ArticlePDF Available

IMPACT OF HYDRO-ECOLOGY ON FISH MIGRATION IN SELECTED EAST COAST ESTUARIES

September 2011

Authors:

Utpal Bhaumik

Central Inland Fisheries Research Institute

Pratham Shrivastava

Mahatma Gandhi Kashi Vidyapith, Varanasi

Bk Satpathy

Indian Institute of Technology Bhubaneswar

Malay Kumar Mukhopadhyay

Post Graduate Government Institute for Physical Education, Banipur, North 24 Parganas, West Bengal, India

Show all 5 authorsHide

Attempts were made to identify the commercially important migrant fish species and study their migration pattern in two selected estuaries i.e. Hooghly and Mahanadi on east-coast facing the Bay of Bengal Sea. Nearly 20 species in such category could be enlisted from Mahanadi estuary, which were also encountered in the Hooghly estuarine system. Most of the migrant species were amphidromous and their estuarine migration was influenced by the hydro-ecological characteristics. Salinity, depth and food niches were amongst the factors governing migration of the fishes. Migration was limited to 35 km in Mahanadi while up to 100 km in Hooghly estuarine system. Hilsa was only anadromous species migrating to freshwater river course and got struck up by the barrages. In Mahanadi river-estuarine system migration of Hilsa was seriously affected. Recruitment and fisheries of Hilsa in Hooghly-Bhagirathi system did not show significant impact of the Farakka barrage.

Numerical abundance of hilsa at different depths of Hooghly estuary

…

. List of migratory fishes recorded in the stretch between sea mouth and Naraj barrage in river Mahanadi

…

. Experimental findings on depth-wise catch of hilsa in Hooghly estuary

…

Figures - uploaded by Utpal Bhaumik

Content may be subject to copyright.

Content uploaded by Utpal Bhaumik

Content may be subject to copyright.

IMPACT OF HYDRO-ECOLOGY ON FISH MIGRATION IN SELECTED

EAST COAST ESTUARIES

UTPAL BHAUMIK, N. P. SHRIVASTAVA, B. B. SATPATHY, M. K. MUKHOPADHYAY

AND A. P. SHARMA

Central Inland Fisheries Research Institute, Barrackpore, Kolkata - 700 120

Received : 24.11.2010; Accepted : 04.02.2011

Attempts were made to identify the commercially important migrant fish species and study their migration pattern in

two selected estuaries i.e. Hooghly and Mahanadi on east-coast facing the Bay of Bengal Sea. Nearly 20 species in such

category could be enlisted from Mahanadi estuary, which were also encountered in the Hooghly estuarine system. Most

of the migrant species were amphidromous and their estuarine migration was influenced by the hydro-ecological

characteristics. Salinity, depth and food niches were amongst the factors governing migration of the fishes. Migration

was limited to 35 km in Mahanadi while up to 100 km in Hooghly estuarine system. Hilsa was only anadromous species

migrating to freshwater river course and got struck up by the barrages. In Mahanadi river-estuarine system migration of

Hilsa was seriously affected. Recruitment and fisheries of Hilsa in Hooghly-Bhagirathi system did not show significant

impact of the Farakka barrage.

Key words : Hydro-ecology, migration, estuary, amphidromous

J. Inland Fish. Soc. India, 43(1) : 1-9, 2011

Introduction

Migration is natural instinct and facilitating act in

fulfillment of bio-physiological urges in animals.

Fishes are no exception and constitute one amongst

the distant migrating groups in aquatic sphere. For

some fish species migration is intra environmental,

limited to shorter range of distance while for

others trans-environmental migration extends from

a few hundreds to thousands of kilometers.

Estuaries being intermediate environment between

sea and freshwater river and eco-biologically rich

habitat, play as favourable destination for both

marine and freshwater fish species. The fish move

to estuarine environment in search of breeding and

nourishment habitats or for feeding and fattening

purposes. The variability of estuarine environment

and eco-biological richness depend on several

intrinsic and extrinsic factors. Post independence

habitation, agriculture and industrial development

activities and consequential increase in dependence

on rivers and also estuaries gradually encroached

upon these resources and interfered the process

of natural renewal of eco-biological potentialities.

As a result the natural biotope of the estuarine

system got affected in qualitative and quantitative

richness including those of fishes.

According to the available records the fish

faunal structure in most of the estuarine

systems has shown shifting trend indicating

disappearance of a few species, decline in

abundance of many and appearance of some

species not recorded earlier. In view of this

striking phenomenon in fish species spectrum it

was felt necessary to develop knowledge on

migration of fishes and investigate the habitat

requirements, purpose and constraints in

migration of fishes in or through estuarine systems.

Materials and methods

Two estuarine systems on east coast facing the

Bay of Bengal Sea, which are hydro-morpho-

metrically different were selected for investigations.

Hydro-ecological conditions were examined

following the standard methods. Spectrum and

species-wise distribution of available fishes were

continuously monitored during 2007-09. The data

on spatio temporal abundance and some

biological aspects were analysed for critical

interpretation and drawing inferences on

migration of fishes in the investigated estuarine

systems.

Experimental netting with gill nets of specific

dimensions (200-250 m x 6.0 m) with uniform

mesh size (80-100 mm) was carried out at

Diamond Harbour and Nababganj during

monsoon in Hooghly estuary. Five nets were

deployed daily for three days at each site and the

fishes caught in three hauls for every net were

recorded for analyses of depth preference for hilsa

in the system.

Results

Mahanadi estuarine system

As per record, Mahanadi estuary in Orissa coast

was dimensionally vast and tidally more than 150

km in length. Erection of Naraj barrage above 100

km from sea face in sixtees brought out significant

alterations in hydromorphometry of the estuary.

During dry season of summer fair-weather roads

come up across the estuary revealing the drastic

fall in discharge down below the barrage and

threatening disintegration of the estuarine

continuity at points of high rate of siltation. Apart

from the biodiversity losses the qualitative and

quantitative decline in fisheries has been a matter

of great concern.

Hydro-ecology

Salinity distribution in Mahanadi estuary indicated

the influence of monsoon discharge from the

upstream Naraj barrage at Cuttack. During dry

season of summer the estuarine stretch from the

sea face up to 2 km upstream near Paradip was

maximum saline followed by medium saline zone

up to 16 km at Bhutmundi and thereafter the tidal

water was fresh with traces of salinity. With

monsoon discharge the freshwater tidal zone

extended downstream leaving only 2 km of the

stretch facing sea as medium saline zone. The

dissolved oxygen concentration was within

favourable range (5.2-8.2 mgl-1) except in the

deeper regions above the sea face reflecting

anaerobic condition of the bottom during dry

season of summer. The ambient pH (6.2-8.0)

indicated lower values of the same in industrially

affected areas near Paradip. Annual mean of

plankton density was recorded as 150 ul-1, 103

ul-1 and 162 ul-1 in upper freshwater, freshwater

tidal and brackish water tidal zones respectively.

The percentile contribution of phytoplankton and

zooplankton varied with the salinity and was

77.5:22.5, 54.4:45.6 and 57.3:42.7 in upper

freshwater, freshwater tidal and brackish

water tidal zones of the estuarine system

respectively.

Migrant fish species spectrum

Fish species spectrum in Mahanadi included a long

list of fin fishes and for the present investigation

those migrating in inland part of the estuary were

considered. Samples of fish specimen collected

from the landing centres and also the fishing boats

were identified and preserved for further studies

all along the estuarine length. A total of 20 species

of fishes could be enlisted within 35 km of the

estuarine span with Hilsa (Tenualosa ilisha)

moving further to down below the Naraj barrage

about 100 km upstream from the sea face. Most

of the fish species migrated to the estuarine

environment during post monsoon months when

BHAUMIK et al.

estuarine ecosystem was stabilized. The water was

quite transparent, temperature ranged between

210C and 300C, oxygen was in semi saturated

condition, salinity fluctuated between traces and

18 ppt, abundance of plankton and benthos was

in peaks and the intertidal depressions were

covered with thick growth of algal mats. Hilsa

specimens were available during monsoon mainly

and the fishes encountered down below the Naraj

barrage were mostly females at different stages of

maturity and the remaining males were in milting

condition.

Biology of fishes

Biological examination of the specimens procured

from the inland estuarine segment revealed 60%

of the enlisted 20 species as carnivore, feeding on

the prey species like small fishes, juveniles of fishes,

prawns and shrimps while 25% was eliophagic

depending on the vegetative matters like different

species of algae and occasionally twigs of soft

hydrophytes. The rest 5% depended on benthic

molluscs mainly. Reproductively the majority of

specimens sampled during the main season of post

monsoon were not in maturing condition. In Hilsa

the situation was different from the others since

most of the examined fish specimens were in

various maturity stages and bulk of the fish catch

was in monsoon months.

Hooghly-Matlah estuarine system

Largest of its kind in India, the estuary estimates

to 300 km in tidal length and holds well

demarcated salinity zones viz. marine, brackish

water and freshwater at the top. Prior to seventees

the salinity incursion used to extend up to about

200 km from the sea mouth. Thereafter,

freshwater induction through the Farakka barrage

installed at the bifurcation point of Ganga to

Bhagirathi and Padma above 500 km from sea

face made remarkable impact on eco-biological

characteristics of the estuarine system. The

freshwater tidal zone extended downstream

covering nearly 70% of the tidal length. The

brackish water zone shrunken by 50% and the

marine zone was pushed seaward.

Hydro-ecology

Salinographically, the Hooghly estuary was

delineated in two demarcated zones within the land

i.e. between Nabadwip and Kakdwip sampling

points. The stretch between Kakdwip and

Diamond Harbour remained brackish water with

seasonal variability in salinity while above Diamond

Harbour up to Nabadwip the environment was

fresh round the year.

Dissolved oxygen (7.63-8.80 mgl-1) and total

alkalinity (100-130.83 mgl-1) remained within

productive range with the support of favourable

pH range (7.6-8.0). Population density of

Table 1. List of migratory fishes recorded in the stretch

between sea mouth and Naraj barrage in river Mahanadi

Sl. No. Species

1Tenualosa ilisha

2Hilsa kelee

3Lates calcarifer

4Pama pama

5Pangasius pangasius

6Sillago sihama

7Arius jella

8Terapon jarbua

9Otolithoides biauritus

10 Eleutheronema tetradactylum

11 Rhinomugil corsula

12 Mugil cephalus

13 Mugil macrolepis

14 Liza parsia

15 Liza tade

16 Gerreomorpha satifer

17 Stolephorus commersonii

18 Stolephorus indicus

19 Leiognathus equulus

20 Stigmatogobius sadanandicus

FISH MIGRATION IN ESTUARIES

plankton varied widely within the estuary and

counted in the order of 292 ul-1 (163-427 ul-1),

220 ul-1 (183-258 ul-1) and 299 ul-1 (136-465

ul-1) in upper, middle and lower zones respectively.

Phytoplankton was predominant over

the zooplankton organisms. The average

macrobenthic density in the entire estuarine stretch

clearly indicated maximum abundance of the

organisms during winter (7442 nos/m2) followed

by post monsoon (4428 nos/m2) and monsoon

(3223 nos/m2) seasons. Molluscs contributed

highest percentage in the benthic population and

within the group the dominance of Gastropods was

observed throughout the stretch.

Migrant fish species spectrum

All the 20 species recorded from the Mahanadi

estuarine system were present in Hooghly-Matlah

estuarine complex. In respect of distance covered

during migration run by different species there was

variation and by and large most of the species were

recorded from the 100 km upstream up to

Diamond Harbour from the sea face. The

seasonality of migration of these species tallied with

those of Mahanadi estuary. The significant

difference was in migration range of Hilsa, which

moved upstream beyond the estuarine span in

freshwater riverine condition up to the

downstream of feeder canal of the Farakka

barrage lock gates.

Reproductive and migration behavior of Hilsa

Field observations were made on the

migration pattern of hilsa, the important target

species in Hooghly and Mahanadi estuaries.

Reproduction and related behavioural activities of

the species were investigated round the year in

Hooghly estuary. To a very large extent, hilsa

completed the breeding run within the estuary,

with favourable influence of high freshwater flow

and reduction of salinity. Only a smaller group

sought for the riverine environment. It appears that

Table 2. Food and feeding habits and range of migration of fish in estuarine environment

Species Food and feeding habits Habitat recovered from

Tenualosa ilisha Planktivorous Marine to freshwater river

Hilsa keele Planktivorous Marine and coastal zone

Lates calcarifer Carnivorous Coastal to freshwater tidal zone

Pama pama Carnivorous Coastal to freshwater tidal zone

Sillago sihama Carnivorous Coastal to brackish water tidal zone

Arius jella Carnivorous Coastal to brackish water tidal zone

Therapon jarbua Carnivorous Coastal to brackish water tidal zone

Otolithoides biauritus Carnivorous Coastal to brackish water tidal zone

Eleutheronema tetradactylum Carnivorous Coastal to brackish water tidal zone

Rhinomugil corsula Eliophagus Estuarine to freshwater river

Mugil cephalus Eliophagus Coastal to brackishwater tidal zone

Mugil macrolepis Eliophagus Coastal to brackishwater tidal zone

Liza parsia Eliophagus Coastal to brackishwater tidal zone

Liza tade Eliophagus Coastal to brackishwater tidal zone

Gerreomorpha satifer Carnivorous Coastal to brackishwater tidal zone

Stolephorus commersonii Carnivorous Coastal to brackishwater tidal zone

Stolephorus indicus Carnivorous Coastal to brackishwater tidal zone

Leiognathus equulus Carnivorous Coastal to brackishwater tidal zone

Stigmatogobius sadanandicus Carnivorous Coastal to estuarine tidal zone

Pangasius pangasius Molluscan feeder Brackish water tidal zone to freshwater river

BHAUMIK et al.

the breeding habitat is propounded all along the

longitudinal axis from Diamond Harbour to the

freshwater head of the estuary. The group of fish

in a lesser maturity stage evidently moves upstream

into the riverine stretches.

Major upstream migration of hilsa was observed

from August to November, beginning with the

commencement of monsoon and consequent

flooding. A milder second phase of migration of

mature hilsa, relatively smaller in size, was also

observed during February-March. The peak

migration of adult fish was found occurring shortly

before the spawning. Larger sized hilsa occurred

during July-August and their number fell sharply

from October to February. Female hilsa were

larger in size and fewer in number in the catch than

the males. The female: male ratio during monsoon

was recorded to be 1:2 or 3 in August. Lunar cycle

had a definite influence on hilsa migration, as

Table 3. Experimental findings on depth-wise catch of hilsa in Hooghly estuary

Experimental site and Gill net (200-250 m) Depth-wise catch

experiment number Mesh size (mm) Width (m) Depth (m) Total of 3 hauls (nos)

Diamond Harbour

1 80-100 6.0 3.6 3

2 4.2 5

3 3.5 2

4 3.8 4

5 3.2 3

1 80-100 6.0 4.5 8

2 3.6 5

3 4.3 11

4 5.2 7

5 4.2 8

1 80-100 6.0 5.0 5

2 4.8 5

3 4.2 8

4 3.0 2

5 3.5 4

Nababganj

1 80-100 6.0 4.4 7

2 3.6 3

3 4.0 3

4 5.0 5

5 3.6 3

1 80-100 6.0 5.6 3

2 4.3 5

3 4.4 5

4 5.4 2

5 4.3 4

1 80-100 6.0 4.7 3

2 5.3 2

3 4.8 5

4 3.8 3

5 5.0 2

FISH MIGRATION IN ESTUARIES

migration activity was observed to be vigorous four

to five days before and after the full moon and

new moon.

The experimental observations at Diamond

Harbour and Nababganj deploying gill nets of

80-100 mm mesh and 6.0 m width (Table 3) and

statistical analysis of the result indicated variation

in depth preference by the migrating shoals of the

species. At the downstream near Diamond

Harbour the depth between 3.0 and 3.6 m was

most preferred (r2 = 0.984; P = 0.016) followed

by 4.8 and 5.2 m (r2 = 0.866; P = 0.333). The

lower depth of 3.0 to 3.6 m was preferred by

comparatively smaller size groups of the fish, while

the larger ones moved through the deeper water

between 4.8 and 5.2 m from the surface. At about

60 km upstream near Nababganj the senario was

different where bulk of the fishes was caught in

the depth range of 4.0 to 4.4 m (r2 = 0.961; P =

0.179). The movement of the fishes through 4.0

to 4.4 m at Nababganj might be due to high

intensity of navigation activities and resultant

turmoil at the surface water level and also

comparatively low depth of water column in the

region.

However, analysis of the pooled data from Dimond

Harbour and Nababgabj revealed that the depth

range between 4.0 and 4.5 m can be considered

as ideal (r2 = 0.780; P = 0.06) for migration of the

adult Hilsa in river - estuarine condition.

The other favourable conditions observed for hilsa

migration were:

•> 20 m/minute current velocity (during high

turbulence and high water current, the fish

moved closer to river banks)

•Larger size of the estuary, especially deeper

and wider estuarine mouth

•Reasonably adequate freshwater discharge

from the upstream stretches

•High salinity, high turbidity, high siltation at the

estuarine mouth have adverse impact on the

hilsa migration

During migration about 90% of the migratory stock

was observed to be in a mature condition

indicating breeding as the main reason for

migration. The studies also brought on record the

killing of hilsa brooders in the sea itself before their

migration to the estuary for breeding purpose. The

present investigation indicated that the breeding

migration of hilsa takes place in July and a good

number of hilsa broods are caught in sea.

Discussion

Fish movement in open water systems is not

Fig. 1: Numerical abundance of hilsa at different depths

of Hooghly estuary

Correlation analysis

Simple statistics

Variable N Mean SD Sum Min. Max.

Catch of Hilsa 6 6.000 1.788 36.000 3.000 8.000

Depth(4.0-4.5 m) 6 4.283 0.172 25.700 4.000 4.500

Pearson correlation coefficient, N=6

Prob > r under HO : Rho = 0

Depth (4.0 to 4.5 m)

Catch of Hilsa 0.7789

0.0679

BHAUMIK et al.

unusual but nearly 2.7% of the world’s

ichthyofauna is recognized as migratory and out of

all these migrants 7.2% are listed as

“threatened” with extinction (Reide 2002 and

2004). Diadromous i.e. species migrating between

freshwater and marine environments form the

major group of migrants. Among the diadromous

those undertaking migration from marine

environment to rivers exclusively for reproduction

are termed as anadromous and those performing

non-reproductive migration are categorized as

amphidromous. Accordingly, most of the species

recorded during present investigation were

amphidromous and hilsa (Tenualosa ilisha)

belonged to the anadromous group.

Simple correlation between the observed

hydro-biological conditions and spatio-temporal

abundance of the migrants in two different

estuarine systems revealed influence of estuarine

eco-environment on species-wise migration

pattern for amphidromous forms.

The salinity gradient acted as prime and common

factor limiting upstream migration of the fish in both

the investigated systems from the sea. Slavik and

Bartos (1997 & 2001) observed sole influence of

water quality in distribution of fishes in Main River

and back water site of Vltava in Prague.

The other attributing factors like availability of food

niches and food abundance, which showed direct

relation with the abundance of individual species,

had also been reported as limiting factors for

movement of adult and juveniles of salmonids

(Slaney & Northcote, 1974; Dill et al., 1981;

Egglishaw & Shackley, 1985; Elliott, 1986).

Discharge related events have wide recognition as

important stimulants for initiation of migration in

large number of fishes. Elevation in river discharge

and subsequent inundation of the low-lying areas

results dissolution of nutrients from the bottom

soil, trigger an outburst of primary productivity and

fuelling aquatic food chain. Junk et al. (1989) and

Bayley (1995) described such productivity

outburst in cyclical order following retreat and

flooding as “flood pulse”. The present

investigation revealed occurrence of flood pulses

during monsoon following rainfall pattern in the

catchment. However, the flood pulse effect like

environmental freshening, fast current coupled with

heavy turbulence, high turbidity brought out

significant change in eco-environment condition

including disintegration of the feeding habitats for

the migrant species, which ultimately interfere the

migration intensity of the fishes during the season.

Further, the environmental deterioration due to the

industrial discharge from Paradip region might have

influenced the fish migration in Mahanadi estuary.

Reaction of eco salmon, pony fish etc. in

contaminated waters have also been reported by

Rehnberg and Schreck, 1986; Sasaki et al., 2003;

Schellart and Wubbels, 1998; Bardach et al.,

1965.

Recorded variability in migration intensity and

production of the species with lunar periodicity in

Hooghly estuarine system was at par with the

observations made by Walker (1949) for

California grunion Leuresthes tenuis at right Duni

where the spawning migration of the species

reached to highest level during full and new moon

days and Grau (1982) for salmon. Impact of

Aswan Dam adversely affecting groundwater,

erosion, agriculture and largely fisheries in

downstream of river Nile has been well

documented by Halim (1991).

Freshwater environment with favourable

hydrography and adequate supply of plankton food

items in Hooghly-Bhagirathi river course provided

ideal breeding and rearing habitats for migrant

population of hilsa as revealed from increasing

FISH MIGRATION IN ESTUARIES

production trend and juvenile recruitment of the

species in the system. On the other hand absence

of favourable habitats in the upstream of Mahanadi

estuary affected the breeding migration and so also

production and recruitment potential of the

species in system.

The observed depth preference for the migratory

hilsa like bigger fish moving in deeper water

has also been reported by Bhaumik (2010).

According to the author the spent fishes mostly

bigger in size move downward during low tide

period.

Remarks and conclusion

In view of the present status of fish migration and

the eco-environmental constraints affecting

natural and free movement of the migratory fish

species to the estuarine habitats, the following

issues emerged for consideration to facilitate the

fish migration activities to the utmost possibilities.

•Estimation and maintenance of environmental

flow effective in facilitating salinity ingress to a

desired extent and also retaining the ecological

variability including those of the mangrove

ecosystems could protect the estuarine system

for the migration of fish stocks, biodiversity

conservation and overall production

potential of the estuaries. The barrages and

dams installed for regulation of river flow in

majority of the river-estuarine systems in the

country stand mostly at safer distance and above

100 km away from the sea face. As such the

fish migration particularly of amphidromous

species in majority of the estuaries might have

not been affected even in the absence of fish

locks or any other devices had there been long

riverine span and no dearth of water flow and

habitat required for the migratory fishes down

below.

•From the present experiences and records

available on role of dams and barrages in hilsa

migration and fisheries in Indian river-estuary

systems, it can be concluded that the fish locks/

gates or such devices might not affect

breeding migration, population recruitment and

production of hilsa if the river course down

below any physical obstruction retain

adequate space of freshwater habitat and

environmentally rich ecosystem for alternative

use required by the species.

Acknowledgements

The authors are deeply indebted to the

Director, CIFRI for scientific support and

guidance during the period of present

investigation. They are also thankful to Dr. B. C.

Jha, Head, Reservoir and Wetland Fisheries

Division, CIFRI for help and cooperation. The

technical support extended by Messrs. C. N.

Mukherjee, T. Chatterjee, D. Sanfui, B. N. Das,

A. R. Choudhury, D. Saha, S. Mondal, C. P.

Singh, K. P. Singh, A. K. Jana, A. K. Barui;

Mrs. A. Sengupta and Mrs. K. Jacquline, is

gratefully acknowledged. The support rendered

by other scientists and staff is also duly

acknowledged. The authors also thank Mr.

Anirban Rej, SRF for his help in statistical

analysis

References

Bayley, P. B. 1995. Under stocking large river-flood plain

ecosystem. Bioscience, 45: 153-158.

Bardach, J. E., Fujiya, M. and Holl, A. 1965.

Detergent: Effect on chemical senses of the fish.

Ictalurus natalish (le Sueur). Science, 148: 1605-1607.

Bhaumik, Utpal. 2010. Status of the fishery of Indian

shad (Tenualosa ilisha) with special reference to

Hooghly river system. Souvenir, 21st All India Congress

of Zoology and National Seminar, published by CIFRI,

Barrackpore, 66-81pp.

BHAUMIK et al.

Dill, L. M., Ydenberg, R. C. and Fraser, A. H. C. 1981.

Food abundance and territory size in juvenile coho

salmon (Onchorhynchus kisutch). Canadian Journal

of Zoology, 59: 1801-1809.

Egglishaw, H. J. and Shackley, P. E. 1985. Factors

governing the production of juvenile Atlantic salmon in

Scottish streams. Journal of Fish Biology, 27: 27-33.

Elliott, J. M. 1986. Spatial distribution and behavioural

movements of migratory trout Salmo frutta in a lake

District stream. Journal of Animal Ecology, 55:907-922.

Grau, E. G. 1982. ‘Is the lunar cycle a factor timing the

onset of salmon migration?’. Proc. Salmon Trout

Migratory Behaviour Sym., pp. 184-9.

Halim, Y. 1991. The impact of human alterations on the

hydrological cycle on ocean margins. pp 301-327. In :

Mantoura R. F. C., Martin, J - M, Wollast, R. (eds.) Ocean

margin processes in global change. Wiley, New York,

Junk, W. J., Bayley, P. B. and Sparks, R. E. 1989. The

flood pulses concept in river flood plain ecosystems.

Canadian special publication of fisheries and aquatic

science, 106: 110-127.

Rehnberg, B. C. and Schreck, C. B. 1986. Acute metal

toxicity of olfaction in coho salmon:Behaviour,receptors

and odor-metal complexation. Bull.Environ.Contam.

Toxicol., 36: 579-586.

Reide, K. 2002. Global register of migratory species.

German Federal Agency for Nature Conservation, Project

808 05 081.

FISH MIGRATION IN ESTUARIES

Reide, K. 2004. Global register of migratory species-from

global to regional scales. German Federal Agency for

Nature Conservation, Project 808 05 081. Final report.

Sasaki, A., Ikejima, K., Azuma, S., Kashimura, N. and

Wada, M. 2003. Field evidence for bioluminescent

signaling in the pony fish Leiognathus elongates.

Environ.Biol.Fish., 66: 307-311.

Schellart, N. A. M. and Wubbels, R. L. J. 1998. The

auditory and mechasensory lateral line system. In: The

physiology of fishes (Evans,D.H.Ed), 2nd ed.,

pp. 283-312. CRC Press, Boca Raton.

Slaney, P. A. and Northcote,T. G. 1974. Effects of prey

abundance on density and territorial behavior of young

rainbow trout (Salmo gairdneri) in laboratory stream

channels. J. Fish. Res. Board. Can., 31:1201-9.

Slavik, O. and Bartos, L. 1997. Effect of water

temperature and pollution on young-of-the-year fish in

regulated stretch of River Vltava, Czech Republic.

Folia Zoologica, 46:367-374.

Slavik, O. and Bartos, L. 2001. Spatial distribution and

temporal variance of fish communities in the channelized

and regulated Vltava river (Central Europe).

Environ. Biol. of fish., 61:47-55

Walker, B. W. 1949. ‘Periodicity of spawning in the

grunion, Leuresthes tenuis’. Ph.D thesis, University of

California, Los Angeles, California.

The biophysical assessments of the hilsa fish (Tenualosa ilisha) habitat in the lower Meghna, Bangladesh

Technical Report

Full-text available

Dec 2015

Seasonal variability of water quality index in the Hooghly Estuary areas of West Bengal, India

Article

Jun 2021

Health of the Hooghly estuary was assessed through Water Quality Index (WQI) developed using ten water quality parameters, viz., specific conductivity, turbidity, pH, total dissolved solids, dissolved oxygen, biochemical oxygen demand, chloride, total alkalinity, total hardness, and nitrate-N, measured at three different stations along the salinity gradient. Weighted arithmetic index method was used for calculation of WQI. For classifying water quality in each of the stations, five-point rating scale was used. Wide fluctuations in monthly WQI were recorded in this estuarine zone with the highest values during pre-monsoon month of May and the lowest values during monsoon month of October. From WQI values (mostly >100) throughout the year, it was evident that Hooghly-Bhagirathi estuarine system is below the water quality standards for drinking and propagation of wildlife. There is anthropogenic influence on most of the water quality parameters.

Stock, Maximum Sustainable Yield, and Management Status of Tenualosa ilisha in Bangladesh Waters

Chapter

Full-text available

Mar 2021

The gregarious hilsa, Tenualosa ilisha, is an anadromous fish predominantly a marine variety migrating from marine environment to estuarine and freshwater environment for spawning, nursing, and feeding purposes. It is the major catchment species particularly in Bangladesh, India, and Myanmar. Presently a major gap in understanding on stock size and maximum sustainable yield (MSY) of hilsa and their habitats ecology has created the new challenges for the researchers and policy makers to implement the science-based hilsa management. Thus, we critically reviewed population dynamics parameters of hilsa, i.e., migration pattern, growth, mortality, exploitation, standing stock status, and MSY to provide information for supporting a more operative hilsa fishery management particularly conservation techniques for sustenance of this fish in the region. T. ilisha migrated throughout the year in the coast and all the main rivers of Bangladesh. Their peak migrations showed in September to October and continuously occurred in every 2 months of intervals. Distribution of hilsa in Bangladesh indicated that remarkable juvenile hilsa starts migration from the February, whereas the migration of matured hilsa is not bounded to monsoon period only, but this fish also migrates for a short duration in the winter season. Exploitation status from 1995 to 2016 indicated that the fish is overexploited in the last decades that affect the MSY of this fishery. Thus, the review summarized the migration pattern, population parameters, stock size, maximum sustainable yield, and their current exploitation status that can be helpful for hilsa shad protection and conservation especially in Bangladesh waters.

Penja fish (Genus: Sicyopterus) from Karama River, West Sulawesi, Indonesia: Growth Pattern and Habitat Characteristics

Article

Full-text available

Oct 2020

Muthiadin C, Aziz IR, Hasyimuddin, Nur F, Sijid SA, Azman S, Hadiaty RK, Alimuddin I. 2020. Penja fish (Genus: Sicyopterus) from Karama River, West Sulawesi, Indonesia: Growth pattern and habitat characteristics. Biodiversitas 21: 4959-4966. Sicydiinae gobies have been widely collected and identified throughout tropical Indo-Pacific, except in Karama River, Mamuju, West Sulawesi, Indonesia. Penja was the goby fish's local name, where their belly has the adhesive disc entirely formed by the pelvic fins. This study aims to describe the habitat and growth patterns of genus Sicyopterus in Karama river, which passes through three sub-districts. The research was conducted in Karama River from four sites: Kalumpang, Bonehau, Arassi, and Kalonding. Fish growth was described by Deroberts and William model, and continued with habitat characteristics. The total number of fish from four sites about 71 adults Sicyopterus species (family Gobiidae): Sicyopterus longifilis and Sicyopterus pugnans. The average growth pattern in all sites is isometric negative (b<3), except in the Kalumpang sites, growth pattern for S. longifilis is isometric (b=3) whereas in S. pugnans in the Kalumpang sites growth pattern is positive allometric (b>3). The value of condition factor (K) ranges between 1.89-2.28, it means the average shape of fish is flat. It is related to the average growth pattern from four sites that are allometric (growth of length more than the growth of weight). Nevertheless, the value of Wr in average 100, which describe that environment of fish is good, related from abiotic measurement in all site showed fit condition for Sicyopterus species habitat. Further studies will be focused on the food supply and predator of Sicyopterus.

Size distribution and abundance of juvenile hilsa, Tenualosa ilisha in the major rivers of Bangladesh

Article

Full-text available

Aug 2019

The study was conducted in the six major rivers (Padma, Meghna, Jamuna, Brahmaputra Surma and Andermanik) of Bangladesh to evaluate the abundance and distribution of juvenile hilsa, Tenualosa ilisha from February to April 2017. Fish samples are collected by using monofilament gill net. The total length and depth of the gill net was 100 m and 4.5 m respectively. The mesh size of first 25 m net was 2.5 cm; second 25 m was 3.5 cm; third 25 m was 4.5 cm and the last 25 m was 5.5 cm. Daytime sampling was done at all the sites on a monthly basis and the Catch per Unit Effort (CPUE), total length (cm) and weight (g) were recorded and analyzed. The result showed that the highest CPUE of juvenile T. ilisha was observed at Ramgati station which was 72 individuals/100 m gill net/30 minutes. The second and third highest CPUE was found in Nalchira (58 individuals/100 m net/30 min) and Charking (46 individuals/100m net/30 min), those stations are located in lower Meghna region. There was a significance variation (P<0.05) of CPUE among the 18 stations. It is clear that the high abundance of juvenile T. ilisha in the lower Meghna River while the low abundance in upper part of the rivers.

Fisheries of Indian Shad (Tenualosa ilisha) in the Hooghly–Bhagirathi stretch of the Ganga River system

Article

Full-text available

Jan 2017

Utpal Bhaumik

Tenualosa ilisha, the Indian Shad, is one of the most important commercial fish of the Indo-Pacific region and the Hilsa fishery in India is dependent on this species. Presently, the fishery resource of the species lies largely within the Bhagirathi–Hooghly component of the Ganga River system. The annual fish catch of Hilsa from the Bhagirathi–Hooghly River has fluctuated over the years ranging between 12,733 and 20,000 t between 2000–2001 and 2010–2012. The monsoon migration of Hilsa commences in July and gradually picks up in August. From September onwards, the magnitude of migration to the freshwater system showed a declining trend. Stretches between Nischintapur and Diamond Harbour downstream, Hooghly Ghat and Kalna in the freshwater tidal zone, and Lalbagh to Farakka in the Bhagirathi River have been delineated as potential breeding grounds for Hilsa. The intense fishing pressure in the coastal estuarine zone almost year round, especially in breeding season, adversely affects the breeding migration, spawning, and recruitment success vis a vis overall fishery of Hilsa in the system. There is an immediate need to implement effective conservation measures to protect breeders, potential breeding grounds, and juveniles for the cause of sustainable Hilsa fishery.

Sustainable fisheries/aquaculture of hilsa, Tenualosa ilisha in changing and dynamic riverine ecosystem of India and its neighborhood

Chapter

Jan 2022

Hilsa (Tenualosa ilisha) is commonly known as the Indian shad and belongs to the family of Clupeidae. This fish is spread over Indo-Pacific province from the Arabian Gulf (Pakistan, India, Bangladesh, and Burma) to South Vietnam. Hilsa is a euryhaline and anadromous fish. This fish naturally attains the growth and maturation in the sea water and later migrates to freshwater rivers for spawning. After spawning, embryonic and larval development take place in freshwater. Larvae migrate to lower regions of rivers (downstream rivers), which is nursery ground and finally to near shore coastal waters. Larvae grow to juveniles hilsa (locally called as jatka in Bangladesh and West Bengal) remain in the nursery grounds for 5–6 months. The juveniles are euryhaline in nature and move to seawater for feeding, growth, and sexual maturation and when the fishes are sexually matured (adult fish, 1.5 years old) migrates toward freshwater rivers for spawning. Different life stages of T. ilisha pass through diverse habitats due to migratory nature, which have different ecosystem and food available. It is an important commercial fish of the Indo-Pacific region, especially Bangladesh, India, and Myanmar where its fishery generates employment and income for millions of people. Now a days, catch of hilsa has dropped because of overfishing and changes in the dynamics of riverine ecosystem. The main causes of the ecological changes are pollution, obstruction of natural migration, and river sedimentation. In our current research, we have refined the artificial breeding of hilsa through dry stripping form wild mature broodstock. We also developed the nursery rearing protocol in pond ecosystem. Further, domesticated F1 broodstock of hilsa is developed in pond and recirculatory aquaculture system (RAS). We also aim to complete the breeding cycle of hilsa in captivity, which will help in development of conservation strategies and aquaculture of hilsa.

Biology and Fisheries of Hilsa shad in Bay of Bengal

Article

Feb 2019

Hilsa (Tenualosa ilisha) or river shad is an anadromous fish species widely distributed in the North Indian Ocean, mainly in the Bay of Bengal (BoB). Hilsa is the national fish of Bangladesh and it contributes 10% of the total fish production of the country, with a market value of $1.74 billion. Hilsa also holds a very important place in the economics of West Bengal of India with 12.5% of the catch and also tops the marine capture in Myanmar. During the last two decades Hilsa production from inland waters has been stable, whereas marine yields in the BoB increased substantially. In order to sustainably manage the trans-boundary stock of Hilsa, the taxonomy, distribution, habitat, migration patterns, population dynamics, fisheries and socio-economics aspects of the fishery have been reviewed here. To achieve a successful trans-boundary management for the Hilsa stock, complete ban on undersize fishing, well-targeted temporal and spatial bans, creation of protected areas in strategic points, incentive for Hilsa fishers and ecological restoration of Hilsa habitats and more work on technological development of Hilsa aquaculture are recommended.

Migration of Hilsa Shad in the Indo-Pacific Region – A Review

Article

Full-text available

Nov 2015

Utpal Bhaumik

Hilsa,Tenualosa ilisha (Hamilton), by habitat is a marine environment species but they migrate to estuarine and fresh waters for spawning purposes. Peak upstream migration of Hilsa in the Rivers mostly starts with the onset of SouthWest monsoon. Tagging experiments have shown that a Hilsa may cover as much as 70.8 km in one day. Hilsa fishery exists with two distinguished peaks in monsoon and winter in Hooghly-Bhagirathi linkage of Ganga River system. In Bangladesh waters, during the peak breeding season the adult fish run in shoals to the estuaries and the rivers and migrate upstream as much as 1200 km (usual run 50-100 km) for spawning. In Indus, the migration takes place up to the Gulam Mohamed Barrage, which is 161 km from the Sea. In the River Irrawady, Hilsa are known to ascend into upper Burma to Mndalay, a distance of about 724 km from the Sea. Sbour (Hilsa) ascend Shatt Al-Arab River to about 150-200 km north of the city of Amara on the Tigris River. During last few decades the fishery has depleted in the Riverine environment of many countries due to rapid siltation and other degraded ecological conditions including wanton destruction of Jatka (Juveniles). It is, therefore, necessary to formulate and implement a good management plan especially conservation strategies for sustenance of this highly prized fishery across the world.

Indian shad (Tenualosa ilisha) and its fishery with special reference to Indian waters

Conference Paper

Full-text available

Nov 2015

Utpal Bhaumik

The Indian shad (Tenualosa ilisha) commonly known as Hilsa, belonging to the sub-family Alosinae of Family Clupeidae, is recognized as one of the most important commercial fishes of the Indo-Pacific region. The age and growth of Hilsa varies with water bodies. Hilsa is heterosexual; the females are distinguishable by the flat urinogenital opening and bulging abdomen when gravid and the males by a narrow genital opening and the presence of prominent papillae. It has been observed that Hilsa may attain first maturity at the end of first year or the beginning of the second year. It is well known that Hilsa ascends the Rivers for spawning. Hilsa catch records have continuity only for a few places and for a few years. Considerable fluctuations have been reported in the catches from different areas. In order to maintain sustainable yield of Hilsa and also to increase production, regulation of selective fishing by adjusting mesh size of the gears and simultaneous control of brood fish and juvenile killing should be encouraged.

Status of the fishery of Indian Shad (Tenualosa ilisha) with special reference to Hooghly river system

Conference Paper

Full-text available

Dec 2010

Utpal Bhaumik

The Indian shad, Tenualosa ilisha (Hamilton) popularly known as hilsa belongs to the sub-family Alosinae of Family Clupeidae. There is no denying fact that hilsa has established itself as one of the most important commercial fishes of the Indo-Pacific region. It has a wide range of distribution and occurs in marine, estuarine and riverine environments. The fish is found in the Persian Gulf, Red Sea, Arabian Sea, Bay of Bengal, Vietnam Sea and China Sea. The riverine habitat covers the Satil Arab, and the Tigris and Euphrates of Iran and Iraq, the Indus of Pakistan, the rivers of eastern and Western India namely the Ganga, Hooghly, Rupnarayan, Brahmaputra, Godavari, Narmada and other coastal rivers, the Irrawaddy of Myanmar, and the Padma, Jamuna, Meghna, Karnafully and other coastal rivers of Bangladesh. The major portion of hilsa (about 95%) is caught by Bangladesh, India and Myanmar. Presently five species under the Genus Tenualosa viz., Tenualosa ilisha (Hamilton-Buchanan, 1822), T. toli (Valenciennes, 1847), T. macrura (Bleekar, 1852), T. reevesii (Richardson, 1846) and T. thibaudeaui (Durand, 1840) have been recognized from the estuaries and coastal waters of tropical Asia. The normal habitat, trend of migratory habit, maximum age and growth differ from species to species. Since, all these species are commercially important, they are subject to heavy fishing pressure and its irresponsible exploitation resulted in decline in catch. Among these five species, only T. ilisha and to a certain extent T. toli are available in Indian waters. Scenario of the hilsa fisheries in the Hooghly estuary Hilsa is the major component of fishery in the Hooghly estuary accounting about 15-20% of the total fish landing. The annual fish catch of hilsa from the Hooghly estuary are highly fluctuating over the years (Fig.1). During pre-Farakka barrage period (1957-74), the annual landings of this species varied between 114 and 6573 t with an average of 1,427.6 t. But, increased level of yield was observed during post-barrage period. The average annual harvest of hilsa was recorded as 2,471 t and 6,370.1 t during 1975-76 to 1990-91 and 1991-92 to 1998-99 respectively (Annual reports, CIFRI). Hilsa landings in the Hooghly estuarine system during 1998-99 to 2002-03 varied between 6448.2 and 15,799.0 t with an average of 10,382.9 t. Maximum harvest (15,799 t) was recorded during 2000-01 (De,2001). Hydrological changes with higher freshwater discharge caused by water diversion at Farakka barrage through Hooghly river might have attracted more hilsa towards Hooghly estuary. Tremendous increase in effort from nineties with enormous improvement of mechanization to catch this higher congregation of hilsa in the estuary mouth also contributed to this 4-fold increase of hilsa

Global register of migratory species: From global to regional scales

Article

Jan 2005

K. Riede

This second volume of the Global Register of Migratory Species complements the reference list of migratory vertebrate species with fishes and songbirds, in printed and digital format. The enclosed GROMS CD contains an improved and updated version of the GROMS database, including 5,600 references, full-text documents and 1,000 species distribution maps in GIS format. These are complemented by additional, relevant geodata sets such as country files, protected wetlands or oil spills. The user guide empowers novices to make simple database searches, and customize their own maps with the enclosed lightweight GIS freeware. Advanced users will find the full tutorial of a GROMS Workshop for Power Users on CD, with examples of advanced data-mining and GIS intersections, to enable pursuit of their own research questions related to migratory species conservation. This volume presents examples of what can be achieved by combining GROMS with other species databases or regional GIS datasets, thereby zooming in from global to regional scales. Up to now, 4,358 species have been identified as definitely or most probably migratory, exhibiting predictable and cyclical migrations of more than 100 km, including 1,895 migratory fish species. Both volumes together illustrate the particular requirements of an information system serving the conservation of migratory species.

Effect of water temperature and pollution on young-of-the-year fishes in the regulated stretch of the River Vltava, Czech Republic

Article

Jan 1997
FOLIA ZOOL

The abundance of young-of-the-year fishes was studied at two sites on the River Vltava, the first situated below the last dam of the cascade of fibre water reservoirs that discharge cold water with low trophic potential from the hypolimnia. The second study site was 29 km downstream the cascade where water is warmer but heavily polluted. Differences were found between the two study sites in terms of fish abundance, species richness and fish body length. Higher values of the population parameters tended to be at the site with warmer but polluted water. In the study are discussed some possible reasons of differences in fish assemblages characteristics.

Is the lunar cycle a factor timing the onset of salmon migration?

Article

Jan 1982

E. Grau

Spatial Distribution and Behavioural Movements of Migratory Trout Salmo trutta in a Lake District Stream

Article

Oct 1986

J. M. Elliott

The 1st spatial change, a decrease in relative clumping soon after the end of the alevin stage in April, was related to the behavioural movement of the fry emerging from the nest, usually at night. About 81% of fry in field experiments rarely fed, soon lost weight after their yolk was exhausted, drifted downstream chiefly at night and died. The others started to feed and either remained near their birthplace or migrated, usually upstream. The proportion migrating was density-dependent, increasing from <1% to c 12% as the number of fry per nest increased. Few fry emigrated out of the stream and therefore population losses in spring were chiefly due to mortality. The 2nd spatial change, an increase in relative clumping in the first winter of the life cycle, was related to the behavioural movements of 1st-year trout when they migrated to deeper pools in the stream. A few 1st-year trout emigrated out of the stream in winter, but population losses in the first summer and winter of the life cycle were chiefly due to mortality, usually within the stream, rather than migration. The 3rd spatial change, a slight increase in the relative clumping of 3rd-year trout, was related to their increased mobility just before they emigrated from the stream as smolts. -from Author

The auditory and mechanosensory lateral line system

Chapter

Jan 1998

Various sense organs have evolved to inform animals about mechanical events that occur in their environment. The octavolateral system is a collective noun for three very different mechanosensory systems, i.e. the auditory, the equilibrium, and the lateral line (LL) system, which have similar receptor cells, the hair cells. The central pathways of these systems are similar and partly overlap. Both the auditory and the LL system detect mechanical vibrations, the LL also detects flow in the surrounding medium. We will start this chapter with a summary of the fundamentals of underwater acoustics and other mechanical vibrations. In the following sections a description of the structure and function of the sensory organs will be given, and we will have a look at how sensory abilities may be related to habitat and behavior.

Food abundance and territory size in juvenile coho salmon (Oncorynchus kisutch)

Article

Sep 1981

Feeding territory size and potential food abundance were measured simultaneously in a field population of juvenile (40–50 mm) coho salmon. Territory size was inversely related to the density of benthic food on the territory, as predicted from an energy-based model of territoriality. The relationship between the abundance of drift food and territory size was in the predicted direction, but was not significant. Territories were also smaller where intruder pressure was higher, but intrusion rate and food abundance were not directly correlated. Therefore, the effect of food abundance on territory size was not caused indirectly by attraction of nonterritorial fish to areas where food was abundant. In the laboratory, the distance from which a resident coho attacked an approaching model intruder increased asymptotically with hunger. The fish therefore appear to possess an appropriate behavioural mechanism (tactic) to adjust territory size to local food abundance.

Effects of Prey Abundance on Density and Territorial Behavior of Young Rainbow Trout (Salmo gairdneri) in Laboratory Stream Channels

Article

Apr 2011

When rainbow trout (Salmo gairdneri) fry (underyearlings) were introduced into laboratory channels at three different prey levels and permitted to emigrate voluntarily, their density remained highest at the highest prey level. The distribution of fry was positively associated with a gradient in prey abundance. Both territory size and frequency of aggressive encounter varied inversely with prey level; the higher the prey level, the smaller the territory and the lower the frequency of aggressive encounter. Emigration from the channels was neither as rapid nor as marked when prey level was reduced, compared to when fry were initially introduced to different prey levels. However, frequency of aggressive encounter significantly increased when the prey level was decreased and significantly decreased when the prey was increased.

Factors governing the production of juvenile Atlantic salmon in Scottish streams

Article

Jan 2006
J FISH BIOL

Data are presented to show how the number and growth of juvenile salmon in streams in the Scottish Highlands are influenced by various physical (temperature, water chemistry, depth and velocity, type of substratum) and biotic (food resources, competition, recruitment) factors.

Field Evidence for Bioluminescent Signaling in the Pony Fish, Leiognathus elongatus

Article

Apr 2003

Luminescence of the pony fish, Leiognathus elongatus, was observed in the natural environment during nighttime diving. The light was emitted from the lateroventral portion of the body, as bright rectangular-shaped luminescence patches turned on and off periodically. Luminescent fish had a distinct clear patch on the flank through which light was emitted, whereas non-luminous fish did not have such a clear patch. Both luminous and non-luminous fish were found within a shoal, where non-luminous individuals were chased by luminous ones. From previous morphological studies, the luminous and non-luminous individuals are likely to be male and female, respectively. Our observations provide field evidence that the luminescence functions as intraspecific communications in L. elongatus.