Steller Sea Lion Diet and Population Trends in the ... · Non-Breeding Season Diet Using DNA and...
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Steller Sea Lion Diet and Population Trends in the Aleutian Islands Lowell Fritz, Dominic Tollit 1 , Edward Laman, Kristi Miller 2 , Angela Schulze 2 , James Thomason, William Walker, Tonya Zeppelin, and Thomas Gelatt Alaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA USA 1 Sea Mammal Research Unit LLC, Vancouver, British Columbia Canada 2 Molecular Genetics Laboratory, Pacific Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia Canada INTRODUCTION • Steller sea lion population counts 1990-2012 - 177°W to 172°E (Areas 1-3): DECLINING - 170-177°W (Areas 4 & 5): STABLE or INCREASING • Relationship between diet diversity and trend? - Inconsistent over time and season - Not as simple as hypothesized by Merrick et al. (1987) or Trites et al. (2007) METHODS Steller Sea Lion Diet • Analyses of scats (feces) collected at 41 sites in the: - Breeding season – May through August - Non-Breeding season – September through April • Prey hard remains collected and assigned to the lowest taxon possible • DNA-DGGE sequencing techniques using semi-nested 16S primer sets (Tollit et al. 2009) applied to soft material from 699 scats collected in 2008 and 2012 (55 in the breeding and 644 in the non-breeding season) - DNA methods improved detection of: • Large prey not entirely ingested (e.g., Pacific cod, octopus) • Small fish with fragile, thin bones (e.g., myctophids, lumpsuckers) • Invertebrates with few chitinous remains (e.g., cephalopods) - 2° cephalopod-optimized gels were used to clarify octopus and squid spp. RESULTS What did DNA add to HARD PART analysis (Non-Breeding 2000s only)? • Same species most prevalent but different order • Larger prevalence of Cephalopods, Pacific cod, and Smooth Lumpsucker using DNA Combined with Hard Parts than Hard Parts alone (Χ 2 , P<0.001) - Cephalopod +250% - Pacific cod + 94% - Smooth lumpsucker + 57% • DNA provided species identification for salmon, rockfish and cephalopods • Salmon - Sockeye/Pink 51% - Chum 36% - Other 13% • Rockfish - Northern/Dusky 98% • Cephalopods - Giant Pacific Octopus 62% - Berryteuthis spp. 10% - Chiroteuthis calyx 1% - Gonatus/Gonatopsis spp. 27% Acknowledgments This work was made possible by a grant from the North Pacific Research Board (#1114), and the captains and crews of the RV Tiĝlâx and RV Norseman. We also thank all at NMML (in particular V. Burkanov, B. Fadely, S. Finneseth, C. Kuhn, E. Sinclair, J. Sterling, K. Sweeney, and R. Towell) and ADFG for their assistance in sample collection and preparation, and K. Maslenikov (Univ. of WA Fish Collection, Burke Museum) for fish tissue samples to augment DNA library for analysis. Research conducted under the authority of MMPA permit 782-1889, 14526 and others issued to National Marine Mammal Laboratory, Alaska Fisheries Science Center, NMFS. References Johnson, D. S. and L. W. Fritz (In review). "agTrend: a method for estimating trend of aggregated animal counts at sites with different survey histories." Methods in Ecology and Evolution. Merrick, R. L., M. K. Chumbley, et al. (1997). "Diet diversity of Steller sea lions (Eumetopias jubatus) and their population decline in Alaska: a potential relationship." Can. J. Fish. Aquat. Sci. 54(6): 1342-1348. Olesiuk, P.F., M.A. Bigg, et al. (1990). “An assessment of the feeding habits of harbour seals (Phoca vitulina) in the Strait of Georgia British Columbia based on scat analysis.” Can. Tech. Rep. of Fish. Aquat. Sci. No: 1730. 135 p. Tollit, D.J., G.J. Pierce, et al. (2010). “Diet”. In Marine Mammal Ecology and Conservation: A handbook of techniques. Edited by I.L. Boyd, W.D. Bowen, and S.J. Iverson. Oxford University Press, Oxford, UK. Tollit, D. J., A. D. Schulze, et al. (2009). "Development and application of DNA techniques for validating and improving pinniped diet estimates." Ecol. Appl. 19(4): 889-905. Trites, A. W., D. G. Calkins, et al. (2007). "Diets of Steller sea lions (Eumetopias jubatus) in Southeast Alaska, 1933-1999." Fish. Bull. 105(2): 234-248. RESULTS How successful were we in identifying prey? • Hard Parts - 54 prey taxa, 6,553 prey occurrences: 2.1 prey taxa/scat • DNA - 37 prey taxa, 1,263 prey occurrences: 2.2 prey taxa/scat RESULTS What do HARD PARTS reveal about Seasonal-Decadal-Regional Differences in Diet? • Breeding season - Atka mackerel dominant prey - Minor decadal and regional differences • Non-Breeding season - Atka mackerel major prey - Pacific cod, walleye pollock, Irish lords, rockfish, and smooth lumpsucker significant prey - More walleye pollock, rockfish and smooth lumpsucker in 2000s - Regions 1-3 - Highest smooth lumpsucker %FO in 2000s - Region 4 - Highest diversity in 1990s and 2000s - Region 5 - Highest Atka mackerel %FO in both decades (Seguam Pass) ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! ! ! ! ! ! ! ! ! ! ! !! ! ! ! 180° 180° 170°E 170°W 50°N 50°N ! Scat Collection Site 0 100 200 50 Kilometers Bering Sea 3 5 4 2 1 Figure 1. Map of the Aleutian Islands showing the sites where Steller sea lion scats were collected (1990-2012) and the 5 Areas used for trend, diet and groundfish community analysis. Steller sea lion Regional Population Trend: Counts of Adult and Juvenile Steller sea lions by Area, 1990-2012 (black dots). Black line is median estimated count each year and vertical black bars are ± 95% credible interval for each count estimated by agTrend (Johnson and Fritz, eview. Blue line is average trend for 2000-2012 period. Table 1. Number of Steller sea lion scats with hard part remains by Season and Area 1990-2012. Areas 1-3 Area 4 Area 5 Aleutian Islands Season 1990s 2000s 1990s 2000s 1990s 2000s 1990s 2000s Total Breeding 859 332 283 66 221 170 1,363 568 1,931 Non-Breeding 151 144 41 414 114 323 306 881 1,187 Total 1,010 467 324 480 335 493 1,669 1,449 3,118 Figure 2. Frequency of Occurrence of Steller sea lion prey in scats collected in 3 areas of the Aleutian Islands (Figure 1) during the Breeding (May-August) and Non-Breeding (September-April) Seasons during the 1990s and 2000s. Figure 3. Comparison of Split Sample Frequency of Occurrences (SSFO; Olesiuk et al. 1990; Tollit et al. 2010) of prey species in Steller sea lion scats (n) collected during the Non-Breeding season in the 2000s as determined by Hard Parts, DNA, and both (Composite) methods. Note the much larger SSFO using DNA than Hard Parts for Pacific cod, smooth lumpsucker and cephalopods. Table 2. Top 10 most prevalent prey in the NON-BREEDING season diets of Steller sea lions in the 2000s based on hard parts, DNA analysis, and a combination of both, along with the percent of the total diet based on percent Split-Sample Frequencyof Occurrence. HARD PARTS DNA BOTH Rank Prey Category % of Diet Prey Category % of Diet Prey Category % of Diet 1 Atka mackerel 20 Smooth lumpsucker 24 Atka mackerel 18 2 Rockfish spp. 15 Pacific cod 22 Pacific cod 13 3 Smooth lumpsucker 9 Cephalopod spp. 14 Smooth lumpsucker 12 4 Irish lord 8 Atka mackerel 13 Rockfish spp. 10 5 Walleye pollock 8 Rockfish spp. 8 Cephalopod spp. 8 6 Pacific cod 8 Walleye pollock 5 Walleye pollock 7 7 Greenling spp. 4 Salmon spp. 3 Irish lord 6 8 Salmon spp. 3 Greenling spp. 2 Greenling spp. 4 9 Rock sole 3 Irish lord 2 Salmon spp. 3 10 Cephalopod spp. 2 Rock sole 2 Rock sole 3 Non-Breeding Season Diet Using DNA and Hard Parts Seasonal, Decadal and Regional Diet Using Hard Parts Steller Sea Lion abundance trend The recommendations and general content presented in this poster do not necessarily represent the views or official position of the Department of Commerce, the National Oceanic and Atmospheric Administration, or the National Marine Fisheries Service.
Transcript of Steller Sea Lion Diet and Population Trends in the ... · Non-Breeding Season Diet Using DNA and...
Steller Sea Lion Diet and Population Trends in the Aleutian IslandsLowell Fritz, Dominic Tollit1, Edward Laman, Kristi Miller2, Angela Schulze2, James Thomason, William Walker, Tonya Zeppelin, and Thomas GelattAlaska Fisheries Science Center, National Marine Fisheries Service, NOAA, Seattle, WA USA1Sea Mammal Research Unit LLC, Vancouver, British Columbia Canada2Molecular Genetics Laboratory, Paci�c Biological Station, Fisheries and Oceans Canada, Nanaimo, British Columbia Canada
INTRODUCTION• Steller sea lion population counts 1990-2012 - 177°W to 172°E (Areas 1-3): DECLINING - 170-177°W (Areas 4 & 5): STABLE or INCREASING• Relationship between diet diversity and trend? - Inconsistent over time and season - Not as simple as hypothesized by Merrick et al. (1987) or Trites et al. (2007)
METHODSSteller Sea Lion Diet• Analyses of scats (feces) collected at 41 sites in the: - Breeding season – May through August - Non-Breeding season – September through April • Prey hard remains collected and assigned to the lowest taxon possible• DNA-DGGE sequencing techniques using semi-nested 16S primer sets (Tollit et al. 2009)
applied to soft material from 699 scats collected in 2008 and 2012 (55 in the breeding and 644 in the non-breeding season)
- DNA methods improved detection of: • Large prey not entirely ingested (e.g., Pacific cod, octopus) • Small fish with fragile, thin bones (e.g., myctophids, lumpsuckers) • Invertebrates with few chitinous remains (e.g., cephalopods) - 2° cephalopod-optimized gels were used to clarify octopus and squid spp.
RESULTS What did DNA add to HARD PART analysis (Non-Breeding 2000s only)?• Same species most prevalent but different order• Larger prevalence of Cephalopods, Pacific cod, and Smooth Lumpsucker using DNA Combined with Hard Parts than Hard Parts alone (Χ2, P<0.001) - Cephalopod +250% - Pacific cod + 94% - Smooth lumpsucker + 57%• DNA provided species identification for salmon, rockfish and cephalopods• Salmon - Sockeye/Pink 51% - Chum 36% - Other 13%• Rockfish - Northern/Dusky 98%• Cephalopods - Giant Pacific Octopus 62% - Berryteuthis spp. 10% - Chiroteuthis calyx 1% - Gonatus/Gonatopsis spp. 27%
AcknowledgmentsThis work was made possible by a grant from the North Pacific Research Board (#1114), and the captains and crews of the RV Tiĝlâx and RV Norseman. We also thank all at NMML (in particular V. Burkanov, B. Fadely, S. Finneseth, C. Kuhn, E. Sinclair, J. Sterling, K. Sweeney, and R. Towell) and ADFG for their assistance in sample collection and preparation, and K. Maslenikov (Univ. of WA Fish Collection, Burke Museum) for fish tissue samples to augment DNA library for analysis. Research conducted under the authority of MMPA permit 782-1889, 14526 and others issued to National Marine Mammal Laboratory, Alaska Fisheries Science Center, NMFS.
ReferencesJohnson, D. S. and L. W. Fritz (In review). "agTrend: a method for estimating trend of aggregated animal counts at sites with different survey histories." Methods in Ecology and Evolution.Merrick, R. L., M. K. Chumbley, et al. (1997). "Diet diversity of Steller sea lions (Eumetopias jubatus) and their population decline in Alaska: a potential relationship." Can. J. Fish. Aquat. Sci. 54(6): 1342-1348.Olesiuk, P.F., M.A. Bigg, et al. (1990). “An assessment of the feeding habits of harbour seals (Phoca vitulina) in the Strait of Georgia British Columbia based on scat analysis.” Can. Tech. Rep. of Fish. Aquat. Sci. No: 1730. 135 p.Tollit, D.J., G.J. Pierce, et al. (2010). “Diet”. In Marine Mammal Ecology and Conservation: A handbook of techniques. Edited by I.L. Boyd, W.D. Bowen, and S.J. Iverson. Oxford University Press, Oxford, UK.Tollit, D. J., A. D. Schulze, et al. (2009). "Development and application of DNA techniques for validating and improving pinniped diet estimates." Ecol. Appl. 19(4): 889-905.Trites, A. W., D. G. Calkins, et al. (2007). "Diets of Steller sea lions (Eumetopias jubatus) in Southeast Alaska, 1933-1999." Fish. Bull. 105(2): 234-248.
RESULTSHow successful were we in identifying prey?• Hard Parts - 54 prey taxa, 6,553 prey occurrences: 2.1 prey taxa/scat• DNA - 37 prey taxa, 1,263 prey occurrences: 2.2 prey taxa/scat
RESULTS What do HARD PARTS reveal about Seasonal-Decadal-Regional Di�erences in Diet? • Breeding season - Atka mackerel dominant prey - Minor decadal and regional differences• Non-Breeding season - Atka mackerel major prey - Pacific cod, walleye pollock, Irish lords, rockfish, and smooth lumpsucker
significant prey - More walleye pollock, rockfish and smooth lumpsucker in 2000s - Regions 1-3 - Highest smooth lumpsucker %FO in 2000s - Region 4 - Highest diversity in 1990s and 2000s - Region 5 - Highest Atka mackerel %FO in both decades (Seguam Pass)
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180°
180°170°E
170°W
50°N
50°N
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0 100 20050 Kilometers
Bering Sea
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Figure 1. Map of the Aleutian Islands showing the sites where Steller sea lion scats were collected (1990-2012) and the 5 Areas used for trend, diet and groundfish community analysis. Steller sea lion Regional Population Trend: Counts of Adult and Juvenile Steller sea lions by Area, 1990-2012 (black dots). Black line is median estimated count each year and vertical black bars are ± 95% credible interval for each count estimated by agTrend (Johnson and Fritz, eview. Blue line is average trend for 2000-2012 period.
Table 1. Number of Steller sea lion scats with hard part remains by Season and Area 1990-2012.
Areas 1-3 Area 4 Area 5 Aleutian Islands Season 1990s 2000s 1990s 2000s 1990s 2000s 1990s 2000s Total Breeding 859 332 283 66 221 170 1,363 568 1,931 Non-Breeding 151 144 41 414 114 323 306 881 1,187 Total 1,010 467 324 480 335 493 1,669 1,449 3,118
Figure 2. Frequency of Occurrence of Steller sea lion prey in scats collected in 3 areas of the Aleutian Islands (Figure 1) during the Breeding (May-August) and Non-Breeding (September-April) Seasons during the 1990s and 2000s.
Figure 3. Comparison of Split Sample Frequency of Occurrences (SSFO; Olesiuk et al. 1990; Tollit et al. 2010) of prey species in Steller sea lion scats (n) collected during the Non-Breeding season in the 2000s as determined by Hard Parts, DNA, and both (Composite) methods. Note the much larger SSFO using DNA than Hard Parts for Pacific cod, smooth lumpsucker and cephalopods.
Table 2. Top 10 most prevalent prey in the NON-BREEDING season diets of Steller sea lions in the 2000s based on hard parts, DNA analysis, and a combination of both, along with the percent of the total diet based on percent Split-Sample Frequencyof Occurrence.
HARD PARTS DNA BOTH Rank Prey Category % of Diet Prey Category % of Diet Prey Category % of Diet
1 Atka mackerel 20 Smooth lumpsucker 24 Atka mackerel 18 2 Rockfish spp. 15 Pacific cod 22 Pacific cod 13 3 Smooth lumpsucker 9 Cephalopod spp. 14 Smooth lumpsucker 12 4 Irish lord 8 Atka mackerel 13 Rockfish spp. 10 5 Walleye pollock 8 Rockfish spp. 8 Cephalopod spp. 8 6 Pacific cod 8 Walleye pollock 5 Walleye pollock 7 7 Greenling spp. 4 Salmon spp. 3 Irish lord 6 8 Salmon spp. 3 Greenling spp. 2 Greenling spp. 4 9 Rock sole 3 Irish lord 2 Salmon spp. 3
10 Cephalopod spp. 2 Rock sole 2 Rock sole 3
Non-Breeding Season Diet Using DNA and Hard Parts
Seasonal, Decadal and Regional Diet Using Hard Parts
Steller Sea Lion abundance trend
The recommendations and general content presented in this poster do not necessarily represent the views or o�cial position of the Department of Commerce, the National Oceanic and Atmospheric Administration, or the National Marine Fisheries Service.
