1. Fish distribution during
smolt migration in the
Penobscot Estuary, ME
Shea Volkel
University of North Carolina at Wilmington
Marine Biology
Healthy Oceans Objective: Improved understanding of
ecosystems to inform resource management decisions
Maine Field Station, Orono, ME
Dr. John Kocik and Justin Stevens
Maine
Field Station
20 pages
NOAA Science and Education Symposium
July 30, 2015

2. Outline
• Background-smolts
• Purpose
• Methodology-
hydroacoustics
• Results
• Summary
• Next Steps
• Acknowledgements
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 2

3. What is a smolt? (a lifestage of Atlantic salmon)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 3

4. Study site
• NEFSC Maine Field
Station
• Penobscot Estuary, ME
• One of few remaining
natural U.S. Atlantic
salmon populations
• Mainstem dam
removals
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 4

5. A Tool For Recovery: Restore Co-evolved
Diadromous Fish
•Prey Buffering Hypothesis (PBH)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 5

6. Smolts (vertical distribution)
• Smolts migrate in top 5 meters (surface)
• What about other species?
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 6
Proportion of detections (%)
Detectiondepth(m)
40
35
30
25
20
15
10
5
0
0 10 20 30 40 50
+
+
+
+
+
+
+
+
+
Estuary
0 10 20 30 40 50 60 70 80 90
+
+
+
+
+
+
+
+
+
Bay

7. Purpose
• Characterize fish
distribution patterns
using acoustics
• Determine overlap
necessary for PBH
• temporally
• spatially
• longitudinally
• vertically
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 7

8. Methods (data collection)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 8
Echoes bounce off swim bladders to give position and size estimates

9. Methods (size class categorization)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 9
Target
strength
Estimated
fish length
Size
classification
< -44 dB <10 cm Small
(potential prey
items)
-44 to -35 dB 10 to 30 cm Medium
(smolts &
potential prey
buffers)
>35 dB >30 cm Large
(potential
predators)
TS (dB)= (19.1 log L)- (0.9 log F)- 62 (Love, 1971)TL (cm)
#ofFishTracks

10. Methods (size class categorization)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 10
Target
strength
Estimated
fish length
Size
classification
< -44 dB <10 cm Small
(potential prey
items)
-44 to -35 dB 10 to 30 cm Medium
(smolts &
potential prey
buffers)
>35 dB >30 cm Large
(potential
predators)
TS (dB)= (19.1 log L)- (0.9 log F)- 62 (Love, 1971)
Fish Tracks
TL (cm)
#ofFishTracks

11. Methods (size class categorization)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 11
Target
strength
Estimated
fish length
Size
classification
< -44 dB <10 cm Small
(potential prey
items)
-44 to -35 dB 10 to 30 cm Medium
(smolts &
potential prey
buffers)
>35 dB >30 cm Large
(potential
predators)
TS (dB)= (19.1 log L)- (0.9 log F)- 62 (Love, 1971)
Fish Tracks
TL (cm)
#ofFishTracks

12. Results (fish distribution 10-30cm)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 12
May 5
May 14
May 19
May 28
N/A*

13. Results (stratified fish distribution 10-30cm)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 13
3-6 m
6-9 m
9-12 m
12+ m
N/A*
May 5
May 14
May 19
May 28

14. Consistencies (middle)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 14
#ofFishTracks
May 5
May 14
May 19
May 28
N/A*

15. Consistencies (bottom)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 15
#ofFishTracks
May 5
May 14
May 19
May 28
N/A*

16. Variability (upper middle)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 16
#ofFishTracks
May 5
May 14
May 19
May 28
N/A*

17. U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 17
Variability (lower middle)
#ofFishTracks
May 5
May 14
May 19
May 28
N/A*

18. Summary
• Peak abundances:
• mid-May
• middle-estuary
• middle depth layers (3-9 m)
• Distribution patterns varied:
• between surveys
• across ecozones
• across depth layers (esp. 3-12m)
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 18

19. Next Steps
• Combine data to gain a more complete
understanding of salmon ecology
• Surface trawling and telemetry data
• Predator distribution
• Physical gradients
• Survival
• Use this understanding to recover fish populations
• My future?
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 19

20. Acknowledgements
Dr. John Kocik
Justin Stevens
Paul Music
MFS Team
NOAA Hollings
program coordinators
U.S. Department of Commerce | National Oceanic and Atmospheric Administration | NOAA Fisheries | Page 20