The impacts of cohort structure on behaviour, growth performance and stress physiology in juvenile barramundi. Digory Hulse Ryan Wilkinson â€“ John Purser. Introduction. Aggressive, cannibalistic species Particularly larval & juvenile Mitigation of cannibalism
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Ryan Wilkinson – John Purser
Picture courtesy Australian Barramundi Farmers Association
1. To evaluate whether inserting passive implant transponder (PIT) tags into the peritoneal cavities of 70 mm long juvenile barramundi impacts growth performance or survival?
4. To examine whether the physiological stress response is linked to population, rates of interaction, damage, growth or growth variability.
5. To make an assessment of the response of juvenile barramundi to olfactory cues of familiar and unfamiliar conspecifics
2. To observe wether barramundi from different hatcheries display different:
3. To examine whether mixing populations of fish from different hatcheries impacts on:
Impact of cohort structure on behaviour & growth performance
Acclimate fish to 12‰ at 30ºC
Distribute into experimental system
Anaesthetise, & PIT tag
Twice daily feed
15 minute interaction video
Weekly length, weight damage
Endocrine response @ termination
Daily mean interactions in 4 categories.
Weekly mean chase events ± standard deviation
Weekly mean body contact events ± standard deviation
Weekly mean anterior contact events ± standard deviation
Weekly mean fight events ± standard deviation
Weekly mean total interactions ± standard deviation
Comprising 4 categories: Chase, body contact, anterior contact, fighting
Mean damage ± standard error
Damage was calculated based on a score combining incidence and severity with a range from 1 – 5.
Feed intake, FCR and SGR ± standard error
Total feed: H1, 365.7 g; H2, 373.8 g
Overall FCR: H1, 0.85; H2, 0.87
Overall SGR: H1, 4.0%; H2, 3.9%
Mean maximum within tank length difference ± standard deviation
No difference in total interactions
Cannibalism possible at 33%
Daily mean total interactions
No differences were observed over the 6 weeks for any of the evaluated parameters either between MIX and H1 or H2, OR the constituent groups within MIX, ie when the H1 fish from MIX were compared to the H2 fish from MIX.