Size Characteristics and Length-Weight Relationship of Cleftbelly Trevally (Atropus atropos) from the Veraval Coast, Gujarat, India

Introduction

Gujarat, located on the western coast of India, possesses extensive marine and inland water resources, including a 2,340.62 km coastline, a continental shelf of about 164,000 km², and an Exclusive Economic Zone (EEZ) of 214,000 km². The state contributes nearly 32% of India's continental shelf and 10% of its EEZ. Over the past four decades, advancements in fishing technologies and allied activities have led to substantial growth in Gujarat's fisheries sector, significantly improving economic returns, employment, and nutritional security (SoI, 2024). At the national level, India's fisheries sector has expanded rapidly, with total fish production increasing from 24.42 lakh tonnes in 1980-81 to 175.45 lakh tonnes in 2022-23, reflecting an average annual growth rate of 7.98%. During 2022-23, fish exports reached 17.35 lakh tonnes valued at ₹63,969.14 crore (DoF, 2023) [5] . Marine fish production alone accounted for 3.53 million tonnes in 2023, positioning India as the world's third-largest fish producer and contributing about 8% to global production. The family Carangidae represents one of the most commercially important groups of marine fishes, comprising jacks, trevallies, scads, pompanos, queenfishes, runners, and amberjacks. Globally, the family includes four subfamilies, 32 genera, and about 140 species, distributed across tropical and subtropical waters of the Atlantic, Pacific, and Indian Oceans. In India, approximately 62 carangid species belonging to 20 genera have been recorded, commonly inhabiting shallow coastal waters up to 60 m depth along both the east and west coasts (Nair, 2000; Joshi et al., 2011) [8] . Carangids form an important component of marine fish landings, particularly during the monsoon season, and are harvested using trawls, purse seines, gillnets, boat seines, and hooks and lines. The total carangid production in India is estimated at about 1.8 lakh tonnes, contributing nearly 4.83% of total marine fish landings (Anon, 2001) [2] . The cleftbelly trevally Atropus atropos (Carangidae) is a commercially important marine fish widely distributed along the Indian coast. It is locally known as "Naryala" along the Veraval coast, "Khadwo Bangada" in Gujarati, "Kat-bangada" or "Zhat Bangada" in Marathi, and "Kunni-parah" in Tamil. Morphologically, A. atropos exhibits a strongly compressed, ovate body resembling larger jacks, with a steep dorsal head profile and no adipose eyelid. The jaws bear small teeth arranged in narrow bands, while the ventral profile is concave with a characteristic deep abdominal groove accommodating the large pelvic fins. The chest region between the pectoral and pelvic fins is scaleless (Carpenter and Niem, 2001 [4] ; Lin and Shao, 1999) [13] .The species possesses two dorsal fins, the first with eight spines and the second with one spine and 19-22 soft rays, while the anal fin has two detached spines followed by one spine and 17-18 soft rays. The lateral line is moderately arched anteriorly with 31-37 scutes on the straight portion. A. atropos attains a maximum length of about 26.5 cm, though individuals are commonly observed below 20 cm. Body coloration is bluish-green dorsally and silvery ventrally, with black pelvic fin membranes and a distinct black spot in adults. Sexual dimorphism is evident, as mature males develop elongated dorsal and anal fin rays, which are absent in females (Randall, 1995 [22] ; Shameem and Dutt, 1984) [24] . Ecologically, A. atropos is a carnivorous predator feeding mainly on small crustaceans and fishes, thereby playing a key role in coastal food webs (Masuda et al., 1984) [14] . The species is distributed throughout tropical and subtropical Indo-Pacific waters and occurs along the entire Indian coastline, with higher abundance reported from Gujarat, Maharashtra, Karnataka, Kerala, and Tamil Nadu. In addition to its fisheries importance, the species is nutritionally valuable due to its high omega-3 fatty acid content, enhancing its significance as a healthy food fish (Hicks et al., 2019) [6] . The length-weight relationship (LWR) is a fundamental tool in fisheries biology for understanding growth patterns, lifehistory traits, and population dynamics of fish species. It provides critical information on fish condition, habitat suitability, and morphological variation under different environmental conditions. LWR is widely used to estimate average body weight from length data, assess stock structure, and evaluate the productivity and resilience of exploited fish populations, thereby supporting effective fisheries management and conservation (Bradford et al., 2014) [3] . Fish size is often considered more biologically meaningful than age, as it directly reflects ecological and physiological influences such as food availability, habitat quality, and environmental stressors (Kalayci et al., 2007) [9] .

Materials and method Location for the research work

The study was carried out at the Veraval fish landing centre (20°54′912″ N; 70°21′355″ E) located in the Gir-Somnath district of Gujarat, India. Veraval is the largest and most active fish landing centre along the Gujarat coast, characterized by a well-developed harbour, a large fleet dominated by trawlers, and numerous fish processing and export units, making it a major hub of fisheries activities in the region.Sampling was conducted over a ten-month period from August 2024 to May 2025 at the Veraval fishing harbour. Fish specimens were collected using a random sampling approach from commercial landings to ensure representative coverage of the catch composition.

Test organisms

The taxonomic position of Atropus atropos is given below. Kingdom: Animalia Phylum: Chordata Class: Actinopterygii Order: Carangiformes Family: Carangidae Genus: Atropus Species: A. atropos (Bloch & Schneider,1801) Specimen for study A. atropos Methodology Specimens of Atropus atropos were collected from multiday trawlers operating along the Saurashtra coast and landing their catch at the Veraval fish landing centre. Sampling was carried out monthly, and specimens of varying sizes and weights were randomly selected from different trawlers to ensure representative coverage. Collected specimens were transported to the Fisheries Resource Management (FRM) Laboratory, College of Fisheries Science, Kamdhenu University, Veraval, for detailed analysis of Size Characteristics, length-weight relationships and associated parameters. For each specimen, total length and standard length were measured, and fresh body weight was recorded using an electronic balance with an accuracy of 0.01 g.

Size characteristics

The total length (cm) of each fish was measured using a measuring board, and body weight (g) was recorded using a digital weighing balance. The collected data were grouped into different length and weight intervals to determine frequency distribution. Monthly mean, minimum, and maximum values of length and weight were calculated to analyze variations.

Length-weight relationship (LWR)

The length-weight relationship (LWR) was examined to understand growth patterns and condition of Atropus atropos. This relationship is particularly useful when either length or weight data are unavailable and provides insights into the health status, feeding intensity, gonadal development, and overall well-being of fish (Le Cren, 1951). The LWR was estimated separately for males and females using the allometric equation proposed by Le Cren (1951) [ 12]: W=a L b or log(W)=log(a)+blog(L) Where, W = Total body weight (g), L = Total Length (cm), a and b are the coefficients of the functional regression between W and L.

Results

Size characteristics

During this study period, a total of 300 specimens of Atropus atropos were collected, 186 males and 114 females. Their total lengths ranged from 12 cm to 25 cm, and their weights ranged from 33.75 g to 259.8 g. The average length was highest in September 21.68 cm, and lowest in March, 12 cm. The smallest specimen (12 cm) was found in March, and the largest (25 mm) in September. The average weight was highest in September (155.91 g) and lowest in December (84.23 g). The lightest specimen, weighing 33.75 g, was recorded in March, while the heaviest (260.1 g) was found in September.

Discussion

Size Characteristics

In the present study, the highest mean total length (21.68 cm) and mean weight (155.91 g) were recorded in September, while the lowest mean length (16.80 cm) was observed in January and the lowest mean weight (84.23 g) in December. The smallest specimen (12 cm; 33.75 g) was recorded in March, whereas the largest specimen (25 cm; 260.1 g) was observed in September. Several studies have examined A. atropos across different regions. Raje (1994) [18] reported on 216 specimens from the Veraval coast of India, including 116 males with lengths of 116-264 mm and weights of 28.5-230.0 g, and 100 females with lengths of 129-283 mm and weights of 30.0-292.0 g. Lanjewar et al. (2024) [11] reported on 90 specimens from the Ratnagiri coast with total lengths ranging from 15.5 to 21.9 cm. Rakhunde et al. (2023) [21] collected 589 specimens from the same region, including 300 males ranging from 11.2 to 25.4 cm in length and 23.9 to 222. [7] analyzed 100 fish from the Bay of Bengal with lengths from 15 to 21 cm and weights from 46 to 136 g, while Rahman et al. (2021) [17] studied 109 specimens from the same region with lengths ranging from 15.0 to 21.7 cm and weights from 49.39 to 161.40 g. Rajesh et al. (2020) [20] further examined 1,601 specimens from the Mangalore coast in Karnataka between August 2015 and May 2017, with sizes ranging from 100 to 260 mm and comprising 704 males and 897 females. Rajesh et al.

(2018) [19] analyzed samples from the same region during two periods. In 2015-2016, among 704 fish, males dominated the 18-20 cm group with 71 percent comprising 105 males and 43 females, while females dominated the 16-18 cm group with 73 percent comprising 87 females and 33 males, In 2016-2017, 897 specimens were recorded, with males comprising 62 percent in the 16-18 cm group including 110 males and 67 females, and females comprising 70 percent in the 20-22 cm group including 120 females and 51 males, total 405 males or 45 percent and 492 females or 55 percent. Kochar (1988) [10] studied 360 specimens from the Mumbai coast, comprising 192 males ranging from 150-244 mm in length and 45-196 g in weight, and 168 females ranging from 137-254 mm in length and 47-212 g in weight.

Qamar and Panhwar (2018) [16] recorded 25 specimens from the northern Arabian Sea coast of Pakistan, with lengths ranging from 12 to 31.6 cm and weights between 24 and 351 g.

Length-weight relationship analysis

In the present study, the length-weight relationship (LWR) of Atropus atropos exhibited negative allometric growth, as indicated by regression coefficients (b) less than [21] reported negative allometric growth for specimens from the Ratnagiri coast, with equations: males W = 0.0361 × L²•⁷¹⁸⁶ (R² = 0.9816), females W = 0.0309 × L²•⁷⁷⁷⁰ (R² = 0.9862), and pooled W = 0.0358 × L²•⁷²³⁴ (R² = 0.9848). Kochar (1988) [10] found strong correlations along the Mumbai coast: males W = 0.02355 × L²•⁸⁴¹³ (R² = 0.9774), females W = 0.0503 × L²•⁵⁸⁸¹ (R² = 0.8933), and pooled W = 0.034369 × L²•⁷²⁰⁷ (R² = 0.9705). Raje (1994) [18] reported logarithmic relationships for Veraval coast samples: males log W = -4.08479 + 2.6699 log L, females log W = -3.8017 + 2.5471 log L, and pooled log W = -3.9535 + 2.6133 log L. Reuben et al. (1992) [23] provided a pooled equation for Indian seas: W = 0.00003165 × L²•⁸⁵⁷⁰³, illustrating general growth trends. In contrast, some populations of A. atropos exhibit positive allometric growth. Rahman et al. (2021) [17] observed pooled growth in the Bay of Bengal as W = 0.0116 × L³•⁰⁹⁸ (R² = 0.957), and Qamar and Panhwar (2018) [16] reported W = 0.024 × L²•⁸⁶⁹ (R² = 0.980) in the northern Arabian Sea, reflecting regional variation in growth patterns. These comparisons indicate that while A. atropos generally exhibits negative allometry along the Gujarat coast, growth patterns may vary across different geographic populations.

Conclusion

The study on Atropus atropos from the Veraval coast indicates that the species exhibits negative allometric growth, showing a greater increase in length compared to weight. The population was dominated by males, with noticeable variation in size distribution across months. Larger individuals were mainly observed in September, while smaller ones were more common during March and December. The majority of specimens belonged to the medium size group (16.5-18.0 cm; 59-85 g), indicating their dominance in the population structure. Overall, the growth pattern and size distribution of A. atropos appear to be influenced by seasonal variations in the environment.

References

1. Abdussamad EM, Kasim HM, Balasubramanian TS. Distribution, biology, and behavior of the giant trevally, Caranx ignobilis: a candidate species for mariculture. Bangladesh Journal of Fisheries Research. 2008;12(1):89-94.
2. Anon. Handbook of fisheries statistics. New Delhi: Government of India, Ministry of Agriculture; 2001.
3. Bradford MJ, Randall RG, Smokorowski KS, Keatley BE, Clarke KD. A framework for assessing fisheries productivity for the Fisheries Protection Program. Ottawa: Canadian Science Advisory Secretariat; 2014.
4. Carpenter KE, Niem VH, editors. FAO species identification guide for fishery purposes: the living marine resources of the Western Central Pacific. Vol. 6. Bony fishes part 4 (Labridae to Latimeriidae), estuarine crocodiles, sea turtles, sea snakes and marine mammals. Rome: Food and Agriculture Organization; 2001. p. v3381.
5. Department of Fisheries. Handbook of fisheries statistics [Internet]. New Delhi: Ministry of Fisheries, Animal Husbandry & Dairying, Government of India; 2023 [cited 2026 Jun 1]. Available from: https://dof.gov.in/sites/default/files/202406/Handbook.pdf
6. Hicks CC, Cohen PJ, Graham NAJ, Nash KL, Allison EH, D'Lima C, et al. Harnessing global fisheries to tackle micronutrient deficiencies. Nature. 2019;574(7776):95-98.
7. Ilah NE, Abedin MJ, Alice EJ, Laboni TA, Khatun S, Sarmin S, et al. Growth and conditions appraisal of Atropus atropos (Carangidae) in the Bay of Bengal. Sarhad Journal of Agriculture. 2023;39(4):823-831.
8. Joshi KK, Nair RJ, Abdussamad EMA, Thomas S, Kakati VS, Jasmine S, et al. The Carangids of India: a monograph. Kochi: Central Marine Fisheries Research Institute, Indian Council of Agricultural Research; 2011. 437 p.
9. Kalaycı F, Samsun N, Bilgin S, Samsun O. Lengthweight relationship of 10 fish species caught by bottom trawl and midwater trawl from the Middle Black Sea, Turkey. Turkish Journal of Fisheries and Aquatic Sciences. 2007;7(1):33-36.
10. Kochar LS. Morphology, osteology and biology of Atropus atropos and Carangoides malabaricus [dissertation]. Mumbai: Central Institute of Fisheries Education; 1988.
11. Lanjewar GN, Bhosale BP, Mohite SA, Shingare PE, Pagarkar AU. Stock discrimination of cleftbelly trevally, Atropus atropos (Bloch and Schneider, 1801), using conventional morphometric techniques from the South Konkan coast of Maharashtra. Journal of Experimental Zoology India. 2024;27(1):1-10.
12. Le Cren ED. The length-weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis). Journal of Animal Ecology. 1951;20(2):201-219.
13. Lin PL, Shao KT. A review of the carangid fishes (Family Carangidae) from Taiwan with descriptions of four new records. Zoological Studies. 1999;38(1):3368.
14. Masuda H, Uyeno T, Yoshino T. The fishes of the Japanese Archipelago. Vol. 1. Amaoka K, Araga C, editors. Tokyo: Tokai University Press; 1984. 437 p.
15. Nair PNR. Carangid resources of India. In: Pillai VN, Menon NG, editors. Marine research and management. Kochi: ICAR-Central Marine Fisheries Research Institute; 2000. p. 317-348.
16. Qamar N, Panhwar SK. Length-weight relationships of nine rarely occurring carangids in the northern Arabian Sea coast of Pakistan. Journal of Applied Ichthyology. 2018;34(1):221-223.
17. Rahman MA, Hossain MY, Tanjin S, Mawa Z, Hasan MR, Habib KA, et al. Length-weight relationships of five marine fishes from the Bay of Bengal. Journal of Applied Ichthyology. 2021;37(2):364-366.
18. Raje SG. Fishery and biology of Atropus atropos (Bloch and Schneider) from Veraval. Journal of the Marine Biological Association of India. 1994;36(2):181-187.
19. Rajesh DP, Anjanayappa HN, Benakappa S. Maturation and spawning frequencies of Atropus atropos from Mangalore coast, Karnataka, India. Journal of Fisheries and Life Sciences. 2018;3(1):46-53.
20. Rajesh DP, Anjanayappa HN, Benakappa S, Nayana P. Length-weight relationship and relative condition factor of Atropus atropos (Bloch & Schneider, 1801) from Mangalore coast, India. Journal of Experimental Zoology India. 2020;23(1):463-467.
21. Rakhunde AV, Nirmale VH, Pawar RA, Metar SY, Bhosale BP. Biology of the cleftbelly trevally, Atropus atropos (Bloch and Schneider, 1801) from Ratnagiri coast of India. Indian Journal of Fisheries. 2023;70(2):33-40.
22. Randall JE. Coastal fishes of Oman. Bathurst: Crawford House Publishing Pty Ltd; 1995. 175 p.
23. Reuben S, Mohamad Kasim H, Sivakami S, Nair PN, Kurup KN, Sivadas M, et al. Fishery, biology and stock assessment of carangid resources from the Indian seas. Indian Journal of Fisheries. 1992;39(3-4):195-234.
24. Shameem A, Dutt S. Sexual dimorphism in carangid fishes. Mahasagar. 1984;17(1):1-8.
25. Snedecor GW, Cochran WG. Statistical methods. 8th ed. Ames: Wiley Blackwell; 2014.
26. Survey of India. Length of coastline of India [Internet]. Dehradun: Survey of India; 2024 [cited 2026 Jun 1]. Available from: https://surveyofindia.gov.in