Sunday, April 27, 2014

Wanted: Alosa fallax - Twaite Shad records from Greece!

Juvenile Alosa fallax caught by HCMR electrofishing team at Pinios River, Summer 2009.

Spring fish migration 2014...

Many fishes enter freshwater from the sea. A few of these are truly anadromous long distance migrants - they journey up river to spawn (e.g. Salmon do this in the Atlantic). In Greece we have a wonderful anadromous clupeid, a Herring family fish, the Twaite Shad Alosa fallax that does this. But few people know it. And, it is a rarity, there are signs of it having declined. We must draw attention to it.

Twaite Shad or Sardelomana in Greek,  can reach up to 50 cm in size: A giant herring-like fish. Reproduction is in May (or maybe April also) in gravel beds in large rivers (mainly in northern and western Greece). Once the eggs are laid they soon hatch and the young fish migrate downstream, often staying in freshwater during the summer. The fish then migrate to sea and adults mature after 3 to 4 years.

My personal experience with this species is minimal. We have recorded the fish only twice, once in the lower Pineios of Thessaly and the lower Kompsatos (both young small-sized individuals in late Summer). But we have collected published records and some anecdotal mention of the fish from various big rivers (Axios, Amvrakikos rivers, etc). We have very interesting anecdotes of large numbers of "Sardine-like" fish running up-river from some places but these are really unconfirmed (i.e. from the Lower Alfeios etc). Such mystery talk by amateurs cannot be confirmed without a photo!!!  So we need to hunt for more documentation. My HCMR colleague, Yorgos Chatzinikolaou obtained the images featured in this post from a tributary of the River Evros, near Didimoteicho in late April 2013. It is well known that in the Evros this species migrated up from the sea to spawn and people collected to dry it (in great quantities) as far up as the Ardas river (near Kastanies). The three photos we post here are testimony that the species is still there! And evidence of the species' presence is vital to assessing this rare animal's conservation status in Greece.

A wider consortium of Greek Ichthyologists is now working together to gather information on 72 species of fishes of European Community Conservation Concern (the Natura Surveillance Project) and the Twaite Shad is one of these important species.

Please if anyone has any feeling of ever seeing or hearing about the presence of this giant 'sardine-mother' (Sardelomana in Greek) do get in touch with us AS SOON AS POSSIBLE. And please, try to get a picture - please note the date and exact location, the number of specimens, any special conditions and the fishes' size.

Keep in MIND: The reason these fish are now suffering from humans is that human-made obstacles such as dams and weirs BLOCK their natural up-stream migration. Our "barriers" and river engineering often totally impeding access to spawning grounds. River barriers to fish are sometimes unintentional and can be re-engineered: think about fish-ladders or small works around river bridge bases, road crossings, river abstraction points, river regulator weirs. These artificial barriers to river connectivity are one of the most significant and least appreciated elements degrading the natural integrity of river ecosystems. Thinking about the Sardelomana is a start. 

Adult Alosa fallax caught at spawning site in the mid Evros in Spring 2013. 

Adult Alosa fallax caught alive at spawning site in the mid Evros in Spring 2013.

Measuring total length (TL) is important as information of any photographed fish (same fish as above).

1 comment:

  1. I've recieved one report of Alosa fallax at one site so far; thanks!