Pingguo He and Petri Suuronen, chairs of the Working Group on Fishing Technology and Fish Behaviour WGFTFB)
'The phrases "fishing gear selectivity", "selective fishing", and "selection of fish" by a fishing gear are widely and sometimes interchangeably used in fisheries science and management. However, they are poorly defined, causing confusion even among professionals on the subject. Our working group provided the authoritative definition of selection and selectivity in 1996:
"Selection of fish by a fishing gear can be considered to be the process which causes the catch to have a different composition to that of the fish population in the geographical area in which the gear is being used. The selectivity of a fishing gear is a measurement of the selection process."
We can define "selective fishing" as the ability to target and capture specific types of marine organisms, allowing unwanted sizes and species to evade or escape capture. Selective fishing may be a result of intentional measures associated with gear design or operational tactics or unequal vulnerability of different sizes and species of marine organisms to the gear.
Size selectivity is the ability of fishing gears to target and retain certain sizes of organism within a species. Size selection covers all processes that cause the probability of capture to vary with fish size. Size selectivity is used to control the impact of fishing on juveniles through the regulation of codend mesh sizes or other devices and designs. With size selective fishing, the age at first capture is typically increased to increase total yield from the stock.
Species selectivity is the ability of fishing gears to target and retain certain species, and less so for other species. Methods that improve species selectivity allow fishers to catch and retain desired target species more efficiently, while reduce the amount of non-target species, often called bycatch species. Species selectivity can be achieved through a range of modification in gear design and operation, and the knowledge of fish behaviour is often fundamental in this development.'