Assessment of pingers and porpoise by

Assessment of pingers and porpoise by-catch
rates in Irish gillnet fisheries
Ronan Cosgrove, Daragh Browne, Steve Robson, Dominic Rihan
BIM
(Irish Sea Fisheries Board)
Outline
Assessment of pingers
Pinger spacing trials
Porpoise by-catch estimates
Assessment of pingers
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Why use pingers?
Deter porpoises from fishing nets
The law - Council regulation 812/2004 and S.I 274 of
2007
• All vessels over 12m using “entangling nets”
• ICES divisions VII e,f,g,h and j
Assessment of pingers
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Why assess pingers?
Several models available
Untested in Irish gillnet fisheries
Assessment of pingers
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What did BIM assess?
Practicalities of deploying pingers
Impact on fishing operations and crew safety
Pinger functionality, durability, cost
Assessment of pingers
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Irish fisheries
Approx. 20 vessels over 12m in 2005
Hake S & SW coasts in spring and autumn
Cod SE coast winter and spring
Tangle nets are more opportunistic
Monkfish and turbot all coasts in summer
Assessment of pingers
Four pinger models (15 of each tested)
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Tonal 10 kHz, audible, 100m, battery
replaceable
Airmar
Fumunda
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Wide Band ~10 – 160kHz, 200m, fixed battery
Aquamark 100
Save wave
Assessment of pingers
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Trial 1 – Gillnets: March –June 05
Normal commercial fishing conditions
2 x 20m vessels
Included pinger endurance/durability trial
• 6 observed trips – 27 days
• 7 unobserved trips – 36 days (63 days total)
Assessment of pingers
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Trial 2 – Tanglenets: Aug – Sep 05
2 vessels, 12m and 10m
18 observed days - test conditions
Tangling - quantified
Different attachment methods assessed
Spencer-Carter NH12 net hauler hauling gill nets on MFV Berachah
Net flaking machine on Western Dawn, tangle net vessel
Assessment of pingers
34% of pingers tangled in tanglenets during
hauling
Net flaking machines were frequently blocked,
crew obliged to climb into net pounds to clear
3/4 of the pingers tested were negatively
buoyant - problematic for tanglenets
Problems with lithium batteries
Assessment of pingers
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Effects of fishing operations on pingers
Heavy impact at net hauler with increased hauling
speeds
Heavy impact from net pound steel bars and gunwale
during shooting
Some deep cuts and abrasions observed
Most likely source of internal damage
Assessment of pingers
Pinger performance
Pinger
Lost
Model
Not
Housing
Fouled
Pinging
Damage
(tanglenets)
%
%
%
Airmar
1
7
0
28
Aquamark
2
46
0
41
Fumunda
1
20
0
23
Savewave
2
62
17
47
Pinger cost - 5 years 20km gear
Model
Airmar
Aquamark
Fumunda
Savewave
Battery life months
12
24
15
3
Battery user replaceable
Yes
No
Yes
No
No. pingers required
200
100
200
100
Unit cost €
46
100
67
60
Est. battery cost €
2
N/a
4
N/a
Initial fitting cost €
9200
10400
13400
6000
6
3
4
20
400
3328
480
18240
11200
27040
15800
97200
Total no. fittings over 5 years
Mean annual service cost €
Total cost for 5 years €
Assessment of pingers
Some solutions
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Modified attachment system
Bait bag/overbraid
bag/overbraid and floats
Reduced impact of collisions on pingers
Decreased tangling tanglenets by 50%
Less blockage of the net flaker
More buoyant, better for tanglenets
Permitted attachment between the ‘joins’ of the net
Contact with manufacturers – improved molding
processes – less risk of rupture
Modified Bait bag
Overbraid with heat shrink tubing + external floats between sheets
Assessment of pingers
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Conclusions
None of the pingers 100% reliable
Slow operations
Modified attachment methods do assist
Stronger materials & pinger durability tests required
Further solutions – Pinger spacing
Pinger spacing
Council Regulation 812/2004 specified maximum spacing
on nets of 200m
However the maximum spacing had yet to be field
tested
Sound characteristics of specific models suggested that
spacing could be higher
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Advantage of increased spacing
Reduction in handling and cost for fishermen
Reduction in pollution from noise and lost/damaged pingers
Potential reduction of porpoise habitat limitation
Pinger spacing
Aquamark pingers tested
Two gillnetters from Dunmore East and Dingle
Gillnets were divided into stations of
approximately 4km in length
Pinger spacing
Pingers attached at 200m and 600m spacings on
individual stations
Control stations with no pingers included
Data supplemented with some hauls from pinger
practicality trials due to low by-catch
152 hauls measuring 637 km monitored from
May 2005 – June 2007 used in the analysis
Pinger spacing
152 hauls used in pinger spacing analysis
Pinger spacing
Pinger Spacing Stations
Without
Control
200m
600m
Total
96
22
27
145
7
0
0
0
103
22
27
152
byby-catch
With
byby-catch
Total
Pinger spacing
No significant difference between 200m and 600m
stations
But no significant difference between these stations and
the control stations
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Danish spacing experiment 2006
Higher byby-catch rates – significant results
100% reduction at 455m spacing
78% reduction at 585m spacing
No significant differences between these groups
Derogation issued June 07 – 500m permitted IRL
Porpoise by-catch estimates
Data compiled from the pinger assessment and
spacing trials
Only validated hauls without pingers were used
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Irish by-catch rates were compared with
Celtic Sea 1993 – 1994 (Tregenza et al)
Danish North Sea 2006 (Finn Larsen)
Total porpoise by-catch estimates
Porpoise by-catch rates
Total
Gear
(km)
Porpoise
byby-catch
No.
Observed
effort
(104km.h)
Porpoises/
Celtic Sea 2005
– 2007
406
7
0.88
7.94
Celtic Sea 1993
– 1994
1203
14
1.99
7.04
North Sea 2006
133
43
0.21
201.69
(104km.h)
Porpoise by-catch rates
Porpoise by-catch rates
Porpoise by-catch rates
Source DAFF
180
<12m
160
>12m
Effort Days
140
120
100
80
60
40
20
0
1
2
3
4
5
6
7
8
9
10
11
12
Porpoise by-catch rates
Danish trials – peak by-catch – June - Sep
7 times higher than Celtic Sea peak season
Porpoise by-catch estimates
Total porpoise by-catch estimate
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Irish fleet - Celtic Sea 2006
278 (fleet effort & by-catch)
430 (seasonal effort & by-catch)
355 (+ 247) (days fished)
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Irish fleet Celtic Sea 1993
1497 (+ 931) (trips fished)
Major reductions in fishing effort by Irish fleet
Porpoise by-catch estimates
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Celtic Sea population impact
Population size 80,613 animals 2005 (Scans II)
Estimated by-catch of 355 animals 2006
Estimated annual removal rate Irish vessels 0.44%
Effort still decreasing
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Other fleets
UK: 730 animals 2006 (SGBYC)
Spain & France: minimal effect
Conclusions
Pingers can be used with modified attachments
500m spacing acceptable
Little change in by-catch rates in Celtic Sea
Lower by-catch rates compared to North Sea
Reduction in fishing effort in same period
Lower impact of fishing on porpoise population
Questions?