The development of novel sampling protocols for endangered fish species in Irish lakes: Trials and Triumphs Inland Fisheries Ireland

Transcription

1 The development of novel sampling protocols for endangered fish species in Irish lakes: Trials and Triumphs Inland Fisheries Ireland Emma Morrissey

2 Overview 15 minute presentation: The idea Introduction (Fish species, reporting requirements & sampling methods) Overview of research objectives Discuss objectives 1 and 2 Summary/Overview Questions

3 Aim The idea was simple.. sample endangered fish species in Irish lakes BUT keep fish mortality low Greenpeace

4 Fish species of interest Killarney Shad (Annex II & V) Alosa killarnensis Killarney Shad Pollan (Annex IV) Coregonus autumnalis Pollan Vulnerable and unique, indicator species Arctic Char Arctic char (Red Data Book) Salvelinus alpinus Indicator species, the presence or absence of these species where they are expected is important to the designation of WFD ecological status to a lake.

5 Aim Develop standard sampling protocols for pollan, Killarney shad and Arctic char for the assignment of status for the WFD and HD.

6 Water framework and Habitats Directive Killarney Shad Pollan Arctic Char

7 Research objectives Objective 1. Investigate the relationship between hydroacoustics and pelagic gillnetting Objective 2. Investigate the relationship between hydroacoustics and pelagic trawling Objective 3. Compare hydroacoustic estimates using different survey designs Methods Objective 4. Compare current WFD and HD sampling methods to experimental pelagic gillnetting. Objective 5. Update information on the biology of these species to inform conservation measures. Objective 6. Identify criteria/indicators and develop a model to evaluate the conservation status of these species for the Habitats Directive Biology & Model Objective 7. Locate spawning aggregations with hydroacoustics

8 Research objectives Objective 1. Investigate the relationship between hydroacoustics and pelagic gillnetting Objective 2. Investigate the relationship between hydroacoustics and pelagic trawling Objective 3. Compare hydroacoustic estimates using different survey designs Methods Objective 4. Compare current WFD and HD sampling methods to experimental pelagic gillnetting. Objective 5. Update information on the biology of these species to inform conservation measures. Objective 6. Identify criteria/indicators and develop a model to evaluate the conservation status of these species for the Habitats Directive Biology & Model Objective 7. Locate spawning aggregations with hydroacoustics

9 Research objective 1 Objective 1. Investigate the relationship between hydroacoustics and pelagic gillnetting

10 Fieldwork has been completed at eight of the eleven lakes Sites: Hydroacoustics V s Pelagic Gillnets

11 Background: Hydroacoustics V s Pelagic Gillnets Gillnetting and acoustics are verified methods but much research has failed to find a direct correlation between the abundance estimates of both. Three possible reasons for this are 1) These methods tend to sample different volumes of water.

12 Background: Hydroacoustics V s Pelagic Gillnets Netting and acoustics are verified methods but much research has failed to find a direct correlation between the abundance estimates of both. Three possible reasons for this are 1) These methods tend to sample different volumes of water. 2) Samples collected at different times. 3) Hydrocoustics is active method independent on fish movement while netting is an passive method dependent on fish movement. Arctic Char

13 Method: Hydroacoustics V s Pelagic Gillnets Set pelagic nets set over the deepest part of the lake from bottom to surface. Net 1 0-6m Net m Nets m Net m Net m

14 Method: Hydroacoustics V s Pelagic Gillnets Set pelagic nets set over the deepest part of the lake from bottom to surface. Carry out transects each side of the pelagic nets every two hours from dusk til dawn. Net 1 0-6m Net m Nets m Net m Net m

15 Method: Hydroacoustics V s Pelagic Gillnets Set pelagic nets set over the deepest part of the lake from bottom to surface. Carry out transects each side of the pelagic nets every two hours from dusk til dawn. Net 1 0-6m Net m Nets m Net m Net m

16 Method: Hydroacoustics V s Pelagic Gillnets Set pelagic nets set over the deepest part of the lake from bottom to surface. Carry out transects each side of the pelagic nets every two hours from dusk til dawn. Net 1 0-6m Net m Nets m Net m Net m

17 Method: Hydroacoustics V s Pelagic Gillnets Set pelagic nets set over the deepest part of the lake from bottom to surface. Carry out transects each side of the pelagic nets every two hours from dusk til dawn. Net 1 0-6m Net m Nets m Net m Net m

18 Method: Hydroacoustics V s Pelagic Gillnets Set pelagic nets set over the deepest part of the lake from bottom to surface. Carry out transects each side of the pelagic nets every two hours from dusk til dawn. Net 1 0-6m Net m Nets m Net m Net m

19 Method: Hydroacoustics V s Pelagic Gillnets Set pelagic nets set over the deepest part of the lake from bottom to surface. Carry out transects each side of the pelagic nets every two hours from dusk til dawn. Nets are lifted after dawn; vertical distribution of fish in the nets are recorded. Fish are numbered, identified and length, weight and scales are taken.

20 Results: Hydroacoustics V s Pelagic Gillnets Preliminary results from Lough Ree & Kylemore Mean acoustic abundance (fish/ha) V s CPUE (fish/m net) for all fish species captured in pelagic gillnets

21 Results: Hydroacoustics V s Pelagic Gillnets Preliminary results from Lough Kylemore Mean acoustic biomass (g/ha) V s BPUE (g/m net) for all fish species captured in pelagic gillnets

22 Summary: Hydroacoustics V s Pelagic Gillnets Summary Initial results provide evidence of a good correlation between pelagic gillnetting and hydroacoustics estimates, when the same volume of water is sampled over the same time period. This is an important step in the development of the sampling protocol as it validates the use of pelagic gillnetting to ground-truth hydroacoustic outputs. Acoustic estimates (fish/ha) can be reported as (pollan/ha)

23 Research objective 2 Objective 2. Investigate the relationship between hydroacoustics and pelagic trawling

24 Obj. 2. Pelagic trawling V s vertical hydroacoustics

25 Research objective 2 Lough Allen: 12 Pollan ( cm) and 1 Perch (7.8cm) captured at the surface; trawl speed 2.4kts Good success, fish density very high up 60fish/ha in some areas

26 Research objective 2 Lough Leane: 1 Perch (10.2cm) captured at the surface; trawl speed 2.4kts Poor success at capturing Killarney shad using otter and fry trawl. Killarney shad are built for speed and I expect the adults are able to out swim the trawl. Killarney Shad

27 Summary: Hydroacoustics V s Pelagic Trawling Summary Lough Allen It is very technical and time/labour intensive. Appears to work well when fish densities are high Appears not to work well when fish densities are low Lough Leane Killarney shad are built for speed and can possibly out swim the trawl

28 Summary/Overview Overview of Protocol Development

29 Overview of protocol development

30 Acknowledgements

31 Thank You & Any Questions