Definition (Oxford Dic): A young salmon (or trout) after the parr - - PowerPoint PPT Presentation

Definition (Oxford Dic): A young salmon (or trout) after the parr stage, when it becomes silvery and migrates to the sea for the first time.

Contains a morphological and a behavioural component Fits fine with Atlantic salmon (apart from autumn migrants), but what about sea migrating brown trout?

Classification:

Parr: Not silver, clear parr marks, black and red spots Pre-smolt: Partially silver, visible parr marks Smolt: Fully silver, no parr marks and streamlined body shape Study hypothesis

• Parr have lesser return rate the Pre-smolt and Smolt respectively
• Parr will have a higher straying rate than Pre-smolt and Smolt respectively
• Larger fish will survive better than smaller fish

• Overall survival, 8.4 and 10.0 % respectively
• Late migrants have higher survival
• Larger fish are shorter time at sea
• 66 % Smolt, 30 % Pre-smolt, 4 % Parr

Conclusions: ¡ Parr ¡group ¡mean ¡size ¡increases ¡over ¡the ¡season, ¡as ¡opposed ¡to ¡smolt ¡ Parr ¡group ¡have ¡higher ¡return ¡rate ¡and ¡return ¡earlier ¡ High ¡straying, ¡no ¡difference ¡between ¡groups ¡ Smaller ¡fish ¡higher ¡probability ¡of ¡straying ¡