Dr. Craig Purchase of Newfoundland and Labrador’s Memorial University led an international team to Ontario’s International Institute for Sustainable Development-Experimental Lakes Area (IISD-ELA) because the facility possessed 40 years of lake trout data and all adult lake trout in the study area experienced similar ecological conditions.
Their findings, published in Proceedings of the Royal Society B: Biological Sciences in January, suggest that senescence, a decline in biological function with age that is typically quantified as an increase in mortality rate or reduced fertility, is easily observed in humans and domesticated animals, but may not be universal. According to Purchase, theory predicts senescence is observed in species that stop growing in adulthood, but not in those that continue to grow, such as trees, some fish, and reptiles.
“We looked at the adult male performance of wild lake trout. Fish with restricted growth had slight declines in body condition and increases in mortality with age, while reproductive performance was maintained. However, we think that fish whose food sources allowed for them to continue growing may escape negative effects of aging altogether,” the researchers noted.
They added, “If this study’s findings extend to fish in larger lakes, where older fish may get much larger, focusing on conserving these old-big fish could allow for both greater capacity for repopulation (more sperm/eggs per animal) and, since they live so long, they could act as reservoirs of past genetic diversity.”
In most studies, lake trout populations that grow to such enormous sizes should show negative signs of aging, but in this case, they actually improved in function, Purchase said.
University of Manitoba biologist and fellow researcher Jason Treberg said that the study could help us understand how the aging process works, especially in humans.