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Preliminary observation of environmental factors around offshore cage system in Jeju island

Preliminary observation of environmental factors around offshore cage system in Jeju island. 18 th July 2005 Won Chan Lee, Rae Hong Jung, Hyun Taik Oh. I. Introduction. II. Case Study . III. Preliminary observation. IV. Future work . Contents. Offshore fish cage. NFRDI.

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Preliminary observation of environmental factors around offshore cage system in Jeju island

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  1. Preliminary observation of environmental factors around offshore cage system in Jeju island 18th July 2005 Won Chan Lee, Rae Hong Jung, Hyun Taik Oh

  2. I. Introduction II. Case Study III. Preliminary observation IV. Future work Contents Offshore fish cage NFRDI

  3. Ⅰ. Introduction Fish culture in the coastal waters of many countries has grown dramatically in recent years, and further growth is expected in coming decade (FAO) - Fish culture production : 2,000 ton (’96) → 37,000 ton (2003) •  The rapid growth led to growing concerns on environmental impact • 1) Dispersion high organic and nutrients →Eutrophication, HAB • - 85% of P, 80-88% of C, 52-95% of N as feed supply to environment • - add organic load of cleaning fouled cage to water • 2) Deposition high organic matter → anoxic, changing benthic ecosystem • - organic contents of sediment is10 times higher than another coastal zone • - macrofauna is lower species diversity & opportunistic species • 3) Chemicals (therapeutants, vitamins and antifoulants) , pathogens and • new gene strains are raising environmental concerns Offshore fish cage Offshore fish cage NFRDI

  4. Ⅰ. Introduction  To prevent environmental effect of fish cage, there is a general tendency to force marine fish-farming offshore in USA, Scotland and Hong Kong etc  to establish monitoring methodology for environmental impact of offshore fish cage - physical, chemical and benthic animal factors Offshore fish cage Offshore fish cage NFRDI

  5. Ⅱ. Case study : Mass balance Fish cage Farm site : Hakdong, 16 net cage(6x6m wide, 5m deep) Culturing period : Feb. to Dec., 1998 N, P in fish and fish food : CHN analyzer/ Acid digestion Sedimentation flux : U-type sediment trap, 10m, 1day  Benthic flux : Chamber (50cm x 7cm diameter) • Parameters used in mass balance • Total Environmental Loss (TEL) • : (fish food and juveniles) – (harvest and fish loss)  Introduction Environmental Loss : TEL - sediment accumulation • Dispersion release from the cage • : TEL - sedimentation • Sedimentation accumulation • : Sedimentation - benthic flux Offshore fish cage NFRDI

  6. Ⅱ. Case study : Mass balance Results Nitrogen is key element in aquatic environments and aquaculture systems N contents is 3.5% of fish food and 2.5% of fish body  Sedimentation flux : 1055 Nmg/m2/day  Benthic flux : 47 Nmg/m2/day Summary of nitrogen mass balance in % of total input unit (kg N) Fish food : 2,548 (95.5%), Juveniles : 121 (4.5%)  Harvest : 704 (26.4), Fish loss : 63 (2.4%)  Sedimentation flux : 218 (8.2), Benthic flux : 11 (0.4) - Total environmental loss : 1,901 (71.3) - Introduction environmental loss : 1,694 (63.5) - Dispersion release : 1,683 (63.1) - Sediment accumulation : 207 (7.8) Offshore fish cage NFRDI

  7. Ⅱ. Case study : Mass balance - TEL : 71.3% Fig. Nitrogen mass balance in the cage farm Offshore fish cage NFRDI

  8. Ⅱ. Case study : Spatial extent  Monitoring method to assess the environmental impact by Carroll et al (2003) - visual diving survey, benthic faunal analysis, sediment chemistry, sediment profile imagery - All method is very well agreement on impact zone , but BFA is the most sensitive method Offshore fish cage NFRDI

  9. Ⅱ. Case study : Spatial extent Numerical Composition of Major Taxonomic Groups Farm B Farm A Offshore fish cage NFRDI

  10. Ⅱ. Case study : Spatial extent Farm B Farm A Distribution of Ecological Index Offshore fish cage NFRDI

  11. Ⅱ. Case study : Spatial extent Distribution of dominant species Offshore fish cage NFRDI

  12. Ⅱ. Case study : Spatial extent Stress: 0.05 T-30m T-20m T-60m Farm A T-15m TE-50m TS-15m T-5m TE-15m TE-30m T-0m T-2m TS-30m TS-50m T-10m Highly enriched Slightly enriched TS-5m TS-0m TE-0m TE-5m Farm B Results of MDS (Multi-Dimensional Scaling) Offshore fish cage NFRDI

  13. Ⅱ. Case study : Spatial extent N1 : suspension feeder N2 : surface detritus feeder N3 : surface deposit feeder N4 : subsurface deposit feeder > 50 : little effect, 20 – 50 : enriched, < 20 : degraded Distribution of Infaunal Trophic Index (ITI) Farm A Farm B Offshore fish cage NFRDI

  14. Ⅲ. Preliminary observation  1st monitoring : 15th – 16th June 2005 - physical factors : WT, salinity etc. - current : draft (1hr), RCM 9 Mk Ⅱ(25hr)  2nd monitoring : 13th – 14th July 2005 - physical and chemical factors - benthic fauna - current : ADCP (16 days) 18th July Offshore fish cage NFRDI

  15. Ⅲ. Preliminary observation Distribution of physical factors around offshore cage in June Offshore fish cage NFRDI

  16. Ⅲ. Preliminary observation Draft trajectory at 2m, 20m depth - NE - 1.12km of 2m, 0.55km of 20m - 35cm/s of 2m, 14.3cm/s of 20m Current speed & direction at 30m depth - semi-diurnal - 1.1m/s - NE ~ NW Offshore fish cage NFRDI

  17. Ⅳ. Future work establish monitoring methodology : 1st stage - gathering & analyzing previous research paper - co-work with NOAA assess environmental effect : 2nd stage - sediment chemistry - benthic fauna analysis estimate mass balance : 3rd stage - nitrogen or phosphorus Offshore fish cage NFRDI

  18. Thank you for your attention !

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