Mummichog
Fundulus heteroclitus
Overview
Habitat
- Inhabits sheltered brackish or saltwater habitats like saltmarshes, tidal creeks and estuaries
- They can tolerate a wide range of salinities, temperatures and oxygen levels and polluted waters
- In the winter months they burrow into muddy sediments to avoid freezing
Description
- Adults range between 12-18cm in length
- Males and females look physically different
- Males are smaller than females, dark olive green in colour on top and lighter yellow underneath with vertical side stripes
- During the mating season males develop blue or orange spotty markings along the sides
- Females are a silvery-yellow underneath and a more pronounced yellow on top
Origin and Worldwide Distribution
- Native to the eastern coast of North America, from Canada to northeast Florida
- Two abundant populations exist in saltmarshes in Spain and Portugal
Potential or Known Impacts
- May cause population declines in native endangered fish species
- Mummichog form dense populations, altering ecosystem structure and increasing competition with native fish
Is it found in Northern Ireland?
- It is not currently present in Northern Ireland
How could it get here?
- Introduction could be a result of the accidental or deliberate release of individuals kept as aquarium pets or from scientific research facilities
- It may be introduced through ship ballast water
- It could be a contaminant of live bait, transported for the use in recreational angling
Management/Methods for Prevention
- Prevention via enforcing the IAS (Enforcement and Permitting) Order (Northern Ireland) ensuring that F. heteroclitus is not introduced to Northern Ireland
- Reporting all sightings so that Rapid Response can be instigated
- If Rapid Response is not successful, management is difficult but can include chemical control
Current Legislative Position (Entry into force: 02 August 2024)
- This species must not intentionally be brought into the Union; kept; bred; transported to, from or within the United Kingdom, unless for the transportation to facilities in the context of eradication; placed on the market; used or exchanged; permitted to reproduce, grown or cultivated; or released into the environment.