Stereo Vision 3D Tracking of Multiple Free-Swimming Fish for Low Frame Rate Video

3D multiple fish tracking has gained a significant growing research interest to quantify fish behavior. However, most tracking techniques have used a high frame rate that is currently not viable for real-time tracking applications. This study discusses multiple fish tracking techniques using low frame rate sampling of stereo video clips. The fish are tagged and tracked based on the absolute error of predicted indices using past and present fish centroid locations and a deterministic frame index. In the predictor sub-system, the linear regression and machine learning algorithms intended for nonlinear systems, such as Adaptive Neuro-Fuzzy Inference System (ANFIS), symbolic regression, and Gaussian Process Regression (GPR), were investigated. Results have shown that in the context of tagging and tracking accuracy, the symbolic regression attained the best performance, followed by the GPR, i.e., 74% to 100% and 81% to 91%, respectively. Considering the computation time, symbolic regression resulted in the highest computing lag of approximately 946 ms per iteration, whereas GPR achieved the lowest computing time of 39 ms

The influence of stocking density and acoustic conditioning on the behavior and growth of Atlantic cod, Gadus morhua

The goal of experiment one (Chapter One) was to determine if stocking density had an influence of the swimming behavior and spatial distribution of adult cod that were being raised in an aquaculture cage at the University of New Hampshire\u27s Coastal Marine Laboratory. Acoustic telemetry and underwater video were used to quantify the behavior and distribution of cod that were stocked at four densities (5, 10, 25 and 45 kg/m³). At the lowest density (5 kg/m³) cod remained deep in the cage and spent 64.3 +/- 0.8% of their time below 1.80m (of a 2.70m cage). This contrasts to the middle density (10 kg/m³) and the high density (25 kg/m³) treatments, during which fish spent 48.7 +/- 1.2% and 46.8 +/- 0.8% of the time below 1.80m, respectively. One of the objectives was to determine if adult cod will school if raised at a high density, therefore reducing milling activity. At no time did the cod school in the experimental cage, regardless of raising the density to 45 kg/m³. The objective of experiment two (Chapter Two) was to determine if conditioning cod with an acoustic stimulus presented during feeding would increase their growth rate. Conditioned fish became active as soon as the sound stimulus was presented and spent less time milling at the surface prior to feeding, as compared to the group which was fed at the same time twice daily, but without a conditioning sound stimulus. Length and weight measurements for each group were not statistically different at the end of the experiment, though the acoustically conditioned group had the lowest food conversion ratio (FCR, 4.17), and a higher daily growth rate (0.11 g/d) than the group with the randomly changing daily feeding times. The results from these two studies further develop our knowledge of cod behavior in an aquaculture setting. Understanding how acoustic conditioning can reduce wasted feed, will allow farmers to reduce waste and increase growth rates. By better understanding how density impacts cod behavior, cages can be better designed for cod in particular, and density can be further considered in farm management to better optimize fish farming

Reproductive adaptations to reduce locomotor costs in viviparous fish (Poeciliidae)

Viviparity, a live-bearing mode of reproduction, has evolved over 100 times independently in vertebrate animals. Despite its frequent evolution, viviparity has a number of hypothesised disadvantages compared to the ancestral mode of reproduction, oviparity (egg-laying). One of these disadvantages is a reduction in locomotor performance during pregnancy, the period of internal development of the embryos. Adaptations to a live-bearing reproductive mode could have evolved to reduce these locomotor costs. In this thesis, I aim to find whether matrotrophy, post-fertilization nutrient provisioning (e.g. through a placental structure), and superfetation, the presence of multiple broods of different developmental stages, reduce the locomotor performance decline during pregnancy in the Poeciliidae, live-bearing fishes. In Chapter 2, we review the literature on the effects of pregnancy on morphology, performance and fitness. The biomechanics of each mode of locomotion (walking, swimming or flying) are distinct, and are affected differently by the added mass and volume of pregnancy. Furthermore, we list the possible adaptations that have evolved to reduce the locomotor costs of pregnancy, and divide them into three different categories: adaptations that reduce the locomotor costs of live-bearing, adaptations with which the locomotor costs of live-bearing are avoided, and adaptations to the life history of the animal. Lastly, we discuss hiatuses in the literature and experimental procedures to quantify the hypothesised benefit of adaptations. In Chapter 3, we compare the morphological changes during pregnancy in two closely-related species of live-bearing fish: Poeciliopsis turneri and Poeciliopsis gracilis. These species mainly differ in their mode of nutrient provisioning: P. gracilis is lecithotrophic and P. turneri is an extensive matrotroph. We tracked the morphological changes in 3D using a non-invasive method that creates three-dimensional body models. We find that P. turneri is more slender during the early stages of pregnancy, but increase in size more rapidly. This is in line with the locomotor costs hypothesis, which predicts that matrotrophic fish are more slender during the early stages of pregnancy, but that the difference between the body shapes of lecithotrophic and matrotrophic fish diminishes as pregnancy progresses. Our results indicate that matrotrophy could indeed provide a morphological advantage during pregnancy. Fast-start performance, a manoeuvre fish deploy to escape predatory strikes, is important for individual survival. In Chapter 4, we use state-of-the-art biomechanical methods to, for the first time, quantify this manoeuvre in three-dimensional space in adult fish (Heterandria formosa). We show that fish can orient their escapes in up- and downwards direction, and that this is correlated with a change in pitch angle of the body. Changes in roll angle of the body were not correlated with orientation of the fish. We furthermore demonstrate that stage 1 of the fast start, often described as a preparatory stage, can already contribute to propulsion. The results from Chapter 4 indicate that three-dimensional measurements of fast-start manoeuvres provide novel insights that were often overlooked. Measuring fast starts in three-dimensional space is relevant in determining the adverse effects of pregnancy on locomotor performance. We did this by comparing three species of live-bearing fish: P. turneri, H. formosa and Phalloptychus januarius. In Chapter 5, we show that pregnancy-induced changes in abdominal width are correlated with a reduction in performance in the horizontal plane (maximal horizontal speed, change in yaw angle), but less so in the vertical plane (maximal vertical speed, change in pitch angle). Furthermore, we demonstrate that an increase in abdominal width is correlated with a decrease in abdominal curvature and, for some species, in a decrease in maximal curvature rate in the abdomen. Lastly, we show that the pregnancy-induced morphological changes depend on the level of superfetation: species with a high level of superfetation experience higher frequency, but smaller amplitude changes in the shape of the abdomen. Whether superfetation actually results in a more slender body shape, as predicted by the locomotor costs hypothesis, depends on the level of reproductive investment. In this thesis, I show that pregnancy induces changes in morphology which comes with a cost in fast-start performance. Both matrotrophy and superfetation affect how body shape changes due to pregnancy, but whether the latter provides beneficial changes depends on the level of reproductive investment. Furthermore, I reveal that fast starts can have a substantial three-dimensional component which is relevant both to biomechanicists that aim to understand the physical and physiological mechanisms underlying this manoeuvre and to evolutionary biologists that strive to answer performance-related questions.</p

Lateral line ablation by ototoxic compounds results in distinct rheotaxis profiles in larval zebrafish

The zebrafish lateral line is an established model for hair cell organ damage, yet few studies link mechanistic disruptions to changes in biologically relevant behavior. We used larval zebrafish to determine how damage via ototoxic compounds impact rheotaxis. Larvae were treated with CuS

A Study of the Hydrostatic and Hydrodynamic Properties of Aeoliscus Straigatus

Aeoliscus strigatus is a highly maneuverable fish found in the Indo-Pacific region. It boasts a unique head down posture and employs median paired fin propulsion to perform precise movements. The need for highly maneuverable underwater AUVs for exploration and testing drove the examination of the hydrostatics and hydrodynamics influencing Aeoliscus. To determine the stability of Aeoliscus the center of gravity and buoyancy were found. Center of gravity was experimentally located using the three plumb line method while center of buoyancy was located using two separate methods. The first method utilized the measured buoyant force, a rigidly mounted fish and a tank of water raised to displace ½ of the buoyant force. Method two utilized a microcomputed tomography (micro-CT) system to create a 3D model of the fish and allowed for computational location of the center of buoyancy. The average normalized approximation of the center of gravity was found to be 0.46 posterior to the mouth and 0.34 ventral to the leading dorsal edge of the fish. The average normalized approximation of the center of buoyancy was found to be 0.46 and 0.45 posterior to the mouth and 0.35 and 0.43 ventral to the leading dorsal edge of the fish by the micro-CT system and the experimental method respectively. Velocity, Reynold’s number and coefficient of drag were found to as a first step to understanding the hydrodynamics of Aeoliscus. The maximum observed velocity was 300 mm/s or about 22 body lengths per second, a Reynolds number of 4222, indicating laminar flow and a coefficient of drag of 0.029, which is similar to that of other fish

Fish4Knowledge: Collecting and Analyzing Massive Coral Reef Fish Video Data

This book gives a start-to-finish overview of the whole Fish4Knowledge project, in 18 short chapters, each describing one aspect of the project. The Fish4Knowledge project explored the possibilities of big video data, in this case from undersea video. Recording and analyzing 90 thousand hours of video from ten camera locations, the project gives a 3 year view of fish abundance in several tropical coral reefs off the coast of Taiwan. The research system built a remote recording network, over 100 Tb of storage, supercomputer processing, video target detection and

Bio-Inspired Robotics

Modern robotic technologies have enabled robots to operate in a variety of unstructured and dynamically-changing environments, in addition to traditional structured environments. Robots have, thus, become an important element in our everyday lives. One key approach to develop such intelligent and autonomous robots is to draw inspiration from biological systems. Biological structure, mechanisms, and underlying principles have the potential to provide new ideas to support the improvement of conventional robotic designs and control. Such biological principles usually originate from animal or even plant models, for robots, which can sense, think, walk, swim, crawl, jump or even fly. Thus, it is believed that these bio-inspired methods are becoming increasingly important in the face of complex applications. Bio-inspired robotics is leading to the study of innovative structures and computing with sensory–motor coordination and learning to achieve intelligence, flexibility, stability, and adaptation for emergent robotic applications, such as manipulation, learning, and control. This Special Issue invites original papers of innovative ideas and concepts, new discoveries and improvements, and novel applications and business models relevant to the selected topics of ``Bio-Inspired Robotics''. Bio-Inspired Robotics is a broad topic and an ongoing expanding field. This Special Issue collates 30 papers that address some of the important challenges and opportunities in this broad and expanding field