Qualitative data is one which can be observed with our senses such as sight, smell, touch, taste, and hearing. Qualitative observations do not involve any measurement. Example: Colour of an object
Quantitative data is one which involves measurement of data in numbers. Example: speed of an object
As the biologist is measuring the length of salmon as they travel upstream , it measures data in numbers and hence is a quantitative data and not a qualitative data.
