BOBLME-2015-Ecology-53

ii BOBLME-2015-Ecology-53

The designations employed and the presentation of material in this publication do not imply the expression of any opinion whatsoever on the part of Food and Agriculture Organization of the United Nations concerning the legal and development status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.

The BOBLME Project encourages the use of this report for study, research, news reporting, criticism or review. Selected passages, tables or diagrams may be reproduced for such purposes provided acknowledgment of the source is included. Major extracts or the entire document may not be reproduced by any process without the written permission of the BOBLME Project Regional Coordinator.

BOBLME contract: LOA/RAP/2013/29

For bibliographic purposes, please reference this publication as:

BOBLME (2015) Procedures and methods for continuing assessment of the status of Hilsa resources in India. BOBLME-2015-Ecology-53

ii iii Procedures and methods for continuing assessment of the status of Hilsa resources in India

Suggested citation CIFRI, 2015. Final project report on "Procedures and methods for continuing assessment of the status of Hilsa resources in India". Report to FAO for the Bay of Bengal Large Marine Ecosystem Project. ICAR-Central Inland Fisheries Research Institute, Kolkata, India. 64p.

Funding agency Bay of Bengal Large Marine Ecosystem Project (Food and Agriculture Organization, Rome)

Executing agency ICAR-Central Inland Fisheries Research Institute Barrackpore, Kolkata-700 120, India.

Project team D. Panda M. Naskar R. K. Raman Subrata Das Yousuf Ali Field assistant (02)

Cover credit Sujit Choudhury

Published by Director ICAR-Central Inland Fisheries Research Institute Barrackpore, Kolkata-700 120, India.

iv Procedures and methods for continuing assessment of the status of Hilsa resources in India

Acknowledgements

We express our deepest sense of gratitude and indebtedness to Dr S. Ayyappan, Director General, Indian Council of Agricultural Research (ICAR), and New Delhi for giving us the opportunity to carry out this research work at CIFRI, Kolkata, India. We are extremely thankful to Dr (Mrs) Meenakumari, Deputy Director General and Dr S. D. Singh, Assistant Director General (Inland Fisheries), Fisheries Science Division, ICAR, New Delhi for their kind support and cooperation for smoothly conducting the research work. We profess our heartfelt gratefulness and sincere regard to Prof. A. P. Sharma, Director, ICAR-Central Inland Fisheries Research Institute, Kolkata, India for his timely, unconditional support and guidance during the project period for the successful completion of this work. We are extremely thankful to Director, Department of Fisheries, Government of West Bengal and Director, ICAR-Central Marine Fisheries Research Institute, Kochi for providing requisite information. We are at loss of words to express our special thanks to Mr Subrata Das, Mr Y. Ali, all field staff and all the staff of CIFRI, Barrackpore for their kind helps in successful completion of the project. The financial assistance provided by the Bay of Bengal Large Marine Ecosystem Project (FAO) is gratefully acknowledged.

Place: Kolkata, India Date: (Debabrata Panda)

v Procedures and methods for continuing assessment of the status of Hilsa resources in India

Table of contents 1. Project outline ...... 1 1.1. Background ...... 1 1.2. Objective ...... 1 1.3. Expected output ...... 2 1.4. Expected outcome ...... 2 1.5. Implementation and arrangements ...... 2 1.6. Technical activity ...... 2 1.7. Timeframe ...... 3 2. Review of status of Hilsa ...... 5 2.1. Analysis of historical data ...... 6 2.1.1. Department of Fisheries, West Bengal ...... 6 2.1.2. CMFRI ...... 9 2.2. Time series analysis ...... 10 3. Procedures and methods ...... 12 3.1. Sampling and data collection ...... 12 3.2. Catch assessment ...... 16 3.3. Spawning profile ...... 16 3.4. Size distribution ...... 17 3.5. Water quality assessment ...... 17 4. Taxonomy ...... 18 4.1. Systematic position: Nelson (2006) ...... 18 4.1.1. Diagnostic features: (Whitehead, 1985) ...... 19 4.1.2. Differentiation: (Whitehead, 1985 and Froese & Pauly, 2015) ...... 19 5. Catch and effort/CPUE assessment ...... 21 5.1. Inland Hilsa landings ...... 21 5.2. Marine Hilsa landings ...... 21 5.3. Total Hilsa landings ...... 22 5.4. Effort/CPUE ...... 24 5.4.1. Inland sector ...... 24 5.4.2. Marine sector ...... 25 6. Length based analysis ...... 27 6.1. Length-weight relationship ...... 27 6.2. Condition factor ...... 27 6.3. Length frequency analysis ...... 29 6.4. Growth parameter ...... 30 6.5. Mortality parameter ...... 31

vi Procedures and methods for continuing assessment of the status of Hilsa resources in India

6.6. Recruitment ...... 31 6.7. Length at first capture (Lc) ...... 32 6.8. Gill net selectivity ...... 33 6.9. Relative yield per recruit (Y’/R) and biomass per recruit (B’/R) ...... 36 7. Maturity and spawning profile ...... 37 7.1. Maturity and spawning season ...... 37 7.2. Spawning frequency ...... 39 7.3. Fecundity ...... 39 7.4. Length at first maturity (Lm) ...... 41 7.5. Spawning ground ...... 42 8. Habitat characteristics ...... 44 9. Crafts and gears ...... 48 10. Summary ...... 53 11. Recommendations ...... 54 12. References ...... 55

Appendix I Length frequency distribution of Hilsa ...... 56 Appendix II Sector-wise catch per unit effort (kg/boat/day) of Hilsa ...... 57 Appendix III Hilsa landings (tonnes) from West Bengal waters ...... 58

List of tables Table 1 Major activity with the timeframe from June, 2013 to December, 2014 ...... 4 Table 2 Parameter estimates of ARIMA model ...... 11 Table 3 Stratification of sampling stations and their positions ...... 15 Table 4 Stages of reproductive development of female gonads ...... 17 Table 5 Condition of individuals of Hilsa stock ...... 27 Table 6 Summary of population parameter estimates of Hilsa ...... 33 Table 7 Stages of reproductive development of female gonads ...... 38 Table 8 Estimated fecundity of Hilsa ...... 39 Table 9 Station-wise recorded physicochemical parameters ...... 46 Table 10 Annual variations of physicochemical parameters of Hooghly-Bhagirathi river system ...... 47

vii Procedures and methods for continuing assessment of the status of Hilsa resources in India

List of figures Figure 1 Non-political map showing major habitats of Hilsa in the Ganga and Brahmaputra river systems ...... 6 Figure 2 Hilsa landings during 1961 to 2012 in West Bengal ...... 7 Figure 3 Hilsa landings during pre-modernisation period (1961-1990) ...... 8 Figure 4 Hilsa landings during post-modernisation period (1990-2012) ...... 8 Figure 5 Sector-wise catch of Hilsa from West Bengal ...... 9 Figure 6 Marine Hilsa catch by different fishing fleets along West Bengal ...... 10 Figure 7 Pattern of marine Hilsa landings and lags of ARIMA model ...... 11 Figure 8 Actual, fitted and forecasted marine Hilsa landings from West Bengal ...... 11 Figure 9 Sampling stations along Bhagirathi-Hooghly River, India ...... 14 Figure 10 Hilsa and Hilsa like fish found in West Bengal waters ...... 20 Figure 11 Tenualosa ilisha ...... 20 Figure 12 Tenualosa toli ...... 20 Figure 13 Station-wise Hilsa landings from riverine zone by non-motorised boats ...... 21 Figure 14 Boat-wise marine Hilsa landings in West Bengal ...... 22 Figure 15 Sector-wise Hilsa landings in West Bengal ...... 22 Figure 16 Monthly Hilsa landings by sector in West Bengal ...... 23 Figure 17 Total Hilsa landings in West Bengal ...... 23 Figure 18 Boat-wise Hilsa landings in West Bengal ...... 24 Figure 19 Monthly variation of CPUE of non-motorised boat ...... 24 Figure 20 Distribution of mean annual CPUE in major inland stations...... 25 Figure 21 Monthly variation of CPUE in motorised and mechanised boats ...... 26 Figure 22 Length-weight relationship of Hilsa ...... 27 Figure 23 Condition factors of individuals of Hilsa ...... 29 Figure 24 Collection of monthly length frequency data ...... 29 Figure 25 Length frequency distribution of Hilsa in commercial catch with sample timing 0.08 (October, 2013) to 1.0 (September, 2014) ...... 30 Figure 26 Age-length key for Hilsa ...... 30 Figure 27 Length converted catch curve for estimation of Z ...... 31 Figure 28 Recruitment pattern of hilsa ...... 32 Figure 29 Length at capture of Hilsa at different probabilities ...... 32 Figure 30 Selectivity curves of Hilsa in different mesh gill nets ...... 34 Figure 31 Gear selection ogive for Hilsa caught by different mesh gill nets ...... 36 Figure 32 Relative Y/R and B/R curves fitted to E ...... 37 Figure 33 Mature male Hilsa ...... 38

viii Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 34 Mature female Hilsa ...... 38 Figure 35 Ova diameter frequency of Hilsa showing spawning frequency ...... 39 Figure 36 Relationship between total length and fecundity of Hilsa...... 41 Figure 37 Length at first maturity (Lm) of female Hilsa ...... 42 Figure 38 Mean Gonado-Somatic Index (GSI) recorded from selected stations ...... 42 Figure 39 Types of fishing units used for Hilsa...... 50

Acronyms used ACF Auto Correlation Function AIC Akike Information Criterion ARIMA Auto Regressive Integrated Moving Average BOB Bay of Bengal BOBLME Bay of Bengal Large Marine Ecosystem CIFRI Central Inland Fisheries Research Institute CMFRI Central Marine Fisheries Research Institute CPUE Catch per Unit Effort DOF Department of Fisheries FAO Food and Agriculture Organisation GSI Gonado-Somatic index HFAG Hilsa Fisheries Assessment Working Group ICAR Indian Council of Agricultural Research ICLARM International Centre for Living Aquatic Resources Management LF length-frequency LOA Letter of Agreement LW length-weight LWR Length-weight relationship PACF Partial Auto Correlation Function RMSE Root Mean Square Deviation SAP Strategic Action Programme SAS South Asian Seas VBGF Von Bertalanffy Growth Function

ix Procedures and methods for continuing assessment of the status of Hilsa resources in India

1. Project outline

1.1. Background Coastal waters are resource rich areas playing a key role in providing food and livelihood security to millions of poor around the world. Rapid population growth, high dependence on resources and increased land use has resulted in over exploitation of resources and habitat degradation. The sustainability of these coastal ecosystems and their resources is becoming questionable. Most of these resources are components of larger transboundary marine ecosystems which require multi-country approaches to their sustainable management and conservation. In this regard, the Bay of Bengal (BOB) is of particular importance given that some 400 million people live in its catchment, many subsisting at or below the poverty level. Key issues to be addressed by the project include: (i) overexploitation of living resources, (ii) critical habitat degradation, (iii) land-based sources of pollution, (iv) the status of these critical habitats, post-tsunami, and their ability to support livelihoods in the future, and (v) the regional and institutional arrangements to facilitate a coordinated approach among the BOBLME countries to address these development and resource issues. Bangladesh, India, Indonesia, Malaysia, Maldives, Myanmar, Sri Lanka, and Thailand are working in a common platform through the Bay of Bengal Large Marine Ecosystem (BOBLME) Project (GCP/RAS/236/GFF) to better the lives of their coastal populations by improving regional management of the Bay of Bengal environment and its fisheries. The BOBLME Project is supporting countries to implement an ecosystem approach to fisheries management of shared fish stocks in the Bay of Bengal. The project will deliver the benefits to the participating countries like (i) diversified livelihoods and improved wellbeing among small-scale fisher communities; (ii) dependable, long-term sustained national production of selected transboundary fish stocks for BOBLME countries; (iii) increased understanding and strengthened national programme in BOBLME-relevant sectors; and (iv) preparation of regional Strategic Action Programme (SAP). In addition to the above, the project will also address the transboundary issues and management of critical habitats beyond the political jurisdictions in the BOBLME. With this backdrop, a letter of agreement was signed between Food and Agriculture Organization (FAO), Rome and Indian Council of Agriculture Research (ICAR), New Delhi through Central Inland Fisheries Research Institute (CIFRI), Kolkata, India on 24th June, 2013 to produce procedures and methods for continuing assessment of the status of Hilsa resources in India.

1.2. Objective The BOBLME Project had five interlinking components. The components had been structured to stress some of the priority transboundary activities to address identified critical issues in BOBLME countries. The present project was formulated under the BOBLME sub-component 2.3: Collaborative Regional Fishery Assessments and Management Plans. The objective of the sub component (2.3) was to introduce and promote collaborative fisheries management approaches for selected key transboundary species through the development of regional and sub-regional management plans and harmonisation of data collection and standardisation. To achieve these objectives, the subcomponent will support the following activities: (i) Development of a regional fishery management plan for sharks; (ii) Development of sub-regional fishery management plan for Indian mackerel (Bangladesh, India, Indonesia, Malaysia, Myanmar, and Thailand); (iii) Development of sub-regional fishery management plan for Hilsa (Bangladesh, India, and Myanmar); and 1

Procedures and methods for continuing assessment of the status of Hilsa resources in India

(iv) Design and implementation of a common fishery data/information system in the BOBLME. To accomplish the activity in Sl. no. (iii) the following objectives for the present study had been structured: a) To standardise the procedures and methods for assessment of Hilsa resources in India. b) To assess the present status of Hilsa stock along the Bhagirathi-Hooghly river.

1.3. Expected output Improved management of selected transboundary fish stock (Hilsa) through: a) Development of regional and sub-regional institutional arrangements and plans to manage the stock, and b) A regionally harmonised fishery data base on Hilsa.

1.4. Expected outcome  Development of integrated sustainable management plan for Hilsa in the BOB region.

1.5. Implementation and arrangements  The Director, CIFRI, Kolkata nominated Dr Debabrata Panda, Scientist as Principal Investigator, Dr Malay Naskar, Principal Scientist and Dr Rohan Kumar Raman, Scientist as Co-Principal Investigators for execution of the project.  Two technical staff of the institute namely Mr Subrata Das and Mr Yusuf Ali were also included in the project for assisting in field data collection and laboratory studies.  Two field assistants for assisting in field data collection were recruited on contract basis. Rigorous training on species identification and on field data collection methodology was given to the project staff.  Regular monthly meetings and discussions were held with all project staff (three scientists, two technical staff and two field staff) for smoothly executing the predefined project activities.

1.6. Technical activity To achieve the defined objectives the following activities were performed: a) A review was made of all historic data available on catch and effort for Hilsa available at CIFRI and other organisations i.e. Department of Fisheries, Government of West Bengal and CMFRI, Kochi. b) Monthly sampling was conducted for collection of length-frequency (LF), length-weight (LW) data from Hilsa catches, covering both the marine and inland fisheries. c) Monthly catch and effort (C & E) data were collected to cover seasonal variations. d) Experimental fishing was undertaken in the Bhagirathi-Hooghly River to estimate fish abundance. e) Location specific survey of ripe (running) Hilsa and egg/larvae was conducted for detection of probable spawning ground during the spawning season. f) Water quality parameter was monitored as a pilot activity during the project period. g) A review meeting of the Hilsa Fisheries Assessment Working Group (HFAG) of the participating countries (India, Bangladesh and Myanmar) was held during 26-28 November, 2014 at CIFRI, Kolkata, India to discuss the progress of research under the project with the presence of Dr Rishi Sharma, Stock assessment coordinator, BOBLME. h) The status of Hilsa resources was assessed by applying the stock assessment models.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

1.7. Timeframe The total duration of the agreement was nineteen months (June, 2013 to December, 2014), initiated just after signing of the LOA during June, 2013 and again revised on June, 2014. The major activities with the timeframe to achieve the defined output are given as in Table 1.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Table 1 Major activity with the timeframe from June, 2013 to December, 2014 2013 2014 Major activities J J A S O N D J F M A M J J A S O N D Planning, implementation and arrangements Submission of Inception report Orientation of field staff (2) for data collection Review and analysis of available historical data Collection of C & F, LF and LW data Collection of water quality parameters Experimental fishing and larval survey Submission of summary progress report Training in stock assessment by BOBLME Data analysis and report writing Submission of final report

Procedures and methods for continuing assessment of the status of Hilsa resources in India

2. Review of status of Hilsa

Shads (Family: Clupeidae, Subfamily: Alosinae) are a cosmopolitan group of fishes inhabiting a wide range of habitats throughout the world. The Indian shad, Tenualosa ilisha, popularly known as Hilsa, has established itself as one of the most important commercial fishes of the Indo-Pacific region. It has a wide range of distribution and occurs in marine, estuarine and riverine environments. The fish is found in the Persian Gulf, Red Sea, Arabian Sea, Bay of Bengal, Vietnam Sea and China Sea. The riverine habitat covers the Satil Arab and the Tigris and Euphrates of Iran and Iraq, the Indus in Pakistan, the Irrawaddy of Myanmar, the rivers of eastern and western India namely the Ganga, Bhagirathi, Hooghly, Rupnarayan, Brahmaputra, Godavari, Narmada, Tapti and other coastal rivers and the Padma, Jamuna, Meghna, Karnafuly and other coastal rivers of Bangladesh. Like Atlantic salmon, Hilsa breeds in freshwater rivers and the young ones migrate to the sea, again returns back as adults for spawning. The species ascends rivers as far as 1200 km inland for breeding and returns to marine habitats after spawning (Pillay and Rosa, 1963). The river Ganga is the most important river system in India and one of the largest in the world, where Hilsa occupies. The river system covers upland stream, warm water, swampy and deltaic habitats during its run from upper Himalayas to the Bay of Bengal. Many tributaries join the Ganga in its course through the plain. The Yamuna is the most important tributary and meets the Ganga on its right bank at Allahabad. From Allahabad the river flows eastwards and after its entry into the state of West Bengal, the river water is regulated through a barrage at Farakka. The main channel after Farakka barrage flows in a south-easterly direction through Bangladesh known as the river Padma where it meets the Brahmaputra River, finally leading to the Bay of Bengal (Figure 1). About 41 km long man-made feeder canal arises from upstream of the barrage and meets the Bhagirathi River at Jangipur in the south. Then the Bhagirathi passes through for about 150 km and thereafter, it joins with the Hooghly River at Nabadwip. The Hooghly flows through Kolkata and finally leading to the Bay of Bengal. The present study pertains to the total stretch of Hooghly-Bhagirathi River from Farakka to Diamond harbour.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 1 Non-political map showing major habitats of Hilsa in the Ganga and Brahmaputra river systems (Source: Google Earth) Three species namely Tenualosa ilisha, T. toli and Hilsa kelee form Hilsa fishery in Hooghly-Bhagirathi River or West Bengal waters. Among the three species, only T. ilisha forms the commercial fishery and scarcely T. toli and H. kelee. The Hilsa fishery is confined to the lower stretch of river Ganga after commissioning of Farakka barrage in 1972 (Sinha, 2000). The contribution of Hilsa varies between 20-25% of the total fish landing in lower stretches of river Ganga (Bhaumik and Sharma, 2012). Thus, present stock assessment study of Hilsa fishery (T. ilisha) was restricted to the lower Gangetic stretch (Hooghly-Bhagirathi River) and the coastal waters of West Bengal, India.

2.1. Analysis of historical data The past available Hilsa information on catch and effort were collected from Department of Fisheries (DOF), Government of West Bengal and ICAR-Central Marine Fisheries Research Institute (CMFRI), Kochi. Only the time series data on catch of Hilsa could be collected from both the organisations. The differences in estimates were observed even for the same period in the data supplied by both the organisations. This might be due to the difference in sampling strategy adopted by both the organisations. The multistage stratified random sampling programme was followed by ICAR-CMFRI, Kochi. 2.1.1. Department of Fisheries, West Bengal The analysis of last 50 years of data revealed that the production of Hilsa was 1058 t during 1961, raised to maximum of 78, 905 t during 1999 and then declined to 8679 t during 2012. Nearly a decadal peak in Hilsa landing was observed during 1971, 1981, 1990, 2001 and 2010 (Figure 2). A better representation of a ten years cycle of peak landings from 1961 to 1990 is given in Figure 3. There was a sudden increase in landing just after 1989 from 1489 to 6656 t in 1990 and 23520 t in 1991 and so on. One of the reasons of sudden increase in landing might be due to the large scale modernisation of fishing gear (adoption monofilament gill net) in the state during the period. The 6

Procedures and methods for continuing assessment of the status of Hilsa resources in India monofilament gill nets are having less visibility in water column allowed better catching of fish. The high catchability efficiency, low cost and long durability of monofilament nets encouraged fishers to adopt it widely. As a result of modernisation the catch was increased up to 53 times in between 10 years (1989 to 1998). However, there was a steady decline in landings after 2001 excluding the peak during 2010 might be due to overfishing of resource during post modernisation period (Figure 4).

Pre-modernisation Post-modernisation

Figure 2 Hilsa landings during 1961 to 2012 in West Bengal (Source: DOF, WB)

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 3 Hilsa landings during pre-modernisation period (1961-1990) (Source: DOF, WB)

Figure 4 Hilsa landings during post-modernisation period (1990-2012) (Source: DOF, WB) The sector-wise (inland and marine) landings of Hilsa were available from 1993 onwards. The contribution of marine sector was in increasing trend with maximum (91%) during 2010. The marine sector has contributed more than 87% of catch during last 3 years. However, Hilsa catch from inland sector was in declining trend with 58% during 1993 to only 9% during 2010 and 11% during 2012. In the year 2002, the catch from both the sectors was remained almost 50% and thereafter the riverine contribution declined drastically (Figure 5).

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 5 Sector-wise catch of Hilsa from West Bengal (Source: DOF, WB) 2.1.2. CMFRI Hilsa catch data for last two decades were collected from CMFRI. The supplied data were collected from 57 marine landing centres comprised of 3 zones of West Bengal. The data also represented Hilsa landings by different categories of boats (mechanised, motorised and non-motorised) from 1992 to 2012. The contribution of non-motorised/artisanal/country boats to the total landing of the state remained less than 1% over last two decades. The landings from the motorised boats were significantly felt from 1999 onwards, with an average of 40% share to the total landings. The overall contribution of this sector during last two decades was more than 10%. Hilsa fishery of the state was mainly supported by the mechanised boats with a mean contribution of about 90% of the total catch landed during 1993 to 2012 (Figure 6).

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 6 Marine Hilsa catch by different fishing fleets along West Bengal (Source: CMFRI, Kochi)

2.2. Time series analysis The collected data from CMFRI were subjected to time series analysis using ARIMA model using statistical software (SAS, 2008). The landings of Hilsa from marine sector followed an increasing trend till 2010 with two peaks during 2004 and 2010. Thereafter the catch was declining (Figure 7). The data was tested for stationary by Augmented Dickey-Fuller test. The lower p value (0.6131) indicated the existence of weak stationarity in the data. Mann Kendall test for trend analysis revealed the existence of trend (p>0.05) in the data set. The two parameters i.e. ACF and PACF showed slightly significance on only first lag. The model was found as (p=1, d=0, q=0). Model accuracy was tested based on RMSE (Table 2). The forecasting Hilsa landing from marine sector was found to have an increasing trend and the catch was found to be fluctuated around mean 20,000 tonnes (Figure 8).

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 7 Pattern of marine Hilsa landings and lags of ARIMA model

Table 2 Parameter estimates of ARIMA model Landing Model parameter for ARIMA Estimated AIC RMSE p d q variance Total 1 0 0 2.77e+08 474.1 16642.07

Figure 8 Actual, fitted and forecasted marine Hilsa landings from West Bengal Since the marine catch constituted nearly 90% of the total Hilsa catch in West Bengal, it could also be inferred that Hilsa catch from West Bengal waters would be fluctuated around mean 20,000 tonnes in future. Hilsa is a migratory species, the yield is depending upon the riverward migration and again the migration assumed to depend on several environmental factors. However, this prediction of yield is purely with reference to a normal condition with optimum environmental parameters.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

3. Procedures and methods

3.1. Sampling and data collection The ideal basis for fish stock assessment is data that fully represent a stock, at least from the moment that it has recruited to the fishery, without any systematic errors or biases. The sampling programme was designed aiming the collected samples would represent the population under investigation, here Hilsa. The widely used stratified random sampling was adopted for this study. The study site was Bhagirathi-Hooghly River of lower Gangetic stretch covering approx. 530 km of length from Farakka to Freserganj in India (Figure 9). There are numerous inland and marine Hilsa landing sites across the river as well as along the coastal areas of West Bengal. Unlike marine sector, landing centres in inland sector are not well defined. In inland sector, fishing of Hilsa in this river largely depends on the tidal effect. The tidal effect is observed up to (Nabadwip) 290 km from sea. Fishers cast their net during the advent of tide and haul when the tide recedes. In the upper zone i.e. from Nabadwip to Farakka, a stretch of 240 km has no tidal effect; hence fishing pattern is different from the down stretch. In the first stage of sampling design, on the basis of the tidal effect and fishing pattern the total river system was divided in two homogeneous strata, one from Farakka to Nabadwip and second from Nabadwip to Diamond harbour. At the second stage, a total of eight landing sites were selected from the above two strata. Since there is no tidal effect from Farakka to Nabadwip, three landing sites (Farakka, Lalbagh, Nabadwip) selected and after Nabadwip to Diamond harbour five landing sites (Tribeni, Sheoraphuli, Bally, Godakhali and Diamond harbour) were selected. The third stage stratification was made based on the unit of Hilsa catch landed by the number of fishing boats. These eight landing sites covers almost all the fishing boats used for Hilsa fishing from Farakka to Diamond harbour in Bhagirathi-Hooghly River. In addition to eight inland stations, two major marine stations i.e. Freserganj and Digha were also selected to observe the daily catch and CPUE from different categories of boats. The major landing stations and their positions are 12

Procedures and methods for continuing assessment of the status of Hilsa resources in India given in Table 3. Hilsa landing information from all the possible nearby sites were collected and treated under the respective stations. To get the information about total catch daily basis in each station at least two people, either fisher or someone having sound knowledge of Hilsa fishery, were engaged for recording Hilsa landings daily based on the format given by CIFRI. Daily information on number of boats engaged in fishing and quantity of Hilsa caught by each boat (CPUE) was recorded from each landing station. All the boats engaged in Hilsa fishing were counted along with the quantity of Hilsa caught, where number of boats was less than thirty. At least 50% of the boats were examined, where number of boats was more than thirty. The stations where getting catch and effort data from fishers were difficult, effort was made to get at least the total no. of boats engaged in fishing and total Hilsa landed during the entire month with number of active fishing days from auctioneer’s data register. A total catch of daily and monthly basis were calculated using catch assessment method described below. Two marine stations i.e. Freserganj and Digha were selected to observe the CPUE of different boats operated in marine sector.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 9 Sampling stations along Bhagirathi-Hooghly River, India

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Table 3 Stratification of sampling stations and their positions Sl. Category Stations Latitude Longitude Sub zones no. 1. Feeder canal Farakka N 24°10’53.2’’ E 88°16’06.6’’ Ganga ghat Beniagram ghat 2. Hazaridwari ghat Lalbagh N 22°46’41.6’’ E 88°22’11.4’’ Krishnamati ghat 3. Dandapani ghat Nabadwip N 23°22’44.2’’ E 88°21’35.1’’ Kharer math Kalna 4. Bolagarh Tribeni N 22°59’00.1’’ E 88°24’10.0’’ Kunti ghat Tribeni 5. Hooghly ghat Bichali ghat Inland Nawabganj Sheoraphuly N 22°10’11.0’’ E 88°12’02.0’’ Seoraphuli ghat Gandhi ghat Srirampore ghat 6. Dakshineswar Bally N 22°38’08.6’’ E 88°21’21.6’’ Bally ghat Nimtala ghat 7. Godakhali Godakhali N 22°23’49.4’’ E 88°08’20.1’’ Burul 8. Raychawk Diamond Diamond harbour N 22°23’49.7’’ E 88°08’19.9’’ harbour Sultanpur FH Nischintapur 9. Kakdwip Namkhana Freserganj N 19°38’34.4’’ E 85°10’13.3’’ Hard wood point 10 mile Bazar Marine Freserganj FH 10. Udaypur Shankarpur Digha N 21°36’13.9’’ E 87°27’40.4’’ Petua ghat (Kanthi) Digha Mohana

Procedures and methods for continuing assessment of the status of Hilsa resources in India

3.2. Catch assessment Daily and monthly catch estimates were calculated as follows: (a) Daily catch estimate i. Daily catch (Cd)

Cd = ∑

Where, Bi = Catch of each boat of the day (B1, B2, B3……Bn). or

ii. Daily catch (Cd)

Cd =

Where, OBt = Total catch for all observed boats B = Total number of observed boats n = Total number of boats landed Hilsa on the day

(b) Monthly catch estimate i. Monthly catch (Ck )

 ∑

Where, Cdi= Daily catch (Cd1, Cd2 Cd3….Cdn). or ii. Monthly catch (Ck)

Mean daily catch (

st th Where, Cd1 to Cdn = Estimated landings from 1 to n sampling day ( ( Where, N = No. of active fishing day during the month. iii. Monthly catch for all (10) stations

Ct= C1+C2+C3+C4+…….+C10

Where, C1 to C10 = Monthly catch of all (10) landing stations

3.3. Spawning profile Experimental fishing was carried out in five selected stations (Godakhali, Sheoraphuly, Tribeni, Lalbagh and Farakka) during the two established spawning seasons i.e. July-October and December-March using multi-mesh gill nets (60-100 mm mesh) for detection of spawning ground. The collected specimens were dissected and the sexes were confirmed. The female gonads were classified into various developmental stages (King, 2007) based on the appearance and ovary and egg (Table 4). The fecundity and length at first maturity (Lm) of the females were calculated following King (2007).

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Table 4 Stages of reproductive development of female gonads Stage Description Ovary Ova I Resting Undeveloped, Small, translucent Non visible to naked eye II Developing Opaque, orange colour Visible and opaque III Ripe Fills body cavity Translucent, large and round IV Spawning/Running Releases egg when pressed Large, translucent, some free in ovary V Spent Shrinking/slack Some residual eggs (Source: King, 2007)

3.4. Size distribution Monthly random measurements of length frequency (LF) and length-weight (LW) data were collected from all the ten zones/stations. The total length (tip of the snout to the tip of the longest caudal fin) was measured for this purpose. The information on craft and gear engaged in Hilsa fishing in each station were also noted. Effort was made to collect at least 400 numbers of length frequency and 100 numbers of length-weight data per month, comprising all the selected stations. The collected length data were fitted to a length frequency table for further analysis using software programs (LFDA (Kirkwood et al., 2003) and FiSAT (Gayanilo et al., 1996). The data were analysed using FiSAT. The length-weight relationship (LWR) was derived by following Le Cren (1951): W = a*Lb Where, W = body weight (g), L= total length (mm), ‘a’ is a coefficient related to body form and ‘b’ is an exponent indicating isometric growth. To test “b” value against the value of “3”, student’s t-test was employed to predict any significant deviation (Snedecor and Cochran, 1967). The t-statistic was calculated as follows: t = (b-3)/Sb Where, Sb = Standard error of ‘b’ = Sb = √ (1/ (n-2))*[(Sy/Sx)2 - b2], Sx and Sy are the standard deviations of x and y respectively. The t-value was compared with t-table value for (n-2) degrees of freedom at 5% significance level.

3.5. Water quality assessment The water quality parameters i.e. salinity, dissolved Oxygen, temperature, pH, alkalinity etc. were collected from eight inland stations (Farakka Lalbagh Nabadwip, Tribeni, Sheoraphuly, Bally, Godakhali and Diamond harbour). The parameters were estimated by following standard methods (APHA, 1996).

Procedures and methods for continuing assessment of the status of Hilsa resources in India

4. Taxonomy

There are three species under the genus Tenualosa viz. Tenualosa ilisha (Hamilton-Buchanan), T. toli (Valenciennes), Hilsa kelee (Cuvier) recognised from the estuaries and coastal waters of India. Among these three species, only T. ilisha forms commercially fishery and scarcely T. toli and H. kelee. Present study was restricted to the species, T. ilisha, popularly known as Hilsa and locally called as ilish in Bengali language in India (Figure 10a).

4.1. Systematic position: Nelson (2006) Kingdom : Animalia Phylum : Chordata Subphylum : Vertebrata Super class : Gnathostomata Grade : Teleostomi Class : Actinopterygii Subclass : Neopterygii Division : Teleostei Super order : Clupeomorpha Order : Clupeiformes Suborder : Clupeoidei Family : Clupeidae Subfamily : Alocinae Genus : Tenualosa Species : ilisha

Valid name: Tenualosa ilisha (Hamilton-Buchanan, 1822)

Procedures and methods for continuing assessment of the status of Hilsa resources in India

4.1.1. Diagnostic features: (Whitehead, 1985)  Body moderately deep, compressed, belly with 30 to 33 scutes.  Head length 28 to 32% of standard length.  Distinct median notch in upper jaw.  Gill rakers fine and numerous, about 100 to 250 on lower part of arch.  Fins hyaline, caudal fin moderate, 25 to 31% of standard length.  A dark blotch behind gill opening, followed by a series of small spots along flank.  Scales (37 to 47) in lateral series, evenly arranged, and the snout usually longer than eye.  Colour in life, silver shot with gold and purple.

4.1.2. Differentiation: (Whitehead, 1985 and Froese & Pauly, 2015)  Resembles T. toli, which has a shorter head (22 to 27% of standard length), a longer caudal fin (31 to 34% of standard length), fewer gill rakers (60 to 100) and no spots along flank, also scutes 28 to 30 (Figure 10b).  The notched upper jaw distinguishes it from other similar clupeids, except H. kelee, which has numerous longitudinal striae on top of head (Figure 10c).  Similar appearance of species like Gudusia chapra has smaller scales, the rows somewhat irregular except on upper part of body, 77 to 91 in lateral series and snout shorter than eye (Figure 10d).

a) Tenualosa ilisha (Hamilton-Buchanan, 1822): known as Hilsa shad

b) Tenualosa toli (Valenciennes, 1847): known as Toli shad

Procedures and methods for continuing assessment of the status of Hilsa resources in India

c) Hilsa kelee (Cuvier, 1829): known as Kelee shad

d) Gudusia chapra (Hamilton-Buchanan, 1822): known as Indian River shad

Figure 10 Hilsa and Hilsa like fish found in West Bengal waters

Figure 11 Tenualosa ilisha

Figure 12 Tenualosa toli

Procedures and methods for continuing assessment of the status of Hilsa resources in India

5. Catch and effort/CPUE assessment

The catch and effort/CPUE data were collected for 12 months i.e. from October, 2013 to September, 2014. The marine Hilsa catch data were collected from CMFRI, Kochi. Both the estimates were summed to get the total catch during the period. The sector-wise and boat-wise effort/CPUE data was collected from the selected 10 landing sites. The daily data on catch and effort/CPUE was collected by the engaged fishers (two fishers at each site) under this study. The daily inland catch was summed to get the monthly estimates of Hilsa landings.

5.1. Inland Hilsa landings The inland (riverine) catch mainly supported by the non-motorised boats. Non-motorised boats mainly concentrated to seven inland stations, from Godakhali to Farakka. A total of 693.4 tonnes of Hilsa was landed in riverine zone during October, 2013 to September, 2014. The station-wise landing is shown in Figure 13. The maximum landings were observed in the lower zone (Godakhali-Bally). In the upper zone, Lalbagh and Farakka were also contributed significantly to the total Hilsa landings. However, Godakhali, Sheoraphuly and Lalbagh were found to be most productive area of Hilsa fishery.

Figure 13 Station-wise Hilsa landings from riverine zone by non-motorised boats

5.2. Marine Hilsa landings Marine Hilsa landing information was collected from CMFRI, Kochi. Catch data were collected from 57 landings centres along the coast of West Bengal for different boats under operation by following multistage stratified random sampling design. A total of 9842 tonnes of Hilsa was landed during October, 2013 to September, 2014. About 95% of marine Hilsa was landed by the mechanised boats, while nearly 5% by motorised boats. The contribution of non-motorised boats in marine sector was less than 1% (Figure 14). No Hilsa was fished during the month of April and May due to fishing closure from 15 April to 31 May every year.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 14 Boat-wise marine Hilsa landings in West Bengal

5.3. Total Hilsa landings A total of 10535.47 tonnes of Hilsa landed in West Bengal during October, 2013, to September, 2014. The marine Hilsa constituted nearly 93% (9842 tonnes) while inland was with 7% (693 tonnes) of the total Hilsa landings (Figure 15). The fishery from January-May was mainly supported by the inland sector (Figure 16). Two peak fishing seasons i.e. July-October and February-March were observed in West Bengal waters (Figure 17).

Figure 15 Sector-wise Hilsa landings in West Bengal

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 16 Monthly Hilsa landings by sector in West Bengal

Figure 17 Total Hilsa landings in West Bengal The major contribution was made by the mechanised boats (gill netters and trawlers) with 89% (9332 tonnes), followed by the artisanal/non-motorised boats with nearly 7% (721 tonnes) and motorised boats with 4% (482 tonnes) to the total Hilsa landings in West Bengal (Figure 18).

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 18 Boat-wise Hilsa landings in West Bengal

5.4. Effort/CPUE The effort/CPUE data were collected from all 10 selected landing sites comprising of both inland and marine sector. The non-motorised boats were operated in inland sector, while the marine sector all the three types of boats were under operation. 5.4.1. Inland sector The CPUE/fish abundance data were collected by conducting experimental fishing and also from the commercial fishing of non-motorised boats. The CPUE of non-motorised boats in riverine zone is shown in Figure 19. The highest CPUE was observed during the month of October (1.28 kg/boat/day) and lowest during December (0.02 kg/boat/day). Above 0.5 kg/boat/day of catch was reported during the month of September, October, November, February, March and April indicating the major fishing season in the riverine zone.

Figure 19 Monthly variation of CPUE of non-motorised boat 24

Procedures and methods for continuing assessment of the status of Hilsa resources in India

The distribution of mean annual CPUE of major stations revealed that there was gradual decline in CPUE from lower (Godakhali) to upper zone (Farakka) of the river. The maximum CPUE was reported Sheoraphuly (0.64 kg/boat/day), followed by Bally and Nabadwip (0.55 kg/boat/day) (Figure 20). However, the number of active boats engaged for Hilsa fishing were more in Godakhali (4343 nos.) followed by Lalbagh (164 nos.), Sheoraphuly (132 nos.) and Tribeni (124 nos.). The number of registered boats operated in and around the sampling station Godakhali was collected from the Department of Fisheries, West Bengal. The total number of active boats engaged in Hilsa fishing for all other stations was collected by surveying all the landings centres located along the Hooghly-Bhagirathi River. The total number of non-motorised boats operated in riverine zone engaged in Hilsa fishing was found as 4924 nos. The mean CPUE, which is also used as index fish abundance, from different inland station is given in Figure 20.

Figure 20 Distribution of mean annual CPUE in major inland stations 5.4.2. Marine sector Both inland and marine Hilsa was being landed at Diamond harbour station. CPUE from selected three major landing sites i.e. Diamond harbour, Freserganj and Digha was recorded. The highest CPUE for motorised boat was recorded during the month of August (20 kg/boat/day), followed by July and October (17 kg/boat/day), while maximum CPUE was recorded for mechanised boats during the month of July (156 kg/boat/day) followed by August (32 kg/boat/day) October (28 kg/boat/day) and 25 kg/boat/day during June (Figure 21). No fishing activity was there during the month of 15 April-31 May due to closed season in West Bengal coast for motorised and mechanised boats.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 21 Monthly variation of CPUE in motorised and mechanised boats The total number of registered boats operated in marine sector for catching Hilsa during 2013-14 was 11,119. Out of which the motorised, mechanised and non-motorised boats were 4156, 2344 and 4619 boats respectively (Source: DOF, WB).

Procedures and methods for continuing assessment of the status of Hilsa resources in India

6. Length based analysis

6.1. Length-weight relationship The length-weight measurements of randomly selected 1160 numbers of specimens (unsexed) were collected from the commercial catch. The measurements were taken on monthly basis with an approx. of 100 measurements per month. The allometric model of L-W was fitted as W = 0.000005L3.12 with R2 = 0.99 (Figure 22). The test of significance of regression coefficient (b) indicated the isometric growth pattern of Hilsa.

Figure 22 Length-weight relationship of Hilsa

6.2. Condition factor Fulton’s condition factor (Kn) was calculated from the randomly selected 1160 specimens. The lowest and highest value of Kn was observed as 0.43 and 3.29. The sampled population was classified into different classes considering Kn = 1 as median value (Table 5). Less than 1% of individuals were classified as very good, while 41.5% were in good condition. Majority of the population (57.6%) were in a state of poor condition (either immature or under-fed). The value of Kn is largely depending on the weight of the individual. Hence, it could be inferred that majority of the population were caught before attaining full sexual maturity or they were poorly fed, indicating existence of stressful environment in West Bengal waters. Table 5 Condition of individuals of Hilsa stock

Class Kn value % of population

Extremely poor <0.5 0.3

Poor 0.5-1.0 57.6

Good 1.0-2.0 41.5

Very good >2.0 0.7

Procedures and methods for continuing assessment of the status of Hilsa resources in India

The condition factor in different maturity stages, environment and length groups were analysed and among the individuals the health condition of adults were better during spawning and in freshwater (Fig. 21).

a) Kn against maturity stages

b) Kn against environment

Procedures and methods for continuing assessment of the status of Hilsa resources in India

c) Kn against length groups

Figure 23 Condition factors of individuals of Hilsa

6.3. Length frequency analysis The total length of randomly selected individuals (11,249 nos.) were measured monthly from selected landing centres from the commercial catch. The samples measured during October, 2013 to September, 2014 are given in Figure 24. The samples were collected with proportion to the total catch landed during the day irrespective of size. The lowest and highest size recorded from the commercial landings was 38 and 510 mm respectively.

Figure 24 Collection of monthly length frequency data The length group of 250 to 400 mm was dominating (nearly 77%) in the commercial catch. However, the highest contribution (nearly 31%) was made by 250-300 mm length group (Figure 25).

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 25 Length frequency distribution of Hilsa in commercial catch with sample timing 0.08 (October, 2013) to 1.0 (September, 2014)

6.4. Growth parameter

The von Bertalanffy growth parameters viz. L∞, K and t0 were estimated using FiSAT-II as 522 mm, 0.69 year-1 and -0.11 year respectively. The fitted VBGF as Lt = 522 mm (1-exp (-0.69*(t+0.11)). The growth performance index (ø’) was estimated as 5.27 (or ø’ = 3.27 when L∞ in cm). The length of fish at different age group was estimated and shown in Figure 26. Hilsa attains its I-VI years of age at length 279, 400, 461, 491, 507 and 514 mm. The age of the largest specimen (510 mm) reported in the commercial catch was estimated as 5+ years, indicating the fishable life span of Hilsa in West Bengal waters.

Figure 26 Age-length key for Hilsa

Procedures and methods for continuing assessment of the status of Hilsa resources in India

6.5. Mortality parameter The total instantaneous mortality rate (Z) was estimated by using length converted catch curve (Figure 27).

Figure 27 Length converted catch curve for estimation of Z The natural mortality coefficient (M) was estimated by using Pauly’s empirical formula. The mortality parameters were estimated as 2.75, 0.94 and 1.81 year-1 for Z, M and F respectively. The exploitation ratio (E) was estimated as 0.66. The summary of the parameter estimates are given in Table 6.

6.6. Recruitment The recruitment took place round the year with two major peaks (Figure 28). This was also confirmed by the appearance of young ones in the commercial catch. The young ones were dominant in the commercial catch during two distinct periods i.e. December-January and March-May, happened to be the recruitment season of Hilsa in Hooghly-Bhagirathi River. The juveniles performed their downward migration to the sea during December-May, during which they were caught by the bag nets operated in the estuarine zone of the river.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 28 Recruitment pattern of hilsa

6.7. Length at first capture (Lc) There multiple gears (gill nets, trawl nets and bag nets) are under operation in West Bengal for catching Hilsa. The present length frequency data were collected from the commercial catch of all the above nets. But the gill nets contributed significantly to the commercial catch. The approx. length at first capture was estimated by backward extrapolation of the linearised length converted catch curve. The length at 25, 50 and 75% of probability of capture was estimated as 250, 284 and 304 mm (Figure 29).

Figure 29 Length at capture of Hilsa at different probabilities The regression slope of LWR reported in the world waters for this species was in the range of 2.73 to 3.13, very close to the present estimate (3.12). The Lmax reported in the present study was smaller than the maximum length (600 mm SL) reported in world waters. Accordingly, the estimate of L∞ was changed. The value of L∞ was reported in the range of 315 to 600 mm TL in different waters against the value of 522 mm TL presently. The growth coefficient (K) was estimated as 0.69 year-1 presently, while the same was reported in the range of 0.36 to 1.5 year-1 in different waters. The

Procedures and methods for continuing assessment of the status of Hilsa resources in India estimated value of ø’ was found to be within the range of the values (3.0 to 3.57) reported earlier. The difference in growth parameters may be attributed with the difference in environmental conditions and level of exploitation, differentiating the stocks in world waters.

Table 6 Summary of population parameter estimates of Hilsa Parameter Present Froese & Pauly (2015) a 0.000005 0.00447 to 0.03150 b 3.12 2.73 to 3.13 R2 0.99 0.72 to 0.99 Asymptotic length (L∞) in mm 522 315 to 600 Growth coefficient (K) in year-1 0.69 0.36 to 1.5

Initial condition parameter (t0) in year -0.11 -0.07 Growth performance index (ø’) (TL in cm) 3.27 3.0 to 3.57 Total mortality rate (Z) in year-1 2.75 - Natural mortality rate (M) in year-1 0.94 - Fishing mortality rate (F) in year-1 1.81 - Exploitation ratio (E) 0.66 - Length at first recruitment (Lr) in mm 38 - Maximum length (L max) in mm 510 600 SL Length at capture (L 50%) in mm 284 -

6.8. Gill net selectivity Gill nets were the main gear to catch Hilsa in both inland and marine sector. Experimental fishing was conducted at different stations with gill net mesh size ranged from 50-100 mm. The numbers caught and the length-weight measurements were recorded. The percentage of retention in the gear against the length groups caught were plotted and shown in Figure 30. The major length groups caught in different mesh nets were 225-300, 300-375 and 350-425 mm in 70 mm, 90 mm and 100 mm mesh gill nets. The different mesh gill nets were also operated in marine sector for Hilsa fishing. The marine gill nets of 50-80 mm and 65-75 mm were mainly represented the length groups ranged between 200-325 mm. The gear selection ogive was plotted for the mesh sizes 70, 90 and 100 mm gill nets (Figure 31). The optimum length (L50) for 70, 90 and 100 mm mesh gill nets were estimated as 260, 315 and 370 mm. The gears below 90 mm mesh resulted landing of large quantity of undersized (immature) Hilsa. Therefore, the mesh above 90 mm nets should be strictly enforced for catching the adults with the objective of allowing the adults at least once to breed in their life time.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 30 Selectivity curves of Hilsa in different mesh gill nets

Procedures and methods for continuing assessment of the status of Hilsa resources in India

a) 70 mm mesh

b) 90 mm

Procedures and methods for continuing assessment of the status of Hilsa resources in India

c) 100 mm

Figure 31 Gear selection ogive for Hilsa caught by different mesh gill nets

6.9. Relative yield per recruit (Y’/R) and biomass per recruit (B’/R) The Y’/R and B’/R were estimated as 0.061 and 0.175 respectively at E = 0.66 by following Beverton and Holt’s relative Y/R model, while taking input M/K = 1.36 and Lc/L∞ = 0.54 (Figure 32). The present estimate of B’/R is only nearly 18% of its virgin biomass. This low level of B’/R indicates that the stock has been facing severe fishing pressure, which won’t be able to support the fishery sustainably in turn which may lead to complete collapse of the fishery in near future. There is an urgent need of increasing the biomass to more than 30% of the virgin stock biomass. Therefore, 24% reduction in present level of fishing effort from 0.66 to 0.50 is recommended to get better biomass per recruit (0.36) and a sustainable Y’/R of 0.054. Further, increase in present length at capture from 284 mm to 322 mm, which is the length at first maturity for Hilsa, will improve the B’/R by additional 2%. This increase in size at capture can be achieved by enforcing the use of above 90 mm mesh gill nets for Hilsa fishing in the region. Hence, it is recommended that 24% reduction in present fishing effort and enforcement of gill nets above 90 mm mesh both in inland and marine sector will help in sustainable management of Hilsa stock in West Bengal waters.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 32 Relative Y/R and B/R curves fitted to E

7. Maturity and spawning profile

Experimental fishing was carried out during the previously established two spawning seasons i.e. July-October and December-March using multi-mesh gill nets (60-100 mm mesh) in selected stations. The samples caught in experimental fishing and samples from landings from commercial catch were taken for reproductive biology study in the laboratory.

7.1. Maturity and spawning season Five maturity stages for female Hilsa were identified based on the appearance and ovary and egg (Table 7). Ripe and spawning individuals were recorded in large quantity during two distinct periods i.e. July-October and February-April. The winter breeding was observed to shift from December-March to February-April during 2013-14. Presently, no mature specimen of Hilsa was encountered during December-January. Hence, based on the occurrence of mature individuals it could be inferred that the peak spawning season of Hilsa in West Bengal waters was July-October and February-April. The Gonado-Somatic index (GSI) was estimated. The lowest and highest GSI value recorded during the spawning season was 4.6 and 21.4 respectively in the riverine zone.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Table 7 Stages of reproductive development of female gonads Stage Description Ovary Ova Ova diameter (mm) I Resting Undeveloped, Small, Non visible to naked <0.4 translucent eye II Developing Opaque, orange Visible and opaque 0.4-0.6 colour III Ripe Fills body cavity Translucent, large 0.5-0.7 and round IV Spawning/Running Releases egg when Large, translucent, 0.6-0.8 pressed some free in ovary V Spent Shrinking/slack Some residual eggs -

Figure 33 Mature male Hilsa

Figure 34 Mature female Hilsa

Procedures and methods for continuing assessment of the status of Hilsa resources in India

7.2. Spawning frequency The existence of two spawning seasons in West Bengal waters was confirmed as above. In order to observe the number of times an individual spawns in a year, ova diameter of different maturity stages of randomly selected ovaries was studied. Here, the stage II (developing) was further sub-divided into two subcategories i.e. early developing and late developing for better understanding (Figure 35). The ova diameter frequency of randomly selected ovaries revealed dominance of a single stage of ova (single peak) in each ovary, indicating Hilsa as an annual spawner. The existence two spawning seasons indicates that the spawning takes place by two groups exists in West Bengal waters. One group takes part in monsoon spawning (July-October) while the other during February-April. Hence, it could be concluded that the individuals spawn once, while the population spawns twice in a year.

Figure 35 Ova diameter frequency of Hilsa showing spawning frequency

7.3. Fecundity The fecundity of randomly selected mature female specimens (Stage III and IV) of Hilsa (n = 37) was estimated by gravimetric method. The lengths ranged from 242-432 mm while the weight from164-980 g. The estimated fecundity was ranged from 0.13-1.23 million eggs per individual. The relative fecundity was ranged from 361-3938 nos. of eggs per gram body weight (Table 8). Table 8 Estimated fecundity of Hilsa Total length Body weight Absolute fecundity Relative fecundity Sl. no. (mm) (g) (million nos.) (nos./g body weight) 1 370 585.0 0.42 718 2 291 304.0 0.22 724 3 252 176.0 0.13 756 4 393 768.0 0.66 863 5 313 386.0 0.34 892 6 300 298.0 0.21 695 7 283 226.7 0.19 859 8 376 670.5 0.50 745

Procedures and methods for continuing assessment of the status of Hilsa resources in India

9 242 164.0 0.15 937 10 395 724.2 0.89 1228 11 295 310.6 0.56 1801 12 416 821.9 0.86 1050 13 305 293.0 0.26 879 14 275 237.6 0.27 1139 15 276 213.1 0.34 1602 16 350 471.0 0.60 1273 17 410 782.5 0.98 1247 18 390 646.0 0.92 1429 19 330 419.2 0.55 1306 20 321 359.7 0.18 494 21 304 312.3 0.52 1659 22 397 740.9 0.96 1291 23 397 694.1 0.84 1209 24 343 773.0 0.64 832 25 370 569.1 0.96 1693 26 318 393.0 0.43 1098 27 412 806.0 0.83 1033 28 420 935.5 0.81 863 29 339 467.0 0.71 1520 30 409 810.6 1.23 1520 31 387 749.8 1.05 1405 32 303 305.3 0.37 664 33 263 222.3 0.20 664 34 246 173.8 0.19 868 35 355 567.7 0.68 3938 36 432 980.1 0.89 1560 37 296 310.5 0.35 361 Range 242-432 164-980 0.13-1.23 361-3938

The non-linear relationship between the length of fish and fecundity was fitted and shown in Figure 36. The model was fitted as Fecundity (F) = 0.000000002*L3.36 with R2 = 0.79.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 36 Relationship between total length and fecundity of Hilsa

7.4. Length at first maturity (Lm) A total of 78 specimens were collected during the spawning season, to estimate the proportion of sexually mature individuals in different length groups in the spawning population. The mean length at first reproduction, or mean length at sexually maturity was estimated by plotting % of maturity with their corresponding length. The length at first maturity of Hilsa was estimated as 322 mm (Figure 37). The age corresponding to 322 mm Hilsa was estimated as 1.5 years.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Figure 37 Length at first maturity (Lm) of female Hilsa

7.5. Spawning ground The survey of spawning ground was initiated based on the two criteria a) occurrence of ripe/running individuals and b) occurrence of early life stages (egg/larvae). The experimental fishing was conducted during the spawning season in inland stations to find the proportion of ripe/running females in the catch. The collected specimens were dissected and GSI of the females were estimated. The highest GSI was observed from Bally (15%) followed by Godakhali (14%). However, higher GSI value was recorded from the stretches of Diamond harbour-Godakhali, Bally-Sheoraphuli-Tribeni and Lalbagh-Farakka (Figure 38).

Figure 38 Mean Gonado-Somatic Index (GSI) recorded from selected stations The maximum recorded value of GSI from these stations indicated occurrence of ripe females as compared to other stations. Hence, it could be inferred that the spawning activities were more in these stretches.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

One and half meter long and 50 cm diameter of zooplankton net of 270 mm mesh was operated both horizontally and vertically during the spawning season in inland stations for collection of early life stages of Hilsa. The collected egg of Hilsa was identified as follows:  Rounded or spherical structure of diameter more than 1 mm  Narrow pervitelline space  Presence of numerous oil globules  Yolk is segmented and centrally placed The fertilised eggs were encountered in lower stretches like Diamond harbour, Godakhali, Bally and Sheoraphuli during September and October. Though there was occurrence of ripe females during July-October and February-April in the river, fertilised eggs were reported during September and October only. Hence, more stringent investigations with sophisticated equipment are necessary for studying the distribution of eggs and larvae, which is beyond the scope of the present study. However, from the findings of distribution of ripe individuals, higher GSI and fertilised eggs, it could be inferred that the spawning activity was more in lower stretches like Diamond harbour-Godakhali, Bally-Sheoraphuli and in upper stretch i.e. Lalbagh-Farakka in the Hooghly-Bhagirathi River.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

8. Habitat characteristics

The quality and quantity of water of the Hooghly-Bhagirathi River was influenced by the monsoon rain, discharge from Farakka barrage and tidal regime. However, the tidal influence was not observed in the upper zone from Nabadwip to Farakka. The physicochemical parameter of water was estimated from all the eight inland stations (Table 9). It was observed that like a tropical river system the water temperature, depth, specific conductivity, hardness and salinity increased, while the parameters like transparency, pH and dissolved oxygen decreased from upper to lower estuarine zone of the river. Broadly three seasons, summer, monsoon (South-West) and winter, were felt in West Bengal. The water temperature dropped to 190C, while it reached 300C during the summer months. Due the monsoon discharge from Farakka as well as from the catchment the decrease in transparency, pH, dissolved oxygen (DO2), specific conductivity, alkalinity, hardness and salinity was observed in monsoon months (June-October). However, except dissolved oxygen concentration all other parameters were recorded maximum during the summer (Table 10). The DO2 concentration was reported maximum during the winter months (December-February) due to decrease in water temperature.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Table 9 Station-wise recorded physicochemical parameters Parameters Farakka Lalbagh Nabadwip Tribeni Sheoraphuly Bally Godakhali Diamond harbour Latitude N 24°10’53.2’’ N 22°46’41.6’’ N 23°22’44.2’’ N 22°59’00.1’’ N 22°10’11.0’’ N 22°38’08.6’’ N 22°23’49.4’’ N 22°23’49.7’’ Longitude E 088°16’06.6’’ E 088°22’11.4’’ E 088°21’35.1’’ E 88°24’10.0’’ E 88°12’02.0’’ E 088°21’21.6’’ E 88°08’20.1’’ E 088°08’19.9’’ Air temp (0C) 26.9±6.2 28.0±5.7 29.8±5.8 30.9±5.8 29.7±5.0 30.4±5.4 28.2±5.0 29.5±4.3 Water temp 25.1±4.8 25.5±4.5 26.4±4.0 26.9±5.0 26.6±5.0 26.9±4.6 26.3±3.7 27.2±3.6 (0C) Transparency 47.4±44.3 39.9±28.1 29.7±14.8 28.3±14.4 30.1±10.6 30.4±15.3 22.9±10.2 20.2±7.7 (cm) Depth (m) 9.0±1.1 10.1±1.8 6.9±2.0 10.5±0.7 9.7±3.3 13.9±6.0 21.8±1.5 28.7±7.0 pH 8.7±0.5 8.7±0.3 8.7±0.4 8.8±0.4 8.7±0.4 8.7±0.3 8.4±0.2 8.4±0.3 Sp. conductivity 340.0±106.4 323.2±84.6 322.8±89.0 335.0±84.2 338.3±102.5 336.7±88.1 352.5±76.6 2251.6±2231.7 (µS/cm) Dissolved O 2 8.2±1.7 7.7±1.9 7.5±1.5 7.7±1.8 7.2±1.9 7.1±1.7 5.3±1.6 6.6±1.1 (ppm) Alkalinity 111.8±23.5 111.8±23.3 112.3±25.4 115.0±23.8 114.3±26.8 115.0±26.1 114.7±20.9 111.5±21.7 (ppm) Hardness 116.7±23.6 116.8±27.2 115.0±30.5 119.5±29.0 120.3±32.8 118.3±34.6 123.5±26.4 283.0±182.6 (ppm) Salinity (ppt) 0.08±0.06 0.08±0.05 0.09±0.06 0.09±0.06 0.09±0.06 0.09±0.06 0.10±0.05 0.99±1.28

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Table 10 Annual variations of physicochemical parameters of Hooghly-Bhagirathi river system Parameters October November December January February March April May June July August September Air temp 30.1±1.1 26.8±3.9 24.0±3.9 17.3±2.4 26.2±3.3 31.5±1.3 33.4±2.0 35.1±2.8 32.1±2.0 29.9±1.2 32.3±1.6 31.5±2.1 (0C) Water temp 28.6±1.0 25.3±3.7 22.0±1.4 19.0±1.1 20.5±0.9 23.8±2.4 28.4±1.2 30.2±2.1 30.0±1.4 30.1±1.1 29.8±1.0 28.9±1.3 (0C) Transparen 13.2±2.0 25.6±3.8 24.4±2.9 39.5±14.5 46.5±21.0 45.7±22.0 49.7±16.4 52.7±43.6 25.6±7.4 19.3±8.4 17.2±4.9 14.1±2.7 cy (cm) Depth (m) 12.9±6.3 12.8±6.1 12.7±6.4 12.7±6.4 12.7±6.4 12.6±6.6 12.4±6.3 15.5±9.2 15.2±8.5 16.6±11.0 12.8±4.6 17.0±11.5 pH 8.4±0.2 8.2±0.4 8.5±0.1 8.8±0.1 8.8±0.3 9.0±0.4 9.2±0.5 8.6±0.1 8.4±0.2 8.7±0.4 8.6±0.1 8.6±0.1 Sp. 246.3±29. 355.8±134. 422.8±148. 598.0±417. 843.3±1146. 890.5±1183. 850.0±1189. 1317.8±2368 535.9±710. 293.3±161. 248.0±17. 298.8±139. conductivity 6 6 3 4 3 7 1 .4 2 4 3 9 (µS/cm) Dissolved 6.6±1.1 8.0±1.0 9.5±1.0 9.0±0.9 8.7±1.4 8.0±1.8 7.2±1.3 6.6±0.4 6.3±1.4 5.6±0.5 6.0±1.2 5.5±0.6 O2 (ppm) Alkalinity 100.8±4.2 110.5±8.9 121.5±6.8 141.6±5.0 132.5±5.3 143.3±6.1 130.3±3.5 133.8±3.9 87.0±5.7 79.8±7.8 86.8±5.1 92.0±2.6 (ppm) Hardness 86.8±6.6 131.5±18.4 143.9±11.1 176.6±42.4 187.3±94.3 191.8±139.3 154.0±73.5 192.0±165.7 124.5±66.4 80.5±12.6 90.5±6.7 110.5±49.4 (ppm) Salinity 0.06±0.01 0.07±0.01 0.09±0.06 0.08±0.01 0.34±0.17 0.48±1.03 0.34±0.67 0.54±1.17 0.18±0.27 0.11±0.08 0.06±0.01 0.11±0.11 (ppt)

Procedures and methods for continuing assessment of the status of Hilsa resources in India

To visualise the effect of water quality parameters (temperature, transparency, depth, pH, sp. conductivity, DO2, alkalinity, hardness and salinity) on CPUE of Hilsa a predictive model was developed for tidal (Godakhali to Tribeni) and non-tidal zone (Nabadwip to Farakka). In non-tidal 2 zone (R = 0.78 and C(p) = 1.18) it was found that the parameters like DO2, alkalinity and hardness showed significant effect on CPUE, while other parameters were insignificant. However, in tidal zone (R2 = 0.95 and C(p) = 6.35) of the river, the parameters like water temperature, specific conductivity,

DO2, alkalinity, hardness and salinity showed significant effect on fish abundance (CPUE). Time series data on physicochemical parameters with corresponding CPUE data is necessary to optimise the habitat parameters for a better CPUE in riverine zone. The historical (time series) data on CPUE of Hilsa is not available in India presently. However, when the physicochemical parameters and CPUE data of last one year for the whole stretch of the river was analysed, it was found that Hilsa abundance was significantly influenced by transparency followed by salinity, specific conductivity, alkalinity, hardness, DO2 and water temperature.

9. Crafts and gears

The gears used for exploitation of Hilsa in inland and coastal water of the Hooghly-Bhagirathi River vary with types and sizes. The most important gears for catching Hilsa are gill net, bag net and trawl net. The gill nets are made of nylon monofilament. There are two types of gill nets viz., drift gill net (Chandijal) and set gill net (Nangarjal). Chandijal is one of the most important gears among the gears for Hilsa. It consists of several pieces of netting, each piece having a length of 8-20 m and height of 5 to 13 m depending on sizes and area of operation. Generally, drift gill net of (60-100 mm mesh) with large sized pieces are operated in the riverine and estuarine zone, while set gill nets of mesh 50-100 mm prevail in coastal and off shore areas. The mesh variation in gill net and selectivity factors are highly variable. Fishing activities are mainly confined to marine zone of the estuary within 30 to 40 km of the shore. The non-selective gears locally called Behundi Jal, a stationary bag net with a wide mouth of 27 m and with very small cod end of mesh size (about 20 mm) operated in the river and estuarine area for catching fishes including Hilsa. Charpata Jal, a screen barrier is also operated locally for catching 48

Procedures and methods for continuing assessment of the status of Hilsa resources in India small fishes in riverine and estuarine zone. The catch from these gears were mostly comprised of juveniles. These gears result landing of huge quantity of Hilsa juveniles during the seaward return migration i.e. December to May. The operation of these gears should be restricted at least during December to May in riverine and estuarine area. Hence, the juveniles can safely migrate into the sea, resulting recruitment success. The fishing crafts used for Hilsa fishing in West Bengal were classified mainly into 3 categories as follows and also is given in Figure 39: a) Mechanised: 4-8 cylinder engine (>30 HP), operates gill and/trawl nets in offshore sea (>18km). b) Motorised: 1-2 cylinder engine (<30 HP), operates gill net and/bag net in inshore and/estuarine areas (<18km). c) Non-motorised: Without engine, operates mostly gill net (occasionally bag net) in riverine, estuarine and inshore areas (<18 km).

a) Non-motorised boat (I) b) Non-motorised boat (II)

c) Non-motorised boat (III) d) Motorised boat (gill netter)

Procedures and methods for continuing assessment of the status of Hilsa resources in India

e) Mechanised boat (trawler) f) Mechanised boat (gill netter)

Figure 39 Types of fishing units used for Hilsa

Procedures and methods for continuing assessment of the status of Hilsa resources in India

10. Summary

 The methods and procedures for collection of Hilsa catch and effort/CPUE data from Hooghly-Bhagirathi River was standardised. The stratified random sampling method was adopted for this purpose.  A total of 10535.47 tonnes of Hilsa landed during October, 2013, to September, 2014 in West Bengal. The marine Hilsa catch constituted nearly 93% (9842 tonnes) while inland was 7% (693 tonnes) of the total Hilsa landings. Two peak fishing seasons i.e. July-October and February-March were observed in West Bengal waters.  The sector-wise landings of Hilsa in West Bengal waters was dominated by mechanised sector (gill netters and trawlers) (89%), followed by the artisanal/non-motorised sector (7%) and motorised sector (4%). The catch per unit effort of non-motorised, motorised and mechanised boats were in the range of 0.02-1.28, 0-20.0, 0-156.0 kg/boat/day during the year.  Hilsa abundance was significantly influenced by transparency followed by salinity, specific conductivity, alkalinity, hardness, DO2 and water temperature in riverine zone.  Hilsa is an annual spawner with two peak spawning seasons i.e. July-October and February-April in West Bengal waters. The fecundity ranged from 0.13-1.23 million eggs per individual with 361-3938 nos. of eggs per gram body weight. The age at first maturity of Hilsa was reported as 1.5 years. The spawning activity was found to be more prevalent in the estuarine (Diamond harbour-Godakhali) and near the upper zone from Lalbagh to Farakka.  The length group of 250 to 400 mm was dominating (nearly 77%) in the commercial catch, while the highest contribution (nearly 31%) was made by 250-300 mm length group. The 53

Procedures and methods for continuing assessment of the status of Hilsa resources in India

VBGF for Hilsa was fitted as Lt = 522 mm (1-exp (-0.69*(t+0.11)). Hilsa attains its I-VI years of age at length 279, 400, 461, 491, 507 and 514 mm. The fishable life span of Hilsa in West Bengal waters was reported as 5+ years.  The exploitation ratio for Hilsa was estimated as 0.66, indicating overexploitation of Hilsa in West Bengal waters.

 The gill nets were the major gear to catch Hilsa. The optimum length (L50) for 70, 90 and 100 mm mesh gill nets were estimated as 260, 315 and 370 mm. The large quantity of undersized (immature) Hilsa was landed by the gill nets of below 90 mm mesh size.  The present estimate of relative biomass per recruit (B’/R) is nearly 18% of its virgin biomass. This low level of B’/R indicates that the stock has been facing severe fishing pressure. Moreover, this low level of biomass won’t be able to support the fishery sustainably, which may lead to complete collapse of Hilsa fishery in West Bengal waters in near future with this present level of exploitation.

11. Recommendations

 At least 24% reduction in present fishing effort and use of gill nets above 90 mm mesh both in inland and marine sector should be enforced for the sustainable management of Hilsa stock in West Bengal waters.  The use of gill nets below 90 mm mesh and other gears like bag nets (Behundi Jal) should be banned in riverine and estuarine zone.  Building awareness and adoption of co-management approach in implementing conservation measures for Hilsa is highly solicited.  Routine collection of catch and effort information to update the current stock status periodically is highly indispensable.  More research intervention on spawning ground survey and migration of Hilsa need to be implemented.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

12. References

American Public Health Association (APHA). 1996. Standard Methods of Water and Wastewater. American Public Health Association, American Water Works Association, Water Environment Federation publication. APHA, Washington D.C. Bhaumik, U. and Sharma, A. P., 2012: Present status of Hilsa in Hooghly-Bhagirathi River. Bull. CIFRI. Kolkata. 179, 42p. Froese, R. and D. Pauly. Editors. 2015. FishBase. World Wide Web electronic publication. www.fishbase.org, (04/2015). Gayanilo, F. C. Jr., Sparre, P. and Pauly, D., 1996. FAO-ICLARM Stock Assessment Tools (FiSAT) users guide, FAO Computerised Information Series (Fisheries) No.8. FAO, Rome, 3 diskettes and 124p. King, M., 2007. Fisheries biology, assessment and management. 2nd Edition. Blackwell publishing, UK. Kirkwood, G.P., Auckland, R., Zara, S.J. 2003. Software: Length Frequency Distribution Analysis (LFDA) Version 5.0. Marine Resources Assessment Group (MRAG) Ltd, London, UK. Le Cren, E. D., 1951: The length-weight relationship and seasonal cycle in gonad weight and condition in the perch (Perca fluviatilis). J. Anim. Ecol. 20, 201-219. Nelson, Joseph S. 2006. Fishes of the world (4th Ed.).John Wiley and Sons,Inc., Canada. P. 601. Pillay, S. R. and Rosa, H. Jr., 1963: Synopsis for biological data on the Hilsa, Hilsa iliisha (Hamilton) 1822. FAO Fish. Biol. Synops. 25, 64p. SAS Institute Inc. 2008. SAS/STAT® 9.2 User’s Guide. Cary, NC: SAS Institute Inc. Sinha, M., 2000: Inland aquatic resources of India, issues and threats. In: Fisheries perspective in environment impact assessment of inland waters for sustainable fisheries management and conservation of biodiversity. M. Sinha, B.C., Jha and M.A. Khan (Eds.). pp.101 Snedecor, G. W. and Cochran, W. G., 1967: Statistical Methods, 6th Edn., Oxford and IBH Publishing Co., New Delhi. 593p. Whitehead, P.J.P., 1985. FAO Species Catalogue. Vol. 7. Clupeoid fishes of the world (suborder Clupeioidei). An annotated and illustrated catalogue of the herrings, sardines, pilchards, sprats, shads, anchovies and wolf-herrings. FAO Fish. Synop. 125(7/1):1-303. Rome: FAO.

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Appendix I Length frequency distribution of Hilsa Length (mm) October November December January February March April May June July August September

0-50 0 0 27 1 0 10 0 0 0 0 0 0

50-100 0 0 149 37 0 121 3 15 0 0 0 0

100-150 1 1 2 13 6 8 124 21 0 2 0 2

150-200 25 22 17 26 9 2 2 0 0 2 2 117

200-250 239 239 136 63 24 49 11 0 42 30 60 398

250-300 296 477 296 243 112 244 38 0 112 368 315 1016

300-350 203 179 142 130 75 148 49 0 146 449 247 684

350-400 220 76 188 221 118 122 21 3 95 678 512 472

400-450 26 6 2 2 39 51 5 4 9 95 96 106

450-500 1 1 0 0 2 8 2 0 1 6 19 12

500-550 0 1 0 0 0 1 0 0 0 0 0 1

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Appendix II Sector-wise catch per unit effort (kg/boat/day) of Hilsa Inland sector: Non-motorised boat

Landing sites October November December January February March April May June July August September

Faraakka 2.246 0.505 0.064 0.023 0.047 0.160 0.250 0.327 0.341 0.697 0.447 0.426

Lalbagh 1.500 0.000 0.000 0.000 0.450 0.650 1.350 0.350 0.078 0.092 0.083 0.419

Nabadwip 0.396 0.156 0.079 0.912 0.943 1.319 0.947 0.619 0.050 0.155 0.205 0.917

Tribeni 0.807 0.396 0.000 0.351 0.598 0.908 0.460 0.243 0.090 0.073 0.118 0.358

Sheoraphuly 2.264 1.188 0.000 0.086 0.321 0.475 0.231 1.427 0.000 0.226 0.582 0.933

Bally 1.457 1.220 0.000 0.159 0.466 0.667 0.420 0.377 0.450 0.474 0.352 0.550

Godakhali 0.317 0.084 0.006 0.386 1.393 1.612 0.198 0.027 0.000 0.124 0.288 0.289

Boat type Marine sector

Motorised 16.710 8.038 9.514 5.042 7.266 3.819 5.819 0.000 8.956 16.961 20.274 9.032

Mechanised 28.390 15.507 8.189 16.691 15.902 11.912 9.313 0.000 24.655 155.742 32.206 11.105

Procedures and methods for continuing assessment of the status of Hilsa resources in India

Appendix III Hilsa landings (tonnes) from West Bengal waters Inland sector: Non-motorised boats

Novembe Februar Septembe October December January March April May June July August Landing sites r y r

Faraakka 5.23 1.45 3.26 3.95 1.08 1.76 1.94 1.64 0.98 2.78 2.15 1.51

Lalbagh 7.81 0.00 0.00 0.00 2.12 3.39 6.80 1.76 0.20 0.25 0.43 1.27

Nabadwip 0.45 0.09 0.07 0.68 1.16 1.80 1.25 0.68 0.06 0.08 0.23 0.85

Tribeni 2.00 0.69 0.00 0.52 2.08 3.49 1.71 0.94 0.13 0.13 0.28 1.33

Sheoraphuly 7.47 4.70 0.00 0.17 1.19 1.19 0.58 3.01 0.00 0.48 2.30 3.33

Bally 1.47 1.43 0.00 0.13 0.73 1.16 0.59 0.65 0.76 0.82 0.61 0.92

Godakhali 31.70 4.73 0.35 52.02 169.33 217.08 25.81 1.76 0.00 16.73 38.80 28.89

Boat type Marine sector

Non-motorise 0 0 0 0 0 0 0 0 0 20.233 0 7.65 d

Motorised 2.015 0.27 12.059 0.915 0.602 0 0 0 36.312 259.555 27.097 143.055

4520.38 1230.60 2314.383 358.391 30.566 12.866 18.709 0 0 203.213 262.26 380.925 Mechanised 7 7