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Keene, Canada

de Kerckhove D.T.,University of Toronto | Milne S.,Milne Technologies | Shuter B.J.,University of Toronto
Fisheries Research

The measurement of school swimming speeds across an acoustic beam from a fixed-platform split-beam transducer is difficult because it is impossible to accurately discern individual fish within a school, or track the displacement of the leading edge of the school over time. However, with two acoustic transducers the swimming speed of schools can be estimated as long as the school swims through both beams, and the detection angle when the school first interacts with the beam is known. Here we present a methodology for (1) measuring school swimming speeds with two 120. kHz elliptical (4°. ×. 10°) split-beam acoustic transducers, and (2) estimating the detection angle of the school using Angular Position data within the school region. We verify the use of Angular Position data by comparing our derived detection angle with Diner's Attack Angle algorithm for a set of mobile vertical surveys on the same lake. Our derived detection angle methodology may also provide a method for fisheries biologists to correct school dimensions under conditions for which Diner's Attack Angle is not appropriate (i.e. when schools are smaller than the beam width), which should be common in lake surveys or generally when using elliptical acoustic beams. © 2015 Elsevier B.V. Source

Petreman I.C.,Ontario Ministry of Natural Resources | Jones N.E.,Ontario Ministry of Natural Resources | Milne S.W.,Milne Technologies
Fisheries Research

Fixed-location, side-looking, multibeam, sonar techniques offer a practical approach to estimate the numbers of migrating fish in rivers that are too large or occluded for traditional sampling methods, such as weir trapping, visual observation techniques, and netting. While this technology has been used to enumerate salmonid escapement in coastal river systems of western North America, little use and evaluation has occurred in inland waters such as the Great Lakes, where rivers and runs of fish are considerably smaller than those along the Pacific coast. We use a "Dual-frequency IDentification SONar" ("DIDSON") imaging sonar system to investigate the error and variability among nine people performing fish counts. There was no significant difference found among observers' estimates of fish abundance per DIDSON file however, the total count of all fish differed from the benchmark value by as much as 26%. Post-processing simple fish counts from DIDSON raw data is labour-intensive and costly. Three subsampling methods of fish passage estimations were developed and evaluated for their accuracy and precision for daily and seasonal time frames. The random and systematic subsampling methods had similar seasonal and daily accuracy and precision with few exceptions. Automation-assisted counting was much more accurate and efficient for seasonal estimates. A ratio of approximately 2:1 was found for the automated to manual fish counts and this varied little among years. The DIDSON multibeam sonar unit is useful in estimating potamodromous fish migrations for large tributaries of the Great Lakes. DIDSON image processing costs can be minimized through suitable subsampling approaches. The automation-assisted method is the most cost-effective means of estimating moderate levels of fish passage over longer study periods. Multiple individuals can be used interchangeably for the manual post-processing of DIDSON data. © 2014. Source

De Kerckhove D.T.,University of Toronto | Milne S.,Milne Technologies | Shuter B.J.,University of Toronto | Abrams P.A.,University of Toronto
Behavioral Ecology

Movement is a fundamental aspect of the population and community ecology of many organisms, yet, until recently, it has been difficult to measure in the wild. Consequently, simple assumptions are often used to represent movement; a key assumption found in many classic theoretical ecological models (e.g., predator-prey interactions) is that organisms move like ideal gas particles. Here, we test whether this assumption adequately describes the movement of the Cisco (Coregonus artedi) and its schools using fisheries acoustic surveys and mathematical models. We find that several of the individual components of an ideal gas model (IGM) have some inconsistencies with Cisco behavior, yet overall patterns of school formation are close to IGM expectations. For both individual fish and schools: 1) the spatial distributions were random or slightly clumped; 2) the swimming speed distributions were unimodal but significantly different from normal; 3) horizontal movement was more frequent than depth changes; and 4) movement trajectories across the acoustic beam sometimes deviated from straight lines. However, including the average individual and school swimming speeds and known nighttime densities in an IGM generated values that were similar to the observed values for: 1) the time required for schools to form in the morning and 2) school encounter rates. © The Author 2015. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved. Source

Patrick P.H.,Arcadis | Mason E.,Arcadis | Powell J.,Arcadis | Milne S.,Milne Technologies | Poulton J.S.,Ontario Power Generation
North American Journal of Fisheries Management

Barrier nets can be an effective alternative for reducing impingement mortality of fish at power plant intakes. In 2010, a paired, split-beam hydroacoustic method was used as the primary assessment tool for comparing relative fish density between the lake ("outside") and station ("inside") side of the Pickering Nuclear Generating Station fish diversion system (FDS) barrier net while it was in place. Behavioral information was also collected using a DIDSON acoustic camera and underwater video camera to determine fish responses to the FDS. Verification monitoring was completed using conventional gill netting. The DIDSON provided useful and valuable information on relative fish densities, relative school sizes, and behavior of fish as individuals, small groups, or schools on both the outside and inside of the FDS, as well as general behavior of fish approaching the FDS. There was no evidence of passage through the net based on DIDSON evaluation; however, fish passage occurred when the FDS net was considered to be in a degraded condition (from biofouling or storm events, or both) and passage occurred over the net, not through it. Analysis of the hydroacoustic data based on the weighted average biomass indicated that FDS effectiveness was 75, 98, and 100% for the spring, summer, and fall periods, respectively, and 98% for the three seasons combined. The summer and fall estimates were based on net performance under optimal net-deployment conditions and if the net degrades, effectiveness is reduced significantly as observed in the spring data. Our study results were supported by impingement monitoring at the station whereby impingement biomass was reduced by greater than 80% for each of the first 3 years after installation compared with before installation of the barrier net. Overall, the FDS was demonstrated to offer significant fish protection from potential impingement at the Pickering Nuclear Generating Station.Received July 21, 2013; accepted December 6, 2013. © 2014 Copyright © Taylor & Francis Group, LLC. Source

Cott P.A.,Natural Resources Canada | Guzzo M.M.,University of Manitoba | Chapelsky A.J.,University of Manitoba | Milne S.W.,Milne Technologies | And 2 more authors.

Determining the habitat use and movements by fish is critical to our understanding of aquatic ecosystem function. The objective of this study was to assess the diel movements of Burbot (Lota lota) over the open water season. We employed a high-resolution acoustic telemetry positioning system to track the movements and activity of four Burbot during the ice-free season (between June and September) in a sub-Arctic lake. Burbot underwent diel bank migration (DBM), a benthic form of diel vertical migration, where depths are transitioned in close association with the bottom rather than through the water column. During daytime, Burbot occupied deeper water, at the transition of soft, low complexity substrates and ascended along the rocky bottom lake banks to shallower water habitats at night. Increased activity rates during shallow water forays suggest active feeding events. DBM was low at the start of summer with nearly 24 h of daylight, but increased towards the mid-summer with a more pronounced night cycle, coalescing towards the fall. The DBM of Burbot is dynamic, with proximate triggers of light and temperature, and ultimate causes likely being foraging opportunities, bioenergetics gain and predator avoidance. © 2015 Springer International Publishing Switzerland Source

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