"So if we can get a chronology, a timeline, of dates and locations and then match that with the size of the fish, we can get a pretty good idea about what was around in the past.

"And I know some of the fish go back to the early part of the last century, 1800s some of them.

"It's a wonderful record of what existed in the past and dare I say what could exist in the future."

Dr Humphries said the cod also gave an insight into the evolving definition of what a "trophy fish" was.