MABL for Area VII Nephrops – What
Can Gear Technology Deliver?
Dominic Rihan, Marine Technical Executive
Bord Iascaigh Mhara
OUTLINE
• Maximum Allowable By-catch limit
• Definitions
• Area VII Nephrops Fisheries
• Want Gear measures can do?
• Some Results
• What Gear measures can’t do?
• Conclusions
Maximum Allowable By-catch Limit
(MABL)
• Outcome/target approach is good
• Onus is on catch rather than landings
• Define where we want to be rather than how to get
there
• Prescriptive to adaptive management
• Industry led management
• Potentially provides a degree of flexibility
• Promotes the use of selective gears
• BUT………………………………..
DEFINITIONS
• What is a discard?
– 50% by weight
– 60% by numbers
• Is this all species?
• Does it include Nephrops heads from tail fisheries?
• What is a Nephrops Fishery?
• Currently under 850/98
– 35% with 70-79mm
– 30% with 80-99mm
• If you move to 100mm are you a Nephrops vessel?
• Simple solution for vessels?
Nephrops Functional Areas
Area VII Nephrops Fisheries
• A number of different fisheries
• Different catch compositions
– Nephrops Catches of 30-80%
– Haddock and Whiting in the Irish Sea
– Hake and megrim in the Porcupine Fishery
• Very different rates of discarding
– High discards in the Irish Sea, Smalls & Aran
– Low discards in the Porcupine
• Very different discarded species
– Haddock, whiting & small Nephrops - Irish Sea, Smalls, Aran
– Megrim – Labadie
– Boarfish, Argentine – Porcupine
– Herring and Horse mackerel – Smalls and Galley
• Very little Baseline data for many discarded species
What can gear measures do?
• Only part of the solution
• A lot of research
• Both size and species selectivity
• Simple changes to mesh size or codend geometry
• A lot of devices
– Square Mesh
– Grids
– Separator Trawls
– Coverless Trawls
• Generally all research has been targeted at commercial species
e.g. cod, haddock and whiting
SOME RESULTS
Swedish Grid & Square Mesh codend
• Grid and square mesh codend combined gave reduced discards
by about 77%
• ~45% less Nephrops
Codend Mesh Size Geometry
• Increasing mesh size from 80mm to 100mm gave a 65-70%
reduction in the catch of small Nephrops but very variable
• Removing the lifting bag reduced discards of haddock by 71%
SOME RESULTS
Inclined Separator Panel
• 87% and 93% of haddock and whiting released across all
size ranges
• 76% of cod across all size ranges
Coverless Trawl
• 50% reduction in haddock and whiting discards
• 50% reductions in marketable catches of haddock and
whiting
SOME RESULTS
Square Mesh Panel (120mm)
• A significant effect for cod, with about 50% of 31cm fish
being released.
• 16% of haddock and 11% of whiting and 44% of cod at
or below mls retained
French Flexible Grid
• Nephrops discards (< 28mm) are reduced by 25 to
35% (13 mm bars spacing)
• No losses of marktable Nephrops
What gear measures can’t do?
• Results can be variable depending on parameters such as catch
size
• Selectivity of Nephrops can be problematical
• What about Herring, mackerel and other pelagic species
• Can be released but what is the level of unaccounted mortality?
• What about species such as boarfish, argentine, gurnards,
dragonets
• In many cases ubiquitous and hard to avoid
• What about crabs and other benthic organisms?
CONCLUSIONS
• Good concept from a gear technology perspective
• Need to define what a Nephrops fishery is?
• Need to acknowledge there are different fisheries
with different problems
• Gear modifications not the whole solution but
• Gear modifications used correctly can reduce
discards of some species by 30-40% or more
• Will be inevitable loss of marketable catch
• Won’t reduce discarding of non-commercial species
• May lead to unaccounted mortality of some species
CONCLUSIONS
• Concentrate on commercial species in first instance
• Concentrate on fisheries with known high discards
i.e. Irish Sea, Smalls, Aran
• Joint BIM/MI project will look at Aran fishery
• Better baseline data
• Easier to enforce
• Will only work if fishermen’s mindset can be changed
• Norwegian system began with one species – cod!!
• Still only applies to a small number fo quota species