Strategic R & D Plan
This proposal fits within the Salmon Aquaculture Subprogram

As a result of FRDC project 2008/217 (The effect of temperature on reproductive development in maiden and repeat spawning Atlantic salmon: understanding the basis for improved egg quality and survival) and a series of earlier studies we know that:

The effect of elevated summer and autumn temperature in inhibiting reproduction in Tasmanian Atlantic salmon broodstock is consistent and potentially profound. Maidens (first spawning fish) and repeats are both affected but repeats are more robust in terms of their capacity to cope. Maidens are a slightly better proposition than repeats in terms of egg quality and survival but only provided that they can be kept cool during summer and autumn.

The inhibitory effects of temperature on reproduction are mediated through the endocrine (hormonal) system.
All parts of the endocrine chain appear to be potentially affected but by far the most sensitive stage is the aromatase-mediated production of estrogen by the ovary. Our experiments have shown that management of aromatase inhibition is the key step in offsetting the effects of high temperature.

Management options are currently limited to managing temperature of broodstock. This approach assumes that the temperature-controlled holding capacity is large enough (or never fails). There is still a strong need for a hormone therapy option as an additional management strategy. Preliminary experiments with juveniles have shown that the fish stay responsive to external estrogen at high temperature. This means that treatment of adults with estrogen at critical periods is a strong candidate for hormone therapy.

Benefit
SALTAS modelling indicates that the current direct effect is a loss of smolt production of ~$250,000 and potential industry production shortfall of ~$20million per annum. This assumes that thermal effects in autumn do not get any worse.