Current status of the Mediterranean Killifish (Aphanius fasciatus) in Malta | A Complex Conservation Question

Between the 21st-26th March 2017 I had the opportunity to visit each of five known localities for the Mediterranean Killifish Aphanius fasciatus on the island of Malta. The Killifish is locally known as “Buzaqq” and has historically inhabited brackish to hypersaline habitats at Marsa, Marsaxlokk, Marsaskala, Salini and Għadira. Salini The population at Salini are the only remaining natural population still residing in their natural habitat, but this habitat has been heavily altered since it was constructed into a large salt pan area by the knights of St John in the 16th century. It is still maintained to this day for cultural purposes and is a designated Natura 2000 site, but a recent Government restoration initiative was criticised for removing and disposing of large volumes of sediment essential for the æstivation and reproduction of Aphanius fasciatus, a locally and internationally protected species. At the end of 2016, the management of the site was officially handed over by the Government to Birdlife Malta who have plans to develop a nature reserve to cater to the migratory birds and help protect some of the endemic flora and fauna which exist here; there is still a great deal of concern though about the supposed plans to recommence the salt production at the salt pans and how that may affect the protected wildlife. 

An aerial shot of the salt pans at Salini show the brackish canal and the estuary opposite the Salt Pans as well as the Aphanius habitat adjacent.

Aphanius habitat at Salini with good algal growth, the typical breeding substrate for Aphanius fasciatus

Male and female pair of Aphanius fasciatus from Salini which are part of the captive breeding program at the Killifish Conservation Project

  A few other issues are also yet to be either formally acknowledged and/or addressed at Salini. In the smaller estuarine canal conditions appear to be hypoxic and I was able to observe several small groups of young Mullet gasping at the surface. The hypoxia here could be a result of a natural stratified hypoxia known to occur in some estuarine habitats due to the mixing of fresh and salt water, but the buildup of very large amounts of seagrass in the reconstructed redoubt could also be preventing sufficient oxygenated water from reaching the lower stretch of mixing zone; feral ducks are also present and are known to cause significant pollution to such waterways. 

A group of young mullet struggle to get enough oxygen in the hypoxic waters of the reconstructed redoubt canal aside the salt pans

A man-made obstruction in the redoubt prevents the natural movement of the seagrass back out to sea and this may be contributing to the hypoxia of these waters; feral ducks are also present.

Marsa Marsa’s population of Aphanius was once considered to be one of the healthiest and largest in Malta. They have since been declared extinct and were last seen within a very restricted range between 1973-1980 and during the distribution investigations by Alan Deidun et al in 2002 they were reported as entirely absent.  At that time of Deiduns investigations, Aphanius fasciatus had been recorded from a total of nine locations in Malta, most of which were populations which had been introduced but Marsa was thought to be a naturally occurring population and so the loss of this population is particularly significant. 

An old photo of the Aphanius habitat in the canal at Marsa by Charles Zammit showing a cleaner and healthier habitat but nevertheless heavily man-altered

On my visit to Marsa, the canal appeared mostly polluted and mistreated and still there was no sign of the once abundant Aphanius. 

Għadira Għadira Nature Reserve is another Natura 2000 site and is managed by BirdLife Malta.  It is reported to have a very strong population of Aphanius which were introduced several years ago by a non-governmental organisation, sadly they had mixed individuals from both ecotypes at Salini and Marsa which renders this population not only useless for conservation purposes but also a potential risk to the natural populations of the island.

Għadira Nature Reserve has a thriving population of Aphanius fasciatus but is not a naturally occurring habitat for the species.

Għadira has prime habitat for Aphanius but the mixed genetics of this population means it poses a risk to natural populations of the island.

A sluice gate regulates the pathway of water between the wetland and the sea, potentially restricting larger numbers of endangered Anguilla from breeding here.

The natural passage of water in and out of the wetland at Għadira is controlled by a sluice which is mostly used here to keep the salinity relatively lower than it otherwise would be since it is more favourable to migratory birds. Aphanius being lovers of more saline and hypersaline habitats are at a disadvantage here but are highly adaptable to varied salinity; the endangered eel Anguilla anguilla has also been spotted here in the past and the sluice gate could potentially be a serious obstacle for its breeding process as it is a catadromous species which requires unrestricted access to freshwater systems from the sea. Marsaxlokk The extirpated population at Marsaxlokk have (like those at Marsa) not been seen for several years now and are entirely absent from this habitat. There is however, a tiny grain of hope for this population, which is also situated within a supposed Nature 2000 site since individuals were translocated and introduced to the brackish habitat at Marsaskala some time ago and reportedly still exist there. They are also part of the Killifish Conservation Project captive breeding program run by Raymond Caruana within the Department of Fisheries & Aquaculture which is a combined effort between Nature Trust Malta and The Aquaculture Directorate (Malta).  

An aerial view of Marsaxlokk gives a good indication that the marsh land here was probably more extensive in the past.

The coastal lagoons are prime habitat for Aphanius but unrestricted access since the recent removal of the gates has allowed a lot of waste dumping to occur polluting this habitat

The substrate where the freshwater flows into the sea is littered with plastics, glass, wood and other waste refuse

A small number of ponds were relatively undisturbed and it was strange to see them without Aphanius

Another reported issue here was the erosion of the habitat due to large swells caused by the very big ship docked in the background; vast chunks of habitat have collapsed into the sea

Male Aphanius fasciatus from the extirpated natural population at Marsaxlokk in the captive breeding program at the Killifish Conservation Project

Female Aphanius fasciatus from the extirpated natural population at Marsaxlokk in the captive breeding program at the Killifish Conservation Project

Marsaskala The final population at Marsaskala (another Natura 2000 site) was introduced from Marsaxlokk in the past so is not a naturally occurring population and this translocation proved beneficial after the extirpation of Aphanius at Marsaxlokk as individuals were able to be incorporated to the ex-situ breeding effort, however the habitat  at Marsaskala is not entirely suitable for habitation by Aphanius. 

An aerial view of the habitat of the translocated population introduced to the waters at Marsaskala

The main water areas were saturated with groups of Mullet, this small pool was the only place which looked like a realistic refuge for Aphanius, although the feral ducks could potentially predate upon them opportunistically.

Disposed waste is a major issue at Marsaskala and the water is highly polluted with litter, especially plastics

Feral ducks are problematic in Marsaskala and considered pests due to the pollution caused by their waste; the habitat also has a healthy population of rats

The future of Aphanius fasciatus throughout the Mediterranean is far from certain and the issues highlighted in this article are not exclusive to Malta. The wide distribution of the species, which is in need of further taxonomic investigation despite recent research, seems to undermine the needs of the species at the regional level.