Fish Senescence: Relevant Findings and Their Importance to Human Gerontology

As they comprise over half of the world\u27s vertebrates, it is not surprising that fish represent a large percentage of the vertebrates which live over 100 years. The questions behind how some fishes manage to survive for such a long time has lead to studies on mortality and the process of senescence. Senescence can be explained as a decrease in fitness from natural, physical degradation that is a side effect of aging; this begins after sexual maturity has been reached. Senescent patterns have evolved from extrinsic mortality rates suggesting that fishes with high mortality rates will have an earlier onset of senescence and shorter lifespans. There is diversity apparent in the varying types of senescence observed among species. The process of senescence occurs in three basic forms: rapid, gradual, and indeterminate or slow. Rapid senescence, also known as parental death, is observed in those species of semiparous fishes that die after a massive spawning event and include the pacific salmon, Salmo safar, and species of lampreys and eels (Anguilla sp.) Gradual senescence is observed in teleosts with a variety of lifespans. They have an age-related increase in mortality, but death does not happen at one particular time for all individuals. Long-lived fishes such as the Atlantic sturgeon, Acipenser oxyrhinchus, and orange roughy, Hoplostethus atfanticus. exhibit negligible senescence and it is either very slow or does not start until late in life, and reproductive capacity may not change with age. Due to their physiological similarities to humans, research findings on fishes are relevant to future studies in human gerontology. As a blueprint for all vertebrates, fishes may serve as a way to gain valuable information on the genetic background of aging diseases such as Alzheimer\u27s and Parkinson\u27s. This paper will serve as a comprehensive review of published scientific literature that encompasses senescence in a variety of fishes, and the relevance of these senescence studies to human gerontology