Environmental and genetic regulation of fish physiology
The basic understanding of fish reproduction and environmental control acquired by the team led to the development of protocols for the fish farming industry to improve fish welfare and increase productivity while safeguarding wild fish stocks. Reproduction in farmed fish stocks results in the reallocation of energy from muscle/flesh to gonads leading to reduced flesh quality and muscle growth, increased susceptibility to disease and welfare concerns. All of these lead to production losses through mortality and product downgrading during processing. Key strategies have been identified and researched to tackle this problem e.g. reduction in the prevalence of early maturing fish prior to harvest either using light manipulations, sterility using genetic manipulation or monosexing. The knowledge that will be gained by the team in these areas will lead to the implementation of protocols, guidelines and practices within the industry that will significantly improve the sustainability of the sector, generating growth and increased profitability.
The main objectives of the project are:
1) To study the impact of genetic manipulations (selection, ploidy, gene editing) and hormonal sex control on fish performance;
2) To better understand the control and regulation of reproduction, growth, development and immune function by environment factors (e.g. light, temperature, salinity and nutrition) in fish including biological rhythms; and
3) To study stress and immune function in fish to changes in the environment (e.g. light, temperature, salinity, nutrition, water quality).
Linkages between invasive plants and salmonids
Non-native species of plants are commonly found along the banks of rivers and streams in the UK. These zones (termed riparian) are naturally dynamic and critical in maintaining connectivity between aquatic and terrestrial habitats but are also highly prone to invasion so they provide ideal locations for the establishment and distribution of invasive species. Non-native plant species in the riparian zone can change the conditions in the river by effecting the amount of shade and changing the nutrient and silt inputs.
Native salmonid fish species (Atlantic salmon, Salmo salar and Brown Trout, Salmo trutte) have specific habitat requirements and are strongly affected by the physio-chemical conditions in rivers. Both theory and expert judgement indicate that seasonal alterations to channel shading, organic material input, channel shape and bank stability resulting from dense stands of three common invasive riparian plant species, could cause changes to these native fish communities, whether directly or indirectly.
Despite various government initiatives, and considerable efforts and resources being invested by river and fishery managers to address the spread and extent of riparian zone coverage by invasive plant species in Scottish catchments it remains unclear (a) how much damage is actually caused to populations of native salmonids by extensive invasive plant cover in the riparian zone, or whether salmonids respond positively to management of riparian invasive plants.
The specific objectives are to:
1) Assess the impact of varying type and cover of invasive riparian plants on the local habitat suitability for and juvenile salmonid fish and their prey.
2) Identify the role of invasive riparian plants in determining population abundance, structure and growth parameters in native juvenile salmonids.
3) Identify and quantify the mechanisms underpinning changes in channel morphology, aquatic invertebrates and salmonid populations that are attributable to RIPs. Responses within salmonids will be investigated using quantitative population sampling, growth rate measurement and gut content analysis.
Culture of sea lice on Atlantic salmon
The aim of this project is to maintain sea lice using salmon so that they can be used to monitor resistance to existing treatments and develop new approaches. Sea lice are the most significant health problem for salmon farming because treatment involves significant cost and because farmed fish may provide a reservoir of sea lice which provide a threat to wild salmon fisheries. Commercial producers cannot always control sea lice because of resistance to current medicines, and the result is losses and early harvest to avoid harm, reducing production. New treatments are needed, and developing them means growing sea lice on live salmon as hosts. To develop more effective treatments, such as new drugs, we need to be able to test them on sea lice in the laboratory. To check whether new drugs work on lice with different patterns of drug sensitivity we need to keep a few varieties of these parasites. Unfortunately, we cannot grow them without using salmon, so we need to use fish in the laboratory too.
Nutritional and environmental interventions to improve aquaculture
The main objectives of this project licence are to advance our understanding of how fish function and how changes in their diet and/or their environment influence their physiological responses. New fish diets are continually being developed because of changes in the raw materials being used and the determination of new requirement levels for nutrients across new and existing species being farmed. As such these nutritional responses need to be studied to ensure they correctly support growth and health, across a range of environmental conditions. The scientific unknowns we aim to specifically assess in this project licence are;
1) Defining the requirements of fish for different nutrients, by evaluating their response to varying levels of those dietary nutrients (e.g. how much of the beneficial omega-3 lipids do fish need at different parts of their production cycle).
2) Evaluate the absorption and utilisation of nutrients by fish from different raw materials under different diet formulations designed to test the effect of raw material type and inclusion (e.g. the inclusion of novel vegetable oils in diets at different levels).
3) Evaluate the response of fish to varying levels of raw materials and dietary nutrients under different types of environmental constraints (e.g. how much omega-3 do fish need with varying temperature).
Sea lice and amoebic gill disease in Atlantic salmon
This licence will allow us to develop treatments for two of the most significant health problems for salmon farming. Sea lice are a damaging parasite that are showing increasing resistance to current drugs, meaning costs are increasing and lice on farmed fish can threaten wild salmon. Amoebic gill disease (AGD) is an increasing problem as sea temperatures rise, and current treatments are either difficult or can be harmful to the salmon themselves. To develop more effective treatments, such as new drugs or physical methods, we need to be able to test them on infected fish in the laboratory, as we cannot grow sea lice without using fish we maintain colonies using infected fish
Pathogenesis and treatment of bacterial pathogens in fish
The overall aim is to reduce fish losses in aquaculture systems from bacterial infections by producing improved understanding of disease outbreaks, leading to the development of better prevention/control/treatment regimes to support the health and welfare of farmed fish species. Disease outbreaks in fish farms significantly impact on the sustainable development of this growing aquatic food sector. The need for improved disease diagnosis, prevention and control strategies is recognised by academic and industry alike.