Journal of Threatened
Taxa | www.threatenedtaxa.org | 26 August 2026 | 18(8): 29515–29520
ISSN 0974-7907 (Online) | ISSN 0974-7893 (Print)
https://doi.org/10.11609/jott.9722.18.8.29515-29520
#9722 | Received 27 February 2025 | Final received 23 June 2026 | Finally
accepted 04 August 2026
Fishermen-led documentation of
bycatch of sea snakes (Serpentes: Elapidae:
Hydrophiinae) on the Malabar coast of southwestern
India
R. Sree Vishnu 1 & S.R. Ganesh 2
1,2 Kalinga Foundation, Guddekeri, Agumbe, Shivamogga,
Karnataka 577411, India.
1 sreevishnuptpm7434@gmail.com, 2
snakeranglerr@gmail.com (correspondence)
Editor: Anonymity requested. Date
of publication: 26 August 2026 (online & print)
Citation:
Vishnu, R.S. & S.R. Ganesh (2026). Fishermen-led documentation of bycatch
of sea snakes (Serpentes: Elapidae:
Hydrophiinae) on the Malabar coast of southwestern
India. Journal of Threatened Taxa 18(8): 29515–29520. https://doi.org/10.11609/jott.9722.18.8.29515-29520
Copyright: © Vishnu & Ganesh 2026. 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: Zooreach Conservation Seed Grant (24ZCSG02H).
Competing interests: The authors declare no competing interests.
Author details: Mr. R. Sree Vishnu is a project candidate with Kalinga Foundation; and postgraduate in Marine Biology from the Kerala University of Fisheries and Ocean Studies (KUFOS) in Kochi, India and researcher with Centre for Ecological Sciences, Bengaluru. His academic work centers on marine biodiversity, classification, and the conservation of marine organisms. Dr. S.R. Ganesh is the director of research, Kalinga Foundation in Agumbe. He conducts research on reptiles and amphibians of southern India. His research themes include documenting the diversity of under-explored ecoregions, updating and refining species characterizations, and elucidating modern-day distribution patterns with respect to southern India’s herpetofauna.
Author contributions: SVR conducted fieldwork and networked with the fishing community and prepared the Malayalam version poster. SRG envisaged and developed this project and its modalities, in consultation with SVR and trained SVR initially regarding on-site project data collection.
Acknowledgements: This study was supported by Zooreach Conservation Seed Grants (ZCSG). We thank the Zoo Outreach Organisation team for positively considering and funding this project, its director Dr. Sanjay Molur and grants coordinator Ms. Trisa Battacharjee. SRG thanks the 1Ocean Program head Mrs. Priyanka Iyer and researcher Ms. Tandrali Baruah for productive academic discussions on sea snake bycatch and fishermen perceptions. We acknowledge that Dr. Kartik Shanker lab collaborations paved the way for our ventures together, especially Dr. Titus Immanuel who introduced us to one another. We thank the fishermen of Karnataka harbours for sharing snake photos that are reproduced here. We thank Drs. S. Suresh Kumar and Limna Mol, KUFOS (Kochi), Sujitha Thomas, CMFRI (Mangalore), P. Padmanabhan, ZSI/MBRC (Chennai), and V. Deepak Samuel, NCSCM (Chennai) for their suggestions on some aspects of the project. We are grateful to the founder director and trustees of our organisation Kalinga Foundation for encouraging our research activities. Thanks to G. Pradeep for Kannada translation.
Abstract: Sea snakes are prominent among
marine fishery bycatch and few studies have examined the gravity of this
problem in Indian coastline fisheries. We examine sea snake bycatch on the
Malabar Coast in southwestern India during a study period from September 2024
to January 2025 that was conducted in eight harbours
in southern Karnataka and northern Kerala over a 15-week period. Sea snake
bycatch photos were obtained directly from fishermen aboard vessels, and among
22 photos we identified three sea snake species: Short Sea Snake Hydrophis curtus (13
dead, 4 live), Annulated Sea Snake H. cyanocinctus
(4 dead), and Hook-nosed Sea Snake H. schistosus
(1 dead). We also interacted with fishermen and shared e-posters on sea snake
bycatch issues during awareness outreach efforts in the study area.
Keywords: Awareness outreach, dead snake,
fishermen, Karnataka, Kerala, Indian coastline fisheries, live snake, photo
sharing, posters, snake bycatch.
Introduction
Marine bycatch refers to the
incidental death and debilitation of marine life that is not within the legal
remit of regulated fisheries (Davies et al. 2009). Marine bycatch of non-target
fauna and their consequent entanglements lead to unnecessary mortality
(Salagrama 1998; Mahesh et al. 2017, 2019). This problem is poorly studied for
Indian coastal fisheries (Dineshbabu et al. 2022),
especially those involving deep-sea trawling (Dineshbabu
et al. 2010, 2012, 2014). Depletion of marine biodiversity is a widespread
anthropogenic threat (Kumar & Deepthi 2006; Velip
& Rivonker 2015; Madhu et al. 2017), and studies
aimed at finding solutions are sparse (Azeez et al. 2021). Commercialisation
and non-human consumption of bycatch are reported to be directly incentivising intensive fishing (Lobo et al. 2010; Aulia et al. 2024).
Sea snakes are commonly
encountered air-breathing fauna that drown in submerged nets cast for fishing
operations (Dsouza et al. 2021; Rao et al. 2021; Jana et al. 2024; Ganesh et
al. 2026). The Indian coastline is home to 20 species of front-fanged, marine
elapid snakes of the subfamilies Hydrophiinae, the
true sea snakes, and Laticaudinae, the sea kraits
(Ganesh et al. 2019). Sea snakes are not target species of fisheries as they
are neither suitable for human consumption nor for poultry feed, hence snake
bycatch is typically discarded. Sea snake bycatch is not well-studied in
general, and little is known about this issue on the western Indian coast
(Kumar et al. 2007; Iburahim et al. 2019; Patel et
al. 2022, 2024). To this end, we studied the frequency of sea snake bycatch in
Malabar Coast, southwestern India and conducted awareness drives in attempts to
improve the situation.
MATERIALS AND METHODS
Study Area
The study was conducted on the
Malabar coast of southwestern India, politically covering parts of Kerala and
Karnataka state jurisdictions, with sampling sites extended across Chombala harbour (Kannur
District, Kerala) to Malpe harbour
(Udupi District, Karnataka), across a distance of about 230 km (Table 1; Image
1). Samplings were concentrated in eight harbours
(south to north) namely: Chombala, Mahe, Thalassery, Kannur, Nileshwaram, Kasaragod, Mangalore, and Malpe
harbours.
Field Surveys
From September 2024 to January
2025, for five months, field surveys were conducted on the Malabar Coast,
southwestern India, focussing on sea snake bycatches.
A total of 15 weeks of field surveys were conducted across all the eight harbours. One and a half to two weeks with 2–3 hours per
day were spent on field surveys in each harbour,
based on the spatial expanse of harbour, fishing
intensity, fishermen visitations and boating frequencies. We networked with
fishermen to source photos of sea snakes on board and to circulate local
language (Malayalam, Kannada) posters depicting awareness messages on sea
snakes. Sea snake species were identified from photographs received following
Ganesh et al. (2019).
RESULTS
During this five month-survey,
lasting for 15 weeks of field days in eight harbours,
we interacted with 141 fishermen and shared posters on 47 occasions. We also
obtained photographic records of sea snake bycatches amounting to a total of 22
sightings comprising three species namely: Short Sea Snake Hydrophis
curtus (n = 17), Annulated Sea Snake Hydrophis cyanocinctus
(n = 4), and Hook-nosed Sea Snake Hydrophis schistosus (n = 1). Details of the awareness and
photographic data collection aspects are detailed in the following.
i. Sea snake bycatch (Table 2;
Image 2)
From all the harbour
visits and awareness drives on sea snake bycatch, we received photographic
records of a total of 22 bycatch of sea snakes, both dead and alive, from two harbours namely Malpe and
Mangalore, both in Karnataka. Based on the photographs received from the
fishermen, it was found that Hydrophis curtus was the most dominant species here, commoner
than both Hydrophis cyanocinctus
and Hydrophis schistosus.
There were no records of sea snake bycatches based on the photographs shared by
the fishermen, from all the six harbours in Kerala.
Only those in the two harbours in Karnataka, shared
sea snake photos. Just 1 (H. cyanocinctus)
photo record was from Mangalore while the remaining 21 were all from Malpe harbour. The fishermen we
engaged with used siene nets, gill nets, and cast
nets usually deployed for half a day at roughly 0.7 km depth. About one fifth
of the snakes that got caught were alive, while the vast majority were dead, as
seen in the photos shared and also stated by fishermen. In Malpe,
a case of mass mortality, with 10 dead snakes belonging to two species (H. curtus, H. cyanocinctus), was
noted. The sea snakes caught in the bycatch all appeared to be adults,
approaching 1 m in total length, as deduced from the photographs. To the best
of our knowledge, no evident injuries could be seen on the snakes from the
photographs.
ii. Awareness Events with Posters
(Table 3)
During the interactions, many fishermen
misidentified eels as sea snakes, especially the younger inexperienced people.
They noted that they greatly benefited from the posters and photographs of the
marine snakes shown during the discussions. Many fishermen were unaware of the
toxic and venomous nature of sea snakes and their differences in appearance
compared to other marine snakes like acrochordids and homalopsids,
both of which have normal tapering cylindrical tails just like any other snake.
A total of 141 fishermen were
interviewed and posters were shared with 47 fishermen across the different harbours. The number of fishermen interactions per harbour ranged from 6 (4.2%) in Kasargod
harbour, to 49 (34.7%) in Thalassery
harbour; and that of poster shares per harbour ranged from 2 (4.2%) in Kasargod
to nine (19.1%) in Mangalore. There were differences in the maximum numbers of
both the aspects studied. The maximum number of fishermen that were interacted
with by our team were 49, while the second and third highest ones numbered less
than half the first value (i.e., n = 21, 20). During interactions, the
fishermen reported no sea snake bite instances at least within the last three
decades, in the sampled areas.
The maximum percentage of
fishermen community that engaged with the awareness posters was at Mangalore harbour (19.1%), followed by Chombala,
Mahe, and Nileshwaram
(17.2% each), with the lowest at Kasargod (4.2%)
(Table 3). The numbers of poster shares were rather constant, with the topmost
one logging nine shares, while the second and third highest ones were
comparable values with marginal differences (n = 8, 6). One third (47 out of
141; 33.33%) of the fishermen engaged with the survey team well enough and
shared contacts to enable mutual sharing of posters and bycatch photos. Despite
the limited time allocated to each harbour (< 2
weeks), and the first-time contact of the survey team with the fishermen
community, it is remarkable to get an engagement level 33.33%. There was no
direct positive correlation between the harbours
having the highest interviewees, poster shares, and sea snake bycatch photo
shares.
DISCUSSION
Kumar et al. (2007) reported
Cochin Banded Sea Snake H. ornatus from
central and southern Kerala Coast and Palot &
Radhakrishnan (2010) recorded Yellow-bellied Sea Snake H. platurus from northern Kerala. There is a record of Viperine Sea Snake H. vieprinus
from the northern Karnataka Coast (Mondal et al. 2023). However, in our study, these species were not
recorded. During our survey we found, H. curtus
was the commonest among the three species that we recorded during the study. Padate et al. (2009), Dsouza et al. (2021), and Rao et al.
(2021) reported H. schistosus to be more
common than H. curtus in Goa and the northerly
Malvan beach, of southern Maharashtra, in Konkan
Coast, respectively. However, Lobo et al. (2004) reported that H. curtus outnumbered the records of H. schistosus, from studies done in the more northern
coast of Goa.
Kumar et al. (2007) studied sea
snake bycatches associated with trawl fisheries in five harbours
in central and southern Kerala Coast and reported 62 instances of four species,
as follows: H. schistosus (n = 43), H. cyanocinctus (n = 10), H. ornatus
(n = 1), and H. curtus (n = 8). This is
perhaps one of the very few studies that reported other snake species, apart
from H. schistosus and H. curtus. A study was done on the trophic ecology of H.
curtus in Goa Coast (Lobo et al. 2005). As for H.
schistosus, three studies, one from Kerala (Jeyabaskaran et al. 2015), one from Goa (Tambre et al. 2020), and one from south Maharashtra (Dsouza
& Rao 2021) coasts reported this species. Dsouza & Rao (2021) even
remarked that H. schistosus to be a rather
resilient species as regards the bycatch problem, based on their sampling in Malvan beach. These studies were done in beaches situated
further north of Malabar Coast and it is understandable to get varied results,
given the inter-regional variations.
Some studies on sea snake
bycatches have been conducted in northern (Patel et al. 2022, 2024) and
southern parts (Padate et al. 2009; Tambre et al. 2020; Dsouza et al. 2021; Dsouza & Rao
2021; Rao et al. 2021) of Konkan Coast and southern part of Malabar Coast
(Kumar et al. 2007; Jeyabaskaran et al. 2015). To the
best of our knowledge, there is no such study from northern part of Malabar
Coast covering southern Karnataka and northern Kerala. Those that exist are not
based on bycatch problems of sea snakes but generally on sighting records.
Citizen science posts of sea snakes also reported the same three species, viz.,
H. schistosus, H. curtus
and H. cyanocinctus from southern
Karnataka–northern Kerala coasts (Blessy & Ganesh
2026). Hence this study fills the void in research bycatch kills of sea snakes.
This study gathered insights into
the status of sea snake bycatch and local perceptions of it. The one case of
mass mortality involving the commonest species H. curtus
and a rarer species H. cyanocinctus constituting
over 10 dead snakes within a single net, raises conservation concern. As our
major focus during the present survey was to make first-time contact and create
awareness among the fishermen community regarding sea snakes and their
mortality in marine bycatch, we did not collect morphometric data, the gender,
the reproductive status nor the presence of young ones inside the dead snakes.
More data on net type, haul duration would also hint of their potential
correlation if any with the bycatch. More such studies on sea snake bycatch and
awareness drives need to be conducted along the coastline of India for the
conservation of sea snakes and other fauna that get into the marine
bycatch.
Table 1. Sampling sites of the
eight harbours in Malabar Coast, Kerala and
Karnataka, India.
|
Harbour name |
District, State |
Latitude °N |
Longitude °E |
|
Chombala |
Kannur, Kerala |
11.6658 |
75.5500 |
|
Mahe |
Puducherry, Puducherry |
11.7022 |
75.5311 |
|
Thalassery |
Kannur, Kerala |
11.7351 |
75.5006 |
|
Kannur |
Kannur, Kerala |
11.8574 |
75.3726 |
|
Nileshwaram |
Kasargod, Kerala |
12.2145 |
75.1160 |
|
Kasaragod |
Kasargod, Kerala |
12.4772 |
74.9832 |
|
Mangalore |
Dakshina Kannada, Karnataka |
12.8508 |
74.8335 |
|
Malpe |
Udupi, Karnataka |
13.3482 |
74.6958 |
Table 2. Details of dead and live
sea snakes recorded as bycatches in sites where seen.
|
Site/Snake species |
H. curtus |
H. cyanocinctus |
H. schistosus |
|
Mangalore live |
0 (0%) |
0 (0%) |
0 (0%) |
|
Mangalore dead |
0 (0%) |
1 (4.5%) |
0 (0%) |
|
Malpe live |
4 (18.1%) |
0 (0%) |
0 (0%) |
|
Malpe dead |
13 (59.0%) |
3 (13.6%) |
1 (4.5%) |
Table 3. Details of the fishermen
interacted and posters shared in each site.
|
Harbours surveyed |
No. of weeks surveyed |
No. of fishermen interacted (in
%) |
No. of posters shared (in %) |
|
Chombala |
1.5 weeks |
21 (14.8%) |
8 (17.2%) |
|
Mahe |
1.5 weeks |
20 (14.1%) |
8 (17.2%) |
|
Thalassery |
2 weeks |
49 (34.7%) |
6 (12.7%) |
|
Kannur |
2 weeks |
12 (8.5%) |
4 (8.5%) |
|
Nileshwaram |
2 weeks |
12 (8.5%) |
8 (17.2%) |
|
Kasargod |
2 weeks |
6 (4.2%) |
2 (4.2%) |
|
Mangalore |
2 weeks |
13 (9.2%) |
9 (19.1%) |
|
Malpe |
2 weeks |
8 (5.6%) |
4 (8.5%) |
|
Total: 8 sites |
15 weeks |
141 |
47 |
For
images - - click here for full PDF
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