0. Modifying Fishing Gears to Achieve Ecosystem Objectives
John Willy Valdemarsen, FAO
&
Petri Suuronen, Finland

1. How fishing gears affect the ecosystem
Removal of organisms that, for various reasons should not been taken (e.g. juveniles, threaten species)
Alteration of the habitat that may be negative to the organisms living there
Injure benthic organisms
Reduce habitat complexities
Reduce biodiversity

2. Harvesting pattern of Baltic Cod today:
Mortality other than
fishery (M)
Too few spawners!
Spawning
stock size
Catch consisting mainly of small fish and …
large part of them are discarded!
(estimated discard rate 12-20% in numbers)

3. Examples of gear modifications that reduce unwanted by-catch
Turtle Excluder Device (TED)
Shrimp-fish separators
Size selective grids
Square mesh windows
Medina panel/ “Backdown” principle to avoid dolphins in tuna purse seining
Bird scaring lines in longline fishing
Selective trap nets

4. Turtle Excluder Device for Shrimp trawls
Releases Turtles
Retains target shrimps
Debris blocking the grid can cause some loss of catch
TEDs are mandatory in many tropical shrimp fisheries
Further developments are directed to also avoid fish bycatch

5. Nordmøre grid for separating shrimp and fish
Retains shrimp
Releases fish by-catch
Improves quality of target catch
Reduces sorting work onboard
Increases yields of non-targets for other fisheries
Mandatory in a number of fisheries

8. Size sorting grid Small, juvenile fish are released
Size sorting with grids is less dependant on high catch rates than meshes
Properly designed and used size sorting grids may allow fishing to continue in areas where the abundance of young fish is high

10. Square mesh window to release small fish
Square meshes stay open during towing
Square mesh panels are cheap and simple size selective devices
Square mesh windows are mandatory in some fisheries

12. By-catch while purse seining
Incidental catch of dolphins while purse seining for tuna species ( taken in the Pacific fisheries in the 60ies)
Capture of juvenile tuna and other non-target fish while fishing with Fish Aggregating Devices (FADs)

13. Medina Panel and backdown principle to release dolphins

14. Modified salmon trap to avoid seal capture
Grid in the entrance prevents seals from entering the trap
Strong outside netting also prevents seals from breaking into the trap
The captured salmon is safe from seal attack and seals are not trapped

15. Bird-Scaring line to reduce seabird capture during longline fishing
Seabirds try to take bait from hooks during setting of longlines and might self be hooked
This is particularly a problem for albatrosses and petrels in Southern Oceans
Mitigations tools such as scaring lines significantly reduce the problem

16. How fishing gears impact the ecosystem
Alteration of the habitat that may be negative to the organisms living there
Injure benthic organisms
Reduce habitat complexities
Reduce biodiversity

17. Three examples of bottom habitats
Coral bottom
Muddy bottom
Sandy/stony bottom

18. Overall effect of various fishing gears on bottom habitats
Bottom otter trawls (---)
Beam trawls (----)
Dredges (-----)
Demersal seines (--)
Bottom-set gillnets (-)
Demersal longlines (-)
Traps and pots (-)

19. Possible technical gear modifications
Lifting gear parts off the bottom
Use electrical stimuli to scare target objects off the bottom

20. Trawldoor track on sandy/stony bottom

21. “Smart trawling technology”
Reduced bottom impact of trawl gears can be achieved by;
Lifting the trawl doors from bottom
Using dropper chain instead of roller gear to keep bottom contact
Other ground gear designs (size, material, and construction of rollers)

22. Change of fishing practise
Close the most sensitive areas for fishing (Monitor activity with VMS)
Concentrating fishing effort where density of fishing objects are highest (High CPUE)
Replace harmful fishing gears with gears that are less harmful to the bottom habitat, like a fish pot!!!

23. Fish pot

24. Conclusions (1)
Modifications of fishing gears has significantly helped to reduce by-catches
Techniques that are not practical or increase costs will most likely fail
Economic rewards should be offered for the creation and use of gear modifications that reduce by-catches and minimize impacts on habitats
Co-operation between fishing industry, scientists and other stake holders is fundamental

25. Conclusions (2)
Characteristics of various trawls grounds should be better known to focus the development and implementation of proper technologies and practises
Reduction of impact on grounds that has a “rich” biodiversity should be given highest priority
Areas with a complex biodiversity, like corals, should be closed for sensitive fishing like trawling and dredging
Fishing practice that has reduced bottom interaction should be promoted on grounds with an intermediate type of biodiversity

26. THANK YOU