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  • Historical and contemporary diet of northern fur seals in the North Pacific

    Rolf R. Ream and Tonya K. ZeppelinNational Marine Mammal Laboratory

  • Overview

    Summarize at-sea diet using multi-national historical data sets

    Describe contemporary food habits from U.S. islands

    Address spatial and temporal variability in diet

  • Robben Island

    Kuril Islands

    Commander Islands

    Bogoslof Island

    Pribilof Islands

    San Miguel Island

    Russia North America

    Northern fur seal distribution and breeding sites

  • Food Habits Data Sources

    Historical: pelagic collections (stomachs) Japan Russia United States

    Contemporary: breeding islands (scats and spewings) United States

    Percent occurrence (PO) of prey =% of samples w/ prey X out of all samples w/ prey

    Primary prey

  • Pelagic DataSpatial and Temporal Coverage

    Japan Western North Pacific (January-June, 1953-1991)

    Russia Commander Islands (June-November, 1965-1982) Sea of Okhotsk (June-August, 1964-1981) Sea of Japan (February-May, 1961-1976)

    United States (ranging from 1958-1974) California (February-May, 1958-1966) Washington/Oregon (February-May, 1958-1972) British Columbia (February-May, 1958-1968) Gulf of Alaska (February-May, 1958-1968) Bering Sea (August-September, 1960-1974)

  • Japanese and Russian Pelagic Collections

  • Japan - Top four prey

    Japanese collections (Jan-June, n=4029)

    0

    5

    10

    15

    20

    Lantern fish Japanese fireflysquid

    Mackerels andtunas

    Japanes sardine

    Perc

    ent o

    ccur

    renc

    e

    Japanese Collections

    010

    2030

    4050

    6070

    8090

    1953 1955 1957 1959 1961 1963 1965 1967 1969 1971 1973 1975 1977 1979 1981 1983 1985 1987 1989 1991

    Perc

    ent O

    ccur

    renc

    e

    Lantern fish Japanese firefly squidMackerels and tunas Japanes sardine

  • Russia - Top five prey by regionCommander Islands

    (June-November, n = 561)

    0

    10

    20

    30

    Walleye pollock Salmon Hexagrammidae(Atka mackerel)

    Pacif ic sandlance

    Berryteuthismagister

    Perc

    ent o

    ccur

    renc

    e

    Sea of Okhotsk(June-August, n = 204)

    0

    10

    20

    30

    40

    50

    Walleyepollock

    Salmon Gonatusfabricii

    Myctophidae Berryteuthismagister

    Perc

    ent o

    ccur

    renc

    e

    Sea of Japan (February-May, n= 1132)

    01020304050607080

    Walleye pollock Berryteuthismagister

    Perc

    ent o

    ccur

    renc

    e

  • PO by year

    Commander Islands (June-November, n = 561)

    0

    10

    20

    30

    Walleye pollock Salmon Hexagrammidae(Atka mackerel)

    Pacif ic sandlance

    Berryteuthismagister

    Perc

    ent o

    ccur

    renc

    e

    Sea of Japan (February-May, n= 1132)

    01020304050607080

    Walleye pollock Berryteuthismagister

    Perc

    ent o

    ccur

    renc

    e

    Commander Islands

    0

    10

    20

    30

    40

    50

    60

    70

    80

    1965 1967 1969 1971 1973 1975 1977 1979 1981Pe

    rcen

    t Occ

    urre

    nce

    Walleye pollock SalmonHexagrammidae (Atka mackerel) Pacific sand lanceBerryteuthis magister

    Sea of Japan

    0102030405060708090

    100

    1961 1963 1965 1967 1969 1971 1973 1975

    Perc

    ent O

    ccur

    renc

    e

    Walleye pollock Berryteuthis magister

  • PO by yearCommander Islands

    0

    10

    20

    30

    40

    50

    60

    70

    80

    1965 1967 1969 1971 1973 1975 1977 1979 1981Pe

    rcen

    t Occ

    urre

    nce

    Walleye pollock SalmonHexagrammidae (Atka mackerel) Pacific sand lanceBerriteuthis magister

    Commander Islands (June-November, n = 561)

    0

    10

    20

    30

    Walleye pollock Salmon Hexagrammidae(Atka mackerel)

    Pacif ic sandlance

    Berriteuthismagister

    Perc

    ent o

    ccur

    renc

    e

    Sampling:

    location

    month

    Sea of Japan (February-May, n= 1132)

    01020304050607080

    Walleye pollock Berryteuthismagister

    Perc

    ent o

    ccur

    renc

    e

    Sea of Japan

    0102030405060708090

    100

    1961 1963 1965 1967 1969 1971 1973 1975

    Perc

    ent O

    ccur

    renc

    e

    Walleye pollock Berryteuthis magister

  • U.S. Pelagic Collections(n=7,933)

  • U.S. - Top five prey or >10% POby region during winter migration (February-May)

    California (n=2097)

    0

    10

    20

    30

    40

    Pacif ic hake Northernanchovy

    Market squid Clubhooksquid

    Pacif ic saury

    Perc

    ent O

    ccur

    renc

    e

    Washington/Oregon (n=2670)

    0

    10

    20

    Pacif icherring

    Northernanchovy

    Marketsquid

    Clubhooksquid

    Gonatidsquid

    Rockfish

    Perc

    ent O

    ccur

    renc

    e

    British Columbia, Canada (n=382)

    0

    10

    20

    30

    40

    Pacificherring

    Sablefish Salmon Walleyepollock

    Gonatidsquid (B.magister)

    Perc

    ent O

    ccur

    renc

    e

    Gulf of Alaska (n=968)

    0

    10

    20

    30

    40

    Pacif icherring

    Pacif ic sandlance

    Capelin Walleyepollock

    Gonatidsquid

    Perc

    ent O

    ccur

    renc

    e

  • PO by month (all years combined)

    California (n=2097)

    0

    10

    20

    30

    40

    Pacif ic hake Northernanchovy

    Market squid Clubhooksquid

    Pacif ic saury

    Perc

    ent O

    ccur

    renc

    e

    Washington/Oregon (n=2670)

    0

    10

    20

    Pacif icherring

    Northernanchovy

    Marketsquid

    Clubhooksquid

    Gonatidsquid

    Rockfish

    Perc

    ent O

    ccur

    renc

    e

    California

    0

    10

    20

    30

    40

    50

    60

    Feb(n=1006)

    March(n=558)

    April(n=268)

    May(n=265)

    Perc

    ent O

    ccur

    renc

    e

    Pacific hake

    Northernanchovy

    Market squid

    Clubhooksquid

    Pacific saury

    Washington/Oregon

    0

    10

    20

    30

    40

    50

    Feb(n=257)

    March(n=583)

    April(n=1181)

    May(n=649)

    Perc

    ent O

    ccur

    renc

    e

    PacificherringNorthernanchovyMarket squid

    ClubhooksquidGonatidsquidRockfish

  • PO by month (all years combined)

    British Columbia, Canada (n=382)

    0

    10

    20

    30

    40

    Pacif icherring

    Sablefish Salmon Walleyepollock

    Gonatidsquid (B.magister)

    Perc

    ent O

    ccur

    renc

    e

    Gulf of Alaska (n=968)

    0

    10

    20

    30

    40

    Pacif icherring

    Pacific sandlance

    Capelin Walleyepollock

    Gonatidsquid

    Perc

    ent O

    ccur

    renc

    e

    Gulf of Alaska

    0102030405060708090

    100

    Feb (n=33)

    March(n=205)

    April(n=225)

    May(n=505)

    Perc

    ent O

    ccur

    renc

    e

    Pacificherring

    Pacific sandlance

    Capelin

    Walleyepollock

    Gonatidsquid

    British Columbia

    0

    10

    20

    30

    40

    50

    60

    Feb (n=89)

    March(n=79)

    April (n=44)

    May (n=170)

    Perc

    ent O

    ccur

    renc

    e

    Pacificherring

    Sablefish

    Salmon

    Walleyepollock

    Gonatidsquid

  • Washington/Oregon (n=2670)

    0

    10

    20

    Pacificherring

    Northernanchovy

    Marketsquid

    Clubhooksquid

    Gonatidsquid

    Rockfish

    Perc

    ent O

    ccur

    renc

    e

    California

    0

    10

    20

    30

    40

    50

    60

    1958 1960 1962 1964 1966Pe

    rcen

    t Occ

    urre

    nce

    Pacific hake Northern anchovyMarket squid Clubhook squidPacific saury

    Washington/Oregon

    0

    10

    20

    30

    40

    50

    60

    1958 1960 1962 1964 1966 1968 1970 1972

    Perc

    ent O

    ccur

    renc

    e

    Pacific Herring Northern anchovy Market squidClubhook squid Gonatid squid Rockfish

    PO by year (all months combined)

    California (n=2097)

    0

    10

    20

    30

    40

    Pacif ic hake Northernanchovy

    Market squid Clubhooksquid

    Pacif ic saury

    Perc

    ent O

    ccur

    renc

    e

  • PO by year (all months combined)

    British Columbia, Canada (n=382)

    0

    10

    20

    30

    40

    Pacif icherring

    Sablefish Salmon Walleyepollock

    Gonatidsquid (B.magister)

    Perc

    ent O

    ccur

    renc

    e

    Gulf of Alaska (n=968)

    0

    10

    20

    30

    40

    Pacif icherring

    Pacific sandlance

    Capelin Walleyepollock

    Gonatidsquid

    Perc

    ent O

    ccur

    renc

    e

    Gulf of Alaska

    0

    10

    20

    30

    40

    50

    60

    70

    1958 1960 1962 1964 1966 1968

    Perc

    ent O

    ccur

    renc

    e

    Pacific herring Pacific sand lanceCapelin Walleye pollockGonatid squid

    British Columbia, Canada

    0102030405060708090

    100

    1958 1960 1962 1964 1966 1968

    Perc

    ent O

    ccur

    renc

    e

    Pacific herring SablefishSalmon Walleye pollockGonatid squid (B. magister)

  • Top 5 prey during summer (August-September) in the Bering Sea

    Bering Sea (n=1816)

    0

    10

    20