, which mean that M. nigriceps in the KKA and KKI rivers were in good condition with all positive allometric patterns. According to Shinkafi and Ipinjolu41 that fish growth is in good condition, if Kn value> 2. The relative condition factor-factor of M. nigrceps from KKA and KKI rivers is higher compared to M. nigriceps from Batang river14. The differences in this condition factors related to biological interactions involving intra-specific competition for food, sex, space between species, feeding intensity, gonad development and food availability20. But in this study, the number of M. nigriceps populations continues to decline due to non-selective fishing activities. The non-selective capture and habitat degradation results in a decline of fish populations including M. nigriceps42.
Fluctuations in condition factors also caused by the suitability and availability of food at a certain time and the feeding intensity related to the fish gonad development process20,33,43. The relative condition factor of M. nigriceps is probably caused by the relatively small population and proportional body length-weight. Fluctuations in condition factors that calculated from different size groups give an indication of the fish is in its growth period. The first peak shows the condition of sexual maturity, which generally shows a fast growth rate, while the second peak coincides with a measure of reproductive sexual maturity, which generally shows a fast growth rate at the time for spawning33,43,44. In addition, conditions factors fluctuated due to metabolic tension during maturity or spawning and the habit of eating and changing seasons13,33. The condition factor is inseparable from changes in water temperature, where the season causes a drastic change in environmental conditions45,46. This means that the relative condition factor shows the suitability of fish with their habitat. The greater the condition factors, means fish are in the better condition36. The relative condition factor can be one of the tools to identify sustainable fishing management by involving the community and local government.
CONCLUSION
Kampar Kanan and Kampar Kiri river ecosystem support M. nigriceps to have positive allometric growth patterns with almost the same Kn value. This data can be used for the management and domestication of M. negriceps in the future. In addition, the capture of this species must be done selectively in these two rivers.
SIGNIFICANCE STATEMENT
This study provide important information regarding growth patterns and relative condition factors of M. nigriceps that carried out for the first time on Kampar Kanan and Kampar Kiri rivers, which the population in numbers continues to decline due to non-selective fishing. Data on growth patterns and relative condition factors can be used in understanding the frameworks regarding management and domestication of M. nigriceps species in Riau province, Indonesia. This study also can be the tools to control fishing activities and identify sustainable fishing management by involving the community and local government.
ACKNOWLEDGMENTS
The author is grateful for the educational assistance from the Ministry of Research and Technology, Directorate of Higher Education, which provides opportunities for continuing education through the Domestic Postgraduate Education Scholarship (BPPDN) scheme. Thank you for the material and moral assistance given by Muara Bungo University and the Genetics and Biomolecular Laboratory, Biology Department, Faculty of Mathematics and Natural Sciences, Andalas University, Padang, West Sumatra, Indonesia.