The physical relief that temperate fish like cod and Atlantic herring experience after they spawn for the first time allows them to breathe in more oxygen and develop a voracious appetite, all of which leads to a rapid increase in body weight.
New research published in Environmental Biology of Fishes turns on its head the widespread notion that fish stop growing after they reach first maturity as a consequence of having to dedicate most of their ‘energy’ to reproduction.
“In fact, growth is strongly affected by oxygen intake,” said Dr. Daniel Pauly, lead author of the study and principal investigator of the Sea Around Us initiative at the University of British Columbia. “As fish develop, the growth of their 2D gills – which supply them with oxygen – cannot keep up with that of their 3D bodies – which demand oxygen. This tension triggers a hormonal cascade that leads to gonad maturation and spawning.”