Photopigments in the Char of Lake Windermere (Salvelinus willughbii (Günther), forma autumnalis and forma vernails)

Abstract

IN a recent communication Munz and McFarland¹ reported that a single retinal extract from the Arctic char (Salvelinus alpinus (L.), from a North American source) contained a rhodopsin with absorption maximum located at 509 ± 2 nm (rhodopsins are photopigments based on retinaldehyde, namely, retinene₁ in the old nomenclature). The present note concerns the photopigments of the closely related Lake Windermere char, S. willughbii (Günther). This char exists as two distinct self-perpetuating populations in the lake, the one spawning in shallow water (3–12 ft.) in the autumn (forma autumnalis) and the other in deep water (50–70 ft.) in the spring (forma vernalis)². Groups of char were netted during the peaks of their spawning activity in November 1964 and February 1965, dark-adapted for a number of hours, then killed and their retinae removed under darkroom conditions. The retinae were placed in light-tight containers over solid carbon dioxide and then transported to London for extraction and analysis (extracts were prepared from a number of batches, each comprising the retinae from ten to twelve fish).