Computer Simulations of the Influence of Ocean Currents on Fraser River Sockeye Salmon (<i>Oncorhynchus nerka</i>) Return Times

Thomson, Keith A.; Ingraham, W. James; Healey, M. C.; LeBlond, Paul H.; Groot, C.H. de; Healey, Christopher G.

doi:10.1139/f94-046

Cited by 31 publications

(40 citation statements)

References 9 publications

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“…These sharks may concentrate in this area during July and August to intercept adult salmon on their return migration from the North Pacific Ocean to natal streams in the region. For instance, salmon returning to the Fraser River-the largest of Canadian salmon runs-use this more northerly route through Queen Charlotte Sound and Johnstone Strait during times of higher-than-normal sea temperatures (Thomson et al 1994, Healey 1998, and they use the more southern route through the Strait of Juan de Fuca when sea temperatures are colder. Sea temperatures at nearby Stn P have been increasing since the late 1950s (Whitney & Robert 2007), thus making it increasingly likely that returning salmon return consistently through Queen Charlotte Sound.…”

Section: Discussionmentioning

confidence: 99%

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Shark aggregation in coastal waters of British Columbia

Williams¹,

Okey²,

Wallace³

et al. 2010

Mar. Ecol. Prog. Ser.

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A concentration of pelagic sharks was observed in an area of western Queen Charlotte Sound, British Columbia, during systematic shipboard line-transect surveys conducted (2004 to 2006) for marine mammals throughout coastal waters of British Columbia. Surveys allowed only brief observations of sharks at the surface, providing limited opportunity to confirm species identity. Observers agreed, however, that salmon sharks Lamna ditropis (Lamnidae) were most common, followed by blue sharks Prionace glauca (Carcharhinidae). Both conventional and model-based distance sampling statistical methods produced large abundance estimates (~20 000 sharks of all species combined) concentrated within a hotspot encompassing ~10% of the survey region. Neither statistical method accounted for submerged animals, thereby underestimating abundance. Sightings were made in summer, corresponding with southern movement of pregnant salmon sharks from Alaska. The previously undocumented high density of these pelagic sharks in this location has implications for understanding at-sea mortality of returning Pacific salmon Oncorhynchus spp. (Salmonidae) and for assessing conservation status of sharks in Canada and beyond. We recommend that a dedicated Canada-US sightings and biological sampling programme be considered, perhaps under the UN Transboundary Species Fishery programme.

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Section: Discussionmentioning

confidence: 99%

“…A warming ocean could enable the development of an effective 'feeding gauntlet' at the northern return route for Fraser River salmon, if indeed a warming ocean climate regime favours the exclusive use of that northern route (e.g. Thomson et al 1994, Healey 1998.…”

Section: Discussionmentioning

confidence: 99%

Shark aggregation in coastal waters of British Columbia

Williams¹,

Okey²,

Wallace³

et al. 2010

Mar. Ecol. Prog. Ser.

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“…Researchers in oceanography are studying the growth and movement patterns of diVerent species of salmon in the northern Paci® c Ocean. Underlying environmental conditions like plankton density, sea surface temperatures (SST), current direction, and current strength aVect where the salmon live and how they move and grow (Thomson et al 1992, Thomson et al 1994). For example, salmon like cooler water and tend to avoid ocean locations above a certain temperature.…”

Section: Oceanography Simulationsmentioning

confidence: 99%

Building a perceptual visualization architecture

Healey¹

2000

Behaviour & Information Technology

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Scienti® c datasets are often diYcult to analyse or visualize, due to their large size and high dimensionality. A multistep approach to address this problem is proposed. Data management techniques are used to identify areas of interest within the dataset. This allows the reduction of a dataset's size and dimensionality, and the estimation of missing values or correction of erroneous entries. The results are displayed using visualization techniques based on perceptual rules. The visualization tools are designed to exploit the power of the low-level human visual system. The result is a set of displays that allow users to perform rapid and accurate exploratory data analysis. In order to demonstrate the techniques, an environmental dataset being used to model salmon growth and migration patterns was visualized. Data mining was used to identify signi® cant attributes and to provide accurate estimates of plankton density. Colour and texture were used to visualize the signi® cant attributes and estimated plankton densities for each month for the years 1956 ± 1964. Experiments run in the laboratory showed that the chosen colours and textures support rapid and accurate element identi® cation, boundary detection, region tracking and estimation. The result is a visualization tool that allows users to quickly locate speci® c plankton densities and the boundaries they form. Users can compare plankton densities to other environmental conditions like sea surface temperature and current strength. Finally, users can track changes in any of the dataset's attributes on a monthly or yearly basis.

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“…It has been suggested that migrating salmon use currents to minimise energy expenditure during migration and therefore maximise energy available for growth (Hansen et al 1993). The strength and direction of ocean currents have also been proposed as being important factors in determining the direction and energetic efficiency of sockeye salmon (Oncorhynchus nerka) migration (Thompson et al 1992(Thompson et al , 1994, and the migration of several Pacific salmon species (Oncorhynchus spp.) appears to be closely associated with the North Pacific Gyre (Pearcy 1992).…”

Section: Introductionmentioning

confidence: 99%

Modelling the trajectories of migrating Atlantic salmon (Salmo salar)

Booker¹,

Wells²,

Smith³

2008

Can. J. Fish. Aquat. Sci.

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This paper describes a model for simulating the trajectories of migrating Atlantic salmon (Salmo salar) in the ocean. Surface current and temperature representations were used as boundary conditions for simulation of migration trajectories. Representations of surface currents were derived from a general circulation model forced by realistic winds and then tested through comparisons with observed trajectories of drifting buoys. Observed climatology data were used to represent sea surface temperature patterns. The model was used to simulate the trajectories of 15 individual salmon that were tagged in their home rivers and subsequently recaptured at sea. In contrast to a random swimming direction model, trajectories simulated using both rheotaxis and thermotaxis as direction-finding mechanisms passed close to the recapture locations of the salmon. The timings and positions of the trajectories simulated using rheotaxis corresponded more closely with the observed data than those simulated using thermotaxis. This work indicates that either rheotaxis or thermotaxis, or a combination of the two, are possible direction-finding mechanisms for migrating Atlantic salmon. Résumé :Notre travail décrit un modèle pour simuler les trajectoires de migration de saumons atlantiques (Salmo salar) dans l'océan. Des représentations de courants de surface et de températures servent de conditions limites dans la simulation des trajectoires de migration. Nous obtenons les représentations des courants de surface à partir d'un modèle de circulation générale forcé avec des vents réalistes et ensuite vérifié par des comparaisons avec les trajectoires observées de bouées en dérive. Des observations climatologiques ont permis de décrire les patrons de température de la surface de la mer. Le modèle a servi à simuler les trajectoires de 15 saumons individuels marqués dans leur rivière d'origine et recapturés plus tard en mer. Contrairement au modèle de direction aléatoire de la nage, les trajectoires simulées, qui utilisent à la fois la rhéotactisme et la thermotactisme comme mécanismes de choix de direction, passent près des points de recapture des saumons. Le calendrier et les positionnements des trajectoires simulées qui utilisent la rhéotactisme correspondent mieux aux données observées que ceux des trajectoires simulées qui utilisent la thermotactisme. Notre travail indique que tant la rhéotactisme que la thermotactisme, ou alors une combinaison des deux, servent de mécanismes possibles de découverte de la direction chez les saumons atlantiques en migration.[Traduit par la Rédaction] Booker et al. 361

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Computer Simulations of the Influence of Ocean Currents on Fraser River Sockeye Salmon (Oncorhynchus nerka) Return Times

Cited by 31 publications

References 9 publications

Shark aggregation in coastal waters of British Columbia

Shark aggregation in coastal waters of British Columbia

Building a perceptual visualization architecture

Modelling the trajectories of migrating Atlantic salmon (Salmo salar)

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