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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.
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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-
1
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
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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
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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
4
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
5
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
6
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
7
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
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California, Los Angeles, California.
... Similar findings were reported by Ahmed et al. (2005), who recorded that water temperature of the Meghna river at surface level ranged between 24.1 and 30.5ºC with a mean of 27.6 ± 0.68. Bhaumik et al. 2011 estimated the threshold values of physicochemical parameters for hilsa migration, breeding, rearing and estimated that the ideal water temperature ranged from 29.3-30.2ºC for breeding activities and 29.8-30.8ºC ...
... Mitra and Devasvndarm (1954) stated that salinity levels ranging from 0 to 0.5 ppt. and from 0.05 to 0.1 ppt were most suitable, and moderately suitable for the juvenile hilsa, but salinity above 1.0 ppt was not suitable for juvenile hilsa, whereas Bhaumik et al. (2011) estimated the ideal salinity as <0.1 for the breeding and nursery activities of hilsa in the Hooghly-Bhagirathi river system. Following the discussion above, it can be said that salinity found in the Meghna-Tetulia river basin during the study period was the most suitable for breeding and nursery activities. ...
... Estuary is also described as an arm of the sea that extends inland for meeting the mouth of a river. Like all other estuaries, Hooghly estuary has variable physico-chemical conditions such as tides, waves and salinity fluctuations (Nath and De, 1998), which are known to exert effects on estuarine organisms of different trophic levels, like plankton, benthos, fish, etc. (Chakraborty et al., 1995;Bhaumik et al., 2011;Manna et al., 2014, Roshith et al., 2018. Fishes capable to cope with wide fluctuations of different physico-chemical parameters flourish by exploiting the abundant resources available (Nath, 1998) leading to huge germplasm resources in this estuary (Ghosh, 2008;Roshith et al., 2013). ...
Article
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.
... The habitat of hilsa shad is in marine environment, but they normally migrate to estuaries and freshwaters for breeding and feeding activities through changing their osmoregulatory exercise by their kidney and gills from saline to freshwater. Hilsa are largely described as anadromous, live in the marine habitat for utmost of its life, but migrate to freshwaters for breeding purpose, and afterwards they again return back to the marine environment (Hora 1938;Pillay 1958;Bhaumik et al. 2011;Bhaumik and Sharma 2012). Nevertheless, few other types of hilsa species don't migrate from the marine environment to the freshwater or vice versa (Blaber et al. 2003;Rahman and Cowx 2006;Hossain et al. 2016). ...
Chapter
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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.
... The larvae drift immediately downstream to the estuary (Iida et al. 2015), and after 2 to 6 months, the post-larvae migrate back into the rivers (Bauer 2013;Shiao et al. 2015;Olii et al. 2017;Tran et al. 2018). Besides hydro-ecological characteristics, highnutrient found in the estuary can cause a high abundance of phytoplankton that affects zooplankton and fish at the early life stage, including postlarvae, which acts as consumers (Bhaumik et al. 2011;Taillebois et al. 2012;Cloern 2018). ...
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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.
... The results indicated that comparatively larger individual migrates from downstream to upper of the river for their growing and feeding purposes when the juvenile T. ilisha catch are banned on the March and April of the year in Bangladesh. The migratory movement of T. ilisha into and from the river was studied recently in the Hooghly River at Diamond Harbour and marine zone of the estuary off Frazerganj (Utpal et al 2011) where fishing of T. ilisha by the gill net was observed during January to March and the recruitment pattern of the fishery in Bangladesh waters from March to July which supports the findings of the present study. Zaher et al (2013) reported that juvenile T. ilisha starts migrating from November in coastal region to freshwater region until April. ...
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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.
... A depth of 4.0-4.5 m from the surface is assumed to be favorable for migration of adult Hilsa. Thus, the total depth in the system should be more than that for favourable migration and spawning of Hilsa (Bhaumik et al., 2011a). ...
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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.
Chapter
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.
Article
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.
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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.
Conference Paper
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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.
Conference Paper
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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
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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.
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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.
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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.
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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.
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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.
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