Fisheries, Conservation, and Sustained Yields
1. What is the fisher’s problem?
The “tragedy of the commons” (1968) -- Garrett Hardin, biologist: “In a
competitive economy, no market mechanism ordinarily exists to reward
individual forbearance in the use of shared resources.”
The problem of the environment (1980) -- Arthur McEvoy, environmental
historian: “Most fisheries . . . do not behave as neatly as [sustained yield]
theory suggested because . . . fish live in a complex and constantly changing
2. The California Fisheries: What makes them so productive?
--ocean: the California current; upwellings of deep, cold, nutrient rich
water; temperature gradient near Point Conception (support for warm &
cold water species); kelp forests near shore
--estuaries: wetlands, nutrient rich
--rivers: freshwater and anadromous species
3. The California Fisheries: What makes them so fragile?
--sensitivity of ocean fisheries to changes in temperature and of inshore
fisheries to changes in temperature and precipitation
--the inefficiency of some species to reproduce at lower levels of population
--many warm and cold water ocean species live near their limits on either
side of the Point Conception divide
--impact of human activity (predation, pollution, environmental change): re:
the impact on salmon of overfishing, silt from farming and mining, and dams
for flood control and irrigation
4. What makes some species of fish more fragile? Less able to survive unsettled
Groundfish (halibut, tuna): free swimming, distributed more or less evenly
over their grounds, & grew steadily with increasing age
Schooling fish (sardines): achieve most of their growth during their first two
years of life & aggregate in groups that are distributed unevenly in the ocean.
Reproductive volatility: their yields vary radically from season to
Catchability: with sonar, fishing boats can track and scoop up entire
schools of fish with large nets
Why did salmon fishing remain viable through World War II and beyond?
Irony: the construction of Shasta Dam in 1983-42 closed about half of
the Sacramento River basin’s remaining salmon nurseries. But by
mitigating the flooding and siltation caused by farming, diking, and
filling, and by providing a stable flow of cool water during the
summer, conditions improved for the salmon that spawned in the
remaining, unobstructed half of the basin.
Also: cooler weather and additional rainfall during & after World
Why did albacore tuna fishing remain viable through World War II and
Spectacular migratory range and extreme sensitivity to temperature:
does best in cool water and congregates near upwelling currents
where the schooling fishes on which it feeds are abundant.
Destruction of fur seals in the early 20th century (which in the 1970s,
when they recovered, ate 7% of the Northern California anchovy
population each year) left more food for tuna and salmon. (SEE
Cooler weather allowed tuna to increase near California’s shore
during and after WW II.
Why did the sardine fishery collapse after World War II?
Industrial fishing: What made it possible? Profitable? Fossil fuels,
open ocean vessels & gear, sardine reduction for poultry feed and
fertilizer. The “Second Industrial Revolution” was critical:
electricity, organic chemistry [esp. oil], internal combustion engines,
etc. And a new twist in the 1930s: stationed reduction ships offshore
– did not have to wait to reach the plants in Monterey Bay and
Japan’s sardine fishery was the largest in the world in the 1930s, but
it spread over a much larger area and depended on 5 kinds of sardine.
The California fishery depended on only 1 kind of sardine.
4/5ths of CA yield went into reduction plants
Fishmeal 20% cheaper than processed meat scraps & included
all the proteins that livestock needed, and included chemicals
that speeded growth. Purchased by all major feed producers:
Quaker Oats, General Mills, Ralston-Purina, and Globe and
Sardine oil cheaper than tallow, and as useful: soap, linoleum,
Huge demand during World War II for livestock feed and to
The biology of destruction of the sardines
Pilchards and their relatives school because they cannot hide
from predators: schooling minimizes losses to attack. Only
the margins are harmed. The schools aggregate into groups of
about 5 miles in diameter. BUT: schooling continues even
when stocks are low. There are fewer schools, and if they are
identified and netted, the species can be wiped out.
Sardines migrate great distances between their feeding and
spawning grounds. The more mature the fish are, the farther
they migrate north to feed: all the way to British Columbia for
those older than 3 years. Mature fish convert most of the oil
they store in their bodies into spawn rather than additional
body tissues, & they spread their spawn over as large an area
as possible to ensure enough larvae found patches of food to
survive. A larger, more mature population spawning over a
large area thus had the best chance of reproductive success.
Problem: the fishery, by depleting the older fish, removed
some of the sardine’s natural insurance. And unlike more
highly developed species like cod or halibut, for whom greater
numbers of spawn survive when the number of adult fish is
lower, the survival rate for sardine spawn is independent of the
number of adult fish. Ergo: sardines are more vulnerable to
Could not bring back the sardines; could not ensure sustained yields because
of the variability of fish populations
6. Global fishing in the late 20th century
The global catch for food, fertilizer, and animal feed: more taken in two
years than in entire 19th century
1 billion people depend primarily on fish for protein
The collapse of various fisheries; the boom and bust economy of fishing
Aquaculture: a solution?
Hermaphrodite male white perch in Lake Erie
Menhaden fisheries and the Omega Protein Corporation