title: Changes in the scotopic vision of juvenile Pacific bluefin tuna (Thunnus orientalis) with growth.
abstract: In cultured juvenile Pacific bluefin tuna (Thunnus orientalis), reducing the mass deaths caused by collision or contact with tank or net walls at night is a priority for seedling production. Pacific bluefin tuna is a visually dependant species, although its scotopic vision is poor. We recorded electroretinograms to investigate the visual function with growth in the dark-adapted eyes of juvenile Pacific bluefin tuna. Peak wavelengths of spectral sensitivity [38-62 days posthatch (dph), 77-167 mm standard length (SL)] were observed between 474 and 494 nm. Visual light sensitivity has a tendency to increase slightly with growth at 28-64 dph in individuals that measured 29-175 mm SL. However, visual temporal resolution did not significantly increase with growth at 38-62 days dph in individuals that measured 77-167 mm SL. These results suggest that the mass death continues between 28 and 64 dph because of low visual function and increasing swimming speed with growth.
authors.affiliation: Department of Fisheries, Faculty of Agriculture, Kinki University, Naka-Machi, Nara 631-8505, Japan.
authors.forename: Taro
authors.initials: T
authors.lastname: Matsumoto
authors.forename: Tokihiko
authors.initials: T
authors.lastname: Okada
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Sawada
authors.forename: Yasunori
authors.initials: Y
authors.lastname: Ishibashi
mesh_terms: D000375:Aging; D000818:Animals; D017756:Aquaculture; D004596:Electroretinography; D006799:Housing, Animal; D055254:Night Vision / Q000502:physiology*; D020795:Photophobia; D014413:Tuna / Q000254:growth & development* / Q000502:physiology*