BRDs have been developed through intensive research, taking into consideration the characteristics of the fishery and geographical peculiarities. There has been a significant reduction in the world bycatch levels during the past two decades due to the increased use of BRDs in trawling. Cooperation among the fishing industry, scientists and other stakeholders is fundamental for the success of bycatch management efforts. BRDs, most appropriate to the regional fishing conditions should be adopted and enforced legally to ensure long term sustainability and biodiversity of the fishery resources.

1. A Credit Seminar On:
Fish By-Catch Reduction Devices (BRDs)

2. Introduction
What Is Bycatch?
• The term bycatchrefers to non-targeted species retained, sold or discarded for any reason (Alverson et
al., 1994).
• 'Targetcatch'is the species or species assemblage primarilysought ina fishery, ‘incidentalcatch'is the retained
catch of non-targeted species and 'discardedcatch' is that portion of catch returnedto thesea because of
economic, legal or personal considerations.
• Bycatch includes both discarded and retained incidental catch. In addition to the non-targeted finfishes and
invertebrates, bycatch also involve endangered, threatened or protected species.

4. Why Reduce By-catch?
• Over7 million mt. of fish bycatch arediscarded every year
(FAO, 2003).
• TheFA0 Code of Conduct for Responsible Fisheries
(CCRF) calls for sustainable use of aquatic ecosystems and
requires that fishing and aquaculture beconducted with
due regardfor the environment (FAO, 1995).
• Reduceenvironmental impact.

5. Bycatchin worldfisheries
• A preliminaryassessmentofbycatchin worldfisheries wasmade bySaila(1983).AccordingtoSaila
(1983),the discardswere 6.72million tonnesin shrimp fisheries.
• Later,Andrew& Pepperell (1992) estimatedglobal bycatchin shrimpfisheries at16.7million tonnes.
• In the year1994,Alverson etal. (1994) estimatedtheannualbycatchin theworldfisheries as28.7
million tonnesof whichanestimated27.0million tonneswerediscarded.
• Shrimptrawlingaccountedfor37.2%(9.5 million tonnes)of thetotal worldbycatch.

6. Bycatchin worldfisheries
• In 1998,FAO estimateda globaldiscardlevel of20million tonnes(FAO, 1999).
• Averageannualglobal discards,hasbeen re-estimatedtobe7.3 million tonnesbyKelleher (2004).
• Globally,shrimp trawlingcontributestothe highest level ofdiscard/catchratiosof anyfisheries
(EJF, 2003;Kelleher,2004).
• Davieset al.(2009) recently redefinedbycatchasthe catchthatis eitherunusedorunmanaged
andreestimatedit at38.5million tonnes,forming 40.4%ofglobal marinecatches.

7. Bycatchin Indian context
• Bycatch in Indian fisheries has been studied by George et al. (1981), Gordon (1991),
Luther & Sastry (1993), Rao (1998), Pillai (1998),Kurup et al. (2003; 2004),Bhathal
(2005), Zacharia et al. (2005), Kumar& Deepthi (2006),Boopendranath et al. (2008) and
Gibinkumar (2008). George et al. (1981)
• estimated bycatch in Indian shrimp trawl fisheries at 3,15,902 tonnes per annum which
formed 79.18%of total shrimp trawl landings in India.
• Gordon (1991) estimated bycatch landings in the east coast of India at 90,000 to 130,000
tonnes per annum.
• Rao (1998)re-assessed the bycatch discards by the fleet based at Visakhapatnam during
1988-89 at between 18,930tonnes and 32,421tonnes, assuming 10-15%of shrimp
catch.

8. Bycatchin Indian context
• A study conducted during 1985-90estimatedthe quantity of bycatch landed by trawlersin Kerala,Karnatakaand
Tamil Nadu, as 43,000tonnes (Menon, 1996).
• Pillai(1998)estimatedthat bycatch landings along Cochin, Visakhapatnam and Saurashtra (Gujarat), was about 70
to 90%and averagediscards was15to 20%of the shrimp trawl catch.
• Bycatch landings wasmaximumin
 Gujarat (90-95%),
 followed by Tamil Nadu (80-90%),
 Andhra Pradheshand Karnataka(80-85%),
 Orissa(75-80%),
 Maharashtra (70-75%)and
 Kerala(65-70%).
 InKarnataka state, bycatch from trawlersformed54.4%and 47.9%of total trawlcatch, inthe year2001and 2002
respectively(Zacharia etal., 2005).

9. Bycatchin Indian context
• Thequantity of discards was 34,958 tonnes (33.9% of total catch) in 2001 and
38,318 tonnes (35.1%) in 2002.
• Discards were more in post-monsoon months.
• Thediscarded quantity estimated during 2000- 2001 was 262,000 tonnes and
during 2001- 2002 it was 225,000 tonnes.
• Thedominant varieties among the discards were finfishes, crabs and
stromatopods (Kurup etal., 2003;2004).

10. Bycatchin Indian context
• Based on their study of marine fisheries in the early 1990s, Luther & Sastry (1993)
reported that the bulk of marinelandings in all the maritime states consisted of juvenile
fish.
• Gordon (1991) estimated that juvenile discards from trawling operations, off
Visakhapatnam was 25 to 30%of total catch.
• Pillai (1998) reported that among the bycatch, about 40%consisted of juveniles.
• Juveniles contributed 36%of the discards (15.9% of total catch) in single day fishing and
78% (23.5% of total catch) in multi-day fishing conducted during 2001-02 in Karnataka
(Zacharia et al., 2005).

11. Steps towardCombating Bycatch Issue
• Trawls with a low headline height to minimise fish catches.
• Ground chain arrangements that reducethe amount of seabedanimals, rocks and
debris taken.
• Avoidance of fishing grounds where bycatch is known to behigh, including
grounds where coral, sponges and rocks are present.
• Regulation of mesh sizes to allow some small animals to escape, and
• Using TEDs and BRDs.

12. Bycatch Reduction Devices (BRDs)
• Any modification to a trawl designed to reducethe capture of bycatch.
• It usually refers to devices that are specifically designed to reduce the capture of
fish bycatch andother small animals and debris.
• BRDs are also known as trawl efficiency devices or trash excluder devices
(Robins-Toeger, 1994; Mounsey et al. 1995;McGilvray et al.,1999).

13. BRDs based on Mode of Action
• Separatethe catch by
size.
These devices use inclined grids or panels of
netting to physically block the passage of
bycatch into the codend and guide it toward
an escape opening.
Ex. JTED, square- mesh codend , TEDs.
• Exploitbehaviouraldifferences.
between target catch and bycatch. Most fish
can swim in a moving net, orientate to the
direction of tow, and swim out through an
escape opening. Ex. fisheye, square-mesh
window, Jones-Davis BRD and RES.

14. Classification of BRDs
BRDs can be broadly classified into three categories based on the type of
materials used for theirconstruction, viz.
1. Soft BRDs,
2. Hard BRDs and
3. Combination BRDs
Accordingto Mitchell et al., 1995;Talavera, 1997;
Broadhurst, 2000;Boopendranath etal., 2008;
Gibinkumar,2008;Sabu, 2008).

15. Soft BRDs
• The soft BRDs use soft structures made of netting and rope frames instead of rigid grids,
prevalent in hard BRDs, for separating and excluding bycatch.
• Based on the structure and principles of operation they are classified into five categories
viz.
i. escape windows
ii. radial escapement section without funnel
iii. radial escapement section with funnel
iv. BRDs with differently shaped slits and
v. BRDs with guiding/separator panel

16. Escape Windows
• Escape windows function based on the
differential behaviour of fishes and
shrimps.
• Fishes that have entered the codendtend
toswim backand escapewhen suitable
escape windows are provided, at the top in
the front section of the codend.
Square Mesh Window
Rope BRD

17. Radial Escapement Section Without funnel
• In radial escapementsection without
funnel, a radial section ofnetting with
large meshes is provided between hind
belly and codend.
• Small sizedfishes, jellyfish and other
bycatch components, having low
swimming ability, are expelled dueto
enhancedwater flow through largemesh
section.
TREND

18. Radial Escapement Section withFunnel
• Funnels are positioned between hind belly
and codend of the trawl.
• A small meshed funnel accelerates the water
flow inside the trawl and carries the catch
towards the codend.
• Actively swimming fishes swim back and
escape through the large mesh netting
section surrounding the funnel, where the
water flow rate is weak, while the shrimps are
retained in the codend.
Radial Escapement devices

19. BRDs with differently shapedslits
• BRDs with differently shaped slits utilize
the difference in the behaviour of fish and
shrimp.
• Fishes that enter the codendare given
opportunity toswim back and escapeby
providing slits in the netting on the
topside of the codendor hind belly, while
shrimps are retained in the codend. Diamond Cut BRD

20. BRDs with guiding or separator panel
• Guiding orseparator panels are used to
achieveseparation ofthe bycatch by
using differences in their behaviour or
size.
• It leads the fishes to escapeopenings,
making useof the herding effect of the
netting panels on finfishes. Separator panel BRD

21. Pros n Cons of Soft BRDs
Pros
• Ease of handling,
• Low weight,
• Simplicity in construction and
• lowcost.
Cons
• An important drawback of soft BRDs
is the vulnerability to clogging ofthe
netting panels used in its
construction due to gilling and
tangling by fish ormarine debris.

22. HardBRDs
• Hard BRDs are those which use hard / semi flexible grids as seperating devices in
their construction.
• Thematerials used to makeHard BRDs are solid steel rods, aluminium rods, steel
oraluminium tubings, fibre glass rods, polyamide grids etc.
• Theycan be broadly classified into
1. BRDs with Grids.
2. BRDs with slots
3. Semi-flexible BRDs.

23. BRDs with grids
BRDswithgrids canfurther bedivided into:
FlatgradeBRDs/Bent Grid BRDs/OvalgridBRDs/SlottedGrid BRDs/HoopedandFixed angleBRDs.
 Flat grade BRDs:
 Mostlyrectangularin shapeswithoutanybend in grid bars.
 Developed in Norwaytokeep thejelly fishatbay.
 Usuallymountedin throatsectionatanangle of 45°-50°fromthe horizontal.
 Associatedwithanacceleratorfunnelforguiding thecatchtothe grid.
 Escapewindowsareprovided eitheratthe toporbottomwitha flapofnetting
 Examples–NordmoreGrid ,Wick’sTED,Kelly/GirourardGrid & Sort-V grid.

24. Flat grade BRDs:

25. BRDs with grids
 BentGrid BRDs:
 Rectangular or Elliptical.
 Grid ends are bent at one end near exit opening to facilitate easy ejection of debris and
bycatch preventing clogging.
 Exits holes are guarded with net flaps.
 Mounted in the aft section of the trawl in front of the codend at an angle of 45°-55°from
horizontal.
 Examples –Super Shooter TEDs, Juvenile Thrash Excluder Device (JTED).

26. BentGrid BRDs

27. BRDs with grids
 Oval Grade BRDs:
 Similar to Flat Grids but areeither oval or circular in shape.
 Mounted in the netting section between throat and codend at an angle of 45°-55°
from horizontal.
 Exit openings are either at the top or bottom of the section.
 Examples –Georgia – Jumper, Thai Turtle FreeDevices (TTFD), CIFT- TED & Halibut
ExcluderGrate.

28. Oval Grade BRDs

29. BRDs with grids
• Slotted Grid BRDs:
 Flat grids aremostly rectangular.
 Inserted in the aft section of the trawl just in front of the cod end.
 Provided with slots for passage of targeted species otherthan shrimps.
 Theslots maybe at the top or the bottom made by welding the cross bars or by
leaving an end of the crossbar without joining to the frame.
 Examples: Flounder TED, Jones TED, Matagorda, Hinged grid & Anthony weedless.

30. Slotted Grid BRDs

31. BRDs with grids
 Hooped and fixed angle BRDs:
 SuchBRDs have circular, oval orrectangular hoops in front and rear of the deflecting grid,
which is rigidly fixed in a framework at the desired angle.
 Main advantages consist of sturdier construction for rugged conditions, constant angle of
deflector bars unaffected by change in length of netting.
 Examples: The NMFS Hooped BRD, Cameron shooter BRD & Fixed angle BRD.

32. Hooped and Fixed angle BRDs

33. BRDs with RigidEscape Slots
• BRDs with rigid escape slots are designed to facilitate the escapement of fish from the cod
end.
• FISHEYE is the most important BRD coming under this category.
• It consists of an oval shaped rigid structure with 8-15cm height and 30-40cm width with
supporting frames made of stainless steel rods.
• Fishes swim backward fromthe codend and escape through the fisheye.
• Examples of some varied designs under this category are Florida Fish Eye(FFE), Florida
Fish Excluder (FFE), Snake Eyed BRD, Sea Eagle BRD etc.

34. BRDs with Rigid Escape Slots

35. Semi Flexible BRDs
• Theyare constructed out of Semi- Flexible orFlexible materials like plastic,
polyamide, FRP and Rubber.
• Flexible Plastic grid of polyethylene and the grid frame consists of plastic tubes used
in the North Sea Brown Shrimp Fishery.
• Polyamide grid with hinges for operation from net drums used in the Danish
experiments in the North Sea Shrimp fishery.
• Polyamide – rubbergrid design from Denmark.

36. Semi- Flexible BRDs

37. Combination BRDs
• Sometimes two or more BRDsarecombined in a singularGear to increaseits
efficiency.
• Researchers proposed different combination of Grids, Slotted BRDs such as mesh
window, big eye BRD and similar ones to work in tandem to obtain optimum
results.

38. Combination BRDs

39. Some Important BRDs
Juvenile Fish Excluder cum
Shrimp Sorting Device (JFE-SSD)
• InIndia, about 40%of the bycatch is contributed byjuveniles (FilIaL 1998).
• CIFThas evolved a uniquesolution for this problem bydeveloping the JuvenileFish Excluder cumShrimpSorting
Device (JFE-SSD)
• TheJFE-SSDbrings down the bycatch of juveniles and small sized non-targeted species in commercial shrimp trawl, at
the same time enabling fishermento harvest and retain large commerciallyvaluable finfishes and shrimp species.
• Inaddition, the fishermenwould benefit economically from higher catch values dueto improved catch quality,shorter
sorting time, longer tow duration,highercatch and lower fuel costs.
• JFE-SSDoperations off Cochin (India) have realised bycatch reduction up to 43%with shrimp retention of 96%-
97%.

40. Schematic Diagram of a
Juvenile Fish Excluder cum
Shrimp Sorting Device (JFE-
SSD)

41. Some Important BRDs
Juvenile and Trash Excluder
Device (JTED)
• It consists of three rectangular panels joined with hinges, installed in the trawl codend.
• The firsttwo panels consist of a framework of parallel vertical bars designed to allow fish
to escape from the codend.
• The third panel consists of a rectangular sheet of small-mesh netting to prevent escaped
fish from re-entering the codend (Chokesanguan et al. 2000; Chokesanguan et al., 2004;
Eayrs et al., 2007).
• The evaluationof JTED in Vietnameseshrimp trawl fishery has shown exclusion of
73% of juvenile fish, 16% of valuablefish, and 8% of shrimp (Eayrs et al, 2007).

42. Juvenile and Trash Excluder
Device
(JTED)

43. Some Important BRDs
Turtle Excluder Devices
(TEDs)
• Turtle Excluder Devices (TEDs) consist of panels of large mesh netting (soft TED) or a frame
consisting of grid of deflector bars (hard TED) installed before the codend of the trawl net
at an angle leading upward or downward to an escape opening.
• Small animalssuch as shrimp, slip through the mesh lumen of netting panel or gap
between the deflector bars and are retained in the codend while large animalssuch as
turtles, large fishes and large elasmobranchs are stopped by the netting panel or the grid of
deflector bars and can escape through the opening.

44. Perspective Diagram Of CIFT-TED

45. Conclusion
• A variety of BRDs have been deployed and used either on a commercial or experimental basis, in
order to mitigate regional bycatch issues and to increase the selectivity of trawl nets.
• Some BRDs have been developed through intensive research, taking into consideration the
characteristics of the fishery and the geographical peculiarities .
• There has been a significant reduction in the world bycatch levels during the past two decades
due to the increased use of BRDs in trawling.
• Cooperation among the fishing industry, scientists and other stakeholders is fundamental for the
success of bycatch management efforts.
• Ease of construction and operation of the BRDs , cost effectiveness of the technology and the
economic benefits influences the adoption of the BRD technology.
• BRDs, most appropriate to the regional fishing conditions should be adopted and enforced
legally to ensure long term sustainability and biodiversity of the fishery resources.

46. References
• Alverson, D.L, Freeberg, M.H., Murawski, S.A. and Pope. J.G. (1994) A Global
assessment of fisheries bycatch and discards, FAO Fish. Tech. Paper 339,
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• Ben-Yami, M. (1994) FAQ Purse Seining Manual, Fishing News Books Ltd.,
Oxford: 406 p.
• Beverly, S., Curran, D., Musyl, M., and Molony, B. (2009) Effects of eliminating
shallow hooks from tuna longline sets on target and non-target species in the
Hawaii-based pelagic tuna fishery, Fish. Res. 96 (2-3): 281-288.
• Boopendranath, M.R and Pravin, P (2005) Selectivity of Trawls, Fish. Technol
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• Boopendranath, M.R. (2007) Possibilities for bycatch reduction from trawlers I
India, In: Indian Fisheries - A Progressive Outlook (Vijayan, K.K. Jayasankar P
and Vijayagopal, P., Eds.), p. 12-29, Central Marine Fisheries Researc Institute,
Cochin.
• Boopendranath, M.R. (2009) Responsible fishing operations, In: Handbook o
Fishing Technology (Meenakumari, B., Boopendranath, M.R., Pravin, P.
Thomas, S.N. and Edwin, L., Eds.), p. 259-295, Central Institute of Fisherie

47. References
• Boopendranath, M.R. and Pravin, P. (2009) Technologies for responsible fishing -
Bycatch Reduction Devices and Turtle Excluder Devices, Paper presented in the
International Symposium on Marine Ecosystems-Challenges and Strategies
(MECOS 2009), 9-12 February 2009, Marine Biological Association of India,
Cochin
• Boopendranath, M.R. Dawson, P. Pravin, P. Remesan, M.P., Prakash, R.R.,
Vijayan V., Mathai, PG., PiIIai, N.S., Varghese, M.D. and Ramarao, S.V.S. (2007)
Design and Development of Turtle Excluder Devices for Indian Fisheries In,
Marine Turtles of the Indian Sub-continent (Shanker, K. and Choudhury, B.C.,
Eds.), p. 244-267, CRC Press, Oxfordshire, UK.
• Boopendranath, M.R., Pravin, P. and Remesan, M.P. (2010a) Responsible fishing
technologies to minimize biodiversity loss, Poster presented at the Fourteenth
Meeting of the Subsidiary Body on Scientific, Technical, and Technological Advice
(SBSTTA) of the Convention on Biological Diversity (CBD) on the theme,
Biodiversity and Climate Change: Achieving the 2020 Targets, 10-21 May 2010,
Nairobi, Kenya.
• Boopendranath, M.R., Prakash, R.R. and Pravin, P. (2010b) A review of the

48. References
• Boopendranath, MR., Pravin, P. Gibinkumar, T.R. and Sabu, S. (2006) Development of bycatch
reduction devices and turtle excluder devices in the context of sustainable seafood production, Paper
presented at National Seminar on Seafood Production: Reflections, Alternatives and Environmental
Control, 23-24 February 2006, Goa, India
• Boopendranath, M.R., Pravin, P., Gibinkumar, T.R. and Sabu, S. (2008) Bycatch Reduction Devices for
Selective Shrimp Trawling, Final Report on ICAR Adhoc Project, Central Institute of Fisheries
Technology, Cochin, 220 p.