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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}