Sampling for Economidichthys trichonis © Hellenic Centre for Marine Research

Study monitors native and alien freshwater fish in Greece

A collaborative project between the Hellenic Centre for Marine Research (HCMR, Dr Eleni Kalogianni), the Bristol Zoological Society (BZS, Brian Zimmerman) and the University of the West of England (UWE, Dr Mark Steer), has recently been collecting data in freshwater systems in Greece, with the aim of wide-range monitoring of native and alien freshwater fish in the country. The project, funded by the A. G. Leventis Foundation, is called Project AFRESH, and covers most of mainland Greece.

We caught up with BZS’s Brian Zimmerman to learn more.

What is the project you’re currently working on with the Hellenic Centre for Marine Research?

Project AFRESH has five main aims:

1. To provide data on the current country-wide status of selected threatened freshwater species in Greece, along with data on the top two alien invasive species, using both conventional fish sampling and eDNA methods.

2. To create a breeding habitat to act as a refugia in the wild for the Critically Endangered Corfu Valencia, Valencia letourneuxI, as well as back up aquaria stocks of two other threatened species.

3. To further disentangle native / alien species interactions – in particular the impacts caused by direct aggression and other stressors – through a detailed behavioural and quantitative study.

4. To provide a Europe-wide project dissemination and knowledge-sharing through the organisation of workshops and the participation in conferences.

5. To reach a wider audience of conservation practitioners working in freshwater habitats in Europe and beyond, via a project website that charts the project’s accomplishments and activities.

Stunned fish caught by electrofishing prior to their re-release in the river

Stunned fish caught by electrofishing prior to their re-release in the river © Hellenic Centre for Marine Research

Project AFRESH is the latest in a series of projects in Greece that started in 2005. Tell us a bit more about these projects.

They have included:

FISH NET: GREECE – The aim was to conserve the Corfu killifish by stabilising the remaining populations of the Critically Endangered Greek killifishes (the sister species Valencia letourneuxi and Valencia robertae), preventing their extinction in the wild. This was achieved by using monitoring, captive breeding, research, trial translocation and awareness-raising.

RESILIENT – A population assessment of the Corfu killifish and other Greek endemic freshwater species was done using established and innovative methods which aimed to assess the current population status of the two Greek killifishes. This project used both conventional fish monitoring methods and eDNA methods.

PACIM – A population assessment of two Critically Endangered Greek fish species, and range assessments of the highly invasive Eastern mosquitofish and Topmouth gudgeon, which aimed to conduct population surveys for four extremely range-restricted and Critically Endangered species in Greece, again using conventional methods and eDNA sampling. An assessment of the expansion range of two extremely invasive alien freshwater fish species at selected Greek basins also used eDNA methods.

Which species is the project aiming to conserve?

Through nationwide monitoring, Project AFRESH targets six threatened, range restricted, Greek endemics (Telestes beoticus, Knipowitschia thessala, Salmo peristericus, Phoxinus strymonicus, Alburnus vistonicus and Alburnus macedonicus).

It also targets the Critically Endangered Valencia letourneuxi and, through the creation and breeding of safety stocks, Pungitius hellenicus and potentially Salaria economidisi and Economidichthys trichonis. The freshwater fish fauna of Greece is of particular importance as a national and global heritage, especially due to its diversity and high degree of endemicity, mainly as a result of the complex geological and climatic history of the Balkan Peninsula (Barbieri et al, 2015).

Collecting Water samples for eDNA analysis

Collecting Water samples for eDNA analysis © Hellenic Centre for Marine Research

What threats do these species currently face?

These species are threatened from anthropogenic changes to the hydrological and hydromorphological conditions of their habitats, caused by water abstraction, habitat loss and degradation through mainly agricultural pollution, disruption of river connectivity and – importantly – alien invasive species.

What role do you think eDNA methods have in freshwater species conservation?

There is a growing amount of literature showing that the eDNA method is becoming increasingly common, and that it offers substantial potential as a non-invasive method associated with highly repeatable and reliable results.

It offers a low impact, speedy sampling method that has the potential to identify ecosystem level changes early. Proper training is needed to prevent contamination of samples, and at the moment we are testing whether “false negatives” can be corrected, but it is showing real promise as a way to conduct presence/absence surveys for freshwater fish, in particular for those species that are cryptic and not easy to find with traditional sampling methods.


Barbieri, R., Zogaris, S., Kalogianni, E., Stoumboudi, M. T., Chatzinikolaou, Y., Giakoumi, S., … & Economou, A. N. (2015). Freshwater fishes and lampreys of Greece: An annotated checklist.

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