Reintroduction: risk factors

Successful reintroductions of species into a new stream habitat require carefully consideration and planning.

The reintroduction of a species brings with it a number of potential disease risks and genetic issues, as well as logistical issues of where, how, and at what life stage aquatic fauna should be moved. We need to consider confounding factors that may influence the success of re-introducing new species, including their life history traits, water and habitat quality, proximity to a source of colonising animals and barriers to dispersal.

Introduced organisms may be caught from other areas or can be reared in a lab or hatchery. Successful reintroduction relies on factors such as dispersal capabilities, survival in the new environment and subsequent reproductive success of the colonists. Reintroduction of populations of invertebrate species, or complex invertebrate communities, is largely a new area of research for stream restoration, but is likely to be further explored as our understanding of dispersal constraints increases.

Psilochorema mimicum prepupa

Important factors to consider when reintroducing organisms to a new habitat:

  • determining what organisms to reintroduce
  • where to obtain the organisms
  • avoiding introducing pests or diseases
  • deciding on the most suitable life history stage
  • determining numbers
  • repeated reintroductions
  • habitat quality
  • seasonality
  • genetic considerations
  • permission and approval (obtained through the Department of Conservation and Ministry of Agriculture and Forestry)
  • long-term monitoring of reintroduction success.
PDF File

 Considerations of reintroduction

Studies on restoration:

PDF File

Robust planning for restoring diadromous fish species

PDF File

 Genetic lineages of freshwater species

PDF File

 Genetic differentiation in New Zealand caddisfly and crayfish