A decrease in photoperiod shortly after first feeding influences the development of Atlantic salmon (Salmo salar)

Four groups of Atlantic salmon fry (n=2000) were exposed to continuous light (LD24:0) from first feeding on 18th April 2001, after which they were exposed to either an 8 or 12 week period of short days (LD10:14) starting on either the 21st May or the 18th June. Each group was then returned to LD24:0 until the conclusion of the experiment the following March. In August 200 fish per treatment were individually PIT tagged. All groups were maintained under an ambient temperature regime. The highest levels of sexual maturation in 0+ male parr were recorded in the 12 week/May group (>11% of the entire male and female population), with the lowest levels (6%) in the 8 week/May and 8 week/June groups (

The effects of daily ration on growth and smoltification in 0+ and 1+ Atlantic salmon (Salmo salar) parr

The effects of long-term variations in feed ration were studied during two experiments on Atlantic salmon parr. In the first experiment, three duplicate groups of approximately 500 salmon parr were fed at rates of 100%, 66% or 33% of the manufacturer’s recommendation from shortly after first feeding. Each group were exposed to a photoperiod regime which was expected to result in smoltification 9 months after first feeding. In the second experiment, three duplicate groups of 550 fish were fed 100%, 66% or 33% of the manufacturer’s recommendation from first feeding and exposed to a simulated natural photoperiod, which was expected to result in smoltification 13 months after first feeding. In both experiments fish size increased with ration, with recruitment to the upper modal group (UMG) of the population also related to ration (85-96%, 64-88% and 28-42% UMG fish for the full, two-thirds and one-third ration groups respectively, recorded at the conclusion of each experiment). Throughout each experiment the full and two-thirds ration fish maintained similar whole body lipid concentrations, although lipid concentrations in the one-third ration fish were generally lower. At the conclusion of experiment 1, gill Na+, K+-ATPase activity in UMG fish fed full rations reached 9.5 μmol ADP hydrolysed. mg-1. protein-1. h-1, whereas ATPase activities were lower in the other ration groups. In experiment 2, all groups had similar gill Na+, K+,-ATPase activities at the conclusion of the experiment (6.4-9.3 μmol ADP hydrolysed. mg-1. protein-1. h-1). Following 24h seawater challenges, conducted during the parr-smolt transformation, UMG fish from the full and two-thirds groups of experiment 1 displayed high survival rates (100%) and low serum osmolalities (335 mOsm.kg-1), with lower survival rates (75%) and higher serum osmolalities (370 mOsm.kg-1) recorded in the one-third ration fish. In experiment 2 similar survival rates (100%) and serum osmolalities (350 mOsm.kg-1) were found in all ration groups. It is concluded that under accelerated production regimes, feed restriction may result in underyearling Atlantic salmon smolts developing a poor hypo-osmoregulatory ability. Variations in ration significantly influence growth, although it is believed that growth is dependant on the maintenance of a specific lipid level in the body

How to measure the economic impacts of changes in growth, feed efficiency and survival in aquaculture

In this article we introduce a variety of bio-economic models that can be used to calculate the economic benefits associated with improved productivity in aquaculture. In the aquaculture industry, three important biological productivity factors are growth, survival and feed efficiency. The profitability of improving productivity factors, especially growth, is highly dependent upon the cost factor structure, production system, its constraints and other factors within the supply chain. Therefore we present a number of different bio-economical models that can be used to robustly assess the economic impacts in different production environments. These models are introduced with case examples across a range of aquaculture species and production systems. We calculate changes in profitability through a reduction in production costs and any potential increases in product price premiums via the use of weight dependent unit profit as the outcome in cost-benefit analysis, so that results may be expanded to cover different volumes

BENEFISH: A European project to put a cost on fish welfare actions.

BENEFISH is a research project funded under the European Commission Sixth Framework initiative. It aims to develop bio-economic models that establish the effects of welfare actions (i.e. measures taken to safeguard welfare) on value chains within the European aquaculture industry, including both production related elements such as growth and feed efficiency, and societal elements such as consumer added value. The project includes wide and integrated scientific competence, which incorporates biological knowledge about fish welfare, industrial knowledge about practical farming, societal knowledge about consumer perception and economical knowledge about bio-economical development. This paper provides an overview of BENEFISH and explains how the project is structured to address its complex multidisciplinary aims. It also outlines how the project consortium plans to achieve its goal of developing bio-economic models relating to fish welfare