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2. PRE-IMPOUNDMENT CONDITIONS


2.1 Water quality

Water of most of the rivers having hydropower structures is well oxygenated, unpolluted and suitable for cold water fish (Table 1).

2.2 Aquatic life

All the rivers mentioned above harbour rich phytoplankton, zooplankton and zoobenthos as the main source of food of fish (Table 2). The average densities of phytoplankton and zooplankton are 206 units/liter and 16.25 units/liter, respectively. In zoobenthos insects dominate (94.34 percent) in the Trishuli River (Shrestha T.K., 1997). The average densities of macroinvertebrates are 91.5 ind/m2 and 178 ind/m2 in the Trishuli and Karnali rivers, respectively. The reported wet weight of large invertebrates averages 1.9 kg/m2 in the Karnali River. Among the large invertebrates, molluscs comprised 36 percent, followed by chironomids (34 percent), oligochaetes (16 percent) and crustaceans (14 percent) (EIA Upper Karnali, 1997). The ecological studies of the Trishuli River have shown a higher density of benthos downstream than upstream (Shrestha T.K., 1997). This may be an important factor supporting the presence of a large number of cold water fish species, with high abundance, in midhill rivers of Nepal.

Table 1

Water quality in selected rivers of Nepal

Parameter

Trishuli

Tamur

Melamchi

Bheri

Babai

Upper Karnali

Budhi Ganga

Seti

Electrical conductivity (mS)

84

42-75

-

-

-

140

143-164

-

Temperature (°C)

-

10.0-12.5

19-21

18-19

23-25

18-20

14.5-15.0

10.9

Dissolved oxygen (mg/L)

-

11.0-13.0

9-10

8.4-10.0

8.0-8.7

11.8

8.6-10.2

7.8

PH

7.6

6.5-7.0

7.0-7.9

8.4-8.6

7.8-8.8

7.6

7.7

8.1

Total hardness (mg/L)

48

-

17-34

13.3-17.0

17.6-20.0

-

28-36

-

Ca hardness (mg/L)

-

-

-

-

-

9.5

60-64

-

Total alkalinity (mg/L)

-

-

17-34

10.4-11.0

16.8-20.7

-

77-95

-

Chloride (mg/L)

8

-

-

-

-

-

2.8-5.7

-

Silicate (mg/L)

-

-

-

-

-

-

10-20

-

NH3 m (g/L)

-

0.01-0.14

-

-

-

-

<0.02

-

Calcium (mg/L)

13

-

-

-

-

-

24-26

-

Magnesium (mg/L)

2

-

-

-

-

1.5

7.0-8.8

-

Nitrate(mg/L)

-

0.001-0.52

-

-

-

-

<0.02

-

Nitrite(mg/L)

-

-

-

-

-

-

<0.03

-

Suspended solids (mg/L)

-

-

-

-

-

58

10-32

-

Total dissolved solids (mg/L)

-

-

-

-

-

95

86-98

-

Transparency

-

Clear

Clear

74-Clear

76-Clear

Clear

Clear

-

Total nitrogen (mg/L)

-

0.042-0.571

-

-

-

-

-

0.38

Phosphate (mg/L)

-

0.01-0.06

-

-

-

-

-

0.00

CO2

-

-

5.0

0.62-12.8

0.26-1.28

-

-

-

Biochemical Oxygen Demand

-

-

-

-

-

0.19

-

-

(mg/L)







Potassium (mg/L)

-

-

-

-

-

1.4

-

-

Sodium (mg/L)

-

-

-

-

-

1.2

-

-

Iron (mg/L)

-

-

-

-

-

0.12

-

-

Table 2

Aquatic organisms (as listed in EIA reports)

Organisms

A

B

C

D

E

F

G

H

Aquatic flora







Chlorophyceae

*

-

-

-

-

-

*

*

Bacillariophyceae

*

-

-

-

*

-

*

*

Cyanophyceae

*

-

-

-

-

-

*

-

Desmidiaceae

*

-

-

-

-

-

-

-

Submerged plants

*

-

-

-

-

-

-

-

Aquatic fauna







Protozoa

-

-

-

-

-

*

-

-

Rotifera

*

*

*

*

*

*

*

*

Copepoda

*

*

*

*

*

*

*

*

Cladocera

*

*

*

*

*

*

*

-

Plecoptera

*

*

*

-

*

-

*

-

Ephemeroptera

*

*

*

*

*

*

*

-

Odonata

*

-

-

*

*

*

*

-

Diptera

*

*

-

*

*

*

*

-

Coleoptera

*

*

*

*

*

*

*

-

Hemiptera

*

*

*

*

-

*

*

-

Source: EIA reports

A - Melamchi

D - Upper Karnali

G - Budhi Ganga

B - Bheri

E - Tamur

H - Seti River

C - Babai

F - Kali Gandaki 'A'

2.3 Fish

Schizothorax and Schizothoraichthys spp are dominant among the cold water fish in all rivers in terms of catch and abundance in all seasons except during floods. They are caught by a series of loops made from a long nylon thread and set across the river in daytime and harvested in the morning. Other common fish species are Barilius sp, Garra sp, Neolissocheilus hexagonolepis, Glyptothorax sp, Glyptosternum spp and Pseudecheneis sp and arecaught by cast nets. The EIA reports for different hydropower projects reported a total of 84 fish species (Table 3). The fish are classified as: i) long distance migratory, ii) mid and short distance migratory, and iii) resident fish species (Tables 4, 5 and 6). The long distance migratory fish include Tor sp, Bagarius bagarius, Anguilla bengalensis and Clupisoma garua. They are captured mainly during the rainy season using long hooks. Mid and short distance migratory species are Amphipnous cuchia, Chagunius chagunio, Labeo angra, L. dero, L. dyocheilus, Neolissocheilus hexagonolepis, Puntius chillinoides, Schizothorax spp and some other. They are abundant througout the year. Some of the cold water species are important for fisheries and need to be protected.

Factors triggering the fish migration in Nepal are not well known. Migration is possibly done to find suitable spawning and feeding grounds. Plankton and benthos are washed away by the turbid monsoon water at lower altitude, but rapid growth of insects takes place in headwaters during the high water level phase (June-September). Abundant food and increased water volume may attract large long distance migratory fish to headwaters during the monsoon. A diminishing flow rate in headwaters and abundance of fish food organisms downstream induce these fish to migrate back. The short distance migratory fish Schizothorax and Schizothoraichthys move upstream in response to high turbidity, higher water temperature, and due to the scarcity of food during the rainy season in the lower reaches.

Table 3

Fish species recorded in EIA studies

Fish species

A

B

C

D

E

F

G

H

I

J

K

L

M

N

O

Tor putitora

*

*

*

*

*

*

*

*

*

-

*

-

*

*

*

T. tor

*

*

*

*

*

-

*

*

*

*

*

*

*

-

-

Bagarius bagarius

*

*

*

*

*

*

*

*

*

-

*

-

-

*

-

Anguilla bengalensis

*

-

*

*

*

*

*

*

*

-

*

*

*

-

*

Clupisoma garua

*

*

*

-

*

-

*

-

*

-

*

-

-

*

*

Schizothorax plagiostomus

*

*

*

*

*

*

*

-

*

-

*

*

*

*

*

S. richardsonii

*

*

*

*

*

*

-

-

*

-

-

*

*

*

-

Schizothoraichthys progastus

*

-

*

*

-

*

*

-

*

*

*

*

-

*

*

S. annandalei

*

-

-

-

*

-

-

-

-

-

-

-

-

-

-

S. esocinus

-

-

-

-

-

-

-

-

-

-

*

-

-

-

-

S. sinuatus

-

-

-

-

-

-

-

-

-

-

-

-

-

-

*

Neolissocheilus hexagonolepis

*

*

*

*

*

*

*

*

*

*

*

*

*

*

*

Barbus chillinoides

*

-

-

*

-

-

-

-

-

-

-

-

-

-

-

Barilius bendelisis

*

*

*

*

*

*

*

*

-

-

*

-

*

*

-

B. barna

*

-

-

*

-

*

*

*

-

*

-

-

-

-

-

B. barila

*

-

-

-

*

*

-

-

-

-

*

*

-

*

*

B. shacra

*

-

-

*

-

*

-

-

-

-

-

-

-

*

-

B. vagra

*

-

-

*

*

*

*

*

*

-

-

-

-

-

-

B. teleo

-

-

-

-

-

-

-

-

-

-

*

-

-

-

-

B. jalkaporei

-

-

-

-

-

-

-

-

-

-

*

-

-

-

-

Chagunius chagunio

*

-

-

*

*

-

-

-

-

-

*

-

-

-

-

Crossocheilus latius

*

-

-

*

*

-

-

-

-

-

*

-

-

-

-

Cyprinon semiplotum

*

-

-

*

-

-

-

-

-

-

-

-

*

-

-

Danio aequipinnatus

*

-

-

-

-

*

-

-

-

-

-

-

*

-

-

Garra annandalei

*

*

*

*

*

-

*

*

*

*

*

-

*

*

-

G. gotyla

*

*

*

*

*

*

*

*

*

-

*

*

-

*

-

G. muliya

*

-

-

*

-

-

-

-

-

-

-

-

-

-

-

Labeo angra

*

*

-

-

*

-

*

-

*

-

*

-

-

-

-

L. dero

*

*

-

*

*

-

*

*

*

-

*

*

-

*

-

L. pangusio

*

-

-

-

-

-

-

-

-

-

-

-

-

-

*

L. dyocheilus

-

-

-

-

-

-

-

*

-

-

*

-

-

-

-

L. gonius

-

-

-

-

-

-

-

-

-

*

-

-

-

-

-

L. ticto

-

-

-

-

-

-

-

-

-

-

-

-

-

-

*

Cirrhina latia

-

-

-

-

-

-

-

-

-

-

-

-

-

-

*

Puntius conchonius

*

-

-

-

*

-

-

-

-

-

*

-

-

-

-

P. sophore

*

*

-

-

-

-

-

-

*

-

-

-

-

-

-

P. ticto

*

*

*

*

*

-

-

-

*

-

-

-

-

-

-

P. chillinoides

-

*

-

-

*

-

-

-

*

-

*

-

-

*

-

P. sarana

*

-

-

*

-

-

-

-

-

-

-

-

-

-

-

Psilorhynchus pseudecheneis

*

-

*

-

*

*

*

-

*

-

*

-

-

*

-

Botia almorhae

*

-

-

-

-

-

*

*

*

-

*

-

-

*

-

B. dario

-

-

-

-

-

-

-

-

*

-

-

-

-

-

-

B. lohachata

*

-

-

*

-

-

-

-

-

-

*

-

-

-

-

Pseudecheneis sulcatus

-

*

-

-

-

-

-

*

-

*

-

-

-

-

*

Heteropneustes fossilis

*

*

*

*

-

*

-

-

-

-

*

-

-

-

-

Euchiloglanis hodgarti

*

*

*

*

-

*

-

-

-

-

-

-

-

-

-

Amblyceps mangois

*

-

*

-

-

*

-

-

*

-

-

-

-

-

-

Channa gachua

*

*

*

-

-

*

-

*

-

-

-

-

-

-

-

C. punctatus

*

*

*

-

-

*

-

-

*

-

-

-

-

-

-

C. marulius

-

*

-

-

-

-

-

-

-

-

-

-

-

-

-

C. striatus

-

-

*

*

-

-

-

-

-

-

-

-

-

-

-

C. stewartii

-

-

-

-

-

-

-

-

-

-

*

-

-

-

-

Amphipnous cuchia

*

*

*

-

*

*

-

*

*

-

*

-

-

-

-

Mastacembelus armatus

*

-

-

-

-

-

*

-

*

-

*

-

-

-

-

M. puncalus

*

-

-

-

-

-

-

-

-

-

-

-

-

-

-

Macrognathus aculeatus

*

*

-

-

-

-

-

-

*

-

-

-

-

-

-

Nemacheilus rupicola

*

*

*

*

*

*

*

*

*

-

*

-

*

*

-

N. beavani

*

*

*

*

*

*

-

-

*

-

*

-

-

*

-

N. botia

-

-

-

*

-

-

-

-

-

-

-

-

-

-

-

N. corica

-

-

-

*

-

-

-

-

-

-

*

-

-

-

-

Glyptothorax pectinopterus

*

*

*

-

*

*

-

-

*

-

*

-

*

*

-

G. telchita

-

-

-

-

-

-

-

*

-

*

-

*

-

*

*

G. trilineatus

*

*

-

*

-

-

*

-

*

-

-

-

-

-

-

G. cavia

*

-

-

*

*

*

-

-

-

-

*

-

-

-

-

G. horai

-

-

-

*

-

-

-

-

-

-

-

-

-

-

-

Pseudeutropius murius

*

-

-

-

-

-

-

-

-

-

-

-

-

-

-

P. garua

*

-

-

-

-

-

-

-

*

-

-

-

-

-

-

P. atherinoides

*

-

-

-

-

-

-

-

*

-

-

-

-

-

-

Balitora brucei

*

-

-

-

-

*

-

-

-

-

-

-

-

-

-

Glyptosternum pectinopterus

*

-

-

-

-

-

-

-

-

-

-

-

-

-

-

G. blythi

*

-

-

-

*

-

*

-

-

-

*

-

-

-

-

Rita rita

*

*

-

-

-

-

-

-

-

-

-

-

-

-

-

Eutropiichthys vacha

*

*

-

-

-

-

-

-

-

-

-

-

-

-

-

Wallago attu

-

*

-

-

-

-

-

-

-

-

-

-

-

-

-

Nandus nandus

-

*

-

-

-

-

-

-

-

-

-

-

-

-

-

Notopterus chitala

-

*

-

-

-

-

-

-

-

-

-

-

-

-

-

Esomus danricus

-

*

*

-

-

-

-

-

-

-

-

-

-

-

-

Xenentedon cancila

-

*

-

-

-

-

-

*

-

*

-

-

-

-

-

Catla catla

-

*

-

-

-

-

-

-

-

-

-

-

-

-

-

Rasbora daniconius

-

-

-

-

-

*

-

-

-

-

-

-

-

-

-

Lepidocephalichthys guntea

-

-

-

-

-

*

-

-

-

-

*

-

-

-

-

Ailia colia

-

-

-

-

-

-

-

*

-

-

-

-

-

-

-

Chaca chaca

-

-

-

-

-

-

-

*

-

-

-

-

-

-

-

Oxygaster bacalia

-

-

-

-

-

-

-

-

*

-

-

-

-

-

-

Source: EIA reports

A - Kali Gandaki 'A'

E - Tamur

I - Upper Karnali

M - Puwa Khola

B - Kankaimai

F - Melamchi

J - Kulekhani

N - Budhi Ganga

C - Marsyandi

G - Bheri

K - Dudh

* present

D - Trishuli

H - Babai

L - Likhu

- absent

Table 4

Biological data for the long distance migratory fish

Species

Migratory pattern (months)

Spawning season

Spawning substrate

Food

Age and size at maturity

Behavior
Economic importance

J

F

M

A

M

J

J

A

S

O

N

D




Tor putitora




­

­

­

­

¯

¯

¯

Sept -Oct.

Gravel beds

Algae, rotifers, protozoa, insects, fish, debris

2-5 yr
45 cm

Rest in deep pools, jumping nature;
Excellent food fish

Tor tor



­

­

­

­

­

¯

¯

¯

Sept -Oct.

Gravel beds

Filamentous algae, insects, molluscs, fish fry & adults, sand and mud

2-5 yr
55 cm

Rest in deep pools, jumping nature;
Excellent food fish

Anguilla

­

­

­

­

¯

¯

¯



June -J uly

Mud and sand

Fry, insects, shrimps, molluscs

-
-

Excellent game fish caught on bait;
Food value and sport fish

Bagarius bagarius

­

­

­

­

­

­

­

¯

¯

¯

July - Aug.

Mud and sand detritus

Fry, large insects, crabs, shrimps, frogs, molluscs

2.5-3.0 yr
75 cm

Dwell in crevices, avoid direct light, piling, snapping, wriggling and overland movement;
Excellent food fish

Clupisoma garua

­

­

­

­

­

¯

¯

¯

June -J uly

Fine sand and pebbles

Fry, fingerlings, tadpoles and frogs

2.0 yr
20 cm

Anadromous migrants, sport fish angling by rod;
Excellent food fish

Table 5

Biological data for the short and mid distance migratory fish

Species

Migratory pattern(months)

Spawning season

Spawning substrate

Food

Age and size at spawning (maturity)

Behavior

Economic importa

J

F

M

A

M

J

J

A

S

O

N

D




Amphipnous cuchia



­

­

­

¯

¯


June-July

Mud & twigs

Algae, copepods, insects, debris

2 yr, 30 cm

Air breathing, moves in sw from lower reaches to floo swamp; food fish

Chagunius chagunio

­

­

­

­

­

¯

¯


May-June

Gravel & pebbles

Microscopic plants, detritus

2 yr, 22 cm

Schooling (6-8), jumping mid-distant migrants; food fish

Labeo angra


­

­

­

­

¯

¯


June-July

Gravel

Filamentous algae, higher plants, debris

2 yr, 28 cm

Residing in deep pools, schooling (10 - 12), sport fish, mid-distant migrants; food fish

L. dero

­

­

­

­

­

¯

¯


June-July

Gravel bed

Filamentous algae, higher plants, debris

2 yr, 28 cm

Take rest in deep pools, sport fish tasty fish

L. dyocheilus



­

­

­

­

¯

¯

July-Aug

Gravel

Microscopic plants, detritus, mud

2 yr, 28 cm

Live with N. Hexagonolepis; tasty fish

Neolissocheilus hexagonolepis

­

­

­

­

¯

¯

¯


May-July

Gravel

Plant, animal, debris

3 yr, 17 cm

Residing in deep pools; good game fish

Puntius chillinoides


­

­

­

­

¯

¯


June -J uly

Pebbles

Algae, diatoms, insects

2 yr, 18 cm

Lives in runs & riffles, jumping; food fish

Schizothorax annadalei

­

­

­





¯

¯

¯

Aug -S ept

Gravel+pebble

Algae, insects, fish fry, mud

1.5 yr,20 cm

Schooling (15-20), female chased by males during breeding season; delicious fish

S. plagiostomus

­

­

­






¯

¯

Sept - Oct

-

Algae, insects, mud, detritus

2 yr, 18 cm

Females chased by males during breeding season; delicious fish

Table 6

Biological data of some important resident fish species

Species

Spawning season

Spawning substrate

Food

Growth rate

(in a year)

Age and size at spawning

(maturity)

Behaviour

Economic importance

Barbus chillinoides

Aug-Sept

Gravel, sand, pebbles

Algae, earthworms, mud, small fish

4-5 cm

2.0 yr, 15.0 cm

Local migration in monsoon and spawn in spring; oily fish, sun&smoke dried

Glyptoth orax trilineatus

June

Gravel bed, pebbles, algal bloom

Aquatic insects (may flies and stoneflies)

3.5 cm

2.0 yr, 10.0 cm

School & mass migration during monsoon floods; used for fish oil, sun&smoke dried

G. telchita

May-June

Gravel bed, pebbles

Aquatic insects, earthworms

3-5 cm

2.0 yr, 9.0cm

School & mass migration to creeks for spawning; fat&oils used to cure gastric ailments

G. horai

June

Gravel, sand, mud

Insects, dragonfly larvae

3.0 cm

2.0 yr, 7.0 cm

School (50-80); oily fish with plump flesh

G. pectinopterus

June

Gravel, sand, rooted vegetation

Insects, mayfly larvae

3.5 cm

2.0 yr, 13.0 cm

School (15-200), local migration during monsoon; oil for healing wounds

G. blythi

May-June

Gravel, sand, pebbles

Aquatic insects, zooplankton

3.5 cm

2.0 yr, 8.0 cm

School under rocks, crevices and backwaters; sun&smoke dried; for flavouring condiments

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