Krill and Krill-Predators: Habitat associations in the dynamic Gulf of the Farallones, California

J. Jahncke, B.L. Saenz, C. Rintoul and W.J. Sydeman

IntroductionIntroduction

Euphausiids are a critical source of carbon in marine food webs.

Very little is known about their spatial and temporal distributions, abundance, and reproductive dynamics.

Krill in the California CurrentKrill in the California Current

Brinton, E. 1981. Euphausiid distributions in the California Current during the warm winter-spring of 1977-78, in the context of a 1949-1966 time series. CalCOFI Rep. 22:135-154.

Euphausia pacifica

Thysanoessa spinifera

E. pacifica

T. spinifera

• More abundant

• Less abundant

• Oceanic and shelf-break

• Shelf

Baja California

San FranciscoJanuary Mar.-Apr. Jun.-Jul.

UPWELLINGx100

Euphausia pacifica

Thysanoessa spinifera

… there is great spatial andtemporal variability in the relative abundance of these species.

… distribution responds to ENSO (Brinton 1981, Marinovic et al. 2002).

… abundance responds to PDO (Brinton and Townsend 2003).

The Gulf of the The Gulf of the FarallonesFarallones

Photo: Jan Roletto

GoalGoal

To determine how seasonal and interannual variability in oceanographic conditions affects the distribution and abundance of krill and krill-predators.

HypothesisHypothesis

Krill and krill-predators aggregate at predictable locations in the continental shelf and slope waters of the Gulf of the Farallones

MethodsMethods

•Research cruises onboard the R/V John H. Martin (MLML) •Research cruises onboard the R/V John H. Martin (MLML) •Research cruises onboard the R/V John H. Martin (MLML) •Surveys from May to October 2004 and February to July 2005.•Surveys from May to October 2004 and February to July 2005.•Survey grid, 9 transects (total 300+ km), 3 oceanographic lines.

L2

L4

L6

CordellBank

FarallonesIsland

MethodsMethods

•Birds/mammals (standardized strip and line transects)•Birds/mammals (standardized strip and line transects)•Birds/mammals (standardized strip and line transects)•Zooplankton/fish (hydroacoustics and nets)•Zooplankton/fish (hydroacoustics and nets)•Oceanography (CTD casts and continuous CT and fluorometery)

MethodsMethods

4. Krill abundance and distribution

SIMRAD EK-60 with 38, 120, 200 kHz transducersCalculated Fiedlers et al.’ (1998) index of krill abundance as follows:

∆SKrill = 0.5 (Sv120 + Sv200) – Sv38

SKrill not converted to biomass, sample analysis not completed.

SKrill integrated vertically (upper 50-m and 200-m).

We modeled 3 levels of krill and krill-predator abundance in 3-km bins (Log+1 transformed). Forward stepwise ordered logistic regression for the analysis (NS variables were dropped)

More krill in 2004 than 2005 More krill in 2004 than 2005 (Ordered Logistic Regression, p < 0.01)(Ordered Logistic Regression, p < 0.01)

ResultsResults

-80

-79

-78

-77

-76

-75

-74

2004 2005

Kril

l Up5

0 S

v (d

B/m

²

-69

-68

-67

-66

-65

-64

2004 2005

Kril

l All

Sv

(dB

/m²

Upper 50-m Upper 200-m

ResultsResults

2004 and 2005 2004 and 2005 were were veryvery different…different…

Alongshore wind and SST; Bodega (46013)Alongshore wind and SST; Bodega (46013)March to July, 2004

March to July, 2005

Win

d (m

/s)

SST (

° C)

Win

d (m

/s)

SST (

° C)

1.5°C

APRIL

SST and lowSST and low--level wind anomalies; 2005level wind anomalies; 2005

Figures: Vernon Kousky (vernon.kousky@noaa.gov)

+1

+.5

+2+.5

0

0

Chlorophyll distribution along central CAChlorophyll distribution along central CA

May 2004 May 2005

Temperature Salinity Fluorescence Krill index

Krill aggregations (… an example)Krill aggregations (… an example)

8

10

12

14

16

Distance (km)

40 20 0

40 20 0

40 20 0

Dep

th (m

) 50

100

150

Dep

th (m

) 50

100

150

Dep

th (m

) 50

100

150

32.2

32.6

33

33.4

33.8

Distance (km)

40 20 0

40 20 0

40 20 0

2

6

10

Distance (km)

40 20 0

40 20 0

40 20 0-85

-75

-65

-55

-45

-35

-25

Distance (km)

40 20 0

40 20 0

40 20 0

Line 2

Line 4

Line 6

Krill habitat associationsKrill habitat associations

Upper 200-mYearMonthLatitudeIsland (SEFI)Cordell BankDepthSteep bathymetryFluorescence

LR X2 =p =

205.60.001

Well… so what???Well… so what???

Salmon with wings Salmon with wings (i.e, (i.e, Cassin’sCassin’s Auklets)Auklets)

Small birds (23 cm; 150-200 g)

Zooplanktivorous 80% krill

Dive 40 m (20-80 m)

Bird productivity is correlated with krill abundance(Abraham and Sydeman 2004)

0.000.250.500.751.001.251.50

1970 1975 1980 1985 1990 1995 2000 2005

Worst year on record for auklets on SEFIWorst year on record for auklets on SEFI

Mean productivity = 0.70

Cassin’s auklets distributionMay 2004

May 2005

July 2004

July 2005

Krill / krillKrill / krill--predator habitat associationspredator habitat associations

Upper 200-mYearMonthLatitudeIsland (SEFI)Cordell BankDepthSteep bathymetryFluorescence

LR X2 =p =

205.60.001

Auklets

54.60.001

=

==

≠≠

ConclusionsConclusions

1. Unusual weather conditions in 2005 (warmer SST, decreased winds) resulted in low krill and krill predator abundance off central California in 2005 than 2004.

1. Unusual weather conditions in 2005 (warmer SST, decreased winds) resulted in low krill and krill predator abundance off central California in 2005 than 2004.

1. Unusual weather conditions in 2005 (warmer SST, decreased winds) resulted in low krill and krill predator abundance off central California in 2005 than 2004.

2. Krill and krill-predators aggregated at predictable locations near Cordell Bank and other areas of rough topography such as the shelf break and submarine canyons.

2. Krill and krill-predators aggregated at predictable locations near Cordell Bank and other areas of rough topography such as the shelf break and submarine canyons.

• This is a work in progress… (15 cruises, next 3 years)

AcknowledgementsAcknowledgementsSue Abbott, Jamie Hall, Dave Johnston, Brandy Johnson,

Carol Keiper, Brenna Langabeer, Derek Lee, Shanon Lyday, Jason Yakich, Pete Warzybok, Sophie Webb

Lee Bradford and Kurt Brown, R/V John H. Martin

Bay Model, US Army Corps of EngineersLifeboat Station, Point Reyes National Seashore

Spud Point Marina, Sonoma County Regional Park Mr. George Nunez, Point St. Joseph Fish Company

Jan Roletto, Gulf of the Farallones National Marine Sanctuary Dan Howard, Cordell Bank National Marine Sanctuary

Nina Karnovsky, Pomona CollegeNancy B. Kachel, PMEL/NOAA

Mariano Gutierrez, IMARPE

Krill images provided by GoldenStateImages.com, (C) Randy Morse

Moore Family FoundationResources Legacy Fund Foundation