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Habitat selection in juvenile pollock, Pollachius virens : behavioural responses to changing habitat availability

McGill University
Publication Date
  • Pollock -- Effect Of Habitat Modification On
  • Pollock -- Habitat
  • Education


This thesis demonstrates how tidal changes in the availability of intertidal zone habitats can affect the distribution and behaviour of juvenile pollock (Pollachius virens). Schools of pollock moved from the subtidal zone to the open habitat in the intertidal zone. On rising tides, pollock switched from the open habitat at low tidal stages to the dense algal habitat at high tidal stages. On falling tides, pollock rapidly schooled downshore in the open habitat. Pollock were rarely solitary in the open habitat and usually formed large schools. In the algal habitats, pollock were usually dispersed and preferred the dense algae over the sparse algae. Predation risk from birds was widely distributed among depths, habitats and stages of the tide, during the day. In a mesocosm experiment, pollock increased their use of the algal habitat and were more difficult to detect following a simulated bird predator threat. Preference for the algal habitat was density-dependent when either pollock abundance or algal habitat area were manipulated. Pollock responded to their potentially high density in the algae by schooling in the open habitat.

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