In a recent paper in the journal Fishes, researchers at the University of British Columbia’s Sea Around Us initiative gathered additional evidence supporting the idea that fish become sexually active – and spawn for the first time – in response to growth-induced respiratory stress, which intensifies in warmer, low-oxygen environments.
By assembling and analyzing data on the mean length at maturity and the maximum length reached by 131 species of coral reef fish belonging to 207 populations, the researchers estimated the ratio of the gill surface area – and hence oxygen consumption of each species at these two sizes. Such a ratio affects the rate at which fish’s proteins – essential components of their cells and tissues – are naturally degraded or ‘denatured’ and require to be resynthesized so that the organism remains alive.
“As fish grow, replacing denatured proteins becomes more challenging, in part because their two-dimensional gills have difficulties providing oxygen to their growing tri-dimensional bodies. Less oxygen means that there is a point at which the oxygen required for growth and for the re-synthesis of denatured proteins become very tight, which ‘tells’ fish that it is time to spawn,” said Dr. Daniel Pauly, co-author of the study and principal investigator of the Sea Around Us.
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