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Title: Development of broodstock management and husbandry tools for improved hatchery performance of ballan wrasse (Labrus bergylta)
Author: Grant, Bridie
ISNI:       0000 0004 5991 4835
Awarding Body: University of Stirling
Current Institution: University of Stirling
Date of Award: 2016
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Cleaner fish, including ballan wrasse (Labrus bergylta) have been proposed as a sustainable solution to sea lice infestations affecting farmed Atlantic salmon (Salmo salar) globally. However, in order to become sustainable, ballan wrasse need to be farmed. This thesis investigated the establishment of captive broodstock and protocols to optimise hatchery performance and productivity of ballan wrasse. High throughput sequencing was used to develop a panel of novel single nucleotide polymorphic markers (SNPs). These SNPs were used to investigate the phylogeographic structuring of ballan wrasse populations within northern geographic ranges including the UK and Norway. Results indicated fine scale population structuring within the UK suggesting that founder broodstock should be sourced locally to minimise the risk of genetic introgression with wild ballan wrasse. Secondly, captive breeding was benchmarked from harems to determine total egg production over the spawning season. Data quantified the spawning periodicity and seasonal changes in egg quality parameters. In addition, microsatellite markers identified the parental contribution to each spawning event of captive broodstock. Results confirmed, for the first time, the repeat-batch spawning behaviour and suggested that spawning events were single-paired matings. Furthermore, bottlenecks in commercial production were investigated including the benthic adhesive eggs and complex spawning behaviours of ballan wrasse within broodstock tanks. Experiments were conducted to optimise the spawning dynamics and egg productivity using fragmented spawning zones and coloured substrates. Finally, an effective bath treatment for removal of the adhesive gum layer of eggs using the proteolytic enzyme alcalaseĀ® was found to assist in egg disinfection and incubation. Overall, this research provides important baseline data on the management of broodstock and the optimisation of hatchery protocols to improve the commercial productivity and performance of ballan wrasse for use as a biological control of sea lice of farmed Atlantic salmon.
Supervisor: Migaud, Herve ; Davie, Andrew Sponsor: Marine Harvest (Scotland) Ltd ; Scottish Sea Farms ; Innovate UK
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Labrus bergylta ; cleaner fish ; phylogeographic structure ; broodstock management ; benthic spawning ; egg quality ; behaviour ; degumming ; Fishes--Breeding ; Ballan wrasse ; Caligidae--Biological control ; Atlantic salmon--Parasties--Biological control