Friday July 21, 2023


Climate change-induced droughts and fish kills affect larger fish more severely than they affect smaller individuals, according to new research.

In a paper published in Environmental Biology of Fishes, researchers from Leiden University, Sportvisserij Zuidwest Nederland and the Sea Around Us initiative at the University of British Columbia compared evidence from drought-induced fish kills in the Netherlands, fisheries management literature and multiple physiological studies. They confirmed that when water becomes warmer and deoxygenated, larger and older individuals within a species tend to die in greater numbers than their smaller and younger counterparts.

“There is usually a discrepancy between the interpretation by the authors of some laboratory studies versus fieldwork experience when it comes to explaining whether and why larger fish are more vulnerable than smaller fish to warming and deoxygenated waters,” said Dr. Daniel Pauly, co-author of the study and principal investigator of the Sea Around Us initiative. “Resolving this discrepancy is urgently needed, as rapid climate change increases periods of drought and extreme heat worldwide and we need to understand the tolerance of fishes of different sizes to these events.”

The explanation for the increased vulnerability of larger fish is that fish gills, as two-dimensional surfaces, cannot keep up with the growth of fish’s three-dimensional bodies. Thus, larger fish have a smaller ratio of gill surface area to body mass.

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