1. Presentation of modified fishing gear
Jordan Feekings, DTU Aqua
BALTFISH Forum and BSAC Meeting
Copenhagen, Friday 29 June 2018

2. Population structure Large reduction in the size structure of cod
Average length and weight of cod caught in the BITS survey
28 June 2018

3. Codends used in the Baltic Sea cod trawl fishery since 2003
Increase in mesh size in 2010
BACOMA
110mm
BACOMA 120mm
T90
120mm
115mm
years in use
since 2010-
since 2018
selection device
square mesh panel
turned meshes (T90)
minimum mesh size
number of meshes in circumference
max. 100 50 80
28 June 2018

4. Selectivity parameters of the gears
Population independent
L50 and selection range
Type
Nominal
mesh size
[mm]
L50 (cm)
SR (cm)
BACOMA
110
38.06
5.36
120
44.25
9.68
T90
39.54
4.69
44.53
6.32
28 June 2018

5. Discard ratios Population dependent Area Period Discard ratio = 0-2 %
28 June 2018

6. Effect of reducing the mesh size on discard ratios
BACOMA
110 mm < DR 120 mm
T90
110 mm = DR 120 mm
Same trend for all years ( )
28 June 2018

7. June 2017 gear trials
T90 codend with a larger circumference, a smaller mesh size, lastridge ropes along the selvedges, and longer
Several parameters modified = difficult to determine what parameter leads to what effect
The effect of circumference on the size selectivity of cod
The effect of material on the size selectivity of cod
28 June 2018

8. June 2017 gear trials
On-board a commercial trawler (R 218 Judith Bechmann)
Twin-rig setup
Compare the selectivity of a modified codend with that of the legislated T mm codend
28 June 2018

9. Effect of industry developed T90 codend
The codend developed by the fishermen significantly increased the retention of cod under 47 cm
28 June 2018

10. Effect of circumference in T90 codends
larger circumference caught significantly more cod <43 cm

11. Effect of material type in T90 codends
Polyester codend significantly increased the retention of cod between cm
at 35 cm the polyester codend caught 5 times more

12. Conclusions Lowering the mesh size in the BACOMA and T90 codends:
Reduces in many cases the discard ratio
Reduces the fishing effort required to catch the TAC
Reduces fuel consumption
Reduces the environmental impact (e.g. seabed disturbance)
Reduces the loss of commercial catch which may increase fishermen’s willingness to comply with existing rules
Should not have any adverse effects on the stock since the discard ratios are similar or lower
28 June 2018

13. Conclusions Increasing the circumference in T90 codends:
Reduces the selectivity for cod.
Should not be modified from what is already described in the legislation for BACOMA 120 mm and T mm codends.
The use of alternative material (Polyester):
Increases the retention of smaller individuals.
28 June 2018

14. Questions?
28 June 2018