Essentials of Ecology

274 CHAPTER 11 Sustaining Aquatic Biodiversity

ECOLOGICAL FOOTPRINT ANALYSIS

A fishprint provides a measure of a country’s fish harvest in

terms of area. The unit of area used in fishprint analysis is the

global hectare (gha), a unit weighted to reflect the relative

ecological productivity of the area fished. When compared

with the fishing area’s sustainable biocapacity, its ability to pro-

vide a stable supply of fish year after year in terms of area, its

fishprint indicates whether the country’s fishing intensity is

sustainable. The fishprint and biocapacity are calculated using

the following formulae:

Fishprint (in gha) 

metric tons of fish harvested per year

productivity in metric tons per hectare  weighting factor

Biocapacity (in gha) 

sustained yield of fish in metric tons per year

productivity in metric tons per hectare  weighting factor

The following graph shows the earth’s total fishprint and bio-

capacity. Study it and answer the following questions.

1. Based on the graph,
   a. What is the current status of the global fisheries with
   respect to sustainability?
   b. In what year did the global fishprint begin exceeding
   the biological capacity of the world’s oceans?
   c. By how much did the global fishprint exceed the bio-
   logical capacity of the world’s oceans in 2000?


2. Assume a country harvests 18 million metric tons of fish
   annually from an ocean area with an average productiv-
   ity of 1.3 metric tons per hectare and a weighting factor of
   2.68. What is the annual fishprint of that country?
   3. If biologists determine that this country’s sustained yield
   of fish is 17 million metric tons per year,
   a. What is the country’s sustainable biological capacity?
   b. Is the county’s fishing intensity sustainable?
   c. To what extent, as a percentage, is the country under-
   or overshooting its biological capacity?

LEARNING ONLINE

Log on to the Student Companion Site for this book at

academic.cengage.com/biology/miller, and choose

Chapter 11 for many study aids and ideas for further read-

ing and research. These include flash cards, practice quiz-

zing, Weblinks, information on Green Careers, and InfoTrac®

College Edition articles.

Year

Breeding pairs

1955 1960 1965 1970 1975 1980 1985 1990

Fishprint

Biocapacity

1950 1995 2000

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