Fishing of any sort pushes the average size of the fish population down. For a number of reasons we want good numbers of large fish. Eels only breed once in their lives and die afterwards. To ensure sustainability it is critical that we manage for plenty of large females to be available for the spawning migration north to the Coral Sea. Males are less important as they migrate when still small (<220g for shortfins and <500g for longfins).
We also want plenty of large longfins as they are the apex predator in our river systems.
Size structure indices are an important management tool as they indicate local depletion and whether we are maintaining a good pipeline of breeding sized fish.
Size Structure by Catchment