Changes in skin colour and cortisol response of Australian snapper Pagrus auratus (Bloch & Schneider, 1801) to different background colours

A two-factor experiment was carried out to investigate the change in skin colour and plasma cortisol response of cultured Australian snapper Pagrus auratus to a change in background colour. Snapper (mean weight=437 g) were held in black or white tanks and fed diets containing 39 mg unesterified astaxanthin kg⁻¹ for 49 days before being transferred from white tanks to black cages (WB) or black tanks to white cages (BW). Skin colour values [L^* (lightness), a^* (redness) and b^* (yellowness)] of all snapper were measured at stocking (t=0 days) and from cages of fish randomly assigned to each sampling time at 0.25, 0.5, 1, 2, 3, 5 and 7 days. Plasma cortisol was measured in anaesthetized snapper following colour measurements at 0, 1 and 7 days. Fish from additional black-to-black (BB) and white-to-white (WW) control treatments were also sampled for colour and cortisol at those times. Rapid changes occurred in skin lightness (L^* values) after altering background colour with maximum change in L^* values for BW and WB treatments occurring within 1 day. Skin redness (a*) of BW snapper continued to steadily decrease over the 7 days (a*=7.93 × e^{−0.051 × time}). Plasma cortisol concentrations were highest at stocking when fish were held at greater densities and were not affected by cage colour. The results of this study suggest that transferring dark coloured snapper to white cages for 1 day is sufficient to affect the greatest benefit in terms of producing light coloured fish while minimizing the reduction in favourable red skin colouration.

Australian perceptions of the Orient 1880-1910

Abstract not supplied. Keywords taken from contents page.

Building the perfect beast : scientific romance and Jewish representations 1880-1914

Various cultural mediums portrayed Jews in Britain in the late Victorian and Edwardian periods. Scientific romance harnessed past communicative 'discourses' such as history, folklore, theology, and mythology and was an innovative form of literature that heralded a new era in the construction of Jewish identity between 1880 to 1914.

Stock-in-trade valuation in the United Kingdom 1840 to 1959

Commentators have made a number of unsubstantiated claims about why the lower of cost and market rule had become the accepted method of valuation. It is demonstrated that none of these explanations can be substantiated. Leon Festinger's theory of "dissonance reduction" is used to explain why the significant criticisms of the rule have been ignored.