EAST, WEST, NORTH & SOUTH: Spatio-Temporal Variation in the Diet & Prey Characteristics of Rhinoceros Auklets in the N. Pacific Ocean Julie A. Thayer & William J. Sydeman (PRBO Conservation Science), Douglas F. Bertram & Mark Hipfner (Canadian Wildlife Service & Simon Fraser University), Leslie Slater (USFWS, Alaska Maritime National Wildlife Refuge), Scott A. Hatch (USGS, Alaska Biological Science Center), Yutaka Watanuki (Hokkaido University, Japan)
Objectives Investigate trends in spatial and temporal variation of marine bird diet in relation to oceanographic variability 6 study sites for Rhinoceros Auklet throughout N. Pacific Long-term datasets spanning 25 years Discuss importance of basin-wide network of marine bird bio-sampling stations to monitor predator & prey responses to ocean climate change
N. Pacific Seabird Colonies with Long-term Data Bluff Teuri Talan Buldir St. George Chowiet Barren Middleton St. Lazaria Frederick Triangle Tatoosh Yaquina Castle SE Farallon Point Reyes Alcatraz Año Nuevo Vandenberg S. Miguel Anacapa S. Barbara S. Benitos 0-200ft 200-1000ft >1000ft N
North Pacific s Middleton St. Lazaria Tsushima Teuri N. Pacific Alaska Transition Zone SE Farallon Triangle Año Nuevo Kuroshio California N
Tertiary Consumer: Rhinoceros Auklet (Cerorhinca monocerata) Ranges throughout N. Pacific rim Diving seabird attains depths of 60m (avg 15m) Preys on mid-water schooling fishes Tim Zurowski Fishes sampled from auklets provisioning young in summer
% Mass Rhinoceros Auklet Diet 10 5 10 5 10 5 10 other squid (Loligo) Juvenile predatory fishes: greenling (Hexagrammidae) sablefish (Anoplopoma) salmon (Oncorhynchus) rockfish (Sebastes) 5 Small coastal pelagic fishes: sardine (Sardinops) 10 herring (Clupea) N 5 10 5 capelin (Mallotus) saury (Cololabis) 10 sandlance (Ammodytes) anchovy (Engraulis) 5 1981 1987 1999
California Forage Fishes other squid (Loligo) Juvenile predatory fishes: sablefish (Anoplopoma) salmon (Oncorhynchus) rockfish (Sebastes) Small pelagic fishes: saury (Cololabis) anchovy (Engraulis) 10 5 Offshore California N 10 5 1981 1987 1999 % mass Nearshore
Transition Zone Forage Fishes other Juvenile predatory fishes: salmon (Oncorhynchus) rockfish (Sebastes) Small pelagic fishes: herring (Clupea) saury (Cololabis) sandlance (Ammodytes) 10 Transition Zone 5 N 1981 1987 1999 % mass Offshore
10 Offshore 5 % mass 10 5 Nearshore Alaska 1980 1982 1986 1988 1992 1994 other 1998 2000 Juvenile predatory fishes: N greenling (Hexagrammidae) Alaska Forage Fishes sablefish (Anoplopoma) salmon (Oncorhynchus) Small pelagic fishes: herring (Clupea) capelin (Mallotus) sandlance (Ammodytes)
10 % mass 5 Offshore 1980 1982 1986 1988 1992 1994 1998 2000 other Juvenile predatory fishes: greenling (Hexagrammidae) Tsushima Small pelagic fishes: sardine (Sardinops) saury (Cololabis) N sandlance (Ammodytes) Tsushima Forage Fishes anchovy (Engraulis)
% Mass Rhinoceros Auklet Diet 10 5 10 5 10 5 10 other squid (Loligo) Juvenile predatory fishes: greenling (Hexagrammidae) sablefish (Anoplopoma) salmon (Oncorhynchus) rockfish (Sebastes) 5 Small coastal pelagic fishes: sardine (Sardinops) N 10 5 herring (Clupea) capelin (Mallotus) saury (Cololabis) 10 sandlance (Ammodytes) anchovy (Engraulis) 5 1981 1987 1999
10 Anchovy (Engraulis) 5 Tsushima % mass El Niño events 1982-1983 1992-1997- 1998 2003 10 5 10 California 5 1981 1987 1999
Pacific Saury (Cololabis) 10 5 Tsushima % mass 10 5 Transition Zone 10 5 10 California 5 1981 1987 1999
Sablefish (Anoplopoma) % mass 5 4 3 2 1 5 4 3 2 1 Alaska 5 4 3 2 1 California 1981 1987 1999
% Mass Rhinoceros Auklet Diet 10 5 10 5 10 5 10 other squid (Loligo) Juvenile predatory fishes: greenling (Hexagrammidae) sablefish (Anoplopoma) salmon (Oncorhynchus) rockfish (Sebastes) 5 Small coastal pelagic fishes: sardine (Sardinops) N 10 5 herring (Clupea) capelin (Mallotus) saury (Cololabis) 10 sandlance (Ammodytes) anchovy (Engraulis) 5 1981 1987 1999
Some Regime-shift Models Model 1 Model 2 Time
% mass of Juvenile Predatory Fishes vs. 10 5 10 5 10 Offshore Juvenile predatory fishes: greenling (Hexagrammidae) sablefish (Anoplopoma) salmon (Oncorhynchus) 5 Nearshore rockfish (Sebastes) Small coastal pelagic fishes: 10 sardine (Sardinops) 5 Offshore herring (Clupea) capelin (Mallotus) N 10 5 Offshore saury (Cololabis) sandlance (Ammodytes) anchovy (Engraulis) Smaller Pelagic Schooling Fishes 10 5 Nearshore 1981 1987 1999
Summary El Niño effects more apparent in lower latitudes Gradual, sweeping fluctuations in prey composition apparent throughout time series (Model 1) Need longer time series, more sampling locations!
Future Directions Examine effects of oceanic variability on forage fish communities in more detail Examine diet of multiple marine bird predators simultaneously Network of marine bird bio-sampling stations throughout N. Pacific basin N
1.5 1 Tsushima 0.5 0-0.5 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 SST Anomaly Feb Juv. predatory fishes Small pelagic fishes -1 % mass of Juvenile Predatory Fishes vs. Transition Zone -1.5 1.5 1.0 0.5 0.0-0.5-1.0-1.5 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Spring SST Anomaly Juv. predatory fishes Small pelagic fishes 2.0 1.5 Smaller Pelagic Schooling Fishes California 1.0 0.5 0.0-0.5-1.0-1.5-2.0 2.0 1.5 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Spring SST Anomaly Juv. predatory fishes Small pelagic fishes 1.0 0.5 0.0-0.5 1976 1979 1982 1985 1988 1991 1994 1997 2000 2003 Spring SST Anomaly Juv. predatory fishes Small pelagic fishes -1.0-1.5
Sandlance (Ammodytes) % mass 10 5 10 5 Tsushima 10 Alaska 5 10 5 Transition Zone 1981 1987 1999
Greenling (Hexagrammidae) 6 4 2 Tsushima % mass 6 4 Alaska 2 1981 1987 1999
10 Rockfish (Sebastes) % mass 5 10 Transition Zone 5 10 California 5 1981 1987 1999
Chick Provisioning Amounts Bill load mass varies significantly between colonies and years in the N. Pacific however, Bill load mass changes in a synchronous manner: - between colonies in the California over time (more strongly between ANI & SEFI, but also with TRI) - between colonies in the Alaska over time (more strongly between MIDD & LAZ, but also with TRI)