© 2019 Aaron Fisk - Trophic Ecology Laboratory. All rights reserved

Movement and Trophic Interactions of Fish and Marine Mammals

Lancaster Sound, Nunavut

About

The changing global climate has resulted in unpredictable Arctic sea ice conditions in recent years.  Understanding the relationships between the sea ice and Arctic marine food webs is essential for predicting the future stability of the Arctic marine ecosystem.  Further exploring the relationships between Arctic fish and marine mammals will allow for a greater understanding of the structure of this ecosystem.  Arctic cod are considered to be at the centre of this food web, but to date have been notoriously difficult to study.  This project aims to directly study Arctic cod in their natural habitat, while consecutively studying ringed seals, sculpin, toothed whales and oceanographic parameters in the same area.   By simultaneously monitoring organism behaviour (throughout the food web) and changing oceanographic conditions, we hope to gain a more comprehensive understanding of the high Arctic marine ecosystem.  This in situ research will be complimented by extensive lab work to process tissue samples for stable isotope analysis, further revealing the trophic ecology of this system. 

 

Arctic cod are widely considered to be the most important organism in the Arctic marine food web.  They comprise an enormous biomass that directly links the upper and lower trophic levels of the Arctic marine ecosystem.  It has been hypothesized that Arctic cod show a strong association to the sea ice, which may influence their behaviour, distribution and migrations.  This in turn may influence the behaviour, distribution and migrations of many larger Arctic marine organisms that prey on them, including larger teleost species, birds and marine mammals.  Thus, results of direct investigation of Arctic cod in the high Arctic region could greater reveal their association to sea ice and allow for more accurate prediction of vast biomass shifts in the Arctic ecosystem.

Objectives

 

  1. To study environmental fish interactions in the context of a changing Arctic marine  environment;

  2. Identify the locations and depths and timings at which Arctic cod schools occur across a full year;

  3. Define food webs in the high Arctic using stomach contents and stable isotopes (Arctic cod are a keystone marine species and its decline in Arctic waters would have a devastating impact on all the birds, mammals and fish that use it as a  major food source);

  4. Test acoustic tags and receiver arrays under Arctic conditions, with low temperatures, salinity stratified waters and ice;

  5. Investigate ringed seal movements and diving behaviour throughout the Lancaster sound area;

  6. Investigate the relationship between ringed seal movements/diving behaviour and teleost abundance/movements;

  7. Investigate the relationship between beluga hunting and Arctic cod and sculpin behaviour;

  8. Determine how Greenland sharks interact with their environment in the Resolute Bay area, including whether they enter Resolute Bay and what large-scale movements/ migrations they undertake throughout the Canadian Arctic Archipelago (CAA);

  9. Make oceanographic observations to a) investigate the freshwater input into the study area, to b) define the temperature, salinity, and density characteristics of the water masses under consideration, to c) determine the tidal variability of the area and check this against available tidal models, to d) improve on our understanding of the bathymetry of the area, and e) to monitor the productivity of the study area.  All these data will be used to develop and use suitable models to aid in the interpretation of the fish and marine mammal components of the study.

Show More