WINGS, FINS, AND THE ‘BLACK BOX’: MANAGEMENT IMPLICATIONS OF MARINE BIRD AND FISH TROPHIC SIMILARITIES

William J. Sydeman 1, Kyra L. Mills 1

Diana Watters 2

Steve Ralston 3, and Tom Laidig 3

1 1 PRBO, Stinson Beach, CAPRBO, Stinson Beach, CA

2 2 California Dept. of Fish and Game, Belmont, CACalifornia Dept. of Fish and Game, Belmont, CA

33National Marine Fisheries Service, Santa Cruz, CANational Marine Fisheries Service, Santa Cruz, CA

Overview

• Introduce basic conceptual model for use of marine birds as ecosystem indicators for fish (during the marine phase of their life cycle)

• Provide 3 case histories on the use of “ecological equivalents” and “ecological indicators”– Herring– Rockfish– Salmon (chinook)

• Discuss potential for a network of marine bird “monitoring stations” in the NPO

Herring Feed at Sea Herring EnterBay

Herring Spawnin Bay

Herring Spawnin Bay

Case Study 1Case Study 1

Can Ecological Indicators (of Oceanic Foraging Conditions) be UsCan Ecological Indicators (of Oceanic Foraging Conditions) be Used ed to Understand Herring Recruitment/Body Condition in the San to Understand Herring Recruitment/Body Condition in the San

Francisco Bay Estuary?Francisco Bay Estuary?

Seabird Productivity on SE Farallon Island *Body Condition

*Spawning Biomass

WINTERWINTERSPRINGSPRING SUMMERSUMMER FALLFALLWINTERWINTER

Productivity (number of offspring/female) = an integrated measurement of foraging conditions for marine birds, from egg-laying through offspring rearing in spring/summer each year.

DIET OF HERRING AND PLANKTIVOROUS SEABIRDS IN THE GULF OF THE FARALLONES,CENTRAL-NORTHERN CALIFORNIA CURRENT

SYSTEM

Common MurreWestern Gull

Pacific Herring

Macrozooplankton (euphausiids: E. pacifica, T. spinifera)

*Cassin’s Auklet –Obligate planktivore

Herring Spawning Biomassand Western Gull Productivity

0

40

80

120

0 0.5 1 1.5 2

Western Gull Productivity – year “x”

Her

rin

g B

iom

ass

x 1

00

0 –

year

“x+

1”

1992

1998

y = 20.3x + 34.0= 0.26R2

P = 0.02

Herring Mass (g, age 6) and Western Gull Productivity

-0.8

-0.4

0

0.4

1983

1985

1989

1991 1993

1995

1997 1999

Year

Pro

duct

ivit

y A

nom

aly

-40

-20

0

20

Wei

ght

An

omal

y

Western Gull Productivity Weight - Age 6

1987

Herring Condition (M/L3)

1 2 3 4 5 6 7 8Western Gull * * *Common Murre * * * *Cassin’s Auklet * * * * *

Herring Age (yrs)

1983

1992

1998

1.3

1.4

1.5

1.6

1.7

1.8

0 0.2 0.4 0.6 0.8 1 1.2

Cassin’s Auklet Productivity - year “x”

Her

rin

g B

ody

Con

diti

on

Cassin’s AukletHerring, Age 6

R2 = 0.71

* = significant at the 0.05 level

• Summary: productivity of planktivorousseabirds, particularly auklets, may be a useful index to the oceanic feeding conditions for herring at sea during the spring and summer months.

• adaptive management of herring fishery in SFB.• contribute novel tool for understanding spawning

biomass and other critical fishery statistics (condition).

Potential Applications :

Herring Data Harvest QuotaCase 1

Herring Data Seabird Data Harvest QuotaCase 2

Case Study 2Case Study 2Can Top Predator (seabird and salmon) Can Top Predator (seabird and salmon) DietDiet be Used to be Used to

Assess Rockfish (Assess Rockfish (SebastesSebastes sppspp.) Recruitment?.) Recruitment?

Pelagic Juvenile Rockfish

Chinook Salmon (adult)

Rhinoceros Auklet

Common Murre Pigeon Guillemot

DATA SETS USED IN STUDY

1. Rockfish Trawls (1983-2002): The National Marine Fisheries Service (NMFS, Santa Cruz) conducts mid-water trawl surveys during May - June.

2. Salmon Gut Contents (1980-1999): NMFS examined Chinook Salmon caught in the vicinity of the Farallon Islands.

3. Seabird Offspring Diet (1972-2002): PRBO has conducted studies (May - July) from “RV Farallon Island”.

*Common Murre (single fish, observed brought to colony)*Pigeon Guillemot (single fish, observed brought to colony)

*Rhinoceros Auklet (multiple fish, collected)

R2 = 0.78

R2 = 0.63

R2 = 0.81

0.0

0.2

0.4

0.6

0.8

1.0

-1 0 1 2 3 4

Rockfish Estimates (NMFS Trawl Surveys 1983-2002)

Prop

ortio

n R

ockf

ish

in D

iet

8392

98

Trawls and Marine Bird Diet: ‘Functional Response’

Murre

Guillemot

Auklet

Seabird data and trawl surveys are correlated

Correlation: Salmon and Seabird Diet

COMUR2 = 0.90

PIGUR2 = 0.84

RHAUR2 = 0.67

0.0

0.2

0.4

0.6

0.8

1.0

0 0.5 1 1.5

Rockfish in Salmon Diet

Prop

ortio

n R

ockf

ish

in

Seab

ird D

iets

COMU (83-99) PIGU (83-99) RHAU (87-99)

The Multivariate Rockfish Index (MRI)

Principal Component Analysis

a. Eigenvalues:Eigenvalue Proportion Cumulative Proportion

PC1 4.13 0.83 0.83PC2 0.52 0.10 0.93

b. Factor Loadings:PC1 PC2

Common Murre 0.47 -0.06Pigeon Guillemot 0.44 0.11Rhinoceros Auklet 0.42 0.71Salmon Gut Contents 0.42 -0.70Trawl Surveys 0.48 -0.04

Multivariate Rockfish Index (MRI) Reveals Decline in Rockfish Recruits

87 88

89

90

91

92

93

94 9596 97

98

99

-4.0

-2.0

0.0

2.0

4.0

6.0

Year

MR

I V

alue

1987 1993 1999

Case Study 3Case Study 3Can Seabird Productivity be Used to Help

Predict Central Valley (CA) Chinook Salmon Returns (hatchery fish)?

Age-Two Return Previous Year (thousands)

0 10 20 30 40 50 60

CVI

Abu

ndan

ce (t

hous

ands

)

200

400

600

800

1000

1200

1400CVI = 286,300 + (Age-Two * 13.906)

R2 = 0.38

Current PFMC method uses jacks to forecast the Central Valley Index (CVI) for the following year

Results of Principle Components Analysis (PCA) that encompasses the reproductive success of 3 seabird species (Brandt’s Cormorants, Common Murres, and Cassin’s Auklets – 3-yr running average), and jack counts (1973-2002).

________________________________________________________________________

a. Eigenvalues: Eigenvalue Proportion Cumulative Proportion

PC1 2.06 0.51 0.51 PC2 1.10 0.27 0.79

b. Factor Loadings: PC1 PC2

Brandt’s Cormorant 0.59 0.15 Common Murre 0.51 -0.39 Cassin’s Auklet 0.62 0.08 Total Jacks 0.07 0.90 _____________________________________________________________________

Regression estimator based on combined seabird/jack index

Combined Bird Index

-3 -2 -1 0 1 2 3

CVI

Abu

ndan

ce (t

hous

ands

)

200

400

600

800

1000

1200

1400

CVI = 703.24 + (163.51 * Bird Index)R2 = 0.63

Comparison of Predictions (1985 – 2002)

JACK Index JACK/BIRD Index

average -8.7% -2.1%

range -50% to +67% -37% to +45%

N

Middleton St. Lazaria

FrederickTriangle

TatooshYaquinaCastle

SE FarallonPoint ReyesAlcatrazAño Nuevo

VandenbergS. MiguelAnacapaS. Barbara

S. Benitos

Chowiet

St. George

Bluff

Talan

Teuri

Buldir

Barren

0-200ft

200-1000ft

>1000ft

Conclusion: (1) Seabird data may be useful to understanding marine fish population and life history fluctuations, with possible management applications. (2) More studies (on calibration) are

needed, but luckily we have much to work with.

N. Pacific Seabird Colonies with “Long-term” Data

Thank you

Potential Use of the “MRI” in Rockfish Stock Assessments

Fishery Dependent:logbook data, etc.

Landings by Gear Type

Stock Assessment

Age/Length Compositions

Fishery Independent:ROV

Trawl SurveysSeabird DietSalmon Diet

Life History Information

MRI}