2014-2015 Overview : Many fisheries are non-selective fishing gear catching animals that they did not intend to. This non-taget extra catch is known as ‘bycatch’. Of these bycatch species, some have a commercial value and are brought back to land by fishers to be sold. However, a large proportion is unwanted and so is discarded-thrown back over the side of the boat. The mean of bycatch & discards environmental & social Impacts Some strategies & solutions Some bycatch reduction devises in shrimp trawls : TEDs JTEDs RES Square mesh codends Fisheyes Square mesh window Relation between effort & bycatch Effects of cod-end mesh size on the catch discarded

1. Bycatch &discards
Faculty of fish resources
Suez university – Egypt
Prepared By ;
Salma Ibrahim Baghdady

2. Overview :
• introduction
• The mean of bycatch & discards
• environmental & social Impacts
• Some strategies & solutions
• Some bycatch reduction devises in shrimp trawls :
TEDs
JTEDs
RES
Square mesh codends
Fisheyes
Square mesh window
• Relation between effort & bycatch
• Effects of cod-end mesh size on the catch discarded

3. Introduction:
• Many fisheries are non-selective fishing
gear catching animals that they did not intend
to. This non-taget extra catch is known as
‘bycatch’.
• Of these bycatch species, some have a
commercial value and are brought back to land
by fishers to be sold. However, a large
proportion is unwanted and so is discarded-
thrown back over the side of the boat.

4. FAO estimates:
7.3 million tonnes of
fish is discarded every
year
• Nearly 20 percent of shark species are
threatened with extinction, primarily as a
result of being caught accidentally on
longlines. Bycatch also includes young fish
that could rebuild populations if they were
allowed to grow and breed.

5. Hundreds of thousands of sea turtles, seabirds and marine
mammals, including whales, dolphins and porpoises, die as
bycatch. As many as 200,000 loggerhead sea turtles and 50,000
leatherback sea turtles are caught annually. Longline fishing also
kills hundreds of thousands of seabirds when they become
entangled in drift nets or caught on longline hooks when they
dive for bait.
This black-browed albatross has been hooked on a long-line.
Seabirds with longline fishing vessel
Not only fish:

6. By catch
is the portion of the catch that is not comprised of the
fishery’s target species .
Species that are caught accidentally
Bycatch from a shrimp trawler

7. The FAO defines discards as
the portion of the catch that is thrown back into the sea either dead or
alive . Like marine mammals , crustaceans , and seabirds ,sharks, birds,
turtles, corals ,etc.

8. catch
Target
species
Valuable
bycatch
• Non valuable
species
• Over quota
species
• Undersized
individuals
market Discarded

9. Bycatch from shrimp trawling usually consists
of many fish species and occasionally large
animals.

10. Results;
• Waste of a natural resource without any
economic returns.
• Major threat to the health of fish stocks
• Threat to the future of the fishing industry
• Capture and discarding juvenile lower catch
opportunities for those species in the future
-Negative impact on the marine ecosystem &
biodiversity
-Decrease The sustainability of fisheries

11. Bycatch also includes sponges and rocks and
may reduce the quality of the shrimp catch.

13. Solution:
• Use and development of species selective gear.
• Monitoring and control of fishing gears
• Motivating Technical conservation measures to
improve gear selectivity.
• Use Electronic logbooks (assessing discard rates during
routine inspection by fishery inspectorate officers. )
• The use of closed areas or protected areas to protect
juvenile and spawning fish.
• fisheries management &marketing strategies
• State’s laws for prohibiting discards & overgrading.
Sustainable development

14. fishermen have been using fishing methods designed to reduce
the capture of many of these animals, including:
• ground chain arrangements that reduce the
amount of seabed animals, rocks and debris taken,
• avoidance of fishing grounds where bycatch is
known to be high, including grounds where coral, sponges
and rocks are present,
• using mesh sizes big enough to allow some
small animals to escape
• using TEDs and BRDs.

15. The first steps toward reducing bycatch is to identify the
type of bycatch to be excluded

16. TEDs
used to exclude turtles
and other large animals
from the trawl.

18. 'turtle excluder device' is any modification to a shrimp trawl designed to reduce the capture
of turtles. These devices are sometimes called a 'trawl efficiency device' because they can
also prevent the capture of other large animals including sharks, stingrays, jellyfish and
some large fish.

19. JTED
• Juvenile and Trash Excluder Device
filters small fish including trash
fish from the catch but not the
larger shrimp

21. RES Radial Escape Section
BRD features a guiding funnel to
concentrate all animals into the middle
of the codend. As fish exit the funnel,
some swim forward and through a panel
of large square-meshes that extend
radially around the codend

22. square-mesh codends
square-mesh netting stays open for the duration of the tow,
unlike diamond-mesh netting that closes under the weight of
the catch. The selection of mesh size is very important and
trial and error is needed to find the mesh size that maximises
fish exclusion

24. T90:

26. fisheye
• is designed to allow strong swimming fish to
escape from the trawl.

27. square-mesh
window
is simply a panel of large meshes hung on the bar so they
remain open during the tow .This is in contrast to diamond
meshes which tend to close under tension.

29. Relation between effort & bycatch:

30. Effects of cod-end mesh size on the proportion
of trawl catch discarded

31. A key to the successful involvement of fishermen is
to explore how they may benefit from reducing
bycatch.
These benefits may include:
1. improved trawling and pocessing efficiency,
2. better product quality and marketing
opportunities, and
3. protecting the marine environment and
extending the life of the fishery.
Longer trawl
duration &
wingend
spread
Reduce
damage to
codend
Quicker
processing &
sorting time
Reduce injures
to crew from
dangerous
animals

32. The catch on the right includes large animals because a TED
was not fitted to the trawl.
The catch on the left is the result of using a TED.

33. Discard weight* by major world region. Source: NRC bycatch database.

34. The top weight-based discard to landed target catch ratios by gear type :

35. References:
• http://www.worldwildlife.org/threats/bycatch
• http://oceana.org/en/our-work/promote-responsible-
fishing/bycatch/overview
• http://www.fao.org/docrep/w6602e/w6602e09.htm
• http://www.seafoodwatch.org/ocean-issues/wild-seafood/bycatch
• http://en.wikipedia.org/wiki/Bycatch
• A guide to bycatch reduction in tropical shrimp
• MCS information sheet on discards and bycatch
• https://www.youtube.com/watch?v=w_Nogi4E35I
• https://www.youtube.com/watch?v=lbSQhy0axH0
• https://www.youtube.com/watch?v=gwe06aoOE9g
• http://www.fao.org/docrep/003/t4890e/T4890E03.htm#fig3
• http://www.fao.org/docrep/003/t4890e/T4890E00.htm#TOC
• https://www.youtube.com/watch?v=-pmv0Wm43MM