Int. J. Life. Sci. Scienti. Res.,
3(3):
1039-1046,
May 2017
Food
and Feeding Habits of Two Major Lizardfishes (Family:
Synodontidae) occurring along North-West Coast of
India Between Lat. 18°-23°N
Ashwini G. Darokar1*, Rohan R Patil 2, Amol
Kumar Patel3, M. Nivetha4
1Assistant
Professor, Department of Physiology, IGGMC, Nagpur India
2Assistant
Professor, Department of Community Medicine, Melmaruvathur
Adhiparasakthi Institute of Medical Sciences and
Research, Melmaruvathur,
India
3Consultant
Plastic Surgeon, Shrawan Hospital, Nagpur India
4Intern, Melmaruvathur Adhiparasakthi Institute of Medical Sciences and Research, Melmaruvathur, India
*Address
for Correspondence: Mr.
Ashwini G. Darokar,
Assistant Professor, Department of Physiology, IGGMC, Nagpur, India
ABSTRACT-
Lizardfishes
are commercially important group of species contributing to the fishery in the
Indian EEZ. Information on predation, prey-predator relationship and their
assessments in respect of Saurida tumbil and Saurida undosquamis have been derived in this study. A total
number of 1630 specimens of S. tumbil and 926 of S.
undosquamis were used for stomach content
analysis. The specimens of S. tumbil examined in the study ranged between 13.0-53.0
cm (TL) and of S. undosquamis
13.0-41.0 cm. Qualitative and quantitative analysis revealed that the species S. tumbil
prefers food in order of abundance as a teleost
fishes (41%), molluscs (9.16%), shrimps (3.64%),
crabs (1.41%) and squilla (0.37%) and S. undosquamis
prefers teleost fishes (49%), molluscs
(11%) and shrimps (3%). In S. tumbil, the highest feeding intensity observed in July
(50%) and in S. undosquamis,
in October (41%) and the lowest intensity recorded in the month of June for
both the species. Monthly Gonado Somatic Index (GSI)
shown that the highest feeding was observed in January (10.55%) and July
(10.76%) for S. tumbil
whereas, in case of S. undosquamis, the GSI was highest in August (16.58% for
males & 17.80% for females). The pieces of sand granules, detritus and
benthic organisms in the stomachs of the species indicating the benthic nature
at the sea bottom in the search of food. Occurrence of juvenile lizardfishes in gut contents of both the species indicates
that the lizardfishes are cannibalistic in nature.
Keywords: Lizardfish, feeding intensity, Gonado Somatic Index (GSI), Cannibalism
INTRODUCTION- Lizardfishes belonging to the family Synodontidae and two lizardfishes Saurida tumbil and S. undosquamis are exploited on
commercial basis in Indian waters. Food and feeding habits of fish provide the
information on the food chain in a particular ecosystem as well as prey and
predator relationship and seasonal variations in the diet composition. This
information will give the understanding on the migration patterns, abundance
and behaviour of the fish. Most of the fishes are
highly adaptable in their feeding habits and utilise
most of the richly available food [1]. Quantitative and qualitative analysis of
food provides the knowledge on the life history and would be helpful for
rational exploitation and management of commercially important species. Though,
the studies on food and feeding habits have been attempted earlier by many
researchers on many species, as changes in the environment and ecosystem taking
place due to pollution and other anthropogenic activities, these studies are
required to be attributed. The North-west coast of India covers the coasts of
Maharashtra and Gujarat. The state of Maharashtra contributes a maximum of
3.128 Million litres a day (MLD) untreated sewage
followed by Gujarat (1,522 MLD). Mumbai city is the largest populated city
ranks at number 6 spot in terms of most populated cities in the world situated
along the North-west coast of India with the current population of over 22 million people, which
the city generate around 2,160 MLD sewage per day [2]. The state of
Gujarat is one of the industrial states of India, discharges around 566 MLD of
untreated industrial effluent in the sea; contribute 33% of the total discharge
in the country whereas Maharashtra state discharges approximately 80 MLD in the
coastal waters these are affecting the food web in the sea which is very
serious [3]. It is imperative to study the food and feeding
habits of a particular region of the coast so as to derive the strategies for
conservation, management and development of these species on sustainable basis.
Research on food
and feeding habits of lizardfishes was attempted
earlier in other parts of Indian Ocean and other International Oceans [4-8]. In Indian
waters along the Bay of Bengal and Arabian Sea these studies were attempted at
various coasts [9-19].Most of the above studies are of qualitative in
nature and the research areas of the studies pertain to very limited area. The
area chosen for this study is North-west coast of Indian EEZ covering the coast
of Gujarat and Maharashtra from the Lat. 18°-23°N/Long. 68°-73°E.
The detailed investigations on qualitative and quantitative assessment of food
and feeding habits have to be attempted regularly as the changes are taking
place in the ecosystem to monitor the resources availability, abundance and
distribution so as to understand the existence of the lizardfish fishery.
Hence, this study has been undertaken.
MATERIALS AND METHODS- Month-wise data for this study was collected from
the exploratory survey vessels of Fishery Survey of India Viz. Mastya Mohini
and Matsya Nireekashani
operating in the northern coast of India and weekly data was collected from the
landings centres located in the North-west coast of
India (Fig. 1) during the period from 2010 to 2012. Eye estimation on the
fullness of stomach, occurrence method (Index of preponderance) was followed [20]. For
understanding the food habits and intensity of feeding method was employed [21]. In the
occurrence method, emphasis was laid on the occurrence of different food items
in the stomach. A total 1630 specimens of S.
tumbil and 926 specimens of S. undosquamis were analysed
for quantitative and qualitative analysis.
For quantitative
analysis, Month-wise, Season-wise, Length group-wise, Sex-wise, Percentage of
feeding intensity was derived. Month-wise data differentiated into quarter-wise
data to understand the seasonal food preferences. The qualitative analysis was
attempted based on dominance, percentage of preference of prey items in the
different months, seasons, and size groups. While attempting the above study,
sex was determined visually after cutting open the belly. The Gonado Somatic Index (GSI) was calculated by using the
formula:
GSI=
Weight of stomach/ Weight of the fish X 100
For qualitative
observations, the stomach contents were broadly classified into Teleost fishes, Molluscs, Shrimp,
Crabs, Squilla, Semi-digested matter and digested
matter.
.png)
Fig.
1: Sampling stations along the North-west coast of Indian EEZ (Study area)
RESULTS- As
per the Index of preponderance method, the main food items observed in Saurida tumbil and S. undosquamis
in order of abundance as Teleost fishes, Molluscs, Crabs and Squilla. Both the species are found carnivorous in
nature. Teleosts fishes found to be more in S. undosquamis
(49%) when compared to S. tumbil (41%). Molluscs,
Shrimps, Crabs and Squilla are found more or less
same in both the species (Fig 2-3). Food preferences in both the species
indicate that these species prefers same type of food available in the
surrounding ecosystem. Different groups/ species identified in the gut contents
of lizardfishes like Acropoma japonicum,
Acanthocepola limbata, Apogon spp., Bregmaceros mcclellandi, Coilia dussumieri, Champsodon sp., Decapterus russelli, Grammoplithes suppossitus, Harpadon nehereus, Lutjanus vittatus, Leiognathid sp., Megalaspis cordyla, Nemipterus japonicus, Nemipterus filamentosus, Platycephalus sp., Rastrelliger kanagurta, Saurida tumbil, Saurida undosquamis, Sphyraena obtusata, Trichiurus sp., Upeneus moluccensis, Sciaenids and
Carangids. Molluscans are Loligo duvaucelli and Sepia aculeata.
Crustaceans like shrimp were Acetes indicus, Metapenaeus sp., Penaeus monodon and Solenocera
sp. Crabs are Scylla
serrata and
Alima larvae, Squilla sp. remains of bivalve
shells, sand grains, detritus and mud.
.jpg)
About 26 teleost
species were identified and reported in the diet of both the species. Among molluscs, squids and cuttlefishes found to be occurring in
the diet. Four species shrimps and one species of crabs were observed during
the study. Cannibalism has been observed in both the species during juvenile as
well as adult stages as the smaller lizardfishes were
found in the diet of these species. In the guts of both the species mud, sand
grains, detritus found along with the food as these species are bottom dwelling
in nature.
Month-wise occurrence of food items
revealed that the guts of S. tumbil and S. undosquamis, the dominant food item were teleost fishes (Fig. 4-5). In S. tumbil, the highest feeding intensity
was observed in the month of April and lowest in the month of July whereas, in
the case of S. undosquamis,
the highest feeding intensity reported in the month of October and the lowest
was in the month of August.
.jpg)
In both the species, percentage of molluscs, shrimps, crabs and miscellaneous food items are
not significant. Teleost fishes are the most
preferred food identified throughout the year in both the species.
Quarter-wise variation of food items in S. tumbil
illustrates that the highest feeding intensity was in IVth
quarter (Oct-Dec) and teleosts (36%) found to be
dominated followed by 34% in IIIrd quarter
(July-Sept), 24% in Ist
quarter and 21% in IInd quarter
(Fig. 6). Molluscs found to be dominated in the IInd quarter. In case of S. undosquamis,
the highest intensity was in IVth quarter
(27%) followed by 26% in Ist
quarter. The percentage of food intensity in IInd
and IIIrd quarters was 18% in both the
species (Fig.7).
.jpg)
Feeding intensity in relation to size of
the fish emphasised that, teleost
fishes and molluscs were mostly preferred by S. tumbil and
are reported in all length groups. This species commences intake of fin-fishes
when they are at minimum length of 13.0 cm (TL) and there is gradual increase
in the percentage consumption of food items with increasing length. The diet of specimens above 21.0 cm total
length revealed that they feed exclusively on fishes, molluscs
and shrimp. The maximum feeding intensity was observed in 51-53 cm length group
and minimum was in 19-21 cm length group. Molluscs
were preferred by the fishes in between the 17-47 cm length group (Fig. 8).
Unlike S. tumbil, S. undosquamis also preferred teleosts fishes and molluscs as
food in all length groups. Molluscs were observed in
15-35 cm length group and shrimps were regularly found in 17-29 cm length
group. Crabs were exclusively observed in the fishes at the length group of
23-25 cm (Fig. 9).
.jpg)
The Gonado
Somatic Index (GSI) values (Table 1 & 2) obtained in each month for S. tumbil and
S. undosquamis
revealed that the index was found to be maximum in January (10.55%) and July
(10.76%) whereas, the female species shown the maximum index in July (9.55%) and
October (8.82%). In case of S. undosquamis, the maximum values of GSI in males were
obtained in August (16.58%) and February (13.04%) and in females, it was in
August (17.80%) and March (14.69%). The peak GSI value obtained in July for S. tumbil and
August for S. undosquamis
(Fig. 10 & 11). This indicates maximum feeding during these months.
Table 1: Gonado-somatic
index (GSI) values of S. tumbil
|
|||||||||||||||||||||||||||||||||||||||
|
|
.jpg)
.jpg)
.jpg)
.jpg)
.jpg)
.jpg)