Status of Hilsa (Tenualosa Ilisha) Management in the Bay of Bengal: an Assessment of Population Risk and Data Gaps for More Effective Regional Management
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Status of hilsa (Tenualosa ilisha) management in the Bay of Bengal: an assessment of population risk and data gaps for more effective regional management Item Type monograph Authors Milton, David A. Publisher Bay of Bengal Large Marine Ecosystem Project (BOBLME) Download date 25/09/2021 11:09:11 Link to Item http://hdl.handle.net/1834/34003 ii BOBLME-2010-Ecology-01 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: CST-GCP 21/02/2010 For bibliographic purposes, please reference this publication as: BOBLME (2010) Status of hilsa (Tenualosa ilisha) management in the Bay of Bengal, BOBLME-2010-Ecology-01 ii Status of hilsa (Tenualosa ilisha) management in the Bay of Bengal An assessment of population risk and data gaps for more effective regional management David A. Milton Email: [email protected] Report to FAO Bay of Bengal Large Marine Ecosystem Project 15 February 2010 Status of hilsa (Tenualosa ilisha) management in the Bay of Bengal Executive summary This report summarises my assessment of the country status papers on hilsa fisheries that were presented at the BOBP – IGO 2nd Regional Consultation held at the Peninsula Hotel in Chittagong, Bangladesh from 7 – 8th February 2010. The three country reports are included as Annexures 2 - 4. A brief assessment of the status of hilsa management in each country is then made. The assessment includes brief recommendations of potential follow-up activities that could enhance management. The status of knowledge on hilsa and the sophistication of fisheries management for hilsa varied greatly between countries. Bangladesh has benefitted greatly from a number of externally-funded projects that have helped the government implement a number of management measures. These appear to be having a positive effect on the catch rates in the artisanal fisheries for hilsa. However, the several stock assessments of hilsa all indicate that hilsa are over-exploited in Bangladesh. This excessive fishing effort has not been addressed. In India, hilsa fisheries management is a state rather than a national responsibility. The Indian status report indicates that there are currently no controls on hilsa fishing effort in West Bengal. A few legislated seasonal fishing closures may protect part of the hilsa population from fishing, but the report does not indicate on their level of enforcement. Limited assessment of the optimal production in India indicates that the hilsa populations are probably overfished. Much less information is available from Myanmar. The country status report indicates that reliable data are available on fishing gears, vessels and overall export catch. No data were included on domestic catch and no scientific studies on hilsa or its habitats were reported. Following the assessment of the country status reports, I undertake a risk assessment of hilsa in each country with Productivity Susceptibility Analysis (PSA). This analysis examined the trend in hilsa productivity and susceptibility attributes in each country with a view to providing insight into the threats hilsa face. The results indicate that there is limited data on the productivity of hilsa in either India or Myanmar. The trends in productivity attributes of hilsa in Bangladesh are better known and the results highlight worrying declines in several attributes. Susceptibility attributes are better known in India and Bangladesh. The analysis indicated that hilsa populations in India are more susceptible to threats than in Bangladesh. Almost no data are available on susceptibility attributes of hilsa in Myanmar. The increasing susceptibility trend in India, the declining productivity in Bangladesh and an absence of any data in Myanmar suggest that ecosystem services are under threat in the region. I include a summary of a new approach recently developed within CSIRO in Australia to assess ecological risk within a structured framework (Annexure 5). This approach is similar to other approaches available to assess risks to ecosystems but has the advantage of using a highly visual approach to conceptualising the focal ecosystem. Conceptual models are developed in workshops of stakeholders and appear to have high levels of engagement. I recommend that BOBLME consider incorporating this or a similar, structured approach to identify the major ecological risks in the Bay of Bengal. This will highlight those ecosystems services and habitats at risk within an objective comprehensive framework. Outputs from this approach are easily mapped or displayed with simple conceptual diagrams. This makes the outputs easily visualised and better understood by most stakeholders. A better understanding by most stakeholders should lead to better-focussed project activities that engage national governments and other stakeholders. I make a number of recommendations for activities to collect additional data in each country that are currently lacking. These data will better inform the development of both national and regional hilsa management strategies. iv Status of hilsa (Tenualosa ilisha) management in the Bay of Bengal Table of contents 1. Background ......................................................................................................................................... 1 2. Summary of recent hilsa fisheries research in Bangladesh undertaken since 1996 with particular reference to the ACIAR-funded hilsa fisheries research project ................................................. 1 2.1. Hilsa population structure ...................................................................................................... 1 2.2. Age and growth ....................................................................................................................... 2 2.3. Reproduction .......................................................................................................................... 2 2.4. Project management recommendations ................................................................................ 2 2.5. Recent biological studies of hilsa in Bangladesh ..................................................................... 2 2.6. Economic assessment of the hilsa fishery in Bangladesh ....................................................... 3 3. Brief assessment of the status of hilsa management in Bay of Bengal .............................................. 3 3.1. Bangladesh .............................................................................................................................. 3 3.1.1. Recommendations for further studies ............................................................................ 4 3.2. India ........................................................................................................................................ 5 3.2.1. Recommendations for further studies ............................................................................ 6 3.3. Myanmar ................................................................................................................................. 6 3.3.1. Recommendations for further studies ............................................................................ 6 4. Productivity Susceptibility Analysis (PSA) of hilsa population and habitat risk .................................. 7 4.1. PSA methods ........................................................................................................................... 7 4.2. PSA results ............................................................................................................................... 8 4.3. Recommendations .................................................................................................................. 9 5. Coastal and marine ecosystem assets assessment ........................................................................... 10 6. Summary of recommendations ........................................................................................................ 11 7. References ........................................................................................................................................ 12 Appendix I Presentation summarising recent hilsa fisheries research in Bangladesh ....................... 13 Appendix II BOBP-IGO/RC-HF2/5: Status of hilsa fisheries in Bangladesh .......................................... 15 Appendix III BOBP-IGO/RC-HF2/6: Status of hilsa fisheries in India .................................................... 29 Appendix IV BOBP-IGO/ RC-HF2/7: Status of hilsa fisheries in Myanmar ........................................... 50 v Status of hilsa (Tenualosa ilisha) management in the Bay of Bengal Acronyms used ACIAR Australian Centre for International Agricultural Research BFRI Bangladesh Fisheries Research Institute BOBLME Bay of Bengal Large Marine Ecosystem Project BOBP-IGO Bay