Full Text (PDF)

Electronic Journal of Ichthyology April, 2008 1: 18-30 ON THE POPULATION AND BREEDING ASPECTS OF CATFISH IN FRESH WATER WETLANDS OF TAMIL NADU, PENINSULAR INDIA. Rajagopal, B* and Priya Davidar Department of Ecology & Environmental Sciences, Pondicherry University, Kalapet – 605 014, Pondicherry, India. *Correspondence: Malankara Catholic College, Mariagiri, Kaliakkavilai – 629153, Kanyaku- mari District, Tamil Nadu, India. E-mail: [email protected], Telephone: +91 04651 244156. Accepted: February 19, 2008 Abstract: Population structure and breeding pattern of a few species of catfish in wetlands from two geographically contrasting regions of peninsular India were studied. Findings of the study show that there is a marked difference in the structure of populations and breeding pattern existed for some species in the two regions. The reason attributes to different climatic factors found in these regions. Apart from this, functional and structural modifications in the anatomy of fish species, its physiological adaptation to the environment also contribute to these differences. Key words: Distribution, Breeding, Seasonality, Rainfall, Recruitment. Introduction Although various studies have been con- Catfishes are an important part of the fish ducted on the taxonomy of catfishes, the fauna in wetlands and many of them are ecology of catfishes in India is less known. economically important with high nutritive Studies in India have focused on feeding value. There are about 158 species of inland habits of several species of catfish (Kaliya- catfishes from 50 genera and 13 families in murthy and Rao 1970; Ramakrishnaiah India. The Indian families include Bagridae, 1983-84; Santhanakumar and Job 1983-84; Siluridae, Schilbeidae, Pangasiidae, Ambly- Devi et al. 1992; Yusuf and Majumdar 1993; cipitidae, Sisoridae, Clariidae, Het- Raj 2002). Whereas, other aspects have been eropneustidae, Chacidae, Olyridae, Akysi- less well studied except a few conducted by dae, Ariidae and Plotosidae (Talwar and Kumar and Mittal (1993), Mukhopadhyay et Jhingran 1991). Diversity of catfish in India al. (1994). is the highest in Northeastern Hills, Gangetic In Tamil Nadu, some studies have been River System and the Western Ghats (Bar- conducted on the feeding ecology of catfish man 1994; Thomas et al. 2002). Generally, (Kaliyamurthy and Rao 1970; Santhanaku- catfishes dwell in diverse habitats such as mar and Job 1983-84; Raj 2002; Raghuna- upland streams, large river channels and sea- than et al. 2003). However, study on the sonal floodplain lagoons with broad feeding population of catfishes is limited, as for the niches that include detritivores, benthic in- other regions of India. sectivores and piscivores (Winemiller and We conducted this study in two regions Winemiller 1996). of southern India in order to look at the size Study on the population structure and dy- distribution of catfishes and to understand namics is important in understanding the life their breeding season in two geographically cycle and conservation of any fish species. varying regions. 18 Rajagopal, Davidar, 2008 On the Population and Breeding Aspects of Catfish Material and Methods Site selection & wetland description Study area Sites were selected based on their differ- Geography ences in geography, climate, rainfall pattern The study regions such as Kancheepuram and catfish species composition. Kanyaku- and Kanyakumari are situated in Tamil Nadu mari is located on the southern most end of State, southern India near two of India’s bio- the State near the Western Ghats and diversity hotspots such as the Eastern Ghats Kancheepuram is located on the north, near and the Western Ghats respectively. Among the Eastern Ghats. Although both the dis- 22 wetlands studied, 9 lie in Kancheepuram tricts have a few catfish species in common, and 13 are in Kanyakumari (Maps 1 & 2, they do have their own unique species. Dif- Table 1). Kancheepuram district is located ferent types of wetlands such as tanks, pools, on North East coast of Tamil Nadu, cover- lake and open wells were selected for study ing about 440 km2 (Square kilometers) area, based on the nature of their surface and sub- between 79o40’ to 80o20’ East and 12o30’ to strate (open or closed with vegetation), sea- 13o10’ North. Kancheepuram contains sonality (seasonal or perennial) and size, many wetlands as being an agricultural dis- based on the findings that different cat fish trict (< kanchi.tn.nic.in >). Kanyakumari dis- species prefers diverse habitats. (Kumar and trict has an area of 167 km2, which is located Mittal 1993). on southern most end of the Indian peninsula at about 77o15’ to 77o36’ E and 8o03’ to Fish collection, identification and meas- 8o35’ N (< kanyakumari.tn.nic.in >). urement Fish sampling was executed in between Rain the period of February 2003 and April 2004 Kancheepuram receives rain mainly from in the wetlands of Kancheepuram and Kan- North East monsoon. The rain in coastal ar- yakumari Districts in different seasons. The eas is normally heavier than inland region (< wetlands were sampled at different sites so kanchi.tn.nic.in >). Kanyakumari receives that a representative section of all habitats rainfall from both South West and North could be covered. Fish were collected with East monsoons. The mean annual rainfall is the help of local fishermen using cast and higher for Kanyakumari than in Kancheepu- seine nets. Seines were used for tanks and ram (Figure 1). Hence, wetlands in Kanya- pools with shallow waters (< 2 meters) and kumari retain water through the year due to cast net was used for tanks and lake with higher rainfall, whereas in Kancheepuram deep waters (>2m). The cast net used was of many wetlands dry up in summer prior to the 4m radius with 0.005m mesh size and two monsoon. types of seines used were of 70m long 6m wide with 0.01m mesh, and the other was of Flora 5m long 2m wide with 0.003m mesh. In ad- Flora of wetlands includes phytoplank- dition, sampling was done during peak sum- tons, micro-algae, (diatoms and other single mer when fish are harvested by draining out cellular algae) and macro vegetation. The the water from wetlands. Hence, all catfish aquatic macro-vegetation of studied wet- species of various sizes of each wetland lands can be classified into three distinct were sampled including juvenile. Different layers, such as emergent, floating and sub- type of nets were used as most of the wet- merged species. The diversity of aquatic lands had diverse habitats such as open wa- flora especially, floating vegetation in Kan- ter, covered water with vegetation, sluice yakumari is comparatively more than in etc. Moreover, only one type of net did not Kancheepuram. seem to be effective to collect all species as some species inhabited only in selected habitats (e.g - Ompok was collected only from the temporary pools in Puthery tank and not from main tank even after repeated efforts). 19 Rajagopal, Davidar, 2008 On the Population and Breeding Aspects of Catfish 20 Rajagopal, Davidar, 2008 On the Population and Breeding Aspects of Catfish 21 Rajagopal, Davidar, 2008 On the Population and Breeding Aspects of Catfish Table 1. List of wetlands and their geographical location with area. Name of Wetland Coordinates Area (ha) Kancheepuram District Latitude Longitude Chembarampakkam Lake 12o55’- 13o5’ N 80o 0’- 80 o 5’ E 35,700 Keeranallur tank 12o55’- 13o0’ N 79o 45’- 79o50’ E 75 Malayankulam tank 12o40’- 12o45’ N 79o 50’- 79o55’ E 250 Mathuramangalam pool 12o55’- 13o0’ N 79o 45’- 79o50’ E 0.1 Pallikaranai Wetland complex 12o55’- 13o0’ N 80 o10’- 80 o15’ E 594 Sivankoodal tank 12o55’- 13o0’ N 79o 45’- 79o 50’ E 100 Thenneri tank 12o50’- 12o55’ N 79o 50’- 79o 55’ E 800 Vandalur tank 12o50’-12 o55’ N 80o 0’- 80o 5’ E 75 Vijayanagar well 12o40’- 12o45’ N 79o45’- 79o50’ E 0.025 Kanyakumari District Erachakulam tank 8o10’- 8o15’ N 77o25’- 77o30’ E 100 Kakkulam tank 8o10’- 8o15’ N 77o25’- 77o30’ E 0.84 Kaniyakulam pool 8o10 - 8o15’ N 77o20 - 77o 25’ E 0.06 Mavadi pool 8o10 - 8o15’ N 77o20 - 77o 25’ E 0.5 Parakkai tank 8o 5’ - 8o10’ N 77 o 25’- 77 o 30’ E 200 Poochankulam tank 8o10’- 8o15’ N 77o25’- 77 o30’ E 0.6 Puthery tank 8o10’- 8o15’ N 77o25’- 77 o30’ E 300 Suchindram tank 8o5’- 8o10’ N 77o25’-77o 30’ E 50 Thathiyarkulam tank 8o10 - 8o15’ N 77o 25’- 77o 30’ E 38 Thazhakudy tank 8o10’- 8o15’ N 77o25’- 77o30’ E 100 Thengamputhur tank 8o 5’- 8o10’ N 77o 25’- 77o30’ E 250 Thotiode tank 8o10 - 8o15’ N 77o20’- 77o25’ E 4 Vishnupuram tank 8o10’- 8o15’ N 77o25’- 77 o30’ E 25 22 Rajagopal, Davidar, 2008 On the Population and Breeding Aspects of Catfish Therefore, use of different nets was man- fied in lab were also confirmed with Ichthy- datory in collecting fish specimen in an ef- ologists from ZSI (Zoological Survey of In- fective manner, as there is a possibility of dia, Southern Circle, Chennai). Morphomet- missing of some juveniles and species if ric measurements such as the standard large sized mesh nets or one type of net length, total length and weight of all indi- alone would have been used. viduals were measured using dial calipers, Fish sampling effort for cast net depended measuring scales and electronic balance. upon size (small / medium / large) of the wetland studied. As, sampling area covered Morphometric analysis in this net was comparatively smaller, three / Individuals of catfish belonging to differ- five / ten samples were done according to ent species were divided into various size the size of respective wetland. The duration classes based on their total length, from 10- of sampling effort for large seine was on an 50 mm (Millimeters) to 300-350 mm and average of 5 hours/seine/day and for small plotted in histograms. Comparisons were seine it was 30 minutes /seine/day.

Load more