Journal of Threatened Taxa |
www.threatenedtaxa.org | 26 January 2022 | 14(1): 20511–20516
ISSN 0974-7907
(Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.7652.14.1.20511-20516
#7652 | Received 08
September 2021 | Final received 12 October 2021 | Finally accepted 02 January
2022
Distribution of Smooth-coated
Otters Lutrogale perspicillata
(Mammalia: Carnivora: Mustelidae): in Ratnagiri,
Maharashtra, India
Swanand Patil 1 &
Kranti Yardi 2
1 Arcane Conservancy
(www.arcaneconservancy.org/home , A/207 Saikrupa BS
Road, Dadar West, Mumbai, Maharashtra, 400028, India.
1,2 Bharati Vidyapeeth Deemed
University Institute of Environment Education and Research, Pune, Maharashtra
411043, India.
1 swanandpatil6@gmail.com
(corresponding author), 2 kranti@bvieer.edu.in
Editor: Nicole Duplaix, Oregon State University, Corvallis, USA. Date of publication: 26 January 2022
(online & print)
Citation: Patil,
S. & K. Yardi (2022). Distribution of Smooth-coated
Otters Lutrogale perspicillata
(Mammalia: Carnivora: Mustelidae): in Ratnagiri,
Maharashtra, India. Journal of Threatened Taxa 14(1): 20511–20516. https://doi.org/10.11609/jott.7652.14.1.20511-20516
Copyright: © Patil
& Yardi 2022. Creative Commons Attribution 4.0 International License. JoTT allows
unrestricted use, reproduction, and distribution of this article in any medium
by providing adequate credit to the author(s) and the source of publication.
Funding: None.
Competing interests: The authors
declare no competing interests.
Acknowledgements:
We would like to express our gratitude to Atul S. Borker
for his support and expertise. We would also like to thank Nikit
Surve for providing us camera traps. We would also
like to thank locals of Anjarle village for helping
us throughout the project. Last we would like to thank you family members for
supporting this entire research.
Abstract: This report describes the
distribution of Smooth-coated otters in Ratnagiri, Maharashtra, and
investigates the utility of scat counts for quantifying otter occurrence. The
study duration was from February to June 2020. Surveys were conducted along the
Jog River in Anjarle and Aade
River in Aadekond using camera traps. The results
subjected to principal component analysis indicated that the occurrence of
Smooth-coated Otters at Anjarle is 76% and at Aadekond 48%. We
also mapped the distribution and threats associated with Smooth-coated Otters.
This study serves as a baseline for efforts
to support long-term otter research and conservation.
Keywords: Anjarle,
conservation, distribution, Otter, scat counts, status, threats.
Otters are prime indicators of
the status of wetland ecosystems, where they are often the key predators.
According to the IUCN Red List, the conservation status of the Smooth-Coated Otter
Lutrogale perspicillata
is ‘Vulnerable’ (Image 1). It is listed in the CITES under Appendix I,
and in India, it is a Scheduled II species under the Wildlife (Protection) Act,
1972, which prevents/prohibits any person from hunting, trapping, trade of its
products and killing of the species.
In Maharashtra, otters have been
largely overlooked, and with growing concerns over deforestation, the shrinking
of wetlands, and the constant conversion of wetlands for development, the focus
needs to be shifted to small carnivores like otters. This paper aims to provide
scientific data on the distribution and status of otters in Anjarle,
Ratnagiri. Spraint/ scat surveys have been widely used and provide a reliable
picture to assess the distribution of otters (Mason & Macdonald 1987).
However, direct observations and counting individuals are difficult especially
since the Smooth-coated Otter is both elusive and has a large home range. For
such species, indirect field census methods (Tracks, scat, territory marking sites,
dens) have been developed to estimate their distribution, and their population
trends (Wilson & Delahay 2001; Sittenthaler et al. 2020).
Methods
Study area
Ratnagiri is a district situated
on the western coast of Maharashtra, having nine talukas (townships). Being
open to the sea, it has a large population dependent on fishing for their
livelihood. Our selected field site for
research on otters is Anjarle (17.846N & 73.087E)
(Image 2), a small village situated in Dapoli Taluka.
It is more significant for wildlife than other talukas, as the Anjarle beach is a nesting site for Olive Ridley Sea
Turtles Lepidochelys olivacea
(Image 3). Every year, tourists flock to see the hatchlings going into the
sea.
Part of the local population is
aware of the otters and their whereabouts; however, knowledge of otters is
scarce amongst the general population in India, and the villagers and tourists
coming to Anjarle are no different.
Scat surveys have become the
method of choice to monitor species distribution, population trends, and
habitat use (Sittenthaler et al. 2020). The total
length of the Jog River, about 33.3 km, and the Aade
River, about 10.62 km, was digitized using Google Earth and QGis;
2.5 km survey grids were placed on the river.
In each grid, a transect was
done; in each transect was of 50 × 250 m (left and right bank of the river) was
used. Six survey replicates were conducted in each grid (Mason & Macdonald
2009; Borker 2014).
Surveys were carried out from
February to June 2020, as the summer season is the best time to survey otters,
as sightings and otter signs are easier to detect. During transects surveys,
otter signs (pugmarks, grooming sites, holts/dens) were recorded. GPS
essentials were used to mark the latitude and longitude of any otter sign. Plots
with otter signs were considered as ‘used plot’ and plots adjacent to that
(upstream and downstream) were termed ‘available plot’ (this is done to reduce
the dependency of plot use).
A plot was only considered a ‘new
plot’ if otter signs are present, and there was a 5 m or more distance between
the new and old otter signs. Camera trapping was used to record species
identification (Image 5, 7; Video 1), but mostly focused on otter
activity and group size (Mudappa et al. 2012; Khan et
al. 2014; Prakash et al. 2014).
Identifying the current status of
otters
Threats faced by otters were
visually identified and recorded during the surveys. These threats were taken
into account during the analysis, which acted as covariates to measure impact
on distribution.
Data analysis
It was assumed (Foster-Turley
1992; Barrios 2020) that otters in human-modified areas would be nocturnal or
crepuscular, and that this would create difficulty in using direct observation
to estimate occupancy. As a result, distribution and frequency of spraint and
tracks (indirect signs) were used. To estimate the percentage of area occupied
by otters, we used principal component analysis (PCA) coupled with logistic
regression with forward stepwise analysis. Scores of those were considered as
the percentage of occurrence of otters.
Results
The estimated length of the Jog River surveyed
is about 33.3 km starting from Sondeghar, flowing to Matwan to Sakurde to Bandhativare to Sarang to Tadil
to Kongale to Murdi, and
ending into Anjarle (Arabian Sea) on the western
Coast of Maharashtra, India. The estimated proportion of the length of Jog
River occupied by Smooth-coated Otters was 76.2% based on our sign survey as
shown in Figure 1.
The estimated length of the Aade River surveyed is about 10.6 km starting from Aade to Adekond to Lonvadi to Borthal dam. The
estimated proportion of the length of Aade River
occupied by Smooth-coated Otters was 47.6% based on our sign survey as shown in
Figure 2.
Threats to the Otter population
Habitat loss: For otters,
the requirement to breed, rest, and defecate is vital. In our study area, these
roles are carried out within the mangrove forests. Places like sandbanks, soil,
or even leaf litter act as grooming and defecation areas for otters along the
river banks. Such areas are in decline owing to illegal sand mining and
increasing conversion of wetlands into agricultural areas (Image 6).
Sand mining poses a direct threat
to habitat of many species, as uncontrolled extraction of benthic sand from
rivers (Image 6) and from riverbanks leads to an increase in water depth, loss
of prey base, and habitat degradation and loss. Some stretches of the rivers
are completely degraded because of sand mining.
Otter-fisherman competition
In certain areas with high fish resources,
high fishing activity and high otter activity have been observed, showing a
positive correlation of 0.663 with otter presence (Table 1).
These are potential otter
conservation zones, but measures need to be taken to ensure fishermen who are
dependent on the particular zone are provided with some alternative, or that
sustainable methods that allow otters to coexist are adopted
Discussion
Otters are widely distributed in Anjarle and Aadekond, and a
survey of spraints using standard methodology gives a reliable picture of otter
distributions. According to informal interviews, food-rich zones are prime
areas for otter-fisherman interactions (Figure 3). During informal interviews
within the village community, a person had killed an otter using stones and
wooden logs, as his only source of income was harvesting mud crabs and fishing.
Such instances are rare, but help us understand the attitude of small-scale
fishermen towards otters. Due to habitat fragmentation and degradation,
unsustainable fishing practices and lack of awareness are such parameters
responsible for the decline in the population of Smooth-coated Otters. There is
limited or no data on otter research and conservation within the forest
department.
According to otter surveys
conducted, a considerable amount of otter distribution lies outside the
protected area, which emphasizes the need for integrating the management of
human-modified land with the management of protected areas (DeFries
et al. 2010).
Conclusion
Though this is a preliminary
study, baseline data was created to guide future otter conservation efforts in
Ratnagiri, facilitated by Arcane Conservancy, an NGO for long-term research and
conservation to improve the protection of otters.
Table 1. Table showing positive
correlation of 0.663 between otter and fishing activity,
|
Correlations |
|||
|
|
Fishing activity |
Otter sign |
|
|
Fishing_Activity |
Pearson Correlation |
1 |
.663** |
|
Sig. (2-tailed) |
|
.000 |
|
|
N |
54 |
54 |
|
|
Otter_Sign |
Pearson Correlation |
.663** |
1 |
|
Sig. (2-tailed) |
.000 |
|
|
|
N |
54 |
54 |
|
|
**. Correlation is
significant at the 0.01 level (2-tailed). |
|||
For
figures & images - - click here
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