Language selection


Terms of Reference

Screening Level Risk Assessment (AIS) for Chain Pickerel (Esox niger), Goldfish (Carassius auratus), Prussian Carp (Carassius gibelio), and Black Crappie (Pomoxis nigromaculatus)

National Peer Review - National Capital Region

March 27-29, 2023
Virtual Meeting

Chairperson: Thomas Pratt


Aquatic invasive species (AIS) that are introduced or spread to ecosystems beyond their natural range can threaten Canada’s biodiversity, economy, and society. Nonindigenous freshwater fishes could enter Canadian water bodies through different pathways, including live trade and through connectivity between Canadian water bodies and those of the United States. Species native to some regions in Canada could also spread to other areas where they are absent, with negative impacts on the recipient ecosystems, e.g., Smallmouth Bass and Northern Pike.

In recent years, the potential ecological impacts of four freshwater fish species were identified as being of particular concern across Canada: Goldfish (Carassius auratus), Prussian Carp (Carassius gibelio), Chain Pickerel (Esox niger), and Black Crappie (Pomoxis nigromaculatus). The latter two species are native or considered naturalized in certain regions of Canada, while Goldfish and Prussian Carp are nonindigenous to Canada. The four species have been introduced to different water bodies across Canada through various natural and anthropogenic pathways, and are expanding their range.

The Aquatic Invasive Species National Core Program has requested a screening-level risk assessment (SLRA) on Goldfish, Prussian Carp, and Chain Pickerel to inform decision-making aimed at preventing their introduction and spread in Canadian waters. In addition, DFO’s Gulf region has requested an SLRA on Black Crappie to inform decision-making around the control of this species in New Brunswick. Recommendations stemming from this science advice could be used to inform management and policy on mitigating freshwater fish invasions across Canada.

A national SLRA will help screen and prioritize high risk aquatic non-indigenous species and provide DFO and Provinces and Territories information to better understand the ecological risk of these four species. It will also help prioritize efforts and resources to control and/or mitigate their spread, inform public education and outreach, and inform socioeconomic screening-level risk assessments.

The SLRA methodological approach will ensure that results will: 

  1. inform on each species’ risk of invasion and establishment in freshwater ecoregions within Canada, and
  2. provide insight on how climate change could influence invasion risks related to the four fish species.


The objective of this advisory process is to:

  1. perform a screening-level risk assessment for Goldfish, Prussian Carp, Chain Pickerel, and Black Crappie, in Canadian freshwater ecoregions, considering their likelihood of introduction, potential ecological impacts, and changes in relative risk under climate change, and
  2. determine how results from the freshwater ecoregions influence conclusions at the national level.

Expected Publications

Expected Participation


Participation to CSAS peer review meetings is by invitation only.

Date modified: