Gujarat is gifted with a beautiful 1600 km coastline, the longest in India, and a wide continental shelf, making its waters nutrient rich and diverse in marine fauna. It tops the charts in fish production, and has the highest quantities of sharks harvested in India (CMFRI, 2013). Existing catch-related data collected over the years indicated dwindling shark harvests. While at ground level, efforts to increase fish catch were intensified, it was important to study shark fisheries and local fishing trends and perspectives towards it, in order to aid in management strategies.
Our year-long study (October 2014 to November 2015) funded by Save Our Seas Foundation, focused on assessing fish landings in Porbandar, Gujarat, in the northwest coast of India. We aimed to document shark diversity, size classes and other life history characteristics, and attempted to understand perspectives of different stakeholders involved in shark fisheries. Our typical day at a trawl or gill-net fish landing site involved identifying, sexing, measuring and weighing sharks. While we carried out these tasks we would also enquire about the duration of their fishing trip, their fishing grounds, assess species composition along with a few other details that interested us if the fishers had time to be questioned!
Sharks (commonly called as magra) landed at both fish landing sites were a part of by-catch. They were either offloaded with other less important species like pufferfish, juvenile ribbonfish, solefish and crabs or segregated in the boat itself to save time later. India is home to over 50 species of sharks. Our study resulted in recording 20 species of sharks, ranging from species found in pelagic waters like the common blacktip shark, demersal species like the bigeye hound shark to bottom dwelling species like the bamboo shark. Amongst all these species the sandbar shark was recorded for the first time in Indian waters (Sutaria et al., 2015). We recorded shark species that grew less than one meter as well as those that grew up to 3 meters in length. The former dominated most of the shark catch in both types of gear – trawls and gill nets. Four of these are also consumed locally and are commercially important (milk shark – Rhizoprionodon acutus, grey sharpnose – Rhizoprionodon oligolinx, spadenose shark – Scoliodon laticaudus, shark and the bigeye smooth hound shark – Iago omanensis). These four species are caught and sold in the local market throughout the year. Commercially popular species like the milk shark and the spadenose were consumed locally while most of the grey sharpnose or son magra were either frozen or packed whole and transported to cities in the south – Calicut, Mangalore, Chennai, Cochin and a few other cities. The bigeye hound shark was of least commercial importance amongst these four as its meat was considered unfit for consumption. Most of it was salt dried or transported to fertilizer processing units.
One of the most abundant species – the spadenose shark (common names – mooshi, morri, sandha) has dominated the shark landing in Porbdandar since the past 20 years. Compared to other small-sized sharks (1m or less), the spadenose shark is capable of reproducing twice (Devadoss, 1979) a year and perhaps has the possibility of replenishing its stocks (Wourms, 1993). Yet its population has been declining and it is categorized as Near Threatened on the International Union for Conservation of Nature (IUCN) Red List. We also recorded pups and gravid females in almost all species indicating that all life stages are vulnerable to fishing pressure and that fishing was taking place at nursery grounds. We worried that the life history traits of most of the sharks being fished would not be able to cope with the extent and nature of fishing taking place in these waters. When we inquired about historic fish catch, everyone we spoke to lamented that the catch had reduced by 90%. We, many a times, would find ourselves sitting at our regular chai stalls pondering over and discussing the plight of our fisheries in the next 20 years. What is happening to wild elasmobranch (cartilaginous fish such as sharks, rays, and skates) stocks? What changes were taking place in trophic chains to adjust to such large removals of top predators? As they decline further we still lack information on their life history traits, maturity lengths and seasonality of species that are needed to ensure sustainability of fisheries. How then are we supposed to construct efficient conservation strategies and management plans?
Sharks contribute about 4 – 6% of the total elasmobranch catch in India. Shark catches in India peaked in the 1980’s and have been drastically declining ever since then, just as the overall fish catch has been falling. Most of this decline in fisheries has been attributed to trawl nets and purse seine nets. Purse seiners are absent in Porbandar, but trawling is rampant. Trawlers were introduced in India in the 1960’s to intensify the efficiency of fish catch and consequently increase coastal revenue. They harvest all marine fauna that comes in their path wiping off communities and desertifying diverse habitat types in a few hauls. They have been modified to bottom trawl and mid-water trawl. Gear-specific fisheries, for examples specific mesh-size gill nets used to catch specific fish by near-shore motorized and artisanal fishers has now become a thing of the past. With 2313 trawlers operating only from Porbandar, the near-shore fisheries here has already collapsed as suggested by interviewee’s from Porbandar and Veraval. As trawls need to make profitable returns from the money invested in a fishing trip, trawlers now go to deeper waters, for longer trips, and if nothing worthy is found, harvest debris from the ocean floor and sell it at Rs.5/kg. Today, fishers from Porbandar go on 20-day fishing trips and come back with mostly ‘Kachra maal’ sent off to the fertilizer and poultry feed factories. Such is the industrial mess of our commercial fisheries.
Sharks have existed on earth since 400 million years. They are apex predators, influencing prey populations and community structures, and thus play an important role in the functioning of aquatic ecosystems. They have evolved to occupy varied habitat niches – coral reefs, mangroves, sea grass beds, lagoons, estuaries, rivers and deep oceanic waters. Most of these habitats are facing high levels of anthropogenic pressures, other than over-fishing, such as coastal infrastructure development, release of industrial pollution, garbage and sewage, and oil and gas exploration.
Sharks are highly vulnerable to overexploitation due to their restrictive life history traits like slow growth, low reproductive rates and late maturity. They exhibit a range of prey preference, have plasticity in reproductive strategies, and can be as small as 20 centimeters and as large as 12 meters (whale shark). Overfishing, compared to other activities, has contributed largely to the decline in 90% of large bodied sharks. A study in the eastern coast of North America (Myres et al., 2007) showed that a decline in the blacktip shark populations overlapped with a steep rise in the population of cownose rays, further overlapping with a decline in North Carolina scallops (Cownose rays feed on molluscs and other crustaceans)!!
Initiating new research and monitoring programs, and collaborating with local communities to understand the role they can play in sustaining fisheries, would be a great start to unravel the story of sharks residing in waters surrounding India. Similar species of sharks are known to exhibit varied life history traits in different geographic regions. Hence, it is crucial for us to gather data at a regional level for better management. Institutions like the Central Marine Fisheries Research Institute, which published Guidelines for the ‘National Plan of Action – Sharks’, have suggested initiating a long – term monitoring project, and have also urged researchers to work with communities.
Fishers are aware that stocks are collapsing, but they are also bound by their livelihood choices. While imposing a blanket ban on shark fisheries is not a solution to the problem, managing the kinds of gear used across time and space is certainly the need of the hour.
We do not know if shark populations can be restored back to stable populations, but we live in the hope that there are people out there who are inquisitive, care about the ocean, and understand the importance of working with communities to bring about efficient management practices. The least we can do is conserve what is left of these diverse taxa and endeavor to restore their habitats. Sharks have been portrayed negatively, as one of the oceans most feared creatures. They are in fact among the most intriguing and graceful denizens of the sea, and symbolize decades of resilience in the face of global changes.
References
- CMFRI (2013). Marine Fish Landings in India. Devadoss, P. (1979). Observations on the maturity, breeding and development of Scoliodon laticaudus Muller and Henle off Calicut coast. Journal of the Marine Biological Association of India 21, 103-110.
- Myers, R.A. et al. (2007) Cascading effects of the loss of apex predatory sharks from a coastal ocean. Science 315, 1846–1850
- Sutaria, D. et al. (2015). First record of the sandbar shark, Carcharhinus plumbeus, (Chondrichthyes: Carcharhiniformes: Carcharhinidae) from Indian waters. Marine Biodiversity Records, 8, e126.
- Wourms, J. P. (1993). Maximization of Evolutionary Trends for Placental Viviparity in the Spadenose Shark, Scoliodon laticaudus. Environmental Biology of Fishes 38, 269–294.
Related, read ‘Studying India’s Marine Mammals — An Interview with Dipani Sutaria’.
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