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Bibliography of the Maurice Lamontagne Institute


Roy, N., Y. SIMARD, C. GERVAISE, 2010. 3D tracking of foraging belugas from their clicks : experiment from a coastal hydrophone array. Applied acoustics, 71: 1050-1056 .

A simple passive acoustic monitoring (PAM) setup was used to localize and track beluga whales underwater in three dimensions (3D) in a fjord. In June 2009, beluga clicks were recorded from a cabled hydrophone array in a regularly frequented habitat in Eastern Canada. Beluga click energy was concentrated in the 30–50 kHz frequency band. The click trains detected on several hydrophones were localized from their time difference of arrivals. Cluster analysis linked localizations into tracks based on criteria of spatial and temporal proximity. At close ranges from the array, the localized click-train series allowed three-dimensional tracking of a beluga during its dive. Clicks within a train spanned a large range of durations, inter-click intervals, source levels and bandwidths. Buzzes sometimes terminated the trains. Repeated click packets were frequent. All click characteristics are consistent with oblique observations from the beam axis, and ordered variation of the source pattern during a train, likely resulting from a scan of angles from the beam axis, was observed before click trains indicated focusing of the echolocation clicks in one direction. The click-train series is interpreted as echolocation chasing for preys during a foraging dive. Results show that a simple PAM system can be configured to passively and effectively 3D track wild belugas and small odontocetes in their regularly frequented habitat.©2010 Elsevier Ltd.

SIMARD, Y., R. LEPAGE, C. GERVAISE, 2010. Anthropogenic sound exposure of marine mammals from seaways : estimates for Lower St. Lawrence Seaway, eastern Canada. Applied acoustics, 71: 1093-1098 .

The impact of shipping noise on marine life and quality of marine mammal habitats in oceans and coastal environments has become a major concern worldwide. Background noise can also limits detection of marine mammal sounds in passive acoustic monitoring (PAM) systems. Characterisation of this noise over long time periods and estimates of the exposure of the different marine mammal groups are still very fragmentary and limited to only a few locations. This paper presents such observations for a part of a busy seaway of North America, the St. Lawrence Seaway, which cuts through the Gulf of St. Lawrence and crosses several cetaceans and pinnipeds feeding areas. Noise was continuously recorded for a 5-month period in summer 2005 by an AURAL autonomous hydrophone deployed close to the bottom in the 300-m deep seaway. The maximum received noise level in the 20 Hz–0.9 kHz band reached 136 dB re 1 μParms. The median level of 112 dB re 1 μParms was exceeded 50 % of the time due to transiting merchant ships. Median spectral level tracks the reference curve for heavy traffic in oceans and 50 % of the noise is within a ±6 dB envelope around it. Strong spectral lines were common at low frequencies and in the 400–800 Hz band. M-weighting functions applied for the three groups of cetaceans and pinnipeds indicate wideband median levels varying from 106 to 112 dB-M re 1 μParms surrounded by a ±5 dB two-quartile interval. Higher values are expected for animals frequenting the sound channel at intermediate depths. As expected, the highest M-weighting levels correspond to low-frequency specialists and pinnipeds. Criteria for assessing the behavioural and physiological impacts of long term exposure of marine mammals to such shipping noise levels need to be worked out. Crown copyright ©2010 Elsevier Ltd.

SIMARD, Y., N. ROY, S. GIARD, C. GERVAISE, M. CONVERSANO, N. MÉNARD, 2010. Estimating whale density from their whistling activity : example with St. Lawrence beluga. Applied acoustics, 71: 1081-1086 .

A passive acoustic method is developed to estimate whale density from their calling activity in a monitored area. The algorithm is applied to a loquacious species, the white whale (Delphinapterus leucas), in Saguenay fjord mouth near Tadoussac, Canada, which is severely affected by shipping noise. Beluga calls were recorded from cabled coastal hydrophones deployed in the basin while the animal density was estimated visually from systematic observations from a fixed-point on the shore. Beluga calling activity was estimated from an algorithm extracting the call events in time–frequency space, while simultaneously tracking the masking intensity resulting from local shipping noise. The activity index was summarized in 15- and 30-min bins using four different metrics. For bins containing more than 40 % of valid data, the metrics were compared to the corresponding visual observations. The estimated mean acoustic detection range generally exceeded the fjord width, and extended to the whole 3-km long monitored area under low-noise conditions. The significant linear relations of the visual estimates with the calling activity metrics allowed assessing expected number of visually detected belugas in the basin from a weighted regression model, with a mean standard error of 7.1. %. Crown copyright ©2010 Elsevier Ltd.

BENOIT, D., Y. SIMARD, J. GAGNÉ, M. GEOFFROY, L. FORTIER, 2010. From polar night to midnight sun : photoperiod, seal predation, and the diel vertical migrations of Polar Cod (Boreogadus saida) under landfast ice in the Arctic Ocean. Polar Biol., 33(11): 1505-1520 .

The winter/spring vertical distributions of polar cod, copepods, and ringed seal were monitored at a 230-m station in ice-covered Franklin Bay. In daytime, polar cod of all sizes (7–95 g) formed a dense aggregation in the deep inverse thermocline (160–230 m, –1.0 to 0 °C). From December (polar night) to April (18-h daylight), small polar cod <25 g migrated into the isothermal cold intermediate layer (90–150 m, –1.4 °C) at night to avoid visual predation by shallow-diving immature seals. By contrast, large polar cod (25–95 g), with large livers, remained below 180 m at all times, presumably to minimize predation by deep-diving mature seals. The diel vertical migration (DVM) of small polar cod was precisely synchronized with the light/dark cycle and its duration tracked the seasonal lengthening of the photoperiod. The DVM stopped in May coincident with the midnight sun and increased schooling and feeding. We propose that foraging interference and a limited prey supply in the deep aggregation drove the upward re-distribution of small polar cod at night. The bioluminescent copepod Metridia longa could have provided the light needed by polar cod to feed on copepods in the deep aphotic layers.©2010 Springer

GERVAISE, C., A. BARAZZUTTI, S. BUSSON, Y. SIMARD, N. ROY, 2010. Automatic detection of bioacoustics impulses based on kurtosis under weak signal to noise ratio. Applied acoustics, 71(11): 1020-1026 .

Passive acoustic monitoring (PAM) of marine mammal vocalizations has been efficiently used in a wide set of applications ranging from marine wildlife surveys to risk mitigation of military sonar emissions. The primary use of PAM is for detecting bioemissions, a good proportion of which are impulse sounds or clicks. A click detection algorithm based on kurtosis estimation is proposed as a general automatic click detector. The detector works under the assumption that click trains are embedded in stochastic but Gaussian noise. Under this assumption, kurtosis is used as a statistical test for detection. The algorithm explores acoustic sequences with the optimal frequency bandwidth for focusing on impulse sounds. The detector is successfully applied to field observations, and operates under weak signal to noise ratios and in presence of stochastic background noise. The algorithm adapts to varying click center frequency. Kurtosis appears as a promising approach to detect click trains, alone or in combination with other clicks detector, and to isolate individual clicks.©2010 Elsevier Ltd

SIMARD, Y., M. HARVEY, 2010. Predation on Northern Krill (Meganyctiphanes norvegica Sars). Adv. Mar. Biol., 57: 277-306 .

We consider predation as a function of prey concentration with a focus on how this interaction is influenced by biological–physical interactions, and wider oceanographic processes. In particular, we examine how the anti-predation behaviour of Northern krill interacts with ocean-circulation process to influence its vulnerability to predation. We describe how three-dimensional (3D) circulation interacts with in situ light levels to modulate predator–prey interactions from small to large scales, and illustrate how the stability of the predator–prey system is sometimes perturbed as a consequence. Northern krill predators include a wide range of species from the pelagic and benthic strata, as well as birds. Many exhibit adaptations in their feeding strategy to take advantage of the dynamic physical–biological processes that determine the distribution, concentration and vulnerability of Northern krill. Among them, baleen whales appear to have developed particularly efficient predation strategies. A literature search indicates that Northern krill are a major contributor to ecosystem function throughout its distributional range, and a key species with respect to the flow of energy to upper trophic levels. A list of future research needed to fill gaps in our understanding of Northern krill predator–prey interaction is provided.©2010 Elsevier Ltd.

SIMARD, Y., 2009. Passive acoustic monitoring during seismic surveys ; Le monitorage par acoustique passive pendant les relevés sismiques. DFO, Canadian Science Advisory Secretariat, Research Document ; MPO, Secrétariat canadien de consultation scientifique, Document de recherche, 2009/068, 26 p .

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The possibility of using passive acoustic monitoring (PAM) to detect marine mammals in the exclusion zone around the airgun array during seismic surveys is explored for the range of sounds produced by marine mammals and the ambient noise conditions during the survey. The probability of detection with a towed hydrophone array is estimated for representative mysticete and odontocete sounds, using published source levels, propagation losses, shipping noise and seismic pulse levels in the corresponding frequency band. This investigation shows that the efficiency of such PAM approach during seismic survey is severely constrained by the high noise levels at the hydrophones. As expected, this is mostly affecting the low-frequency sounds and infrasounds. However, when the airguns are not active, the detection ranges of the tested sounds always exceeded a safety radius of 500 m, assuming ideal conditions, which may not always materialise. During the firing of the airguns, this was not the case.

SIMARD, Y, M. SOURISSEAU, 2009. Diel changes in acoustic and catch estimates of krill biomass. ICES J. Mar. Sci., 66: 1318-1325 .

Krill-biomass estimates can be compromised by diel variabilities in acoustic backscatter and the catch efficiencies of various nets. This paper describes an effort to quantify these variabilities at fine temporal and spatial scales during a three-day experiment at a fixed location, using high-resolution, stratified Bioness samples and echo-integration, and assuming a fixed distribution of krill orientations. Night-time catches in the krill scattering layer (SL) were 15 times the acoustic estimates. The situation was reversed during daytime, when the acoustic estimates in the SL were 5 times larger than the catches. This collectively resulted in a ± 10–dB gradual diel cycle in the difference of vertically integrated biomass from both sampling methods. Use of a strobe light on the Bioness reduced avoidance of the net by krill and significantly increased (×10) daytime catches in the SL, but had no significant effect on night-time catches. The difference in volume-backscattering strength at 120 and 38 kHz (?Sv120 - 38) in the densest parts of the SL agreed with predictions using a target-strength (TS) model and an assumed normal distribution of tilt (mean ø = 11°; s.d. = 4°). The ?Sv120 - 38 was smaller for lower densities and during night-time. It appears that the ø and, therefore, TS distributions of krill significantly change during their diel vertical migrations. At twilight and at night, when they are feeding and swimming vertically, they exhibit lower mean TS and ?Sv120 - 38 and react less to strong strobe-light pulses, in contrast to daytime. Diel patterns in TS and net avoidance should be taken into account in krill-biomass assessments that use round the clock acoustic-survey data and multi-frequency TS models for target classification. ©2009 ICES Journal of Marine Science.

SIMARD, Y., 2009. Le parc marin du Saguenay-Saint-Laurent : un habitat exceptionnel pour les baleines. Naturaliste can., 133(3): 57-61 .

BAHOURA, M., Y. SIMARD, 2009. Blue Whale calls classification using short-time Fourier and wavelet packet transforms and artificial neural network. Digit. Signal Process., 20(4): 1256-1263 .

Two new characterization methods based on the short-time Fourier and the wavelet packet transforms are proposed to classify blue whale calls. The vocalizations are divided into short-time overlapping segments before applying these transforms to each segment. Then, the feature vectors are constructed by computing the coefficient energies within two subbands in order to capture the AB phrase and D vocalization characteristics, respectively. Finally, a multilayer perceptron (MLP) is used to classify the vocalization into A, B and D classes. The proposed methods present high classification performance (86.25 %) on the tested database.©2009 Elsevier Inc.

SIMARD, Y., 2009. Le Parc marin Saguenay-Saint-Laurent : processus océanographiques à la base de ce site unique d'alimentation des baleines du nord-ouest Atlantique;The Saguenay-St. Lawrence Marine Park : oceanographic processes at the basis of this unique forage site of northwest Atlantic Whales. Rev. Sci. Eau;J. Water Sci., 22(2): 177-197 .

The results from an ecosystem research pro gram are summarized. It was conducted in the Saguenay-St. Lawrence Marine Park to understand the basic processes responsible for the existence of this traditional whale feeding ground, discovered by the Basques whalers 450 years ago. Persistent processes maintain aggregated whale preys at the head of the main deep-water channel of eastern Canada continental shelf. What are they? This site is the richest krill aggregation yet documented in the northwest Atlantic. The mechanisms responsible are the pumping, retention and concentration of adult krill from the Gulf of St. Lawrence, by the strong estuarine circulation of the St. Lawrence. Tidal currents upwelling along channels and bank slopes combine with adult krill vertical behavior and concentrate it. This process is more intense at the head of the channels where tidal upwelling is amplified. It is locally enhanced by wind-driven coastal upwelling. The mean circulation transports the rich krill patches along the slopes of the basins. At the mouth of the estuary, the concentrated krill at the margin of the large cyclonic Anticosti gyre (counterclockwise) is injected into the lower estuary on the northern side, under favorable circulation conditions. The narrow slope current Rowing upstream along the estuary then imports it towards the Marine Park krill aggregation zone. Pelagic forage fish such as capelin also aggregate at the channel head and entrance of the fjord under the action of the tidal upwelling currents and fronts, whieh also concentrate and enhance the availability of their preys. They contribute to the feeding of whales and sea birds. Special oceanographie features, sel dom found elsewhere, combine in the Marine Park to generate this whale feeding ground. Anthropogenic pressures and climate change are the main threats to its preservation for the next centuries.©2009 RSE inc.

HANDEGARD, N.O., D.A. DEMER, R. KLOSER, R., P. LEHODEY, O. MAURY, Y. SIMARD, 2009. Toward a global ocean ecosystem Mid-trophic Automatic Acoustic Sampler (MAAS). 8 p in J. Hall, D.E. Harrison & D. Stammer (eds.). Proceedings of OceanObs’09 : Ocean Information for Society (V.1), Venice, Italy, 21-25 September 2009 .

Despite their huge biomass and pivotal role, the mid-trophic levels of marine ecosystems are not generally subject to systematic monitoring. Data from such monitoring is crucial for parameterizing, validating, and constraining numerical models of mid-trophic communities. In recent years, acoustic sampling technology has matured, and we argue that acoustic sampling technology, due to long-range propagation in water, is the only means to efficiently observe the large biomass of the mid-trophic levels at ecologically important temporal and spatial scales. We argue that it is timely to propose a collaborative effort to utilize these new techniques, and we propose to widely deploy automated acoustic recorders, using a variety of platforms, to achieve this goal. Without such large-scale coordinated monitoring, we will continue to lack an understanding of how the effects of climate variability are mediated from primary production up to the higher trophic levels and, conversely, how changes in higher trophic levels may affect the lower trophic levels. The objective of the MAAS project is, therefore, to provide near-real-time global-scale monitoring of mid-trophic-level organisms.

MOUY, X., M. BAHOURA, Y. SIMARD, 2009. Automatic recognition of Fin and Blue Whale calls for real-time monitoring in the St. Lawrence. J. Acoust. Soc. Am., 126(6): 2918-2928 .

Monitoring blue and fin whales summering in the St. Lawrence Estuary with passive acoustics requires call recognition algorithms that can cope with the heavy shipping noise of the St Lawrence Seaway and with multipath propagation characteristics that generate overlapping copies of the calls. In this paper, the performance of three time-frequency methods aiming at such automatic detection and classification is tested on more than 2000 calls and compared at several levels of signal-to-noise ratio using typical recordings collected in this area. For all methods, image processing techniques are used to reduce the noise in the spectrogram. The first approach consists in matching the spectrogram with binary time-frequency templates of the calls (coincidence of spectrograms). The second approach is based on the extraction of the frequency contours of the calls and their classification using dynamic time warping (DTW) and the vector quantization (VQ) algorithms. The coincidence of spectrograms was the fastest method and performed better for blue whale A and B calls. VQ detected more 20 Hz fin whale calls but with a higher false alarm rate. DTW and VQ outperformed for the more variable blue whale D calls.©2009 Acoustical Society of America

SOURISSEAU, M., Y. SIMARD, F.J. SAUCIER, 2009. Corrigendum : krill diel vertical migration fine dynamics, nocturnal overturns, and their roles for aggregation in stratified flows. Can. J. Fish. Aquat. Sci., 66: 509 .

ROY, N., Y. SIMARD, J. ROUAT, 2008. Performance of three acoustical methods for localizing whales in the Saguenay - St. Lawrence Marine Park. Can. Acoust., 36(1): 160-164 .

Three algorithms are explored to localize fin whale calls recorded from a large-aperture hydrophone array deployed in the Saguenay - St. Lawrence Marine Park. The methods have to cope with varying sound speed in space and time, errors in time differences of arrival (TDoA) measurements in a noisy environment, and often a limited number of hydrophones having recorded a particular event. The array was composed of 5 AURAL autonomous hydrophones with a total aperture of about 40 km, coupled with 2 hydrophones from a small-aperture cabled coastal array. The autonomous hydrophones clock drifts were estimated with a level of uncertainty from timed sources and the coastal array time reference. The calls were then localized by constant-speed hyperbolic fixing, variable-speed isodiachron Monte-Carlo simulations, and a ray-tracing propagation model. The Monte-Carlo simulations generate clouds of possible localizations from the uncertainty in hydrophone positions, TDoAs and the effective horizontal sound speeds along the different source-hydrophone paths. The ray-tracing model produces a fixed grid of TDoAs which can then be consulted to find the likeliest positions of the whales. Results from the different methods are compared and their relative advantages or limitations are discussed.©2008 Canadian Acoustical Association

SIMARD Y., N. ROY, 2008. Detection and localization of blue and fin whales from large-aperture autonomous hydrophone arrays: a case study from the St.Lawrence estuary. Can. Acoust., 36(1): 104-110 .

The feasibility of using passive acoustic methods (PAM) to monitor time-space distribution of fin and blue whales in the Saguenay-St. Lawrence Marine Park was explored using large-aperture sparse hydrophone arrays. The arrays were deployed during summers 2003 to 2005 at the head of the 300-m deep Laurentian Channel. They were composed of 5 AURAL autonomous hydrophones moored at mid-water depths, near the summer sound channel. A small coastal array complemented the deployment in 2003. The apertures were from 20 to 40 km and the configurations were changed from year to year. The most frequent calls recorded were blue and fin whale signature infrasounds. Noise from transiting ships on the busy St. Lawrence Seaway often masked the calls on the nearest hydrophones. Sometimes this resulted in an insufficient number of receivers for localizing the whales using time difference of arrival (TDoA) methods. The technical characteristics of the arrays and data processing are presented, with an example of call detection and localization. Despite the difficulties inherent to this environment, PAM can be effectively implemented there, eventually for real-time operations.©2008 Canadian Acoustical Association

GERVAISE, C., S. VALLEZ, Y. STEPHAN, Y. SIMARD, 2008. Robust 2D localization of low-frequency calls in shallow waters using modal propagation modelling. Can. Acoust., 36(1): 153-159 .

We propose a new method to localize low-frequency calls in 2D in shallow waters from a sparse array of hydrophones using modal propagation modelling. An analysis of modal propagation modelling of transients signals in shallow water environment shows that the dispersive behaviour of the waveguide can be exploited to design a robust localization scheme without requiring any knowledge of the acoustics properties of the environment (bottom and water column) nor any simulation of propagation, The localization scheme also does not require synchronization of the array and is therefore independent of any clock drift. Promising results are obtained for Northern right whale gunshot calls from 'Bay of Fundy data set of the 2003 Workshop on Detection and Localization of Marine Mammals Using Passive Acoustics.©2008 Canadian Acoustical Association

BENOIT, D., Y. SIMARD, L. FORTIER, 2008. Hydroacoustic detection of large winter aggregations of Arctic cod (Boreogadus saida) at depth in ice-covered Franklin Bay (Beaufort Sea). J. Geophys. Res. (C Oceans), 113(6), art. no C06S90, 9 p .

In the Canadian Arctic, the large biomass of Arctic cod that must exist to explain consumption by predators has eluded detection. From December 2003 to May 2004, acoustic estimates of Arctic cod biomass at a 225-m-deep station in central Franklin Bay (southeastern Beaufort Sea) increased progressively by 2 orders of magnitude, reaching maximum values of 2.7 and 55 kg m-2 in April. During accumulation in Franklin Bay, the fish occupied the lower part of the Pacific halocline (140 m to bottom), where the temperature-salinity signature (-1.4 to 0.3 °C; 33 to 34.8 practical salinity units) corresponded to slope waters. Currents at 200 m along the western slope of Amundsen Gulf headed SSE in early winter, suggesting the passive advection of Arctic cod from Amundsen Gulf into Franklin Bay. Retention in Franklin Bay against the general circulation resulted from the fish keeping at depth to reduce predation by diving seals and/or to benefit from relatively warm temperatures in the lower halocline. Extrapolating a standing biomass of 11.23 kg m-2 at the station in April to the whole of Franklin Bay, the availability of polar cod would amply satisfy the requirements of predators. Dense accumulations of Arctic cod in embayments in winter likely play an important role in structuring the ecosystem of the Beaufort Sea. Understanding how climate change and the reduction of the sea ice cover will affect the stability of the oceanographic/behavioral accumulation process requires further research and modeling.© 2008 American Geophysical Union.

SIMARD, Y., N. ROY, C. GERVAISE, 2008. Passive acoustic detection and localization of whales: Effects of shipping noise in Saguenay-St. Lawrence Marine Park. J. Acoust. Soc. Am., 123(6): 4109-4117 .

The performance of large-aperture hydrophone arrays to detect and localize blue and fin whales' 15-85 Hz signature vocalizations under ocean noise conditions was assessed through simulations from a normal mode propagation model combined to noise statistics from 15960 h of recordings in Saguenay-St. Lawrence Marine Park. The probability density functions of 2482 summer noise level estimates in the call bands were used to attach a probability of detection/masking to the simulated call levels as a function of whale depth and range for typical environmental conditions. Results indicate that call detection was modulated by the calling depth relative to the sound channel axis and by modal constructive and destructive interferences with range. Masking of loud infrasounds could reach 40 % at 30 km for a receiver at the optimal depth. The 30 dB weaker blue whale D-call were subject to severe masking. Mapping the percentages of detection and localization allowed assessing the performance of a six-hydrophone array under mean- and low-noise conditions. This approach is helpful for optimizing hydrophone configuration in implementing passive acoustic monitoring arrays and building their detection function for whale density assessment, as an alternative to or in combination with the traditional undersampling visual methods.©2008 Acoustical Society of America

ANDERSON, J.T., D. VAN HOLLIDAY, R. KLOSER, D.G. REID, Y. SIMARD, 2008. Acoustic seabed classification: current practice and future directions. ICES J. Mar. Sci., 65(6): 1004-1011 .

Acoustic remote sensing of the seabed using single-beam echosounders, multibeam echosounders, and sidescan sonars combined and individually are providing technological solutions to marine-habitat mapping initiatives. We believe the science of acoustic seabed classification (ASC) is at its nascence. A comprehensive review of ASC science was undertaken by an international group of scientists under the auspices of ICES. The review was prompted by the growing need to classify and map marine ecosystems across a range of spatial scales in support of ecosystem-based science for ocean management. A review of the theory of sound-scattering from seabeds emphasizes the variety of theoretical models currently in use and the ongoing evolution of our understanding. Acoustic-signal conditioning and data quality assurance before classification using objective, repeatable procedures are important technical considerations where standardization of methods is only just beginning. The issue of temporal and spatial scales is reviewed, with emphasis on matching observational scales to those of the natural world. It is emphasized throughout that the seabed is not static but changes over multiple time-scales as a consequence of natural physical and biological processes. A summary of existing commercial ASC systems provides an introduction to existing capabilities. Verification (ground-truthing) methods are reviewed, emphasizing the difficulties of matching observational scales with acoustic-backscatter data. Survey designs for ASC explore methods that extend beyond traditional oceanographic and fisheries survey techniques. Finally, future directions for acoustic seabed classification science were identified in the key areas requiring immediate attention by the international scientific community.©2008 The Authors

SOURISSEAU, M., Y. SIMARD, F. J. SAUCIER, 2008. Krill diel vertical migration fine dynamics, nocturnal overturns, and their roles for aggregation in stratified flows. Can. J. Fish. Aquat. Sci., 65: 574-587 .

A set of high-resolution observations on short-term dynamics of krill diel vertical migrations (DVM) in the St. Lawrence Estuary are presented here, including vertical mass transfer measurements from multifrequency echo-sounding coupled with stratified net sampling and tracers of individual vertical movements from stomach pigments over a 72 h period. The data set is supplemented by vertical migration speeds and biomass diel patterns from ADCP (acoustic Doppler current profiler) time series lasting up to 3 months. All krill always rapidly migrated to the surface in synchrony at sunset. Soon after the ascent, fed krill started to swim downward. A scattering layer was then formed at their daytime depth with sometimes a significant backscatter at intermediate depths, especially around midnight. A reorganisation in the upper water column then occurs, likely for a predawn feeding bout. At dawn, the krill mass still feeding in upper water column synchronously swam downward to their daytime depth. This nocturnal asynchronous vertical behaviour, conforming to the DVM hunger-satiation hypothesis, repeated between August and October in two different years, the DVM timing being determined by day length.©2008 NRC Canada

SIMARD, Y., J.T. ANDERSON, 2007. Terms and acronyms. Pages 147-151 in J.T. Anderson, D.V. Holliday, R. Kloser et als (eds). Acoustic seabed classification of marine physical and biological landscapes. International Council for the Exploration of the Sea (ICES Coop. Res. Rep., 286) .

ANDERSON, J.T., D.V. HOLLIDAY, R. KLOSER, D. REID, Y. SIMARD, 2007. Future directions for acoustic seabed classification science. Pages 139-146 in J.T. Anderson, D.V. Holliday, R. Kloser et als (eds). Acoustic seabed classification of marine physical and biological landscapes. International Council for the Exploration of the Sea (ICES Coop. Res. Rep., 286) .

Gervaise, C., S. VALLEZ, C. IOANA, Y. STEPHAN, Y. SIMARD, 2007. Passive acoustic tomography : new concepts and applications using marine mammals. J. Mar. Biol. Assoc. U.K., 87: 5-10 .

This paper presents the new concept of passive acoustic tomography which allows ocean data collection with a passive acoustic remote sensing process. The originality lies in using acoustic sources of opportunity such as surface noise, radiated ship noise and marine mammal calls. Such use of passive tomography is a promising way to reduce acoustic emissions in oceans. A review is first presented, including the description of new concepts of covert active, assisted passive and autonomous tomography, followed by applications on real world data. Under the assumptions of multipath propagation and measurements performed by a sparse network of hydrophones, a time–frequency processor is proposed to simultaneously estimate the source location and the impulse response of the propagation channel for marine mammal calls used as opportunistic sources (multipath structure, time delay and attenuation are estimated). Promising results are obtained on real data coming from the Laurentian channel where wideband beluga calls (1 to 3 kHz) are measured by a sparse network of 6 bottom hydrophones.©2007 Marine Biological Association of the United Kingdom

SIMARD, Y., A. STEPNOWSKI, 2007. Classification methods and criteria. Pages 61-72 in J.T. Anderson, D.V. Holliday, R. Kloser et als (eds). Acoustic seabed classification of marine physical and biological landscapes. International Council for the Exploration of the Sea (ICES Coop. Res. Rep., 286) .

ANDERSON, J.T., D.V. HOLLIDAY, R. KLOSER, D. REID, Y. SIMARD, C.J. BROWN, R. CHAPMAN, R. COGGAN, R. KIESER, W.L. MICHAELS, A. ORLOWSKI, J. PRESTON, J. SIMMONDS, A. STEPNOWSKI (eds), 2007. Acoustic seabed classification of marine physical and biological landscapes. International Council for the Exploration of the Sea (ICES Coop. Res. Rep., 286), 188 p .

SIMARD, Y., 2007. Impacts of constructing a methane port at Gros-Cacouna on marine mammals. Science response (Canadian Science Advisory Secretariat), 2007/010, 7 p .

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SIMARD, Y., 2007. Impacts de la construction d'un port méthanier à Gros-Cacouna sur les mammifères marins. Réponse des sciences (Secrétariat canadien de consultation scientifique), 2007/010, 7 p .

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SIMARD, Y., M. BAHOURA, C.W. PARK, J. ROUAT, M. SIROIS, X. MOUY, D. SEEBARUTH, N. ROY, R. LEPAGE, 2006. Development and experimentation of a satellite buoy network for real-time acoustic localization of whales in the St. Lawrence. 6 pages in Oceans 2006 MTS/IEEE, Boston revolutionizing marine science and technology, Boston, Massachusetts, September 18-21, 2006 .

An integrated system of intelligent acoustic buoys have been developed to detect, identify and localize whales in real-time in their environment and communicate this information to land-based stations or ships via satellite and Internet, and RF communications. The low-cost portable buoy network can be used as a marine mammal observatory to gather continuous space-time series of vocalizing animals over large basins, or as early warning systems for improving whale protection on navigation routes or around moving or fixed platforms during threatening high-level acoustic activity. The unit buoy is powered by two 12-V batteries connected to solar panels. The processor is an 800 MHz Pentium III PC equipped with 400-MB fast memory and a 100-GB hard disk. The clock is synchronized with the embarked GPS. Data from two georeferenced hydrophones equipped with depth and temperature sensors are flowing to a 16-bit 500-kHz A/D-DSP board. Two-way communication is through 900-MHz and an Iridium satellite modems. Specific whales target calls are detected in time-frequency domain after adaptive noise-filtration. The selected master buoy collects the precisely time-tagged detections from all units via RF communication, and locates the calling whales from hyperbolic and isodiachron-Monte Carlo fixing algorithms. A simple tracking algorithm then builds the individual tracks. All acoustic data or users' selected portions of them can be stored on the hard disk. The system is designed to accommodate future developments and be easily adapted to various tasks. It can be deployed as a drifting network or anchored to the bottom, as well as from the ice sheet. First sea trials will be in August 2006 in the St. Lawrence.©2006 IEEE

BÉDARD, C., Y. SIMARD, 2006. Automated detection of white whale (Delphinapterus leucas) vocalizations in St. Lawrence Estuary and occurrence pattern. Can. Acoust. Acoust. Can., 34(3): 84-85 .

SIMARD, Y., N. ROY, C. GERVAISE, 2006. Shipping noise and whales : world tallest ocean liner vs largest animal on earth. 6 pages in Oceans 2006 MTS/IEEE, Boston revolutionizing marine science and technology, Boston, Massachusetts, September 18-21, 2006 .

The noise spectra radiated by the world tallest ocean liner, the Queen Mary II (QM2), when she sailed over the blue whale feeding ground of the Saguenay—St. Lawrence Marine Park in Sept. And Oct. 2004 are presented. Recordings for her 4 transits were made from an array of AURAL autonomous hydrophones moored at mid water depth along the navigation corridor at the head of the Laurentian channel. Typical ship noise Lloyd's mirror patterns on spectrogram generally allowed identification of the closest points of approach (CPA) to the hydrophones. The analysis of the Doppler shift of stable QM2 spectral rays allowed estimating CPA ranges and sailing speed. QM2 noise signature is characterized by several strong rays between ˜100 to 500 Hz, likely from her propulsion pods. Her average noise spectra are however enclosed within the envelope of the merchant ship noise measured in the area, except for high peaks below 40 Hz and the above rays. Broadband (10-1000 Hz) rms levels varied from 121 to 136 dB re 1μPa. As for most other merchant ships, this radiated shipping noise makes a barrier masking the low-frequency vocalizations of calling blue and fin whales over a large part of the basin.©2006 IEEE

PARK, C.W., Y. SIMARD, M. BAHOURA, J. ROUAT, M. SIROIS, 2006. The remote monitoring system for the buoy to localize the whale by Labview. 6 pages in Oceans 2006 MTS/IEEE, Boston revolutionizing marine science and technology, Boston, Massachusetts, September 18-21, 2006 .

In this paper we propose internet based real time telemetry distribution system to broadcast the telemetry data from any control base station in the world through telemetry web site. Any related person can access the telemetry web site to verify their interesting telemetry data in real-time with permission. This kind of real time telemetry broadcasting system is cost-effective solution for small organization that has a limit to access the large private communication network infrastructure to send and receive the data in real time. This proposed internet based real-time telemetry system will be very useful to reduce the cost of operation owing to the current stable internet infrastructure in the world. This system consists of ground base station to receive the telemetry signal from satellite including antennas, receiver, transmitter, modulator, demodulator, and sub-system, with interface board to give all the telemetry information to the telemetry PC. The received telemetry data will be extracted, archived, displayed and published across web in real time. In this paper we will demonstrate the hardware structure of this system, related software requirement.©2006 IEEE

SOURISSEAU, M., Y. SIMARD, F.J. SAUCIER, 2006. Krill aggregation in the St. Lawrence system, and supply of krill to the whale feeding grounds in the Estuary from the Gulf. Mar. Ecol. Prog. Ser., 314: 257-270 .

Persistent high-density krill aggregations make the St. Lawrence Estuary and the Gulf of St. Lawrence important feeding-grounds for large marine mammals. To estimate the effects of the circulation on the seasonal krill distribution, a krill biomass-concentration equation with active vertical migration was coupled to a 3D regional sea ice–ocean circulation model. The results show recurrent spatial patterns of aggregation and advection controlled by the circulation and a high sensitivity to the parameters of the biological model. The time spent in the surface layer is crucial for the retention of organisms in the estuary. The simulated krill aggregation areas are associated with 3 processes (tidal interactions with bathymetry, wind-driven upwelling and mean circulation). Zooplankton generally aggregate near the edges of the Laurentian Channel and other secondary channels, at locations that are consistent with the sparse synoptic information on the distributions of large marine mammals in the gulf. The simulations also indicate that changes in the seasonal circulation significantly affect the krill distribution within the gulf through gyre intensities, the seasonal thermocline and the strength of the estuarine circulation. Finally, the variability of zooplankton transport to the estuary from the gulf appears to be controlled by processes acting on the circulation mode at the mouth of the estuary and estuarine pumping of the krill layer towards the head of the Laurentian Channel. The simulated krill biomass imported into the estuary changed by a factor of 2 over the 3 simulated years.©2006 Inter-Research

McQUINN, I.H., Y. SIMARD, T.W.F. STROUD, J.-L. BEAULIEU, S.J. WALSH, 2005. An adaptive, integrated "acoustic-trawl" survey design for Atlantic cod (Gadus morhua) with estimation of the acoustic and trawl dead zones. ICES J. Mar. Sci., 62(1): 93-106 .

The objectives of this study were to design an operationally efficient groundfish survey integrating both acoustic and trawl methodologies, to measure the changing vertical availability of cod to each method over 24 h and to compare cod-biomass estimates from the two methods within two experimental sub-regions. The two-phased sampling design involved (i) conducting an initial systematic acoustic survey to locate an area of high cod concentrations, (ii) using the acoustic-backscatter information to stratify the sub-regions into density strata for the allocation of trawl hauls, and (iii) conducting a second systematic acoustic survey at the same time as a random-stratified trawl survey. This protocol permitted the optimization of trawl sampling according to population density and the realization of simultaneous trawl and acoustic estimates for direct comparison. These cod showed extensive diel vertical migrations, which affected their availability to the trawl gear at night and the acoustic beam by day. An acoustic dead-zone correction was applied to the acoustic estimates, averaging 4-15 % of the biomass for the night-time transects and 11-36 % for the daytime transects. The detailed temporal acoustic monitoring of the vertical migrations permitted the quantification of the change in cod availability to the trawl gear. From 6 % to 47 % of cod were above the effective trawl height at night, while 0-10 % of cod were in the "trawl dead zone" by day. Estimated cod densities were very similar between the two methods on a haul-by-haul basis after correcting each method for their respective inherent sampling biases. The total biomass estimates were also comparable between the two methods for one sub-region, although significantly higher from the trawl data for the other. The discrepancies were most likely a result of differences in the sampling density of the two methods.©2004 Elsevier Ltd on behalf of International Council for the Exploration of the Sea

COTTÉ, C., Y. SIMARD, 2005. Formation of dense krill patches under tidal forcing at whale feeding hot spots in the St. Lawrence Estuary. Mar. Ecol. Prog. Ser., 288: 199-210 .

Hydroacoustics (38 and 120 kHz) was used to estimate the abundance and 3-dimensional distribution of krill and small pelagic fishes at the downstream end of Ile Rouge Bank (St. Lawrence Estuary) over the semidiurnal tidal cycle in July 2002. During the flood, upwelling and strong tidal currents (>1 m s-1) forced the krill to aggregate in a patch against the slope of the bank and the mouth of the South Channel. This rich krill patch was then advected in the Laurentian Channel during the ebb. The mean krill density changed from 4 g m-3 in the neighbouring scattering layer of the Laurentian Channel to 500 g m-3 in the shoaling zone where the patch formed. This aggregation is ascribed to the interaction between the semidiurnal tidal currents, the local topography, and the negative phototactism of krill. The krill scattering layer was composed of Thysanoessa raschi and Meganyctiphanes norvegica. Its upper limit was at a depth corresponding to a light level of 3.1 x 10-1 to 1.2 x 10-3 μW cm-2 mm-1 which varied with the turbidity gradient and chlorophyll a concentration. The upper krill scattering layer at this light level was observed to swim down with a mean speed of 5 cm s-1 (maximum 13 cm s-1). The recurrent and tidally predictable availability of rich krill patches makes this part of Ile Rouge bank a highly attractive area for predators such as small pelagic fishes and whales, the latter of which forage on both types of prey during the flood tide©2005 Inter-Research

HUTIN, E., Y. SIMARD, P. ARCHAMBAULT, 2005. Acoustic detection of a scallop bed from a single-beam echosounder in the St. Lawrence. ICES J. Mar. Sci., 62(5): 966-983 .

Single-beam seabed echoes combined with epi-macrobenthos photographs were used to remotely detect a scallop bed and characterize the specific acoustic signal of Iceland scallop (Chlamys islandica). A dense scallop bed was surveyed in 2002, with a QTC VIEW Series IV acoustic ground-discrimination system (AGDS) connected to a 38 kHz, 7° split-beam SIMRAD EK60 scientific echosounder. In 2003, a 50 kHz, 42° single-beam SUZUKI ES-2025 echosounder was connected to a QTC VIEW Series V AGDS. The QTC VIEW data were analysed with QTC IMPACT following the standard procedures and classified into acoustic classes. Several approaches were tested: unsupervised and supervised survey strategies directed to specific benthic communities. The SIMRAD EK60 seabed volume-backscattering strength (Sv) was submitted to a principal component analysis (PCA), before and after removal of a depth trend, and the scores on the first 10 principal components were classed by a K-means cluster analysis. The same seabed Sv data were submitted to stepwise discriminant analysis whose training data sets were defined with the ground-truth photographs using different groupings: biotope types, community types, and finally scallop-density classes. All the QTC AGDS approaches failed to reveal the scallop bed, community structures, or biotopes. The QTC classifications mimicked the bathymetry with a strong correlation of the acoustic classes with depth. The seabed Sv PCA + K-means approach presented similar depth-dependence, but, the PCA + K-means on the Sv residuals revealed the scallop bed. The discriminant analysis was the best solution for the scallop density with a general classification success rate of 75 % and up to 91 % for the highest density class. The Sv signature of the scallop bed is presented, and the most discriminant part of the acoustic signal is identified.©2005 Elsevier Ltd on behalf of International Council for the Exploration of the Sea

SIMARD, Y., M. BAHOURA, N. ROY, 2004. Acoustic detection and localization of whales in Bay of Fundy and St. Lawrence estuary critical habitats. Can. Acoust., 32(2): 107-116 .

The detection and localization of marine mammals using passive acoustics is explored for two critical habitats in Eastern Canada. Two-dimensional hyperbolic localization is performed on time differences of arrivals of specific calls on grids of coarsely spaced autonomous recorders and on a shore-linked coastal array of closely spaced hydrophones. Delays are computed from cross-correlation and spectrogram cross-coincidence on signals enhanced with high-frequency emphasis and noise spectral suppression techniques. The outcomes and relative performance of the two delay estimation methods are compared. The difficulties encountered under the particular conditions of these two environments are discussed for the point of view of automated localisation for monitoring whales.©2004 Canadian Acoustical Association

SIMARD, Y., D. MARCOTTE, K. NARAGHI, 2003. Three-dimensional acoustic mapping and simulation of krill distribution in the Saguenay - St. Lawrence Marine Park whale feeding ground. Aquat. Living Resour., 16: 137-144 .

SIMARD, Y., D. LAVOIE, F.J. SAUCIER, 2002. Channel head dynamics : capelin (Mallotus villosus) aggregation in the tidally driven upwelling system of the Saguenay - St. Lawrence Marine Park's whale feeding ground. Can. J. Fish. Aquat. Sci., 59: 197-210 .

Capelin (Mallotus villosus) tridimensional distribution at the head of the Laurentian Channel in the St. Lawrence estuary was investigated using 38- and 120-kHz acoustic surveys in the summers of 1994, 1995, 1997, and 1998. The results are interpreted with the help of a high-resolution tridimensional tidal circulation model. Total biomasses were small (93-4583 t) and showed rapid fluctuations, whereas mesoscale distribution was more constant. Capelin tended to occupy the very end of the channel head, especially the slopes and shallows surrounding the basins. This pattern did not coincide with the krill distribution, but the two total biomass series were significantly correlated. Capelin tidal dynamics is characterized by herding of capelin against the channel head slopes by the starting flooding currents, followed by an upwelling over the sills and shallows during maximum flood currents, and a return to the channel by the surface outflow during ebb. Each side of the channel head has a distinct capelin retention tidal cycle involving passive advection, swimming, and the two-layer estuarine circulation. This capelin distribution and tidal dynamics closely match the local fin whale (Balaenoptera physalus) and minke whale (Balaenoptera acutorostrata) distributions observed from the whale-watching fleet and typical tidal feeding strategies at the channel head.

SIMARD, Y., I. McQUINN, M. MONTMINY, C. LANG, C. STEVENS, F. GOULET, J.-P. LAPIERRE, J.-L. BEAULIEU, J. LANDRY, Y. SAMSON, M. GAGNÉ, 2000. CH2 : Canadian Hydroacoustic data analysis tool 2 user's manual (version 2.0). Can. Tech. Rep. Fish. Aquat. Sci., 2332, 123 p .

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CH2 is the acronym for Canadian Hydroacoustic data analysis tool 2. It is a Windows 95 Multiple Document Interface (MDI) C++ application, developed by the Department of Fisheries and Oceans within the framework of the Data Analysis Tools (DAT) project of its National Hydroacoustic Program (NHP). It is dedicated to the display and processing of the standard HAC (Simard et al. 1997) multi-channel (multiple frequencies or beams) multi-echosounder acoustic data produced by the CH1 acquisition and real-time monitoring module (Simard et al. 1998). Data can originate from various analog or digital echosounders (e.g. Biosonics 102 type, Simrad EK500, or EY500). CH2 version 2.0 includes several editing TOOLS, to edit, eliminate, ignore, threshold, filter, or correct the raw HAC data, without erasing any original information. It also incorporates multi-channel classification tools, to partition the acoustic data into echo categories according to user decisions, and multi-channel echointegration capabilities for each echo category. The user can always track the various processing steps that have been applied to the original raw data. CH2 holds full undo and redo facilities for the various operations applied to the raw data. Edited files can be saved under the standard HAC format and contain the raw data plus the parameters of the editing/classification operations. The echointegration data are exported in ASCII text files that are directly usable by common data analysis or visualisation packages such as worksheets, statistical packages, and 2-D and 3-D mapping packages.

LAVOIE, D., Y. SIMARD, F.J. SAUCIER, 2000. Aggregation and dispersion of krill at channel heads and shelf edges : the dynamics in the Saguenay - St. Lawrence Marine Park. Can. J. Fish. Aquat. Sci., 57: 1853-1869 .

The spatial organization of the euphausiid (Thyanoessa raschi and Meganyctiphanes norvegica) aggregation at the head of the Laurentian Channel is examined using 120-kHz echointegration data from eight surveys in the summers of 1994 and 1995 and currents obtained from a high-resolution three-dimensional circulation model. Circulation is the main factor controlling the abundance and distribution of krill. The main aggregation pattern is U-shaped and includes an entrance corridor along the northern edge of the channel, a major accumulation zone off Les Escoumins, and an exit corridor along the southern edge. However, this mesoscale aggregation exhibits rapid fluctuations in spatial pattern and global abundance, due to the redistribution of krill within and out of the study area. The local accumulations are controlled by the interactions between the semidiurnal tidal currents, the topography, and the negative phototactism of krill. The strong vertical currents found along the channel slopes upstream of Les Escoumins and at the sills act to concentrate and pile up krill. The aggregation and dispersion mechanisms are strongly influenced by the deepwater blocking process taking place at the sills. The fortnightly tidal cycle and freshwater runoff modulate the blocking intensity. This krill aggregation dynamic is of primary importance for the trophic link with the baleen whales and fish in the Saguenay - St. Lawrence Marine Park.

SIMARD, Y., 2000. CoML, un nouveau sigle à connaître, un nouveau programme de recherche. Naturaliste can., 124(2): 66 .

SIMARD, Y., J.K. HORNE, D. LAVOIE, I. McQUINN, 2000. Capelin TS: Effect of individual fish variability. J. Acoust. Soc. Am., 108(5) pt. 2, p. 2458 .

McQUINN, I.H., Y. SIMARD, T.W.F. STROUD, J.-L. BEAULIEU, B. McCALLUM, S. WALSH, 1999. An adaptive integrated acoustic-trawl survey on Atlantic cod. ICES C.M., 1999/J:11, 22 p .

MARCHAND, C., Y. SIMARD, Y. GRATTON, 1999. Concentration of capelin (Mallotus villosus) in tidal upwelling fronts at the head of the Laurentian Channel in the St. Lawrence Estuary. Can. J. Fish. Aquat. Sci., 56 : 1832-1848 .

In 1994 and 1995, continuous monitoring of physical characteristics and echo integration were used to detect aggregations of capelin (Mallotus villosus) in the upper water column in relation to thermal fronts and to examine the tidal dynamics in an intense upwelling area at the head of the Laurentian Channel. During the four cruises, fish aggregations were recorded for 72 % of the fronts (n=61) resulting from the periodic upwelling of cold waters. Over the tidal cycle, only a low fish biomass was detected when the cold intermediate waters (< 2 °C) upwelled during high tide; 90 % of the 2-year-old capelin biomass was detected in water temperatures greater than 2 °C. Capelin zooplankton prey were concentrated primarily over the deep Laurentian Channel, with very small numbers being found in the shallower areas nearby, where the fronts occurred. The prey concentrations did not increase at the fronts at any phase of the tidal cycle. The few zooplankton patches detected by the optical plankton counter did not correspond to either physical structures or fish concentrations. The gut fullness index and the stomach contents of the capelin caught in fronts did not differ from those of capelin caught elsewhere. These frontal aggregations of capelin seem therefore to be driven more by a threshold response to low temperatures than by trophic interactions based on a higher prey density.

SIMARD, Y., D. LAVOIE, 1999. The rich krill aggregation of the Saguenay - St. Lawrence Marine Park : hydroacoustic and geostatistical biomass estimates, structure, variability, and significance for whales. Can. J. Fish. Aquat. Sci., 56: 1182-1197 .

The euphausiid aggregation at the head of the main channel of the estuary and Gulf of St. Lawrence was surveyed using 120- and 38-kHz hydroaccoustics in the summers of 1994 and 1995. A systematic sampling grid covering an area of 1319 km2 was visited eight times. Fish echoes were separated from kill echoes using the difference in backscattering strength at the two frequencies. Global estimates were obtained from geostatistical methods for both total biomass and the fraction exceeding 5 g wet•m-3. The euphausiids were always exclusively composed of individuals of the oldest cohorts (2+) of the two species Thysanoessa raschi and Meganyctiphanes norvegica. Total biomass varied from 8 ± 96 ± 8 kt and cutoff biomass from 0 to 56 ± 6 kt. The two types of estimates were linearly related. Biomass was autocorrelated up to distances of 10-15 km. An anisotropic structure with radii of similar 2 x 5 km, stretched along the channel axis, was discernible at a small scale. The particular size distribution of euphausiids and the large variations in the global estimates appear to be controlled by horizontal transport. The study area appears to be the richest krill aggregation site yet documented in the northwest Atlantic, with densities similar to the rich krill aggregation areas of the Antarctic. The krill aggregation is at the heart of this traditional whale feeding ground.

SIMARD, Y., I. McQUINN, M. MONTMINY, Y. SAMSON, C. LANG, C. STEVENS, D. MILLER, 1998. CH1, Canadian Hydroacoustic Data Analysis Tool 1, user's manual (version 2.0). Can. Tech. Rep. Fish. Aquat. Sci., 2256, 100 p .

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CH1 is the acronym for Canadian Hydroacoustic data analysis tool 1. It is a Windows 95 Multiple Document Interface (MDI) C++ application, developed by the Department of Fisheries and Oceans within the framework of the Data Analysis Tools (DAT) project of its National Hydroacoustic Program (NHP). It is a versatile tool designed to acquire hydroacoustic data produced by analog or, digital multi-channel (multiple frequencies or beams) echosounders under a standard, upgradable, and versatile data format, called HAC format (Simard et al. 1997). Both analog echosounders (e.g. Biosonics 102 types) and digital echosounders (e.g. Simrad EK500 or EY500) are considered by CH1, which is able to acquire data from many echosounders simultaneously. It incorporates variable threshold functions (TVT, Time Varied Threshold) which can adapt to ambient noise. Data from analog echosounders are collected via Bridgenorth Inc. 16-bit A/D converters and a Digital Signal Processor (DSP), coupled to a signal conditioning box to which the analog outputs of the detected echosounder channels are connected. Data from the Simard EK500 digital echosounder are acquired via an Ethernet port. CH1 can configure the EK500 by sending its parameters through a serial port. The NMEA-183 GPS position is read from a serial port. This manual is a guide to the use of CH1. Some of the information presented is also available from the CH1 on-line help. Other tools of the NHP-DAT project are designed to read, display or, translate *.HAC files to or from other formats. These tools are known as CH2 and HAC-trafic.

SIMARD, Y., I. McQUINN, M. MONTMINY, C. LANG, D. MILLER, C. STEVENS, D. WIGGINS, C. MARCHALOT, 1997. Description of the HAC standard format for raw and edited hydroacoustic data, version 1.0. Can. Tech. Rep. Fish. Aquat. Sci., 2174, 65 p .

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The international scientific community has recently stressed the need for a standard format to facilitate the exchange of fisheries acoustic data and/or their processing tools. This report presents a versatile standard format for raw and edited hydroacoustic data. This format resulted from a workshop held by DFO and from discussions with various users and echosounder manufacturers around the world. It is called the HAC format.

LAVOIE, D., Y. SIMARD, J. BENOÎT, P. LAROUCHE, B. THIBEAULT, 1996. Distribution des masses d'eau à la tête du chenal laurentien dans l'estuaire du Saint-Laurent aux étés 1994 et 1995. Rapp. tech. can. hydrogr. sci. océan., 176, 126 p .

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Satellite thermal images and temperature and salinity profiles, taken during the summers of 1994 and 1995, are used to describe the water masses at the head of the Laurentian channel. The three typical water masses of this system; the surface, the intermediate and the bottom layers showed : 1) a thinning and an elevation of the cold intermediate layer at the end of the summer, associated with a thickening of the bottom layer, 2) a colder intermediate layer in 1995, 3) a recurrent spatial structure, characterized by a convergence of the cold intermediate layer off Les Escoumins. Upwelling of intermediate cold waters at the head of the Laurentian channel was observed most of the time, as well as many fronts associated with its contact with adjacent waters from the Saguenay and the upper estuary. Our results suggest that the intensity and occurrence of these phenomena were modulated by the fortnightly tidal cycle and by the wind which regularly generated cold water upwelling along the north shore.

MITSON, R.B., Y. SIMARD, C. GOSS, 1996. Use of a two-frequency algorithm to determine size and abundance of plankton in three widely spaced locations. ICES J. Mar. Sci., 53: 209-215 .

BOROBIA, M., P.J. GEARING, Y. SIMARD, J.N. GEARING, P. BÉLAND, 1995. Blubber fatty acids of finback and humpback whales from the Gulf of St. Lawrence. Mar. Biol., 122: 341-353 .

SIMARD, Y., 1995. Overview of the krill of the Gulf of St. Lawrence. Fisheries Centre Research Reports, 3(3): 53-57 .

SAVARD, L., Y. SIMARD, 1994. Northern shrimp in the estuary and the Gulf of St. Lawrence (fishing areas 8, 9, 10 and 12). Pages 91-113 in L. Savard (ed.). Status report in invertebrates 1993 : crustaceans and molluscs on the Québec coast and northern shrimp in the Estuary and Gulf of St. Lawrence. DFO (Can. Manuscr. Rep. Fish. Aquat. Sci., 2257) .

SIMARD, Y., 1994. Comment la mer nourrit-elle les baleines à Tadoussac? ou Le pourquoi océanographique de la visite estivale des rorquals dans l'estuaire maritime du Saint-Laurent, à la tête du chenal laurentien (Tadoussac, Les Escoumins, Grandes-Bergeronnes). L'Euskarien, 16(2): 33-38 .

SAVARD, L., Y. SIMARD, 1994. Crevette nordique de l'estuaire et du golfe du Saint-Laurent (zones de pêche 8, 9, 10 et 12). Pages 103-128 in L. Savard (éd.). Rapport sur l'état des invertébrés en 1993 : crustacés et mollusques des côtes du Québec et crevette nordique de l'estuaire et du golfe du Saint-Laurent. MPO (Rapp. manus. can. sci. halieut. aquat., 2257) .

BOUDREAU, B., E. BOURGET, Y. SIMARD, 1993. Effect of age, injury, and predator odors on settlement and shelter selection by lobster Homarus americanus postlarvae. Mar. Ecol. Prog. Ser., 93: 119-129 .

SIMARD, Y., D. MARCOTTE, 1993. Assessing similarities and differences among maps : a study of temporal changes in distribution of Northern shrimp (Pandalus borealis) in the Gulf of St. Lawrence. Pages 865-874 in A. Soares (ed.) Geostatistics Troia '92 : proceedings of the 4th International Geostatistics Congress, Troia (Portugal), 13-18 Sept. 1992 : volume 2. Kluwer Academic Publisher, Dordrecht .

BOUDREAU, B., E. BOURGET, Y. SIMARD, 1993. Behavioural responses of competent lobster postlarvae to odor plumes. Mar. Biol., 117: 63-69 .

SIMARD, Y., D. MARCOTTE, G. BOURGAULT, 1993. Exploration of geostatistical methods for mapping and estimating acoustic biomass of pelagic fish in the Gulf of St. Lawrence : size of echo-integration unit and auxiliary environmental variables. Aquat. Living Resour., 6: 185-189 .

SIMARD, Y., J. BENOÎT, 1992. Geostatistical estimations and maps of the Northern shrimp biomass in the Gulf of St. Lawrence from 1990 to 1992, by size group and for all sizes together. CAFSAC Res. Doc., 92/96, 26 p .

Stationary geostatistical methods are used to compute estimates and map the fall biomass of northern shrimp (Pandalus borealis) in the Gulf of St. Lawrence in 1990, 1991 and 1992. Estimates and maps are computed separately by size groups and globally for all sized. The samples used were collected during daylight from the FRV/Alfred-Needler with a shrimp bottom trawl. Isotropic models of the spatial variability are estimated form the data, for each year separately and for all years together. The all-years models were less erratic than the annual models and were used for estimating the biomass and its confidence interval. The global estimates are computed for the fishing grounds deeper than 150 m, separately for four zones corresponding to the management units of the fishery. Global estimates showed that the Gulf biomass below the 150 m depth contour were 63.7, 69.9 and 47.5 kt for 1990, 1991 and 1992 respectively. Local variations occurred, some zones increased their shrimp biomass while it decreased in others. Similarly, the global biomass by size groups exhibited a large variability in its distribution and abundance pattern in time and space. The notable decrease of global biomass in 1992 was the fact of a weakening of the oldest cohorts (female) only, in the two zones of Esquiman channel and Sept-Îles region.

BOUDREAU, B., Y. SIMARD, E. BOURGET, 1992. Lobster juvenile recruitment and adult landings : influence of larval behaviour, temperature stratification and strong wind events. Pages 53-54 in Y. De Lafontaine, T. Lambert, G.R. Lilly, W.D. McKone & R.J. Miller (ed.). Juvenile stages : the missing link in fisheries research : report of a workshop. DFO (Can. Tech. Rep. Fish. Aquat. Sci., 1890) .

SIMARD, Y., J. BENOÎT, M. DESGAGNÉS, L. SAVARD, S. HURTUBISE, 1992. Atlas de la pêche à la crevette nordique (Pandalus borealis) dans le golfe du Saint-Laurent 1982-1991 : captures, effort, rendement, saison ; Atlas of the northern shrimp (Pandalus borealis) fishing in the Gulf of St. Lawrence 1982 - 1991 : catch, effort, yield, season. Rapp. tech. can. sci. halieut. aquat. ; Can. Tech. Rep. Fish. Aquat. Sci., 1900, 73 p .

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The information gathered in the fishing logbooks of shrimp trawlers operating in the Gulf of St. Lawrence during 1982 to 1991 inclusively is used to generate an atlas of this important fishing activity. The data are first checked for erroneous or incomplete records. The proportion of available valid information compared to the landings at the fish plants is calculated for each of the 5 fishing management units. Simple maps of weighted catch, of available effort and yields are then computed per year and per season; March-May and June– December. Maps of best significant annual yields, based on the available data, are then calculated. Summary maps joining the information of all years follow. They are maps of : total catch, mean catch and its standard deviation, for the whole fishing period or per season; mean monthly relative catch; weighted mean yield and its standard deviation over the whole fishing period or per season.

BOUDREAU, B., Y. SIMARD, E. BOURGET, 1992. Influence of a thermocline on vertical distribution and settlement of post-larvae of the American lobster (Homarus americanus Milne-Edwards). J. Exp. Mar. Biol. Ecol., 162: 35-49 .

SIMARD, Y., P. LEGENDRE, G. LAVOIE, D. MARCOTTE, 1992. Mapping, estimating biomass, and optimizing sampling programs for spatially autocorrelated data : case study of the Northern shrimp (Pandalus borealis). Can. J. Fish. Aquat. Sci., 49: 32-45 .

BOUDREAU, B., Y. SIMARD, E. BOURGET, 1991. Behavioural responses of the planktonic stages of the American lobster (Homarus americanus) to thermal gradients, and ecological implications. Mar. Ecol. Prog. Ser., 76: 13-23 .

SIMARD, Y., 1991. The Northern shrimp biomass in the Sept-Îles region of the Gulf of St. Lawrence during the 1980's : a geostatistical estimation. CAFSAC Res. Doc., 91/79, 27 p .

Stationary geostatistical methods are used to compute global and partial estimates of the biomass of northern shrimp (Pandalus borealis) present in the Sept-Iles region in the falls of 1982, 194, 1985, and 1987 to 1990. Biomass samples were collected during daylight from trawlers equipped with shrimp bottom trawls. Isotropic models of the spatial variability are estimated from the data, for each year separately, and are used for estimating the biomass and its confidence interval. The optimal model and kriging parameters for the estimation are chosen from the results of "jackknife" cross-validation tests. The estimates are computed separately for two envelopes, one on the east of the region, the other on the west. Kriging results are compared to an alternative estimation from polygonal tessellation. Global estimates showed that the biomass in the area under study increased from 4.8 to 10.4 kt during the period of observation. Partial estimates indicated that the biomass of the areas richer than 1 t/km2 changed by one order of magnitude, from 0.9 to 9.5 kt during the same period. The eastern basin was responsible for the major part of the biomass increase.

LEBLOND, P., D. LEFAIVRE, G. BUGDEN, D. CAIRNS, A. CONDAL, M. EL-SALH, L. FORTIER, D. GREENBERG, M. JEAN, V. KOUTITONSKY, Y. SIMARD, P. YEATS, 1991. Report of the Workshop on Physical Oceanography. Pages 6-12 in J.-C. Therriault (ed.). The Gulf of St. Lawrence : small ocean or big estuary ? Dept. of Fisheries and Oceans (Can. Spec. Publ. Fish. Aquat. Sci., 113) .

LEBLOND, P., D. LEFAIVRE, G. BUGDEN, D. CAIRNS, A. CONDAL, M. EL-SALH, L. FORTIER, D. GREENBERG, M. JEAN, V. KOUTITONSKY, Y. SIMARD, P. YEATS, 1991. Rapport de l'atelier de travail sur l'océanographie physique. Pages 6-12 in J.-C. Therriault (éd.). Le golfe du Saint-Laurent : petit océan ou grand estuaire? Ministère des pêches et des océans (Publ. spéc. can. sci. halieut. aquat., 113) .

SIMARD, Y., 1991. Comparison of kriging estimates of Northern shrimp biomass obtained from two different trawlers in the Sept-Îles fishing grounds in 1990. CAFSAC Res. Doc., 91/80, 7 p .

The northern shrimp biomass (Pandalus borealis) of the Sept-Iles fishing grounds in the fall of 1990 is estimated by means of ordinary kriging from stationary geostatistics, separately for the sets of samples collected by two different trawlers using slightly different trawls. The estimates are computed separately for two envelopes, one on the east of the study area, the other on the west. The samples collected from the M/V Alfred Needler produced larger global estimates, which were 9.2  ± 1.9 kt, 4.5 ± 1.1 kt and 13.6 ± 2.2 kt, respectively for the west envelope, the east envelope and for their sum. The corresponding estimates for the Marie-Simon were 6.0± 1.0 kt, 3.5± 0.7 kt and 9.5± 1.2 kt. The too low number of samples collected combined with their different locations from one trawler to the other, do not allow to distinguish if the observed difference was related to a different sampling of the spatial organization of the biomass, or to a difference in the sampling efficiency.

SIMARD, Y., P. BRUNEL, J. LACELLE, 1990. Distribution and growth of pre-recruit cohorts of the northern shrimp (Pandalus borealis) in the western of Gulf of St. Lawrence as related to hydrographic conditions. Can. J. Fish. Aquat. Sci., 47: 1526-1533 .

Samples collected with a suprabenthic sled from May to October were analysed to determine the number of prerecruit cohorts in the northern shrimp (Pandalus borealis) population of the Gulf of St. Lawrence and to estimate their growth and distribution. An unexpected cohort was found with carapace lengths of 4.5 - 9.5 mm. This appeared to be cohort I, thus indicating three pre-recruit cohorts : cohorts 0 (2.5 - 4.5 mm), I (4.5 - 9.5 mm), and II (9.5 - 14.5 mm). The comparatively slow growth rate of 4 -5 mm per year was attributed to the low temperatures (0.5 - 2.0 °C) in the bottom water inhabited by the pre-recruits, immediately below the intermediate cold water mass of the Gulf of St. Lawrence. Growth rates peaked in August-September, reaching 1 mm per month. Benthic settlement of the postlarvae also appeared to occur in August-September, at an age of 4 - 5 mo. Sexual differentiation in males started at an age of 16 mo and maturity was reached by 30 - 37 mo. Two strata were sampled, 0.3 - 0.7 m and 1.0 - 1.4 m above the bottom. More than 70 % of the shrimps were concentrated in the first 0.3 - 0.7 m stratum. Maximum density observed for one single cohort was 67 individuals per 100 m2. Large spatial and temporal variations of densities occurred daily, semimonthly, and seasonally, and are thought to be partially related to horizontal transport of water masses. Densities in the strata sampled were significantly lower at night, as a result of vertical migrations in the water column.

SIMARD, Y., L. SAVARD, 1990. Variability, spatial patterns and scales of similarity in size-frequency distributions of the Northern shrimp (Pandalus borealis) and its migrations in the Gulf of St. Lawrence. Can. J. Fish. Aquat. Sci., 47: 794-804 .

RUNGE, J.A., Y. SIMARD, 1990. Zooplankton of the St. Lawrence Estuary : the imprint of physical processes on its composition and distribution. Pages 297-320 in M.I. El-Sabh & N. Silverberg (ed.). Oceanography of a large-scale estuarine system : the St. Lawrence. Springer-Verlag, Berlin (Coastal and Estuarine Studies, 39) .

BOUDREAU, B., E. BOURGET, Y. SIMARD, 1990. Benthic invertebrate larval response to substrate characteristics at settlement : shelter preferences of American lobster (Homarus americanus). Mar. Biol., 106: 191-198 .

SIMARD, Y., L. SAVARD, 1989. A multivariate approach to study the variability and structure of length-frequency distributions : an example with the Gulf of St. Lawrence Northern shrimp population. NAFO SCR Doc., 89/97, 7 p .

SIMARD, Y., D.L. MACKAS, 1989. Mesoscale aggregations of euphausiid sound scattering layers on the continental shelf of Vancouver Island. Can. J. Fish. Aquat. Sci., 46: 1238-1249 .

SIMARD, Y., 1988. Hydroacoustics in biological oceanography. Pages 29-33 in Hydroacoustics Workshop Proceedings. Dept. of Fisheries and Oceans (Can. Tech. Rep. Fish. Aquat. Sci., 1641) .

SIMARD, Y., R. DE LA DURANTAYE, J.-C. THERRIAULT, 1986. Aggregation of euphausiids along a coastal shelf in an upwelling environment. Mar. Ecol. Prog. Ser., 32: 203-215 .