Transcript Where Have All the Salmon Gone

Where Have All the Salmon
Gone?
Graphing Results
Fish Catch on the Columbia River
35
30
Millions of pounds
25
20
1-Chinook
2-Coho
3-Chum
15
4-Sockeye
5-Steelhead
10
5
0
1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980
Decades
1880s: Canning
of Chinook
increases 6x
First
35
attempts to
regulate
fishing
30
1930s-50s: logging
increases in lower
river system
World War I
1930s:
Bonneville
Dam is built
1950s: 8
new
dams
built
20
15
Canneries start
using other fish
species
10
1980s: Regulations
ban ocean catch of
Chinook, Coho
Regulations: only
gill netters
allowed on river.
25
Millions of pounds
Fish Catch on the Columbia River
1920s:
First
ocean
trawlers
5
1940s: 4
new
dams
built
Nitrogen
supersaturation
around
dams kills
small fish
1960s-80s:
Hatchery
techniques
improve
0
1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980
1866: First fish
cannery
Decades
1950s: massive
hatchery
program
1-Chinook
2-Coho
3-Chum
4-Sockeye
5-Steelhead
On the back of your graph:
• What advantages and drawbacks are
there to using fish catch data as a way of
measuring salmon populations?
• Which human-caused factors had the
most effect on salmon populations? Why?
• Should salmon recovery efforts focus only
on habitat restoration, only on reducing
fishing and predation, or both? Why? Find
and cite a section in your textbook that
supports your answer.