Skeletal Nutrition, Development, and Health of Ballan Wrasse (Labrus bergylta Ascanius, 1767)

Abstract

Ballan wrasse (Labrus bergylta, Ascanius 1767) is a species of commercial interest as a form of biological control of sea lice copepods, a key parasite challenge in Atlantic salmon (Salmo salar) aquaculture. Due to this, a commercial ballan wrasse aquaculture industry has developed, and the first steps have been taken to domesticate this species. As with many marine species new to aquaculture, there is a high frequency of skeletal abnormalities in juvenile fish. This includes vertebrae, opercular, and jaw deformities, which have been shown to negatively impact welfare, reduce growth, increase energy expenditure and swimming effort, mortality rates and stress susceptibility in other species. Skeletal abnormalities lead to rejection of as much as 30% of the stock by customers. This shows the importance of understanding the normal development and mineralisation of ballan wrasse skeletal systems, as well as understanding the aetiology and pathology of abnormalities. The following chapters introduce the commercial use and production of ballan wrasse, outline the potential impacts of abnormalities on the performance, health, and welfare of aquaculture species, and provide an overview of teleost skeletal development and bone metabolism (Chapter 1). Chapter 2 details the materials and methods used throughout, and the method development involved. Development of the vertebral column and skeletal appendages is described in Chapter 3. Chapter 4 investigates larval quality data using commercial sampling protocols and Chapter 5 investigates the impact of phosphorus and vitamin D3 on the performance and skeletal health of juvenile wrasse.