In this introduction module, elders, fishers and scientists describe in various ways how fisheries are declining everywhere. Fish and other economically important marine species are declining in both abundance and size, and these declines have been dramatic within living memory of many people. These declines are primarily driven by increases in human populations, the expansion of markets, and improvements in fishing technology.
The concept of ‘fishery production’ is explained, along with key idea that recruitment is related to stock size. This will be examined in more detail in later modules. We also illustrate, using animations, some of the main techniques used by scientists to measure changes in abundance and size of fish and other species, including catch-per-unit-effort, and transect surveys.