- The coast of Odisha is home to two of the three horseshoe crab species found in Asia — the coastal horseshoe crab and the mangrove horseshoe crab.
- Globally recognised as living fossils, horseshoe crabs are valued for their medicinal properties. In India the species is included in Schedule IV of the Wildlife (Protection) Act 1972.
- However, shoreline alterations, sea level rise that affects their spawning habitats, and destructive fishing practices that lead to the crabs becoming bycatch, threaten the population of the species.
- Scientists and conservationists working on horseshoe crabs have urged the government to develop a robust protection mechanism for the conservation of these living fossils.
The northeastern coast of Odisha has been home to the horseshoe crab, a globally recognised living fossil, as its basic form has remained nearly unchanged over millions of years. Within the state reside two of the four species worldwide: the coastal horseshoe crab (Tachypleus gigas) and the mangrove horseshoe crab (Carcinoscorpius rotundicauda). The horseshoe crabs in the state are found along the northeast coast of Balasore and Kendrapara districts, with sporadic nesting grounds at several coasts.
However, the sites that once witnessed the nesting of these species, now hardly see any horseshoe crabs, and their numbers are steadily declining. Despite concerns about the diminishing population being raised in the past, little to no measures have been implemented to safeguard the species.
Talking to Mongabay-India, a former scientist at the Wildlife Institute of India (WII), and a trustee of the Wildlife Trust of India (WTI), BC Choudhury says, “We have informed the government about this time and again, but there are hardly any steps being taken in this direction.” BP Dash, a professor at Fakir Mohan University in Balasore, echoes the same thoughts, and shares that they have met with officials in the forest and marine departments several times since 2016. Some funds were raised for research work in 2017, but nothing significant has happened since then.
Based on his year-long experience of visiting breeding sites, Anil Chatterji, a former scientist at the National Institute of Oceanography also notes that the number of horseshoe crabs is rapidly decreasing and emphasises the urgent need for intervention.
After several in-person consultations in the last few years and with no concrete action on the ground, they decided to write letters to the central and state governments to take immediate and necessary steps for its conservation.
Call for action
In a letter sent in July via email, scientists and conservationists working on horseshoe crabs have urged the central and the Odisha state governments to immediately develop a robust protection mechanism for the conservation of living fossils and devise a species recovery plan. A species recovery plan enlists the management activities required to halt or reverse the decline in a threatened species population.
If the state wildlife organisation in Odisha doesn’t take action, the horseshoe crabs, which used to be in large numbers, could disappear in the state. Only a few remaining populations might be left in West Bengal and some parts of Andaman and Nicobar. A similar letter was written in March, but to no avail. In the letter, the experts have suggested the government to ensure breeding grounds remain undisturbed.
The letter claims that an official from the Odisha State Biodiversity Board has discovered a breeding population of horseshoe crabs at a different location along the Balasore coast, which has not been disturbed. And that it might be essential to revisit this new breeding ground before destructive fishing practices encroach, and consider declaring the area a conservation reserve to safeguard the species.
Dash from Fakir Mohan University in Balasore, reflects on how they used to see small estuaries covering an area of 8,000 square metres in with good conditions for breeding in the early 2000s. Over the years, this area has reduced to 25-30 square metres, and human activities have increased. Ensuring these breeding grounds are undisturbed will help manage the population of horseshoe crabs.
However, the Odisha state government has not yet put a plan in place to conserve the species. When contacted, a senior official from the forest department who wishes to remain anonymous said, “We are aware of the issue. This needs a detailed roadmap for assessment and understanding of what can be done. Some research work in the area is already being undertaken.”
Global call for conservation
Horseshoe crabs, considered distant relatives of spiders, have endured for over 450 million years. Valued for their medicinal properties, these blue-blooded crabs play a vital role in medical sciences and biomedicine. The blood of horseshoe crabs can clot in the presence of bacteria, rendering them harmless. This clotting ability has been extensively utilised in testing injectable medicines, vaccines, and sterile medical equipment, including its recent use in Covid-19 vaccines.
Beyond their blood, the outer layer of horseshoe crabs consists of chitin, enhancing wound healing and serving as a crucial component in treating severe wounds like burns.
Highlighting the essential role of horseshoe crabs in coastal biodiversity, the International Union for Conservation of Nature (IUCN) noted in 2020 that two Asian horseshoe crab species will soon be added to the IUCN Red List. The American horseshoe crab (Limulus polyphemus) was already listed as Vulnerable in 2016, and the tri-spine horseshoe crab (Tachypleus tridentatus) was termed endangered in 2019.
Came into the scene in 2012 due to the growing concerns about horseshoe crab conservation worldwide, the IUCN Horseshoe Crab Specialist Group (SSG) is also pursuing the possibility of designating horseshoe crabs as the first “World Heritage Species” under the UNESCO World Heritage Programme.
Additionally, in 2020, the IUCN SSC Horseshoe Crab Specialist Group formally designated June 20 as International Horseshoe Crab Day annually. This day is dedicated to showcase collective conservation efforts for the four horseshoe crab species.
During the IUCN SSC Horseshoe Crab Specialist Group international workshop in Guangxi, China, in June 2019, participants from 14 countries and regions endorsed the Beibu Gulf Declaration on Global Horseshoe Crab Conservation. This declaration calls for strengthened policy-making and enforcement, increased scientific research, sustainable horseshoe crab management, restoration of natural populations, protection of critical habitats, and the promotion of public and multi-party participation in horseshoe crab conservation.
Destructive fishing along the Odisha coast: an imminent threat
According to the IUCN, “The world’s horseshoe crab populations are imperiled because of overharvesting for use as food, bait, and biomedical testing and because of habitat loss from coastal reclamation and development. Shoreline alterations that are engineered to protect beaches from erosion and sea level rise due to climate change also affect their spawning habitats.”
In India, the horseshoe crab was included in Schedule IV of the Wildlife (Protection) Act 1972 in 2009. This inclusion means that catching and killing a horseshoe crab is an offence.
However, scientists and researchers claim that destructive fishing practices, poaching, and changes in climatic conditions have all adversely affected the species population.
“Over the years, fishing practices have changed. The fishermen now use wide nets mounted on bamboo sticks during low tide. These nets catch everything, including the crabs that are harvested or killed. In some instances, they are also poached for their shells. But these activities continue unabated. These need checks and balances,” said Choudhury.
“These unregulated activities affect the spawning activities. Throughout the year, there is a sporadic movement of the horseshoe crab to the shore for breeding. Through our fieldwork, we have noticed that the horseshoe crabs have found new breeding grounds, but the numbers are still very low. But it is important that the eggs being laid are also protected. Because of its importance, the focus was always on harvesting and never on conservation. This has only deteriorated the condition,” he added.
Chatterji also reflected on his experience of the dwindling population. “Back then in late 90s and early 2000s, the population was pretty high- around 40 specimens in a 200 square metres area. But we hardly found any species during my recent visit,” he said.
However, as fishing remains a primary source of income for the coastal communities in Odisha, addressing this threat also requires due consideration for the livelihood of the fishing communities.
“We have always urged the concerned departments that conservation intervention should begin at places where livelihood activities are minimal or non-existent. The coastal communities living along the coast should also be made aware of the importance of the species and why they should conserve it,” Dash said.
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Banner image: Horseshoe crab in the Sundarbans. The species also referred to as the living fossils have survived over 400 million years. Photo by David Raju/Wikimedia Commons.