Hilsa Fishery Research Articles

Developing a frame of reference for fisheries management and conservation interventions

Effective implementation of management interventions is often limited by uncertainty, particularly in small-scale and developing-world fisheries. An effective intervention must have a measurable benefit, and evaluation of this benefit requires an understanding of the historical and socio-ecological context in which the intervention takes place. This context or ‘frame of reference’ should include the baseline status of the species of interest, as well as the most likely counterfactual (a projected scenario indicating what would have occurred in the absence of the intervention), given recent trends. Although counterfactuals are difficult to estimate and so are not widely specified in practice, an informative frame of reference can be developed even in data-poor circumstances. We demonstrate this using a case study of the Bangladesh hilsa (Tenualosa ilisha) fishery. We combine qualitative and some quantitative analyses of secondary datasets to explore ecological trends in the hilsa fishery, as well as patterns of social, economic, institutional, and physical change relevant to its management over the last ∼50 years. We compile all available information on the key parameters that determine hilsa abundance and distribution (movement, reproduction, growth, and mortality), as well as all available information on stock status. This information is used to produce a baseline and qualitative counterfactual which can be used to guide decision-making in this complex, data-poor fishery. A frame of reference provides a systematic way to break down potential drivers of change in a fishery, including their interactions, reducing the potential for unexpected management outcomes. Critical evaluation of contradictions and commonalities between a set of potential counterfactuals, as well as the reliability of sources, allows the identification of key areas of uncertainty and information needs. These can then be incorporated into fisheries management planning.

Productivity and coastal fisheries biomass yields of the northeast coastal waters of the Bay of Bengal Large Marine Ecosystem

Myanmar (Burma) is the second largest territory in Southeast Asia with a 2200 km coastline and continental shelf of 230,000 km2. The Myanmar exclusive economic zone (EEZ) occupies 80% of the northeast coastal waters of the Bay of Bengal Large Marine Ecosystem (BoBLME); a 300 km stretch of the Bangladesh coastline completes the area. Four decades ago a combination of extensive mangrove forests, large continental shelf and fertile deposits from the rivers systems discharging into the Bay from two mega deltas (Ganges–Brahmaputra–Meghna and the Ayeyarwady) generated high productivity and valuable coastal fisheries. In terms of productivity, the end of the dry season (April) is the most productive, with 2590 ± 1560 mg C m⁻2 day⁻¹ and high concentrations of chlorophyll a (3.14 ± 2.64 µg L⁻¹). In 2016, the Department of Fisheries (DoF Myanmar) reported marine fishery landings in Myanmar's waters of 2.9 million metric tons (mt), which would have accounted for 47% of the total BoBLME fish catch and 3% of global fisheries coming from 10% of the BoBLME maritime area of 6.2 million km2. Sequential fisheries assessments by Fridtjof Nansen Fisheries Research vessels over four decades have shown that in 2015 a combination of factors has led to reduced yields of valuable fish species by 80% while low value, fast-recruiting fish species have increased. A 2011 Transboundary Diagnostic Analysis (TDA), delivered by the Global Environment Facility (GEF) co-funded FAO implemented BoBLME eight-country project, describes the causes for this dramatic reduction in biomass yields. A Strategic Action Programme (SAP) designed to mitigate the problems was endorsed in 2016 and will be implemented in 2019. The area's coastal fishing fleets are 95% artisanal. There is a combined total of 442 species of fish, prawn, shrimp and lobster in the area. The transboundary hilsa (Tenualosa ilisha) fishery is the most economically important in both Bangladesh and Myanmar. WorldFish and the DoF (Bangladesh and Myanmar) are currently operating hilsa conservation projects in both countries with the International Institute for Environment and Development (IIED) and USAID funded Enhanced Coastal Fisheries in Bangladesh (ECOFISH) projects. A 2018 FAO-WorldFish fisher folk vulnerability and social protection study has demonstrated the precarious nature of coastal fishers.

Catch Trend and Stock Assessment of Hilsa Tenualosa ilisha Using Digital Image Measured Length‐Frequency Data

AbstractThe annual global average catch shares of the anadromous Hilsa Tenualosa ilisha of Bangladesh increased rapidly from 74.5% all through 1984–2013 to 86.7% during the 2010–2015 periods. With a few exceptions, an increasing trend of Hilsa production over the last three decades was found in Bangladesh. Initially three options incorporating digital image measurements were compared to determine the best method for obtaining accurate length data. The length‐frequency data measured from digital images showed that Hilsa have a moderate growth rate (K = 0.90 year−1) of up to 58.70 cm (L) TL. High fishing mortality (F = 2.83 year−1) and exploitation level (E = 0.67) suggest a slight overexploitation of the Hilsa fishery; the maximum sustainable yield (MSY) was estimated at 526,000 metric tons/year if the recommended TL at first capture (Lc) of 27 cm is adhered to. The present annual Hilsa catch is about 496,417 metric tons, which indicates the potential benefit of achieving MSY through sustainable fisheries management by regulating mesh size of nets and protecting brood fish. Size distribution of Hilsa within sanctuaries revealed a remarkable presence of juvenile fish during February–March in some areas, which suggests a need to readjust the fishing ban period from March–April to February–March. More fisheries management is necessary to reduce the exploitation level of Hilsa by 17% and at the same time increase the allowable Lc to potentially increase the MSY and CPUE.

Social Considerations of Large River Sanctuaries: A Case Study from the Hilsa Shad Fishery in Bangladesh

The establishment of a sanctuary is often suggested as an effective strategy for ecological restoration, though social aspects of such attempts are often overlooked. This study analyzed the socioeconomic status of 248 fishing households who are dependent on hilsa shad (Tenualosa ilisha) sanctuaries in southern Bangladesh. Also, the fishers’ perceptions were investigated to assess the status of ecological restoration, level of participation in the hilsa sanctuary management, their livelihoods constraints, and coping strategies during crises. Based on the fishers’ perceptions and fishery catch data of the government, it appears that the establishment of the hilsa sanctuary in the Bangladesh waters helped to restore the hilsa fishery and also enhanced the fishers’ income. However, a large section of hilsa fishers were found to be poor in terms of socioeconomic capital such as monthly income, housing conditions, and assets ownership. Particularly, these households suffer seasonal food insecurity during the banned period of fishing in the sanctuaries. The government’s compensation scheme is a good example of payment of ecosystem services in an open water fishery; however, this scheme does not include all the affected fishers. Food and income insecurity during ban period often force fishers to use illegal fishing as a livelihood strategy that undermines the success of sanctuaries as an ecological restoration strategy. The findings reflected that sanctuaries and other similar management strategies have social impacts on stakeholders and human societies, and these social impacts can have surprising feedbacks that influence management success. Thus, the success of ecological restoration relies on understanding the human dimensions of the system and that ecological and social restoration must go together. To address this goal, we call for developing fisheries policy that will facilitate engagement of resource users and other local stakeholders in sanctuary comanagement, which will ultimately strengthen fishers’ livelihoods and sustain the benefit from ecological restoration.

Impacts of water regulation on Tenualosa ilisha in the Narmada Estuary, Gujarat, India

Hilsa, Tenualosa ilisha is a highly prestigious fish for esteemed delicious taste, high market demand and price. It forms an important fishery of funnel-shaped 72 km long Narmada Estuary. Rapid decline in hilsa catch has been recorded in the Narmada Estuary over last few decades. Hilsa catch was recorded 5180 ton in 2006–07 that reduced to only 419 ton in 2014–15. Pre-impoundment of dam showed that T. ilisha contributed to the tune of 977.1 to 3727 ton from 1974–75 to 1982–83 and the highest catch of hilsa was 15319 ton during 1993–94. Sardar Sarovar Dam started functional in the year 1994 which has impacted natural water flow of the river and resulted in a reduction of freshwater availability in the estuary; the development of sand bars at the mouth of the estuary also reduced the tidal ingress into the system; low depth, loss of breeding, nursery and feeding grounds, over fishing may be the most important factors affecting hilsa fishery in Narmada estuary. Catching of juvenile hilsa during winter by ‘Golava’ net (small meshed bag net) also led to a rapid decline in hilsa catch. To maintain the sustainable yield of hilsa, selective fishing and control of juvenile catch are the prerequisites along with maintaining regular flow from the dam.

Impacts of water regulation on Tenualosa ilisha in the Narmada Estuary, Gujarat, India

Hilsa is a highly prestigious fish for esteemed delicious taste, high market demand and price. It forms an important fishery of funnel-shaped 72 km long Narmada Estuary. Rapid decline in hilsa catch has been recorded in the Narmada Estuary over last few decades. Hilsa catch was recorded 5180 ton in 2006–07 that reduced to only 419 ton in 2014–15. Pre-impoundment of dam showed that T. ilisha contributed to the tune of 977.1 to 3727 ton from 1974–75 to 1982–83 and the highest catch of hilsa was 15319 ton during 1993–94. Sardar Sarovar Dam started functional in the year 1994 which has impacted natural water flow of the river and resulted in a reduction of freshwater availability in the estuary; the development of sand bars at the mouth of the estuary also reduced the tidal ingress into the system; low depth, loss of breeding, nursery and feeding grounds, over fishing may be the most important factors affecting hilsa fishery in Narmada estuary. Catching of juvenile hilsa during winter by ‘Golava’ net (small meshed bag net) also led to a rapid decline in hilsa catch.

Present Status of the Sustainable Fishing Limits for Hilsa Shad in the northern Bay of Bengal, India

The hilsa, Tenualosa ilisha fishery in the northern Bay of Bengal (nBoB) is passing through a crisis manifested by the persistent decline of fish catch in spite of increasing efforts. During the period 2002–2015, the number of boats engaged in the fishery increased by 25% while the hilsa catch decreased by 13%. The exponential value (b) and condition factor (K) of hilsa has also decreased by 46% and 28% respectively. The value of fishing mortality (F = 2.34 year-1) has considerably exceeded the natural mortality (M = 0.56 year-1) during the study period. It is observed that in place of maximum exploitation rate (Emax) of 0.78, the current exploitation rate (E) of hilsa is 0.81 which is above the sustainable limit. It is a matter of serious concern that with 75% probability the first spawners of the population are being targeted by the present fishing practice. The present study observes that the hilsa population of nBoB are being significantly overexploited in the present level of fishing pressure. The maximum sustainable yield (MSY) limit for hilsa is estimated to be around 25,440 tons per year with the corresponding effort (fMSY) that may be deployed to achieve the above mentioned catch ranged from 3571 to 3987 (number of boats). It can be inferred that the hilsa fishery in the nBoB is being unsustainably exploited.

Present status of hilsa shad (Tenualosa ilisha) in Bangladesh: A review

Hilsa (Tenualosa ilisha) is the national and most important commercial fish species of Bangladesh. Hilsa widely occurs mainly in marine and estuarine environment but started to decline gradually over 30 years and reach to minimum during 1991-1992 that continued up to 2002-2003. Realizing the decreasing trend of hilsa, government took initiative to increase production by implementing regulation on jatka catch and restriction on brood hilsa catch from the breeding season of 2003-2004 under the Protection and Conservation of Fish Act, 1950. Hilsa management strategies help to contribute 11 percent of the total fish production and 1 percent of the Gross Domestic Product (GDP) of Bangladesh. Based on secondary literature this study describes biology of hilsa, existing hilsa management strategy and its impact on hilsa. To improve the situation a number of suggestions are elicited for effective management of the hilsa fishery that could be incorporated in the national policy.

Power, profits and payments for ecosystem services in Hilsa fisheries in Bangladesh: A value chain analysis

Commitments for sustainable growth often look good on paper but are messy in the practice. The Government of Bangladesh shows huge initiative towards SDG 14 (conservation and sustainable use of marine resources) by establishing measures to improve the stock of hilsa fish in the country, thus ensuring the supply of a valuable and charismatic fish species. Initial reports of the measures are optimistic, suggesting larger sizes of fish caught across the seasons. Bigger hilsa fetches better prices – as high as US$25 per kilo in niche markets. It is conservation business with profits. Yet the costs of these regulations are falling squarely on the shoulders of small fishermen who are poor, uneducated and in permanent debt. The government offers a small in-kind payment for ecosystem service (PES) in the form of rice, which is good but does not compensate for the loss of revenues and household protein during bans. These small fishers have no bargaining power and no voice in the design of policies that affect them. A common problem in policy design is the lack of clarity of the markets they affect, especially if they are informal. This study uses value chain models to unpick the hilsa value chain. It study provides hard data and evidence on processes, power, and profit creation. This consultation can help policy makers design better strategies to re-govern markets in more inclusive ways and help to achieve Sustainable Development Goals commitments.

Fisheries of Indian Shad (Tenualosa ilisha) in the Hooghly–Bhagirathi stretch of the Ganga River system

Tenualosa ilisha, the Indian Shad, is one of the most important commercial fish of the Indo-Pacific region and the Hilsa fishery in India is dependent on this species. Presently, the fishery resource of the species lies largely within the Bhagirathi–Hooghly component of the Ganga River system. The annual fish catch of Hilsa from the Bhagirathi–Hooghly River has fluctuated over the years ranging between 12,733 and 20,000 t between 2000–2001 and 2010–2012. The monsoon migration of Hilsa commences in July and gradually picks up in August. From September onwards, the magnitude of migration to the freshwater system showed a declining trend. Stretches between Nischintapur and Diamond Harbour downstream, Hooghly Ghat and Kalna in the freshwater tidal zone, and Lalbagh to Farakka in the Bhagirathi River have been delineated as potential breeding grounds for Hilsa. The intense fishing pressure in the coastal estuarine zone almost year round, especially in breeding season, adversely affects the breeding migration, spawning, and recruitment success vis a vis overall fishery of Hilsa in the system. There is an immediate need to implement effective conservation measures to protect breeders, potential breeding grounds, and juveniles for the cause of sustainable Hilsa fishery.

SOCIOECONOMIC AND LIVELIHOOD ANALYSIS OF HILSA FISHERS OF LOWER STRETCH OF GANGA

The present study was conducted to understand the socio-economic and livelihood features of the hilsa fishers in Hooghly-Bhagirathi river system and also to find out the reasons of decline in hilsa fishery as perceived by the fishers. Results of the analysis revealed that 60% of the hilsa fishers belonged to jele/malo community and the average experience in hilsa fishing was for about 20 years. Hilsa fishery contributed 38.84% in annual family income of fishers’ households. Lower hilsa catch in Hooghly-Bhagirathi river system during the past ten years led to large scale forced migration among the fishers’ community. The younger generation of fisherfolk had lost their interest from fishery particularly of hilsa fishery due to uncertain income. Six reasons behind decline of hilsa fishery as perceived by the fishers were documented and ranked. According to the fishers, ‘use of destructive fishing gears’ (mean score 66.06) was ranked as first among the reasons behind decline in hilsa fishery followed by ‘erratic rainfall’ (64.54); ‘huge catch of hilsa fish in lower part of Hooghly/sea mouth’ (60.3); ‘industrial pollution in Hooghly River’ (52.3) and ‘freshwater discharge/influx’ (35.07). Poor implementation of mesh size regulation, poor enforcement of closed season in rivers, ineffective extension services, and recurring climatic hazards made the hilsa fishery more vulnerable. The government, fishery cooperatives, NGOs and other related organisations need to join hands to support the hilsa fishers for sustainable hilsa fishery management.

Economic incentives for sustainable hilsa fishing in Bangladesh: An analysis of the legal and institutional framework

Bangladesh's hilsa shad (Tenulosa ilisha) comprises the largest single-species fishery in the country, constituting 11 per cent of the total catch and employing 2.5 million people directly or indirectly. Since 2003, following a sharp decline in catch figures, the hilsa fish has been the subject of a government conservation programme offering fishers economic incentives or payments for ecosystem services (PES). While PES schemes are widely used to conserve natural resources such as forests and watersheds, Bangladesh's programme is a rare example of PES for sustainable fishery management. Catch figures have improved since the programme was introduced; but concerns remain about fishers’ socioeconomic conditions and the long-term sustainability of Bangladesh's hilsa fishery. This paper analyses the conservation scheme's legal and institutional frameworks, identifying challenges to its design and implementation, and makes recommendations to overcome them.

Socio Economic Aspects of the Fishers Engaged in Hilsa Fisheries in Hooghly Estuary of West Bengal, India

Socio Economic Aspects of the Fishers Engaged in Hilsa Fisheries in Hooghly Estuary of West Bengal, India

Monitoring artisanal hilsa fishery for economic efficient fisheries policy

The hilsa shad (Tenualosa ilisha) fishery contributes to the largest single species fishery in Bangladesh. In this paper, a simple bio-economic year-class based model was developed from 1987 & 2007 fishing data to describe the fishery and examine its properties. With the help of this model, the optimum sustainable yield of the fishery was calculated and compared to the existing situation. The model was further used to locate socially and economically reasonable dynamic paths from the current situation to the optimal state. The results indicate that the fishing effort (measured in standardized boat units) required maintaining a maximum sustainable economic benefit is about one-third of the current fishing effort. At this sustainable fishing effort level, annual net economic benefits from the fishery amounted for closed to US$ 260 million compared to virtually nothing at present. The present value of the fishery along a moderate effort adjustment path to this long term equilibrium position was US$ 3,650 million at 6% rate of discount. The dynamic path that maximized the present value of the fishery involved quite dramatic effort reductions for the first two years. Such a path would probably increase the present value of the fishery by perhaps 8-10%.Bangladesh J. Zool. 43(1): 37-53, 2015

Fishers’ local knowledge on impact of climate change and anthropogenic interferences on Hilsa fishery in South Asia: evidence from Bangladesh

The anadromous fish species Hilsa (Tenualosa ilisha) constitutes the largest single fishery in Bangladesh and West Bengal, India. River Meghna is the important habitat for Hilsa as the major breeding and nursing grounds are situated along this portion of the river. In this paper, we investigate fishers’ perceptions on effect of climate change and anthropogenic impact on Hilsa fishery at lower Meghna. Fishers’ ecological knowledge indicates that the stock of Hilsa is declining due to several adverse climatic conditions such as increased water temperature, salinity intrusion and low freshwater discharge from upstream. Fishers believe that dams and polders have immense effect on river sedimentation which already blockade several upward migratory route of Hilsa. Fishers’ experience shows that intensity of coastal cyclone is gradually increasing, which causes severe physical and economical damage. The study also indicates that the major constraints to adopt with the change situation are low level of human capital and restricted access to the formal credit system. Therefore, incorporation of local knowledge in governmental policy formulation and public support to improve human skill are essential for the adaptive management.

Sustainable exploitation of hilsa fish (Tenualosa ilisha) population in Bangladesh: Modeling and policy implications

This paper presents a computer model of hilsa fish (Tenualosa ilisha) to predict the long-term trends in the hilsa population over several decades and to assess the impacts of harvesting the juveniles and spawning adults of hilsa fish. The model is designed to keep track of the population in various phases of the life cycle. The computer model of hilsa fish is based on system dynamics methodology. The full history of the cause and effect relationships of the population dynamics of hilsa fish is presented using causal loop and flow diagrams. STELLA software is used to model the population dynamics of hilsa fish and the parameters of the model are estimated from field data and reports. Maximum sustainable yield and carrying capacity were simulated to be 268,000tons and 670,000tons, respectively. The overall situation of hilsa fishery is under severe stress in Bangladesh and vulnerable to over exploitation. Simulation results show that increased harvesting of the adults entering the rivers and the juveniles in the rivers cause gradual decline in hilsa fish population and even may cause to disappear this valuable resource within a short period of time. Also the optimal strategies for sustainable development of hilsa fishery have been addressed and the optimization results show that optimized operation of the hilsa fishery not only stabilizes the system, but also enhances the harvested adult hilsa. The model has the potential to analyze the harvesting strategies of the adults entering the rivers and juveniles in the rivers for sustainable exploitation of the hilsa fish.

Population statistics of the migratory hilsa shad,Tenualosa ilisha,in Sindh, Pakistan

In order to estimate the population dynamics of the hilsa shad, Tenualosa ilisha, fishery in Sindh, the key population parameters of growth, mortalities, recruitment pattern, exploitation and maximum sustainable yield are discussed. Length frequency data were collected from April to October 2004 from the main commercial (hilsa) landings at Thatta, Sindh. Estimated parameters of the von Bertalanffy (Hum. Biol. 10, 181–213) growth model were L∞ = 31.5 cm, K = 1.5 year−1, t0 = −0.10 year as obtained by the electronic length frequency analysis (ELEFAN I). Estimated natural, fishing, and total mortalities were 2.21, 0.673, 2.89 year−1, respectively. The relative biomass per recruit (B′/R) was 0.95 and yield per recruit (Y′/R) was 0.06 using the knife-edge selection. The exploitation ratio at the maximum sustainable yield (MSY) was Emax = 1.0 year−1, fishing mortality at MSY was Fmax = 2.89 year−1, average target Fopt = 0.5 year−1 and Flimit = 1.47 year−1. The catch and effort data from 1981 to 2004 (MFD, Karachi) were analyzed using the catch and effort data analysis (CEDA) computer programme. Estimated biological reference point of MSY for the Fox model was 891 tonnes (t), R2 = 0.75; for the Schaefer and Pella-Tomlinson models MSY = 744 t, R2 = 0.49, the outputs of which appeared to be more conservative than the Fox model which indicated a better fit. The overall situation of hilsa fishery is in severe stress and appears vulnerable to overexploitation. On the basis of the present findings, serious attention is required to provide appropriate access of the fish to the Indus River during the spawning period as well as to impose a ban on fishing during upstream migration and on undersized catch to prevent this traditional fishery in this area.