Using phylogenetic analysis to
identify market substitution of
Atlantic salmon for Pacific
salmon: an introductory
biology laboratory experiment
Erica Cline
University of Washington Tacoma
Environmental Science, Interdisciplinary Arts & Sciences
The Issue:
Market
Substitution
“The Cove”
• Intentional substitution of one species for
another (more valuable or rare) species
• When and where it occurs:
– Collapsed fisheries; e.g., cod
– Illegal, unreported, or unregulated fishing
– Difference in price
Cases of substitution in the US
You buy:
Should be:
Scientific name
But actually is:
AKA:
Red snapper Lutjanus
campechanus
Sebastes spp.
Oreochromis spp.
Coryphaena hippurus
Ictalurus punctatus
Rockfish
Tilapia
Mahi Mahi
Channel catfish
Cod
Gadus morhua
Theragra chalcogramma
Alaska pollock
‘Wild’
salmon
Oncorhynchus
spp.
Salmo salar
Atlantic salmon
(farmed)
Based on Jacquet & Pauly 2008
Renaming—a related problem
Scientific name
Original market
name
Renamed
Squalus acanthias Spiny dogfish
Rock salmon,
Hass
Sebastes spp.
Rockfish
Anoplopoma
fimbria
Sablefish
Pacific red
snapper, Rock cod
Black cod
Oncorhynchus
keta
Chum salmon
Silver brite
salmon
Based on Jacquet & Pauly 2008
How common is it?
• FDA testing 1988-1997
– 37% of fish mislabeled
• High school student project in NYC, 2008
– 23% of seafood mislabeled
• Local fish processor sentenced to prison for
substituting coho for king salmon
• NY Times and Consumer Reports studies:
40 to 75% of ‘wild’ salmon isn’t
Learning Objectives
1. Master the fundamental concepts of cell and
molecular biology with application to a unifying
theme and a socially relevant project.
2. Understand how molecular biology can be
applied to a local environmental issue in our
community.
How it works:
• Students bring in salmon from local stores or
restaurants
• Lab 1: DNA extraction and set up PCR reaction
using mitochondrial cytochrome oxidase I (COI)
• Lab 2: Gel Electrophoresis and set up for
sequencing
• Lab 3: Sequence analysis
Equipment and Supplies
•
•
•
•
•
•
•
•
Thermal cycler
Gel boxes, light box, and camera
Microcentrifuge
Pipettes, tips, tubes, gloves
Agarose, Taq polymerase, primers
DNA isolation kit, $2/sample
Sequencing: $175 per 96 samples
Sequence analysis: MEGA5
Example of Student Gel:
PCR Products
DNA + ladder, ctr, ctr,
Student samples
1
2
3 4
Results
coho
king
chum
pink
sockeye
Atlantic
salmon
Atlantic salmon substituted for Pacific
Financial costs
Quantity
For 14% substitution
Total US consumption of coho, 83,000,000 lbs
sockeye, chinook salmon (2004)
Amount of this that was actually =83,000,000 *
Atlantic salmon
substitution rate
11,620,000 lbs
Wholesale price if sold as
Atlantic salmon
=$0.50/lb *
mislabeled Atlantic
salmon (lbs)
$5,810,000
Wholesale price if sold as coho,
sockeye, or chinook (average
price)
=$2.00 * mislabeled
Atlantic salmon (lbs)
$23,240,000
Difference in price (cost to
consumers)
Pacific salmon price – $17,430,000
Atlantic salmon price
• Other costs of salmon
farming:
– Environmental
problems
• Nutrient runoff
• Spread of disease
• Escapes
– Human health
• Up to 10x higher PCBs,
dioxins, PBDEs
Publications and future work
Lab manual and instructor manual will be on
Curriculum for the Bioregion website and SERC
educational materials site
– www.evergreen.edu/washcenter/bioregion
– http://serc.carleton.edu/bioregion/index.html.
• Cline, ET, Gogarten, J. Using phylogenetic
analysis to detect market substitution of Atlantic
salmon for Pacific salmon: an introductory
biology laboratory experiment. Submitted to
American Biology Teacher.