Subscribe Now Subscribe Today
Research Article
 

Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal Water



M.M. Rahman and A. Hafzath
 
Facebook Twitter Digg Reddit Linkedin StumbleUpon E-mail
ABSTRACT

This study described the Condition factor, Length-Weight relationship, Gonadosomatic index and sex ratio of Indian mackerel (Rastrelliger kanagurta) which is an important fish in the Kuantan coastal water, Malaysia. Data were obtained from December 2011-May 2012 and a total of 1064 Indian mackerel specimens were studied in this research. The result showed that male Indian mackerel was significantly more than female (χ2 = 7.91; p<0.01) in the population in the Kuantan coastal area. Length-Weight relationship of each month was significant (p<0.01) with all coefficients of determination (R2) values being higher than 0.72. The allometric coefficients (b) of length-weight relationship varied between 2.5128 (April) and 3.0807 (May). A negative allometric growth of Indian mackerel was observed in January, March and April. An isometric growth was observed in December and February while a positive allometric growth was observed only in May. The b-value of the length-weight relationship of Indian mackerel in April was very low compared to other month. The condition factor ranged from 1.0499-1.1320 and was significant difference between months (p<0.05). The significantly lowest mean condition factor was found in December and the highest in February and April. Overall higher mean condition factor was observed in smaller fish of both sex. The overall mean condition factor of female was better than male. Gonadosomatic index of Indian mackerel in February was higher than those observed in March and April and followed by May. Gonadosomatic index rapidly increased after January and reached at peak in February and decline after February. A positive relationship was observed between gonadosomatic index and condition factor of Indian mackerel. The peak spawning season of Indian mackerel in Kuantan coastal water was from February to April. The spawning season of Indian mackerel in Kuantan coastal water falls within the period between end of January and end of May.

Services
Related Articles in ASCI
Search in Google Scholar
View Citation
Report Citation

 
  How to cite this article:

M.M. Rahman and A. Hafzath, 2012. Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal Water. Journal of Biological Sciences, 12: 426-432.

DOI: 10.3923/jbs.2012.426.432

URL: https://scialert.net/abstract/?doi=jbs.2012.426.432
 
Received: October 01, 2012; Accepted: October 05, 2012; Published: January 10, 2013



INTRODUCTION

Fisheries industry plays an important role in the economy of many countries including Malaysia. In Malaysia, fisheries sector contributed 1.2% to GDP (Gross Domestic Product) in 2008 which was increased by 1.3% in 2009. However, the world fisheries have been showing poor capture production since the last decade (FAO, 2011). In 2000, the global capture production was about 950 million MT and in 2010 the capture production was decreased nearly 900 million MT. However, the total capture production in Malaysia has increased in the last decade. Since, year 2000 (1.2 million MT) the total capture production in Malaysia has increased by 10% (FAO, 2011).

Marine fisheries sector is of fundamental importance to Malaysia in terms of revenue generation, employment and food security. In 2009, the total production of marine fisheries was nearly 2 million MT and it valued nearly 9000 million Malaysian Ringgit which contributed 1.3% to the Malaysian GDP (Gross Domestic Product). Besides this, this sector provided nearly 150 thousand jobs directly and/or indirectly (DOF, 2009). In Malaysian about 60-70% of total animal protein is supplied by marine fisheries (Lihan et al., 2006) which is dominated by a wide variety of fish species (e.g., Indian mackerel, slimy mackerel, yellow striped scad, bleeker smoothbelly sardinella, smoothbelly sardinella, kawakawa, longtail tuna and torpedo scad, etc.).

Among variety of fishes, Indian mackerel is one of the important fish in Malaysia. Indian mackerel is coastal pelagic species, often found in a large shoal at a depth range of 20-90 m (Pauly et al., 1996). Adults Indian mackerel feed on macro plankton such as larval shrimps and fish. Spawning occurs in several batches with eggs fertilized externally. Both eggs and larvae of Indian mackerel are pelagic (Collette, 2001). It is widely consumed in many parts of Malaysia due to it’s abundance, ease in the capture and low market price. In 2010, the capture production of Indian Mackerel was 186225 MT and it accounts for 10% of total capture fish production. However, in Malaysia, total capture production of many marine fishes is decreasing day by day. Therefore, management of wild population is necessary for an urgent basis to obtain sustainable capture production.

Understanding population dynamics in particular their stock condition, growth, spawning seasons, recruitment, mortality, etc. are prerequisite before identifying proper management techniques on any wild fish stock. There is some information about wild population of Indian mackerel. Unfortunately, such information of most fishes including Indian mackerel on the east coast of peninsular Malaysia especially in the Kuantan area is lacking. As a starting point, this research quantifies some population parameters namely condition factor and its temporal variation, length-weight relationship, gonadosomatic index of Indian mackerel populations in the Kuantan coastal water, Malaysia. The objectives of this study were (1) to determine length-weight relationship of Rastrelliger kanagurta, (2) to determine the condition factor of Indian mackerel and (3) to determine gonodosomatic index and spawning season of Indian mackerel.

MATERIALS AND METHODS

Area of capture and sample collection: All fishes were collected early in the morning from Kompleks Lembaga Kemajuan Ikan Malaysia (LKIM), Kuantan, Pahang, Malaysia. All fishing vessels used purse seine nets to catch Indian mackerel and Fig. 1 shows the area of capture of Indian mackerel based on the information received from fisherman. Fishing vessels were equipped with icing systems and fish were kept at lower temperature to keep fresh. In this experiment, all fish samples were collected before sorting to avoid biasness on size. After collection, they were immediately preserved with ice in the ice box and transported to the laboratory. Samples were collected monthly for a period of 6 months (December to May, 2012). A total of 1064 Indian mackerel was sampled in this study.

Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water
Fig. 1: Map showing area of Indian mackerel capture

Sample measurement: Upon arrival at the laboratory, total Length (L) and Standard Length (SL) of fishes were measured using a special measuring board with a meter rule calibrated in centimeters, Fish length was measured to the nearest centimeter. Body weight (W) of 2 decimal points was measured after blot drying with a piece of clean tissue. After recording length and weight of fish, it was dissected to collect gonad and determine the sex. All gonads were weighted with a digital balance. In some cases, the gonad was not developed. In those cases the sex of fish was unidentified. The length-weight relationship was calculated using the Equation (Pauly, 1983, 1993):

W = aLb

where, W is the weight of fish (g), coefficient a is the intercept in the y-axis, regression coefficient b is an exponent and L is the total length of fish (cm). The value of b indicates isometric growth when close to 3. The statistical significance level of R2 was estimated and the parameters a and b were estimated by linear regression analysis based on the natural logarithms:

log W = log a + blogL

Additionally the coefficient of determination r2 were estimated. The Fulton’s Condition factor (K) for each experimental fish has been calculated using the formula:

Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water

where, K is the Condition factor, W is the Weight of fish, L is the Total length of fish (cm).

Gonadosomatic index (GSI) was calculated using the Equation:

Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water

Statistical analysis: All regressions and correlation were statistically analyzed using SPSS (version 16.0) which was also applied to differing between months on condition factors and gonadosomatic index. Difference between monthly condition factors and gonadosomatic index were analyzed through the analysis of variance (ANOVA) and the difference between sex ratio was analyzed through the Chi-square (χ2) test.

RESULTS

Length-Weight relationship: Monthly of Length-Weight Relationships (LWR) of Indian mackerel were presented in Table 1 and Fig. 2. LWRs of Indian mackerel in all months were found to be linear. LWRs showed that the allometric coefficients vary between 2.5128 (April) and 3.0807 (May). LWRs of each month was significant (p<0.01) with all coefficients of determination (R2) values being higher than 0.72. A negative allometric growth of Indian mackerel was observed in January (W = 0.0155L2.8839, r2 = 0.8484, p<0.01) (Fig. 2b), March (W = 0.0135L2.9298 ,r2 = 0.8193, p<0.01) (Fig. 2d) and April (W = 0.0483L2.5128, r2 = 0.7261, p<0.01) (Fig. 2e). An isometric growth was observed in December (W = 0.0098L3.0244, R2 = 0.8841, p<0.01) (Fig. 2a) and February (W = 0.0113L3.0015, R2 = 0.8141, p<0.01) (Fig. 2c) while a positive allometric growth was observed only in May (W = 0.0086L3.0807, R2 = 0.8840, p<0.01) (Fig. 2f).

Condition factor: The condition factor (K) ranged from 1.0499-1.1320 (Fig. 3). Condition factor was significantly different between months (p<0.05). The significantly lowest mean K value was found in December and the highest was in February and April. The mean condition factor in February was comparatively slightly higher than in April, although they were statistically same (p>0.05). The mean condition factors in January, March and May were significantly lower than in February and April and significantly higher than in December. The mean condition factor (Km) in relation to size class for both sexes is shown in Fig. 4. Overall higher Km was observed in smaller fish of both male and female. Overall Km of female was better than male.

Sex ratio: Out of the total of 1064 specimens of R. Kanagurta collected from December 2011 to May 2012, only 329 were able to determine the sex. Out of 329, 190 (57.75%) were males and 139 (42.25%) were females.

Table 1: Monthly descriptive statistics and estimated parameters of length-weight relationship of Indian mackerel from December 2011 to May 2012
Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water
*Indicates significant at p<0.01

Table 2: Reported a and b values of different fish in different locations
Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water

Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water
Fig. 2: Relationship between total length (cm) and body weight (g) in (a) December 2011, (b) January 2012, (c) February 2012, (d) March 2012, (e) April 2012 and (f) May 2012

Overall the sex ratio differed significantly (χ2 = 7.91; p<0.01). Male was significantly more than female in the Indian mackerel population in the Kuantan coastal area.

Gonadosomatic index: Monthly changes of mean gonadosomatic index (GSI) of Indian mackerel are presented in Fig. 5. The lowest GSI of Indian mackerel was observed in December and January. GSI of Indian mackerel in February was higher than March and April and followed by May. GSI rapidly increased after January and reached at peak in February (1.1958%). After February GSI was declining again. A positive relationship was observed between GSI and condition factor of Indian mackerel (Fig. 6).

Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water
Fig. 3: Monthly mean (±95% confidence intervals) condition factor. Mean with no letter in common differ significantly (p<0.05)

Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water
Fig. 4: Mean condition factor (Km) per length class (total length) for both sexes

DISCUSSION

Length-weight relationship is very useful in fisheries science for both applied and basic use to (1) estimate weight from length observations because direct weight measurements can be time consuming in the field (Beyer, 1987; Martin-Smith, 1996; Sinovcic et al., 2004); (2) calculate, growth, biomass and production of a population (Le Cren, 1951; Pauly, 1983) and (3) compare the life history of fishes of different localities (Petrakis and Stergion, 1995); (4) determine the relative condition of small fish compared to large fish and (5) set yield equations for estimating number of fish landed and compare the population in space and time (Beverton and Holt, 1957). Besides these, length-weight relationships allow conversion of length-growth equations to weight-growth equivalents in yield-per-recruit and related models.

The exact relationship between length and weight differs among species of fish according to their inherited body shape and within a species according to the condition (robustness) of individual fish (Schneider et al., 2000). So the equation derived from the Equation logW-loga+blogL differs every time. In the present study, the coefficient b of length-weight relationship was ranged between 2.5128-3.0807 which was in the acceptable range (Bagenal and Tesch, 1978).

Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water
Fig. 5: Monthly changes of mean (±95% confidence intervals) gonadosomatic index (GSI) of Indian mackerel in the coastal water of Kuantan. Mean with no letter in common differ significantly (p<0.05)

Image for - Condition, Length-Weight Relationship, Sex Ratio and Gonadosomatic Index 
  of Indian Mackerel (Rastrelliger kanagurta) Captured from Kuantan Coastal 
  Water
Fig. 6: Relationship between GSI and Condition Factor

The b value of most fish is around 3 (Table 2) but it can vary from 2-4 (Bagenal and Tesch, 1978). There is no previous study in the Kuantan coastal water comparing the b value of Indian mackerel. However, Sivadas et al. (2006) reported 3.38 as the b value of Indian mackerel in Calicut, India (Table 2).

In this study, the b-value of the LWR in April was very low (2.5128) compared to other month. However, this might be influenced by environmental or habitat factors. For example, differences in the water temperature, availability of food, etc. are known to influence the growth. According to Tesch (1971) length-weigh relationship of fish are affected by many factors including season, habitat, gonad maturity, sex, diet, health and preservation techniques. In this study, environmental or habitat factors were not analysed. However, more research is needed including analyzing environmental or habitat factors to understand the cause of low b value in April in Kuantan coastal water.

Condition factor is a quantitative parameter that indicates the state of the fish (fatness, maturity and spawning gonadal development and general well-being of the fish) and determine present and future population success by influencing growth, reproduction and survival (Wootton, 1990). Condition factor shows the population’s condition (welfare) during the various stages of the life cycle. The condition factor normally decreases at the start of the spawning period due to very high metabolic rates. According to Mde and Ambrosio (2002) normally condition factor increases during the reproductive period and normalization occurs immediately after spawning. However, the study of the condition factor is very important for understanding the life cycle including spawning season of fish species and contributes to adequate management. In the present study, the condition factor of Indian mackerel was lower in December and January. Condition factor of Indian mackerel in February, March and April were higher than the other months. Condition factor of Indian mackerel in May was still higher than December and January. In the present study, it was also observed that the condition factor was positively correlated with gonadosomatic index of Indian mackerel. Based on condition factor and gonadosomatic index, it can be concluded that the peak spawning season of Indian mackerel in the Kuantan coastal water is from February to April. However, the spawning season of Indian mackerel in Kuantan coastal water may fall within the period between end of January and end of May.

CONCLUSION

This study provided a basic information on the length-weight relationship and condition factor of R. Kanagurta that would be useful for fisheries management. This data can be specifically used to impose adequate regulations for sustainable fishery management in the Kuantan coastal water, Malaysia. In this study, the b-value of the length-weight relationship of Indian mackerel in April was very low compared to other month. This might be influenced by environmental or habitat factors. Therefore, more research is needed including analyzing environmental or habitat factors to understand the cause of low b value in April in Kuantan coastal water. The peak spawning season of Indian mackerel in the Kuantan coastal water was from February to April. The spawning season of Indian mackerel in the Kuantan coastal water may fall within the period between the end of January and end of May.

REFERENCES

1:  Abowei, J.F.N., 2009. The abundance, condition factor and length-weight relationship of Sardinella madernensis (Jenyns, 1842) from Nkoro River Niger Delta, Nigeria. Ad. J. Food Sci. Tech., 1: 66-71.

2:  Bagenal, T.B. and F.W. Tesch, 1978. Age and Growth. In: Methods for Assessment of Fish Production in Freshwaters, Bagenal, T. (Ed.). Blackwell Scientific Publications, Oxford, pp: 101-136

3:  Beverton, R.J.H. and S.J. Holt, 1957. On the dynamics of exploited fish populations. Fish. Invest. Ser. II, 19: 1-533.
Direct Link  |  

4:  Beyer, J.E., 1987. On length-weight relationships. Part I: Computing the mean weights of the fish in a given length class. Fishbyte, 5: 11-13.
Direct Link  |  

5:  DOF, 2009. Annual fisheries statistics 2000-2007. Department of Fisheries, Malaysia.

6:  FAO., 2011. Fishstat Plus. Fisheries and Aquaculture Department, Food and Agriculture Organization, Rome, Italy

7:  Hejjej, G., A. Hattour, A. Hejjej, H. Allaya, O. Jarboui and A. Bouain, 2011. Biometry, Length-length and lenth-weigh relationship of little tuna Euthynnus alletteratus in the Tunisian wataer. J. Fish. Aquat. Sci., 6: 256-263.
Direct Link  |  

8:  Kalayci, F., N. Samsun, S. Bilgin and O. Samsun, 2007. Length-weight relationship of 10 fish species caught by bottom trawl and midwater trawl from the middle black sea, Turkey. Turk. J. Fish. Aquat. Sci., 7: 33-36.
Direct Link  |  

9:  Le Cren, E.D., 1951. The length-weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis). J. Anim. Ecol., 20: 201-219.
CrossRef  |  Direct Link  |  

10:  Lizama, M.D.L.A.P. and A.M. Ambrosio, 2002. Condition factor in nine species of fish of the characidae family in the upper parana river floodplain, Brazil. Braz. J. Biol., 62: 113-124.
CrossRef  |  PubMed  |  Direct Link  |  

11:  Martin-Smith, K.M., 1996. Length/weight relationships of fishes in a diverse tropical freshwater community, Sabah, Malaysia. J. Fish Biol., 49: 731-734.
Direct Link  |  

12:  Morato, T., P. Afonso, P. Lourinho, J.P. Barreiros, R.S. Santos and R.D.M. Nash, 2001. Length-weight relationships for 21 coastal fish species of the Azores, North-Eastern Atlantic. Fish. Res., 50: 297-302.
CrossRef  |  

13:  Pauly, D., 1983. Some simple methods for the assessment package of tropical fish stocks. FAO Fisheries Technical Paper 234, Food and Agriculture Organization of the United Nations, Rome, pp: 1-52.

14:  Pauly, D., 1993. Editorial fish byte. Naga ICLARM Q., 16: 26-26.

15:  Pauly, D., A. Cabanban and Jr. F.S.B. Torres, 1996. Fishery Biology of 40 Trawl-Caught Teleosts of Western Indonesia. In: Baseline Studies of Biodiversity: The Fish Resource of Western Indonesia, Pauly, D. and P. Martosubroto (Eds.). ICLARM, Manila Philippines, pp: 135-216

16:  Schneider, J.C., P.W. Laarman and H. Gowing, 2000. Length-Weight Relationships. In: Manual of Fisheries Survey Methods II: With Periodic Updates (Fisheries Special Report 25), Schneider, J.C. (Ed.). Chapter 17, Michigan Department of Natural Resources, Ann Arbor, MI., USA., pp: 1-18

17:  Sinovcic, G., M. Franicevic, B. Zorica and V. Cikes-Kec, 2004. Length-weight and length-length relationships for 10 pelagic fish species from the Adriatic Sea (Croatia). J. Applied Ichthyol., 20: 156-158.
CrossRef  |  Direct Link  |  

18:  Sivadas, M., P.N.R. Nair, K.K. Balasubramanian and M.M. Bhaskaran, 2006. Length weight relationship, relative condition, size at first maturity and sex ratio of Indian mackerel Rastrelliger kanagurta from Calicut. J. Mar. Biol. Ass. India, 48: 274-277.
Direct Link  |  

19:  Tesch, F.W., 1971. Age and Growth. In: Methods for Assessment of Fish Production in Fresh Waters, Ricker, W.E. (Ed.). Blackwell Scientific Publications, Oxford, UK., pp: 98-103

20:  Vallisneri, M., S. Montanini and M. Stagioni, 2010. Length-weight relationships for the family Triglidae in the Adriatic Sea, northeastern Mediterranean. J. Applied Ichthyol., 26: 460-462.
CrossRef  |  

21:  Wootton, R.J., 1990. Ecology of Teleost Fishes. 1st Edn., Chapman and Hall, London, UK., ISBN-13: 9780412317200, Pages: 404

22:  Petrakis, G. and K.I. Stergiou, 1995. Weight-length relationships for 33 fish species in Greek waters. Fish. Res., 21: 465-469.
CrossRef  |  

23:  Collette, B.B., 2001. Scombridae: Tunas (also, Albacore, Bonitos, Mackerels, Seerfishes and Wahoo). In: FAO Species Identification Guide for Fishery Purposes: The Living Marine Resources of the Western Central Pacific, Carpenter, K.E. and V. Niem (Eds.). Vol. 6, FAO, Rome, Italy, pp: 3721-3756

24:  Lihan, T., N. Ismail, M.A. Mustapha and S. Abd Rahim, 2006. Kandungan logam berat dalam makanan laut dan kadar pengambilannya oleh penduduk di Tanjung Karang, Selangor. Malaysian J. Anal. Sci., 10: 197-204.
Direct Link  |  

©  2022 Science Alert. All Rights Reserved