Functional feeds, biomarkers to play major role in Scottish salmon gill health project

The Scottish Aquaculture Innovation Centre (SAIC) is funding a new project aimed at helping the country's salmon farming industry manage gill health challenges in their fish stocks.

Photo: Scottish Sea Farms

Fish feed group, BioMar, salmon farming company Scottish Sea Farms (SFF), the University of Aberdeen, and Marine Scotland Science, are all involved. The initiative wants to identify innovative diagnostic tools to closely monitor the gill condition of salmon in seawater pens, as well as finding feeds to promote optimum salmon health and welfare.

The project is valued at almost £800,000 (US$985K), and SAIC is contributing £284,000 in terms of a grant towards the investigative work.

Heather Jones, CEO of SAIC, told this publication challenges to gill health in salmon concern farmers in all producer countries, from Tasmania to Norway.

“This week sees over 100 delegates from Ireland, Norway, Australia, Spain, Scotland and Chile attend the 6th International Gill Health Initiative in Galway ​- demonstrating that this is a global issue. ​

“The appearance of compromised gill performance of fish reared in Scottish waters resulted in SAIC hosting a gill health workshop in Oban in December 2016. This included presentations from Scottish and international experts on gill issues, and resulted in a number of project proposals.”​

Gill problems account for a large proportion of production losses in the sea phase. Like other species, fish are dependent on having sufficient access to oxygen, and it is the gills that ensure they can utilize the oxygen dissolved in the water they live in. Many infection agents and particles in the water can harm the gills and thereby be a threat to the welfare, health and survival of the fish. 

Functional feeds

Nutrition is well-established as a key aspect of health management in salmon farming, and functional feeds are known to improve health performance, said Elisabeth Aasum, global R&D manager, health, at BioMar.

“The diets that will be assessed during the project have been designed with a strategic combination of additives that will focus on strengthening the gills, and supplying ingredients associated with tissue repair and inflammatory response modulation.​

“Moreover, these additives will stimulate different aspects of innate and adaptive immune response in order to increase the systemic robustness of fish, while strengthening the mucosal barriers of fish through modulation of the quality of the mucus composition as well as other important parameters such as quantity and viscosity,” ​she told us

The diets are also aimed at ensuring the health of the fish circulation system, which is said to be strongly associated with gill function.

Biomarkers for gill health 

It is hoped the new diagnostic tools will enable salmon farmers to fine-tune their husbandry practices to the conditions of the local marine environment, aided by rapid-response modelling of risk factors, said SAIC.

Salmon gill health will be assessed though a large panel of molecular markers already developed for health by the University of Aberdeen. “Additional gill markers will be added by proteomic and transcriptomic methodologies. The biomarkers will be defined in relation to refined gill health at both gross and histological levels,”​ explained Professor Sam Martin of the University of Aberdeen.

Jones said SAIC has a number of projects in its pipeline that will address other aspects of the gill health challenge, and that will also look to tackle other "environmental and health challenges of global aquaculture as they manifest themselves in Scottish waters."​

She said SAIC, ultimately, seeks to promote sound science and promulgate best practice in the interface between scientific and academic research and then apply that knowledge to the active management of fish and shellfish production.