Mummichog

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.

Species Related Files:

RA_Fundulus_Heteroclitus_Mummichog