Fishing for a future- Studies of. Coregonus autumnalis (Pallas) in Lough. Neagh, Northern Ireland. Warren Campbell. Supervisors: Dr. Chris Harrod (QUB).
Fishing for a future- Studies of Coregonus autumnalis (Pallas) in Lough Neagh, Northern Ireland
Warren Campbell Supervisors: Dr. Chris Harrod (QUB) Dr. Derek Evans (AFBI) IFM Rare & protected species conference 28th March 2012
Lough Neagh • Large (383 km2) • Shallow (mean depth 8.9 m) • Highly eutrophic – Total P ca. 180 µg.l-1
• Long standing fishery (largely eel) – 350 employed in 2010 – Co-operative owns fishing rights
• Unusual fish community – Species of conservation concern [coldwater] • • • •
Pollan (Red list- vulnerable) River lamprey Brown trout Eels (Red list- critically endangered)
– Invasive & naturalised species [cool and warmwater] • • • •
Perch Roach Bream Gudgeon
Pollan
• Salmonid • Glacial relict species • Ireland supports only sub-Arctic population – Known as the Arctic cisco – Populations in Russia, Canada and Alaska
• Short lived (c.5yrs) • Rapid growth rate • Early maturing (2yrs)
Conservation value of Irish pollan • IUCN red listed – “Globally endangered”
• The only European vertebrate found uniquely in Ireland – All 5 European populations are Irish
• Lough Neagh described as having the last viable population (Harrod et al, 2002) • Irish populations have unique life history strategy cf. rest of the world – Wholly lacustrine, non-anadromous
Lough Neagh scale fish fisheries •
Rights owned by Lough Neagh Fisherman’s Cooperative Society Ltd. – Created in 1965
•
Perch – Potential re-emergence with population recovery, post crash due to overfishing
•
Roach and bream – Low value (31.5p/Kg) incidental fishery
•
Pollan – Medium value (£1.10/Kg) – Most important fishery during 1st half of 20th Century – Last records kept suggest yield of 100-400 tonnes 1893-1914
PhD Aims- “An assessment of the fisheries potential of Lough Neagh, Northern Ireland” 1. Characterise the current status of the fish community of Lough Neagh to: • Develop long-term monitoring methodology • Allow science-informed management • Investigate current and future status of fisheries
2. Identify alternative fisheries to that of the declining eel fishery •
Inform diversification to support rural economy and a traditional way of life
PhD Research questions • Fish community structure – What is there? Is it consistent over time? • Fisheries assessment – What is being taken? How much? – Management advice under loss of eel fishery, climate change • Development of a standardised sampling methodology for LN • Status of key species – Pollan
Methodology 7 areas sampled every 7weeks • Gill netting- European CEN standard multimesh • Draft netting- encircling of fish with a net of known size - a semi quantitative method
Parameters measured: • Length & Mass • Sex- Gonadosomatic Index of maturity • Age & growth-scales operculae otoliths • Diet- Gut contents
Lough Neagh sampling sites
BR - Ballyronan Bay AR – Ardboe WB – Washing Bay CR – Cranfield Bay FL – Flats; BA – Bartins Bay LM– Lennymore Bay.
60 40 20 0
Percentage composition
80
100
What is the current status of Lough Neagh pollan?
Perch
Pollan
Eel
Brown Trout
Roach
Species
Gudgeon
Bream
3 spined stickleback River lamprey
Population decline? Comparison of draft netting catches 2006 (Inger et al)
Species
Mean n ha-1 + 95% CI
2011 (present study)
Mean biomass (kg h-1) + 95% CI
Mean n ha-1 + 95% CI
Mean biomass (kg h-1) + 95% CI
C. autumnalis
409.7 + 83.1
35.7 + 7.2
78.4 + 21.6
4.52 + 1.8
P. fluviatilis
76.7 + 14.4
2.9 + 0.5
136.7 + 34.3
2.9 + 0.7
R. rutilus
473.4 + 316.9
54.4 + 36.4
3.3 + 2.0
0.1 + 0.1
S. trutta
16.4 + 4.9
4.4 + 1.3
12.8 + 4.0
2.1 + 0.7
G. gobio
13.8 + 4.5
0.2 + 0.1
4.0 + 3.5
0
A. brama
20.8 + 10.9
21.2 + 11.1
1.1 + 1.1
3.9 + 6.2
A. anguilla
127.4 + 23.1
7.6 + 1.4
12.3 + 6
2.2 + 1.1
L. fluviatilis
3.3 + 1.5
0
0.2 + 0.4
0
G. aculeatus
8.8 + 7.8
0
0.6 + 0.7
0
0
0
Roach-Bream hybrid
1.2 + 1.1
0
• 81% decline in abundance within 5 years
200 150 50
100
Fork Length (mm)
250
300
Population decline?
1998
1999
2006
2011
Year
Temporal changes in pollan LF
• Pollan LF has declined (median values: 1999 – 231 mm; 2011 – 164mm). • Cannot rule out overfishing of larger pollan.
Development of a monitoring programme for Lough Neagh
Why? •
European CEN standard sampling protocol using gill nets unsuitable for Lough Neagh – Too productive – Too large
•
Draft netting provides a quick estimate of fish abundance, allowing sampling on a larger scale than with gill nets
•
Draft netting requires 1 day of suitable weather conditions, gill netting requires 2 consecutive days – Can occur infrequently on such a large water body
Methods for a long term monitoring programme? Draft and gill net comparisons Gill netting effort hampered by weather this season –
Harrod (2001) described no significant difference between pollan length frequency distributions of multi-mesh gill vs draft net captured fish However, draft netting captured some small (