Science · Environmental Science
Chapter 1: Environmental Systems and Science
Sustainable means taking no faster than it returns.
Cod off Newfoundland were fished for five hundred years. Catches peaked at about 800,000 metric tons in 1968, and in July 1992 Canada closed the northern cod fishery because so few breeding fish were left.
Cod breed every year. How can a renewable resource run out?
Make your guess to turn the page.
Still to come: 10 pages · Lab · Words to Know · What We Learned · 4 questions · Explain It in Writing · Open Questions
The idea this lesson is working on — Students treat "renewable" as a guarantee. The book sets it against northern cod, which bred every year and still collapsed, and against a lab stock that regrew every year and emptied in 40 because more was taken. Ask: how much is taken each year, and how much comes back? The idea to reach is that sustainability is harvest against regrowth, and that the stock, not the catch, is what has to be measured.
The figures and where they come from — Northern cod (NAFO divisions 2J3KL) catches are rounded from Canadian Department of Fisheries and Oceans series: a peak near 800,000 t in 1968 and roughly 200,000 to 270,000 t a year through the 1980s; quotas were cut from 1989, and the moratorium began on July 2, 1992. The Saint Matthew Island counts are David Klein’s (1968). The hump-shaped regrowth curve is the logistic model, whose peak at half of carrying capacity is the basis of "maximum sustainable yield".
Human carrying capacity is not a fixed number — It depends on technology, diet and consumption per person as much as on the land. That is why estimates range enormously and why the question is partly about choices rather than limits.