RESEARCH
AQUATIC SPATIAL ECOLOGY
  • Schooling behaviour in the pelagic zone

  • Effects of wind on foraging efficiency in lakes

  • Population genetics of dendritic landscapes

  • Ideal Gas movement in predator-prey interactions 

FISH PRODUCTIVITY MODELLING
  • Habitat-linked area-per-individual population models

  • Morpho-edaphic climate models of sustainable yield

  • Angler-fishery landscape consumer-resource model

  • Statistical Catch-at-Age harvest models

AQUATIC ECOSYSTEM MONITORING
  • Fisheries acoustics methodology development

  • Fish size-spectrum as a tool for monitoring change

  • Estimation of rates of habitat degredation

  • Broadscale cumulative effects monitoring

Selected Current Projects

Ideal Gas Model of Predator-Prey Encounters in the Pelagic Zone

 

Much of our understanding of animal ecology is founded in classic models developed at a time when studying spatial questions was very difficult.  As a consequence, simple characterizations of animal movements remain the dominant ecological representations of many natural systems. One of these models is the Ideal Gas representation of movement. We have recently found that:

  1. Lake Herrings form schools and move along the expectations of Ideal Gas Models

  2. Under this model, the density of schools in lakes is not directly correlated with the overall population size

  3. Predator-prey encounters under these conditions can thus lead to unusual functional responses where the predator feeds at a higher rate at low population sizes

 

Size-Spectrum of Lake Fisheries Across Time and Space

 

Hydroacoustic surveys are an efficient method for estimating the frequency of different fish size classes within a lake, however, they are not yet an effective means of determining the species composition of those classes. Over the last couple decades interest has grown over using fish size-spectrums to monitor the effect of fisheries on fish communities, for which species specific information is not required. In this project we ask whether hydroacoustically derived size-spectrum information might provide an effective indicator to monitor aquatic ecosystems across Canada's many lakes. There are a few basic questions that need to be addressed before moving forward:

  1. What is the natural variation expected among repeated surveys in the absence of habitat degradation?

  2. What is the spatial variation in size-spectrums found in lakes across Canada?

  3. Given this temporal and spatial variation, what is the magnitude of change to the size-spectrum that would be noticeable within 20 years? 

 

Habitat-Linked Fish Productivity Models

 

With the 2012 change in the Canadian federal Fisheries Act, the previous policy of the managing the health of fish stocks through preserving the quantity and quality of fish habitat has been shifted to a focus on directly protecting the ongoing productivity of commercial, recreational or aboriginal fisheries. While the earlier policy recognized the role of habitat in maintaning fish productivity, under the new Fisheries Protection Program policy there is a great need for this link to be made explicit. We are developing models in partnership with academics, government bodies and industrial stakeholders to meet the challenge of this new management framework. Some examples:

  1. Area-per-individual model developed for productivity estimates in Oil Sands rivers

  2. Morpho-edaphic based model of lake yeilds for landscape level monitoring of Ontario fisheries

 

75 years of Lake Trout Population Dynamics on Lake Opeongo

 

The Harkness Fisheries Laboratory, operated by the Ministry of Natural Resources and Forestry, has been monitoring the Lake Trout population of Lake Opeongo since 1936. Over this time period the population has experienced 1) stocking of a valuable prey fish species, 2) rapid growth in body size and abundance, 3) a fisheries collaspe in the late 1970s, and 4) a recovery in abundance but a regression to pre-stocking body size. We are analyzing the creel data on the fishery with a Virtual Population Analysis methodology to ask questions on predator-prey body size relationships and alternative ecological states. 

 

© Derrick T. de Kerckhove