progress
November 2014
The first objective of the WP22 is to identify by a multifactorial experiment the main stressful factors which affect the growth performances, physiological and immune status of pikeperch juveniles in order to increase the production and quality of pikeperch juveniles.
In order to standardize some analytical protocols for physiological and immune markers which will be used for the multifactorial experiment, two preliminary experiments are ongoing:
(a) In the first preliminary experiment we tested the sensitivity of pikeperch juveniles to a single or repeated stress emersion consisting of a complete removal of tank water + 30-second emersion. Such manipulations mimic the grading which is often made along the ongrowing stage of pikeperch in farm production. Results concerning the growth response to the emersion stress and some physiological markers are available, but the analyses of immune markers are still ongoing for that experiment.
(b) A second preliminary test will be conducted during November and December 2014 in order to determine the lethal dose of Aeromonas hydrophila or A. salmonicida that will be used for the disease tests in the further experiments.
To adapt the rearing conditions of the UL facilities to the multifactorial protocol requirements, it is planned that the multifactorial experiment will start by June 2015 since the deliverables are expected on month 24.
The first objective of the WP22 is to identify by a multifactorial experiment the main stressful factors which affect the growth performances, physiological and immune status of pikeperch juveniles in order to increase the production and quality of pikeperch juveniles.
In order to standardize some analytical protocols for physiological and immune markers which will be used for the multifactorial experiment, two preliminary experiments are ongoing:
(a) In the first preliminary experiment we tested the sensitivity of pikeperch juveniles to a single or repeated stress emersion consisting of a complete removal of tank water + 30-second emersion. Such manipulations mimic the grading which is often made along the ongrowing stage of pikeperch in farm production. Results concerning the growth response to the emersion stress and some physiological markers are available, but the analyses of immune markers are still ongoing for that experiment.
(b) A second preliminary test will be conducted during November and December 2014 in order to determine the lethal dose of Aeromonas hydrophila or A. salmonicida that will be used for the disease tests in the further experiments.
To adapt the rearing conditions of the UL facilities to the multifactorial protocol requirements, it is planned that the multifactorial experiment will start by June 2015 since the deliverables are expected on month 24.
Participating organizations (WP leader in bold): P15. UL, P16. FUNDP, P21. DTU, and P29. ASIALOR
Task 22.1 Effect of husbandry practices and environmental factors on pikeperch growth, immune and physiological status (led by FUNDP). In order to identify the main stressful factors, pikeperch juveniles will be exposed to various potentially stressful husbandry practices and environmental conditions and examined for physiological stress responses, immune competence and global resistance to infectious diseases. This first experiment will last around 8-12 months. At that level, the application of a multifactorial experimental design will be used as a first screening approach. We will test 8 factors (2 modalities per factor, using 16 experimental units). Based on physiological and immunological variables as outputs, that screening approach will allow identifying an optimal combination of environmental and husbandry factors that will apply on commercial farm conditions as a validation step.
The analytical approaches will include behavioral as well as biochemical, cellular and molecular techniques. Concerning behavior, a major objective will be the identification of specific behavioral traits or changes before the sudden mortality and the proposal of real-time behavioral indicators (video recording). Pertaining to the possible immune consequences of stressors, bacterial challenges will be imposed to the fish and both internal organs/fluids involved in immune function and primary barriers will be investigated. In addition metabolic costs will be evaluated, using an approach where oxygen consumption is measured in fish following a stressful event, also known as post stress oxygen consumption, this provides valuable insight on the metabolic cost of recovering from different stressors, and the duration recovery. The approach allows for assessing different severities or durations or repetitions of a stress event that may occur during husbandry or transport.
Task 22.2 Characterization of pikeperch growth, immune and physiological status in farm conditions (led by ASIALOR). Based on the results from multifactorial experiments (see Task 22.1), growth and physio-immunological status of 2 or 3 batches of pikeperch at different developmental stages will be compared, in farm conditions, between standard husbandry conditions usually applied in routine by the SME and the best rearing conditions identified in Task 22.1. From this task, the expected results will help (i) to recommend the best conditions applicable in pikeperch farming for reducing stress level and supporting maximal growth performances.
Task 22.3 Effect of pikeperch domestication level and geographical origin on growth and stress sensitivity (led by FUNDP). Due to recent intensive culture, pikeperch populations displaying various domestication levels are reared so far. Domestication highly affects the stress and immune status of fish in farm conditions. The effects of domestication process (wild vs domesticated strains) and geographical origin (freshwater vs brackish water strains) will be investigated. Different batches of juveniles (3 or 4 geographical origins, 1 or 2 populations of the same geographical origin with 2 levels of domestication) will be produced from larval stage in similar conditions. The genetic variability and value of the different populations will be characterized. Then, using the optimal combination of factors identified on Task 22.1, fish will be reared and examined for physiological stress responses, immune competence and global resistance to infectious diseases. This task will specify the effect of domestication level and geographical origin on pikeperch growth and stress sensitivity, allowing the further selection of pikeperch strain according to the rearing conditions of commercial fish farms.
Task 22.1 Effect of husbandry practices and environmental factors on pikeperch growth, immune and physiological status (led by FUNDP). In order to identify the main stressful factors, pikeperch juveniles will be exposed to various potentially stressful husbandry practices and environmental conditions and examined for physiological stress responses, immune competence and global resistance to infectious diseases. This first experiment will last around 8-12 months. At that level, the application of a multifactorial experimental design will be used as a first screening approach. We will test 8 factors (2 modalities per factor, using 16 experimental units). Based on physiological and immunological variables as outputs, that screening approach will allow identifying an optimal combination of environmental and husbandry factors that will apply on commercial farm conditions as a validation step.
The analytical approaches will include behavioral as well as biochemical, cellular and molecular techniques. Concerning behavior, a major objective will be the identification of specific behavioral traits or changes before the sudden mortality and the proposal of real-time behavioral indicators (video recording). Pertaining to the possible immune consequences of stressors, bacterial challenges will be imposed to the fish and both internal organs/fluids involved in immune function and primary barriers will be investigated. In addition metabolic costs will be evaluated, using an approach where oxygen consumption is measured in fish following a stressful event, also known as post stress oxygen consumption, this provides valuable insight on the metabolic cost of recovering from different stressors, and the duration recovery. The approach allows for assessing different severities or durations or repetitions of a stress event that may occur during husbandry or transport.
Task 22.2 Characterization of pikeperch growth, immune and physiological status in farm conditions (led by ASIALOR). Based on the results from multifactorial experiments (see Task 22.1), growth and physio-immunological status of 2 or 3 batches of pikeperch at different developmental stages will be compared, in farm conditions, between standard husbandry conditions usually applied in routine by the SME and the best rearing conditions identified in Task 22.1. From this task, the expected results will help (i) to recommend the best conditions applicable in pikeperch farming for reducing stress level and supporting maximal growth performances.
Task 22.3 Effect of pikeperch domestication level and geographical origin on growth and stress sensitivity (led by FUNDP). Due to recent intensive culture, pikeperch populations displaying various domestication levels are reared so far. Domestication highly affects the stress and immune status of fish in farm conditions. The effects of domestication process (wild vs domesticated strains) and geographical origin (freshwater vs brackish water strains) will be investigated. Different batches of juveniles (3 or 4 geographical origins, 1 or 2 populations of the same geographical origin with 2 levels of domestication) will be produced from larval stage in similar conditions. The genetic variability and value of the different populations will be characterized. Then, using the optimal combination of factors identified on Task 22.1, fish will be reared and examined for physiological stress responses, immune competence and global resistance to infectious diseases. This task will specify the effect of domestication level and geographical origin on pikeperch growth and stress sensitivity, allowing the further selection of pikeperch strain according to the rearing conditions of commercial fish farms.