Threatened species and critical ecosystems | WWF India

The International Union for the Conservation of Nature (IUCN) has listed over 90,000 marine species in their Red List of Threatened Species. At WWF-India, we work to mitigate fishery-related mortality to priority marine species, such as sharks, turtles and cetaceans. Bycatch refers to fish or other marine animals such as cetaceans, turtles and sharks that are unintentionally caught during fishing. Non-selective fishing gear can exacerbate bycatch, leading to wastage of produce and potentially disrupt reproduction cycles when juveniles get caught. Over a period of time, this leads to depletion of the fish population in the area. WWF-India also works to monitor and address the issue of unsustainable shark harvests and illegal trade of shark products and explores alternative approaches for managing marine conservation areas.  

To protect marine species, preventing and reversing degradation of the habitats they occupy is critical. Marine ecosystems in India such as coral reefs, mangroves and wetlands are either quickly degrading or are under severe threat of degradation. For instance, global demand for shrimp has resulted in mangroves being rapidly cleared for shrimp farming. The saline and climatic conditions as well as natural occurrence of wild shrimp larvae make mangroves the ideal habitat for shrimp farming[1]. With a large proportion of the world’s mangroves present in developing or underdeveloped countries, shrimp farming provides a welcome and promising livelihood, and India is no exception.

MITIGATING BYCATCH OF SHARKS IN TRAWL NETS

Considered one of the world’s deadliest predators, sharks seem to have met their match in human beings. Sharks populations grow slowly, with pups taking years to mature. Once they reach maturity, sharks give birth to few young at a time, and have long reproductive cycles. Slow reproduction means that shark populations need to be given enough time to recuperate when fished.

India has a rich diversity of over 160 species of sharks and rays known to occur in its commercial fishing zone. Only ten of these species (Whale shark, Knifetooth sawfish, Pondicherry shark, Gangetic shark, Speartooth shark, Ganges stingray, Green sawfish, Giant guitarfish and Porcupine ray) are protected under the Wildlife Protection Act (WPA, 1972). Additionally, four species of sharks (Oceanic Whitetip sharks, Scalloped Hammerhead sharks, Great Hammerhead sharks, Smooth Hammerhead Sharks,) and two species of rays are listed in Appendix II of CITES that commonly occur in India’s commercial fishing zone. 

Sharks constitute an important component of commercial fisheries in Indian waters, and India ranks third highest globally for total shark landings (FAO 2016). The mechanization of fisheries, coupled with an increased international demand for commodities, such as shark fins and ray gill plates, has led to an increase in the number of sharks and rays being fished. While there has been an international movement to dissuade trade in such commodities, local demand for shark and ray meat continues, and has even increased in recent years. Unregulated fishing clubbed with the biological characteristics of these species, make the group particularly vulnerable to overfishing leading to questions regarding the sustainability of shark and ray fisheries in India.

India has been identified as a global priority for improving fisheries sub-strategy in WWF’s Global Priorities for Conserving Sharks and Rays. Incidental catch from the mechanised sector has been identified as a large source of subadult and juvenile mortality in the country. Trawl nets, off-shore large gill net operations and longlines operated by the mechanised sectors contribute to 71% of all shark landings in India. Approximately 60% of rays and 72% of shark catches are landed from trawls.  WWF-India is working in Veraval, Gujarat to understand the shark biodiversity in the state’s waters, and their interaction with trawl gear. We’re looking to develop viable solutions to address bycatch of juvenile sharks in the area.

Mapping cetacean occurrence and bycatch in Indian waters

Whales, dolphins, and porpoises have long been a magnificent part of the wildlife in India’s coastal waters, some of them even being revered by Indian fishing communities.

© Abhishek Jamalabad/WWF India

These marine mammals, however, also share the oceans with a large and growing  number of fishing operations that sometimes inadvertently capture them and threaten their populations. While cetaceans are not popularly caught for meat and are illegal to hunt in India, significant numbers of whales and dolphins get caught in fishing gear - globally, as well as in India. A selective study conducted by the Central Marine Fisheries Research Institute (CMFRI), in 2008, suggested from harbour landings alone that the cetacean bycatch from gill nets, in Indian waters, is estimated to be between 9000-1000 per year - but better estimates of that is lacking.

WWF-India has initiated the collection of baseline data from a network of fisher groups along the Indian west coast. We are working to bridge information gaps regarding cetacean interactions with fishing gear, an important step for informed conservation decisions in the future.

Addressing Turtle bycatch along the East Coast of India

© WWF India

Did you know?
Five species of turtles are found in India, Olive Ridley (Lepidochelys olivacea), Green (Chelonia mydas), Hawksbill (Eretmochelys imbricata), Loggerhead (Caretta caretta) and the Leatherback (Dermochelys coriacea).

Five of the seven species of marine turtles found in India are listed as endangered under Schedule I of the Indian Wildlife (Protection) Act, 1972 and in Appendix I of CITES. The shores of Odisha in particular are home to one of the largest nesting sites of the popular Olive Ridley turtles. Every year around May, thousands of turtles come to the Garhimatha and Rushikulya, in what is referred to as an arribada, a mass nesting of turtles. Sporadic nesting has been documented in Andhra Pradesh, Tamil Nadu, Kerala, Goa Maharashtra and Karnataka.

Turtle bycatch in non-selective fishing gear is a major threat to these marine reptiles. Trawl nets used in fishing have a tendency to trap everything in their path, including turtles. With trawling lasting for 2-3 hour stretches, trapped turtles are unable to surface for air and often drown. During the migration season, a single trawl net fishing along turtle migratory paths could cause multiple casualties and significantly threaten turtle populations.

While turtle mortality due to fishing is largely under-documented, conservative estimates indicate that turtle bycatch mortality due to trawl fisheries along the Odisha coast might be up to 10,000 individuals annually (Shanker pers comm). Additionally, a perception survey conducted by WWF-India among trawl operators indicates that turtle bycatch in trawl nets along the coast of Odisha is likely upto 20,000 individuals annually. High turtle bycatch mortality rates have been reported from Andhra Pradesh and Tamil Nadu, as well (Rajgopalan et al. 2008). The Convention on Biological Diversity has identified the Bay of Bengal as a migratory corridor for Olive Ridley marine turtles and as an Ecologically and Biologically Sensitive Area (EBSA) for turtles in India.

WWF-India is working to drive a  reduction in marine turtle bycatch mortality in the tropical shrimp trawl fishery in Odisha, India over the next few years. We are currently engaging with coastal communities to create self-sustained momentum for Olive Ridley conservation and with fish workers, to ensure that Turtle Excluder Devices (TED) are used while trawling.

TEDs or Turtle Excluder Devices are scientifically designed bycatch reduction devices that can be attached to trawl nets to allow turtles to escape during trawling operations. This lowers the risk of turtles drowning in these nets. WWF-India is working with fishing communities to understand existing concerns with regard to turtle conservation and TED adoption in order to help design conservation activities that address these issues and facilitate harmonious coexistence.

While efforts are being made to reduce turtle bycatch, it is also important to develop a system for monitoring the off-shore population of Olive Ridleys. We are also working to develop a community monitoring initiative that will encourage coastal communities to report turtle sightings in offshore waters. A well-established monitoring system will assist in understanding the migratory routes of Olive Ridley sea turtle populations, to help facilitate more informed conservation and fishery-management decisions.

Marine intertidal habitats

© Tabitha Kuruvilla/WWF India

Marine habitats are often difficult to access and study, and have been largely left out of the conservation dialogue in India. Although more attention has recently been given to some marine habitats and species (such as coral reefs, cetaceans and commercially exploited species), the intertidal zone of seashores remains largely ignored. Intertidal zones are areas along the shoreline that are exposed to air during low tide and submerged during high tides. These zones offer a rare opportunity for people to interact with marine wildlife. Rocky intertidal zones in particular are rich in biodiversity.

WWF-India is working to build knowledge on rocky intertidal biodiversity, by cataloguing biodiversity, identifying threatened and protected species, and assessing threat levels in key sites. The information gathered through citizen science initiatives, with ecological training, will lead to robust information that can not only raise awareness among coastal communities and users of intertidal areas, but also drive management of these unique habitats.

Horseshoe crabs

Horseshoe crabs are representatives of an ancient lineage of marine arthropods, and are ‘living fossils’.

© Jürgen Freund / WWF

Of the four globally extant species of horseshoe crabs, two species are found along India’s coast, namely Tachypleus gigas and Carcinoscorpius rotundicauda. Found exclusively along India’s northeast coast, horseshoe crab populations have been described from the states of West Bengal, Odisha and Andhra Pradesh (Basudev et al. 2013). Large congregations of both species have been recorded during new and full moon high tides along breeding beaches in Odisha and West Bengal (Mishra 2009). In addition to their economic value in the biomedical field as a source of lysate, to the fisheries industry as bait, and the potential in ecotourism, these living fossils have enormous biodiversity value. Horseshoe crabs have underappreciated yet crucial ecological roles in food webs and are hosts for a variety of epibionts such as barnacles and limpets in the coastal ecosystems they are found in (Botton 2009). However, the conservation status of both species has been listed as Data Deficient and current population trends are unspecified (World Conservation Monitoring Centre 1996), with significant knowledge gaps in distribution, and a lack of long term monitoring.

Population declines have been witnessed over time, despite a lack of consequential commercial exploitation by the medical industry in India (Mishra 2009). Some of the threats to both species include extractive activities such as sand mining, nearshore fishing, and prawn aquaculture. Coastal development activities, such as beach armoring, tourism, habitat loss from the loss of coastal vegetation has also adversely affected the species and continues to do so (Basudev et al. 2013). Disrupted breeding cycles have resulted in a gradual decline in the number of nests following high tide and in the number of breeding pairs witnessed on beaches (Mishra 2009). Furthermore, water quality parameters have been shown to predominantly influence survival in horseshoe crabs. Exposure to contaminants such as heavy metals, oil and organic compounds resulted in developmental impairments and abnormalities in embryos. Such instances have severely impacted efforts to reestablish horseshoe crab populations in Japan. The degradation of breeding beaches appears to most significantly impact India’s horseshoe crab populations. The use of shorelines for activities such as boat construction and repair, and the removal of sand for construction purposes appears to impact nesting numbers at Balramgadi, Odisha.

Physical characteristics of nesting beaches can drastically influence Horseshoe crab breeding success. For example, it has been found that breeding pairs move towards preferable substrate, based on the time of the year (Mishra 1991). Given the loss of breeding grounds and reproductive potential, populations of T. gigas, which nest on sandy beaches, are threatened. There is currently ongoing work on mapping breeding sites, quantifying breeding potential and an ethnographic analysis of horseshoe crab use by local communities along six coastal districts of the state of Odisha, where T. gigas populations are found. This project will aim to synthesize the results of current research (carried out by the principal researcher on this project) along with a threat assessment of upstream and offshore threats to T. gigas breeding sites, and to prioritize sites for conservation interventions. Based on results of the threat assessment, habitat mapping, and habitat suitability, a framework for participatory management will be developed. This will include a social research component at sites prioritized for horseshoe crab conservation. The perceptions of local stakeholders towards participatory management and the conservation of T. gigas populations will serve to create the baseline information for a community-conservation based action plan.

The primary goal of this project is to safeguard existing horseshoe crab populations and minimize the rate of population decline along Odisha’s coast by mapping upstream riverine and offshore marine and coastal activity threats on T. gigas, the species that breeds on sandy coastal beaches adjacent to river deltas. Using this information along with results from ongoing research on habitat mapping and population, participatory management of breeding grounds by local fishing communities will be assessed to create a framework for inclusive conservation of the species in the area, at key breeding sites.

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