Morphometric relationships as computer vision parameters for growth development and sexual maturation status of Atlantic salmon (Salmo salar)

Masteroppgave i biologiBIO399MAMN-HAVSJMAMN-BI

Validation of Atlantic salmon (Salmo salar) weight estimation by stereo camera, and morphometric analysis for assessment of growth performance and maturation status

Stereo image analysis of free-swimming farmed Atlantic salmon is today used for purposes such as individual size estimation and sea lice counting. This technology may in the future be used to score welfare and life history traits. This thesis aims for answering: 1. whether current stereo camera image analysis of size estimation reflects the true size distribution of caged salmon, and 2. whether morphometrical relationships of individual salmon, measured in images, can provide novel insights to growth performance and detection of sexual maturation. The data was collected from an experimental cage production with individually PIT-tagged salmon (n=4500 and n=2786 at harvest) that were manually size recorded multiple times over the production cycle. Stereo images were taken within the sea cage during the last 6 months prior to harvest. Individual images taken at harvest were linked with PIT-ID to enable individual comparison of recorded morphometrics with growth history. Stereo images allow for frequent and numerous measurements of free-swimming salmon, but the precision in estimating individual fish size and accuracy of size distribution within sea cages are largely undocumented. Weight estimations of free-swimming fish based on stereo image analysis are here compared with the true size distribution of the fish at the average weights 2.0, 4.0 and 5.5kg, including a comparison at an individual level by the stereo images taken at harvest. The results show that stereo image analysis gives a highly accurate weight estimation on an individual and populational level, but can to some degree be sensitive to fish size segregation in swimming depth. Morphometrical relationships of the salmon body, and knowledge of how this reflects the growth performance and sexual maturation is largely underexplored. The morphometric analysis includes the ratios of body height central/anal, eye diameter and head size vs. standard length, and are here compared with the harvest size of the fish, individual growth, and sexual maturation status. Harvest weight was reflected in growth rate already from ~50g size, and the largest fish had the highest body height central ratio, and the smallest fish had the largest head ratio. Sexually mature fish showed a clear difference to immature salmon for body height anal and head size, which may be used for detecting early signs of maturation. In conclusion, this thesis proves current stereo image analysis of size estimation as useful, and validate novel salmon morphometrics as relevant parameters for automatization in stereo image analysis.Masteroppgave i biologiBIO399MAMN-BIOMAMN-HAVS

Multispectral Imaging for Determination of Astaxanthin Concentration in Salmonids

Multispectral imaging has been evaluated for characterization of the concentration of a specific cartenoid pigment; astaxanthin. 59 fillets of rainbow trout, Oncorhynchus mykiss, were filleted and imaged using a rapid multispectral imaging device for quantitative analysis. The multispectral imaging device captures reflection properties in 19 distinct wavelength bands, prior to determination of the true concentration of astaxanthin. The samples ranged from 0.20 to 4.34 g per g fish. A PLSR model was calibrated to predict astaxanthin concentration from novel images, and showed good results with a RMSEP of 0.27. For comparison a similar model were built for normal color images, which yielded a RMSEP of 0.45. The acquisition speed of the multispectral imaging system and the accuracy of the PLSR model obtained suggest this method as a promising technique for rapid in-line estimation of astaxanthin concentration in rainbow trout fillets

The effects of temperature, egg quality and nutrition on the early development of triploid Atlantic salmon (Salmo salar L.)

This thesis has successfully advanced understanding regarding potentially sub-optimal early life stage triploid culture. Further investigation of egg incubation temperature requirements elucidated that a constant temperature of 6 °C from fertilisation to first feeding would improve survival and performance of triploids compared to the diploid standard of 8 °C or any temperature alterations throughout embryogenesis. Triploids were more sensitive to post-ovulatory ageing as shown with significantly higher mortality and larger size variation compared to their diploid siblings. Quality indicators suggested that ageing resulted in increased lipid peroxidation and decreased antioxidant activity in unfertilised eggs, suggesting fertilising eggs within five days post-ovulation is beneficial for triploid culture. Nutritional programming was successfully demonstrated in Salmo salar of both ploidy. A nutritional intervention at the point of first feeding resulted in better acceptance and utilisation of vegetable-rich diets in later life. Ploidy generally responded the same, however triploids showed a higher variation in nutrient retention and LC-PUFA biosynthesis, highlighting the need to understand further the difference between nutritional requirements. Fundamentally, the impact of the second set of maternal chromosomes present in triploids is not understood. A panel of expressed microsatellite loci was identified and exploited to assess allele expression and results confirmed codominant expression of these genes in diploid fish. There was clear evidence that all three alleles present in triploids were expressed at both the offspring whole animal level and in blood samples, however poor amplification of RNA from single cells prevented further understanding. Collectively, these studies highlight differences in early life culture requirements of diploid and triploid Salmo salar

Short communication: Application of machine-vision to assess weight of fish (Case study: Oncorhynchus mykiss)

Computer Vision (CV) is a relatively young discipline which has been widely used to automate quality evaluation. CV inspection of fish and fish products can provide efficient, consistent and cost effective alternative, so efforts focused on speed and accuracy of machine vision as a substitute for human inspection of foods. Machine vision is explained as the construction of explicit informative and meaningful descriptions of a physical object via image analysis. Actually it encloses the capturing, processing and analysis of two-dimensional images, and by modeling human vision electronically perceives and understands images. ... This study tries to evaluate the relationship between weight of fish and visual features derived from image processing and present best fit relationship between weight and visual features

Nonintrusive methods for biomass estimation in aquaculture with emphasis on fish: a review

Fish biomass estimation is one of the most common and important practices in aquaculture. The regular acquisition of fish biomass information has been identified as an urgent need for managers to optimize daily feeding, control stocking densities and ultimately determine the optimal time for harvesting. However, it is difficult to estimate fish biomass without human intervention because fishes are sensitive and move freely in an environment where visibility, lighting and stability are uncontrollable. Until now, fish biomass estimation has been mostly based on manual sampling, which is usually invasive, time‐consuming and laborious. Therefore, it is imperative and highly desirable to develop a noninvasive, rapid and cost‐effective means. Machine vision, acoustics, environmental DNA and resistivity counter provide the possibility of developing nonintrusive, faster and cheaper methods for in situ estimation of fish biomass. This article summarizes the development of these nonintrusive methods for fish biomass estimation over the past three decades and presents their basic concepts and principles. The strengths and weaknesses of each method are analysed and future research directions are also presented. Studies show that the applications of information technology such as advanced sensors and communication technologies have great significance to accelerate the development of new means and techniques for more effective biomass estimation. However, the accuracy and intelligence still need to be improved to meet intensive aquaculture requirements. Through close cooperation between fisheries experts and engineers, the precision and the level of intelligence for fish biomass estimation will be further improved based on the above methods

Welfare Indicators for farmed Atlantic salmon: Tools for assessing fish welfare

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Welfare Indicators for farmed Atlantic salmon: tools for assessing fish welfare

Fish welfare is a key issue in commercial farming and is central to many decisions that farmers take during their daily husbandry practices and longer term production planning. It is also a prominent topic for NGO’s, animal welfare organisations and charities, regulatory bodies, policy makers and consumers. Farmers have long been interested in optimising the welfare of their animals and actively employ strategies that address fish welfare concerns and attempt to minimise threats to fish welfare. Independent third party organisations have even developed fish welfare standards and certification schemes for certain aquaculture species (e.g. RSPCA welfare standards for farmed Atlantic salmon and rainbow trout, RSPCA, 2018a, b). The topic of fish welfare has also been covered in numerous aquaculture research and review papers over the years, both from a fundamental and also applied perspective. This wealth of information and documentation can be spread over a wide range of sources that may not be easily accessible for the farmer and other end users. In many cases the wealth of information requires interpretation and re-presentation before it is suitable for use out on the farm. Once the farmer has information on fish welfare, they need to implement it in their production systems and daily husbandry practices. This can be a serious challenge as even measuring fish welfare can be challenging and the tools available for measurement may not be suitable for all species or all life stages. To assess the overall welfare status of the fish we use Welfare Indicators (WIs). Welfare indicators can either be direct animal-based (something you get from the fish), or indirect resource-based (e.g. rearing environment, infrastructure etc.). However, some WIs may be too complex or too difficult to apply on a farm. WIs that are appropriate for on-farm use are termed Operational Welfare Indicators (OWIs). WIs that can be sampled on the farms, but need to be sent to a laboratory or other remote analytical facility are termed Laboratory-based Welfare Indicators (LABWIs). There are other potential WIs that cannot currently be classified as either OWIs or LABWIs, these are mainly used in research but may be useful in the future or under specific circumstances at present. From the suite of appropriate OWIs or LABWIs available, the end user then needs to apply these to different production systems and husbandry routines. This is the goal of this handbook – to assemble a farm-friendly toolbox of fit for purpose Operational Welfare Indicators (OWIs) and Laboratory-based Welfare Indicators (LABWIs) for use out on fish farms in different production systems and husbandry routines. It also includes advice on their implementation and interpretation