Why was this NOT used in the Surprise Gulf of Maine Cod Assessment?

Most models of fish population dynamics are based on fisheries-independent surveys, fixed over a particular area during a specific season, and rarely cover the entire range of habitat that fish use. Many fish are highly mobile ectotherms – an animal that cannot regulate its own body temperature, so its body temperature fluctuates according to its surroundings. They often shift their distributions in response to dynamic properties of the ocean such as changing water temperature. When surveys do not sample the entire range of habitat fish use, systematic shifts in species distribution into, or out of, survey areas can be misinterpreted as increases or decreases in population size. Read the rest here 14:25