Predator-prey relationships in California Current

Jim HarveyMLML

Horned Puffin

Heerman’s Gull

Black-footed albatross

Brown Pelican

Bran

dt’s

corm

oran

t

Wilson’s Storm-Petrel

SEA

BIRD

S

Blue WhaleGray Whale

Sperm Whale

Minke Whale

Killer Whale

Fin Whale

CETACEANS

Steller sea lion PINNIPEDS

Fur seal

Elephant seal

Harbor seal

California sea lion

Sea otter

Whales

from: J. Harvey

Biomass Consumption ModelBiomass Consumption Model

BBxaxa == ∑∑ ((BBxsxs ∑∑ ((NNss * A* Ass * W* Wss * E* E ii * D* Dss) * P) * P xsxs / / VVxx))

NNs s = mean number of animals during season = mean number of animals during season s s AAs s = proportion in each age class during season = proportion in each age class during season ssWWs s = proportion of animals at sea during season = proportion of animals at sea during season s s EEii = age= age--specific daily energetic requirements in size class specific daily energetic requirements in size class ii

Size classes: adult, subSize classes: adult, sub--adult/female, and juvenile adult/female, and juvenile

DDss == number of days in season number of days in season ssPPxsxs == proportion of prey species proportion of prey species xx in sea lion diet during season in sea lion diet during season ss

Two models, MTwo models, Mean % Mass and Biomass Reconstructionean % Mass and Biomass ReconstructionVVxx = energetic value of prey species = energetic value of prey species xx

S=1S=1 t=1t=1

Biomass Reconstruction Model (Harvey 1987)

) * / * (

)/ ( )( /

)/( )(

)( )(

* **

∑

∑ ∑

∑

=

=

=

==

=

iiii

totallength

season

i

ii

kCalpreyNumberkCalpreyNumberipreyofconsumedenergytotalofn proportioeatenEnergy

MassrequiredkCallaboratorymassneedsEnergeticneedsEnergy

MassMasscapturespredatorofmassalproportionMass

CountsurveyspredatorofPopulationPop

iitempreyperConsumedBiomassExpectedEBC

eatenEnergyneededEnergyMass Pop EBC

Population Assessment:counts and correction factors

Actual Number = Count *

# total marked # marked ashore(Correction factor)

Example:

100 indiv. marked and 50 marked animals ashore during survey

therefore, 50/100 = 50% of marked ashore during survey

and the correction factor is 100/50 = 2.0

or number of animals is 2 times that counted.

* **= ii eatenEnergyneededEnergyMass Pop EBC

PROPORTIONALLY STRATIFIED SAMPLE

120 flipper-mounted radio tags placed on arepresentative sample based on:

Sex (50:50 males/females)Age class (10% first year, 30% subadult,

60% adult)Location (50% in northern CA, 50% in

central CA, numbers/haul-out proportional to past counts)

Aerial Survey Periods6/22-7/22 7/3 7/16 8/29

# tagged seals ashore (Na): 69 74 74 44

# known functioning tags (Nf): 114 102 91 unk

Correction factor (Nf/Na): 1.65 1.38 1.23 unk

Correction Factor

0.9379 0.9143 0.9522 0.8310survival probability (Phi):

Modelled Correction factor: 1.62 1.38 1.31 1.84

112 102 97 81# estimated functioning tags:

Mean correction factor = 1.54 ± 0.38 (95% CI)

Number of seals in California

Count of seals (22 June – 22 July) = 26,333M. Lowry et al. (NMFS)

Correction factor at time of survey = 1.65

Future correction factor = 1.54 ± 0.38 (95% CI)

Compared with OR/WA correction factor of 1.53

Estimated number of seals in CA = 43,449

0 50 100 150Mass (kg)

0

10

20

30

40

50

60

70

80

90

100Fr

eque

ncy

0.00

0.02

0.04

0.06

0.08

0.10

0.12

Proportion per Bar

0 50 100 150Mass (kg)

0

10

20

30

Freq

uenc

y

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

Proportion per B

ar

Captured - 2004

Captured – before 2004

Comparison of mass of seals captured in 2005 with those captured previously in CA.

(n = 158)

(n = 797) * **= ii eatenEnergyneededEnergyMass Pop EBC * **= ii eatenEnergyneededEnergyMass Pop EBC * **= ii eatenEnergyneededEnergyMass Pop EBC

* **= ii eatenEnergyneededEnergyMass Pop EBC

Biomass of food consumed per kg of predator mass (Innes et al. 1987)

) ( 068.0 ) ( 054.0

)( 068.0

78.0

84.0

78.0

adultsgrowingnonMassBiomassIngestedadultsgrowingMassBiomassIngested

juvenilesMassBiomassIngested

−=

=

=

Food habits data provide information on:

• Seasonal prey utilization• Prey availability• Feeding locations

Food HabitsFood Habits

AngularAngular

TeethTeethRadialsRadials

VertebraeVertebrae

METHODSSeal # Name Sex Age Class Weight (kg) SL (cm)HS1 Seymour Male SA 30.5 105.5HS2 Quincy Male A 95.1 160.8HS3 Rowdy Male SA 49.7 121.3HS4 Theo Male A 83.2 152.5HS5 Ulysses Male A 75.9 150.5HS6 Vinnie Male A 62.8 144.0HS8 Willis Male A 62.0 145.5

177 Trials2,700+ prey fed256 days

Citharichthys sordidus

Sebastes jordani

Oncorhynchus mykiss

Oncorhynchus gorbuscha

Loligo opalescens

Merluccius productus

Sardinops sagax

HS1 - Seymour

Harbor seal consumption during 1980 in OR(Harvey 1987)

Species Biomass (x103 kg) Number (x103 kg)

• Staghorn sculpin 732 11,730• Herring 459 5,909• Shiner surfperch 447 10,481• English sole 434 9,463 (5%)

• Sandlance 254 41,771• Salmon 532 89

• Total: 5,667 112,811

by S. Cerchio

Foraging ecology of large whales

Predator-prey relationships of large whales

122.15o 122.05o 121.95o 121.85o 121.75o

36.6

0o36

.70o

36.8

0o36

.90o

37.0

0o

Santa Cruz

Monterey

MossLanding

50m

200m500m1000m

100m

2000

m

Krill patch – D. Croll (UCSC)

Collaborators:UCSC, CRC, SAIC, AAD

Blue Whale – Balaenoptera musculus

Tagging blue whales off central California

Order Procellariformes

Family Procellariidae (shearwaters, fulmars, gadfly petrels, and prions, 55 species)

Nostril united in single tube atop bill

Occur in all oceans of the world.

Many species capable of underwater flight; prionshydroplane

Northern Fulmar(Fulmarus glacialis)

Sooty Shearwater(Puffinus griseus)

Pink-footed Shearwater

Sooty Shearwaters: most abundant seabird off CA in summer

Shearwaterfood

rockfish squid

sardine

anchovy

krill

Sooty Shearwaters migrating back to New Zealand to nest

Common Murre consumption during 2004(Roth et al. 2008)

Species Biomass (x103 kg)

• Market squid 57,776• Pacific hake 55,452• Anchovy 23,033• Shiner surfperch 22,570• Rockfish 21,446• Plainfin midshipman 12,546• Pacific herring 8,030

• Total: 225,025

Northern

Anch

ovy

Dover

SoleRoc

kfish

English

SoleOcto

pus

Spotted

Cusk

-eel

Plainfin

Midsh

ipman

White

Cro

aker

Speckled

Sanddab

Pacific

Sanddab

Pacific

Hak

e

Other Flat

fish

Salmon

id

1997-19981998-1999

1999-20002000-2001

0

10

20

30

40

50

60

Perc

enta

ge F

requ

ency

O

ccur

renc

e

CA sea lion diet in Monterey Bay (Weise and Harvey)

San Nicolas Island

San Clemente Island

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

Mk squidSardineShtbly rkfshP mackJk mackAnchovyHake

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100S

FO (%

)

Mk squidSardineShtbly rkfshP mackJk mackAnchovyHake

M. Lowry (2008)

Market squid

SCI

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

SNI

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

Market squid

SCI

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

SNI

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

Market squid

SCI

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

SNI

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

SCI

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

SNI

1980 1985 1990 1995 2000 2005Year

0

20

40

60

80

100

SFO

(%)

Red = El NiñoBlue = La Niña

M. Lowry (2008)

Modelling indicates that intermediate-sized predators have greatest effect on

prey population(Brose et al. 2008)

Whales

from: J. Harvey

Leatherback with suction-cup tag on back in Monterey Bay

Purple stripe jellyfish

Sea nettlejellyfish Moon jelly

Leatherback turtles eat mostly jellyfish

10

20

30

40

50

Egg-yolk jelly

Aerial Survey Results 2002-2005

W123o W122o

N37o

N38o

Half MoonBay

100m

Leatherbacks 2002 2003 2004 2005

50m

Santa Cruz

FarallonGrid

PescaderoGrid

MontereyBay Grid

Benson et al. 2006Benson et al. 2006

Leatherback habitatLeatherback habitat