29 Jun 2012

Slovenian and Italian researchers document the longest movement ever recorded in a common dolphin

Morigenos researchers and their Italian colleagues have documented the longest movement ever recorded in the short-beaked common dolphin (Delphinus delphis). A female dolphin swam from Greece to the Gulf of Trieste, travelling more than 1000 km! Even though dolphins are known to be very mobile animals, this is the longest movement ever documented in this species, worldwide.

The study was recently published in the scientific journal Marine Biodiversity Records and involved researchers from Morigenos, Tethys Research Institute, Dolphin Biology & Conservation, and the Miramare marine reserve.

Morigenos researchers mostly study bottlenose dolphins (Tursiops truncatus), the only regular dolphin species in the northern Adriatic. But in 2010, in collaboration with colleagues from Miramare reserve, they recorded a female short-beaked common dolphin with her calf in the Gulf of Trieste. Seeing a common dolphin was surprising in its own right, as this species has virtually disappeared from the Adriatic Sea. But an even greater surprise came when researchers discovered that this dolphin had already been seen in Greek waters in 2008. A method called photo-identification was helpful here – individual dolphins can be identified by natural marks on their dorsal fins. Morigenos researchers photographed the dolphin and sent the photos to their colleagues at Tethys Research Institute, which study common dolphins in Greece. It turned out they already knew this particular dolphin.

Morigenos and Miramare researchers monitored the dolphin since then. She spent most of her time in the port of Monfalcone. The calf disappeared in the beginning of 2011. After that the female was often seen around Trieste until September 2011, when she disappeared as well.

The short-beaked common dolphin has been considered extirpated in the Adriatic Sea in the last 30 years, despite being common in the past. The most likely causes are deliberate killing in the previous century, as well as the ecosystem changes resulting from pollution and overfishing. The common dolphin has also became rare in other parts of the Mediterranean, except in the Alboran Sea. The nearest population to the Adriatic Sea is found in the Ionian Sea off the coasts of Greece.

With a single case being reported here, these findings about the long-distance movement cannot necessarily be generalised to the entire species. Unfortunately, this also does not mean the common dolphin is returning to the Adriatic. Still, this study shows the effectiveness of photo-identification in common dolphin research, and shows that international collaboration is vital to the study, monitoring and conservation of mobile marine species.

The scientific paper can be viewed here:

Genov, T., Bearzi, G., Bonizzoni, S. & Tempesta, M. 2012. Long-distance movement of a lone short-beaked common dolphin Delphinus delphis in the central Mediterranean Sea. Marine Biodiversity Records, 5 , e9 doi:10.1017/S1755267211001163.

Slovenski znanstveniki dokumentirali doslej najdaljše potovanje pri navadnem delfinu

Raziskovalci društva Morigenos so v sodelovanju z italijanskimi kolegi dokumentirali doslej najdaljše potovanje oz. selitev pri navadnem delfinu (Delphinus delphis). Gre za samico, ki je na svoji poti od Grčije do Tržaškega zaliva preplavala več kot 1000 km! Čeprav je znano, da so delfini zelo mobilne živali, je to doslej najdaljša dokumentirana pot pri tej vrsti, kjerkoli na svetu.

V raziskavi, ki je bila nedavno objavljena v mednarodni strokovni reviji Marine Biodiversity Records, so poleg znanstvenikov iz društva Morigenos sodelovali še italijanski raziskovalci inštituta Tethys, skupine Dolphin Biology & Conservation in rezervata Miramare.

Raziskovalci društva Morigenos, ki se sicer ukvarjajo predvsem s preučevanjem velike pliskavke (Tursiops truncatus), edine stalne vrste delfinov v severnem Jadranu, so v sodelovanju s kolegi iz rezervata Miramare v letu 2010 v Tržaškem zalivu zabeležili samico navadnega delfina z mladičem. Opažanje je bilo že samo po sebi nekaj posebnega, saj navadnih delfinov v Jadranu praktično ni več. Še večje presenečenje pa je raziskovalce doletelo ob spoznanju, da je bil prav ta delfin leta 2008 že opažen v grških vodah. Pri tem so si pomagali z metodo imenovano foto-identifikacija – posamezne delfine je med seboj mogoče ločiti po naravnih oznakah na hrbtnih plavutih. Raziskovalci društva Morigenos so delfina fotografirali, fotografije pa poslali italijanskim kolegom inštituta Tethys, ki v Grčiji preučujejo prav to vrsto. Izkazalo se je, da tega delfina že poznajo.

Raziskovalci društva Morigenos in rezervata Miramare so delfinko opazovali in spremljali vse odtlej. Največ časa je preživljala v pristanišču Monfalcone (Tržič). Mladič je v začetku leta 2011 izginil, samico pa so nato v okolici Trsta videvali vse do septembra 2011, ko je tudi ona izginila.

Navadni delfin je vrsta, ki zadnjih 30 let v Jadranskem morju velja za izumrlo, čeprav je bila nekoč pogosta. Razlogi temu so predvsem načrtno pobijanje v prejšnjem stoletju ter ekosistemske spremembe, ki so posledica onesnaženja in prekomernega ribolova. Navadni delfin je danes redek tudi drugod v Sredozemlju, v večjem številu pa ga najdemo le še ob južni obali Španije. Nam najbližja populacija živi v Jonskem morju ob obalah Grčije.

Ker gre za en sam primer,  teh izsledkov seveda ne moremo posplošiti na celotno vrsto. Žal to tudi ne pomeni, da se navadni delfin vrača v Jadransko morje. Kljub temu ta raziskava kaže na učinkovitost foto-identifikacije pri preučevanju navadnih delfinov ter na pomembnost mednarodnega sodelovanja pri preučevanju, spremljanju in varstvu mobilnih morskih vrst.

Strokovno objavo si lahko ogledate tukaj:

6 Jun 2012

Two striped dolphins (Stenella coeruleoalba) in Portorož, Slovenia

Yesterday (5th June 2012) Morigenos received several reports of two dolphins sighted along the main beach and piers in Portorož, Slovenia. We responded and managed to identify the two animals as striped dolphins (Stenella coeruleoalba), which appeared in good condition. Examination of photographs revealed that these two dolphins have recently been sighted in a nearby Italian port of Grignano. As we reported in the scientific literature a few years ago, this species is occasional in this part of the Adriatic Sea (unlike the bottlenose dolphin, which is regular). If you spot any dolphins in Slovenian waters during the following days, or if you have spotted them recently, please report it at +386 31 77 10 77. This helps us monitor the occurrence of these animals in our waters. If you have any photos or video, we would also be very interested.

Photo: Špela Guštin, Morigenos

Dva navadna progasta delfina (Stenella coeruleoalba) v Portorožu

Društvo Morigenos je včeraj, 5. junija 2012, prejelo več klicev o dveh delfinih, ki sta se zadrževala ob plaži in pomolih v Portorožu. Zadevo smo preverili in ugotovili, da gre za dva navadna progasta delfina (Stenella coeruleoalba), ki sta zaenkrat videti v dobrem stanju. Po pregledu fotografij smo ugotovili, da gre za osebka, ki sta bila nedolgo nazaj že opažena v italijanskem pristanu Grignano. Ta vrsta se v Tržaškem zalivu pojavlja občasno (v nasprotju z veliko pliskavko, ki je tu stalna), o čemer smo v sodelovanju z Italijanskimi kolegi pred leti že objavili raziskavo v strokovni reviji Annales. Če v prihodnjih dneh na morju opazite delfine, ali pa ste jih opazili v preteklih dneh, vas prosimo, da nam to sporočite na številko 031 77 10 77 in nam tako pomagate spremljati pojavljanje teh živali v naših vodah. Če imate fotografije ali video posnetke, jih bomo zelo veseli.

Fotografija: Špela Guštin, Morigenos

1 Jun 2012

New e-book about dolphins of Slovenia

Morigenos and Dolphin Biology & Conservation are proud to present the electronic book »Dolphins of Slovenia: Marine mammals at the end of the Adriatic Sea«, which portrays the lives of dolphins off the Slovenian coast. The book is authored by Tilen Genov and Giovanni Bearzi. Photographs, taken by Tilen Genov and Polona Kotnjek, are the result of 10 years of research carried out by Morigenos.

To view the booklet click: Dolphins of Slovenia: Marine mammals at the end of the Adriatic Sea

Nova e-knjiga o delfinih v Sloveniji

Društvo Morigenos in Dolphin Biology & Conservation predstavljata elektronsko knjigo »Dolphins of Slovenia: Marine mammals at the end of the Adriatic Sea« (Delfini Slovenije: morski sesalci na koncu Jadranskega morja), ki prikazuje življenje delfinov v slovenskem morju. Avtorja knjige sta Tilen Genov in Giovanni Bearzi. Fotografije so plod 10-letnega raziskovalnega dela društva Morigenos, posnela pa sta jih Tilen Genov in Polona Kotnjek.

Za ogled knjige kliknite: Delfini Slovenije: morski sesalci na koncu Jadranskega morja

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