1. The Mediterranean common dolphin (Delphinus delphis ), considered to have been very common in the past, had undergone a dramatic decline across most of the basin by the end of 1970s. In the northern Adriatic Sea, one of the regions with most available historical information, the common dolphin is thought to have been the most common and abundant cetacean throughout most of the 20th century. However, by the end of 1970s, it had virtually disappeared from the region and is now considered generally absent from the entire Adriatic Sea.
2. This contribution summarizes the occurrence of common dolphins in the Gulf of Trieste and provides a brief review of published records in other parts of the Adriatic Sea.
3. Systematic boat surveys in the wider area of the Gulf of Trieste between 2002 and 2019 confirmed that the common bottlenose dolphin (Tursiops truncatus ) is the only regularly occurring cetacean species in this area. Despite this, several records of common dolphins were documented in the Gulf of Trieste between 2009 and 2012, through sightings of live animals or recovery of dead stranded animals.
4. Dorsal fin markings allowed the photo‐identification of some of these, suggesting that at least four different live individuals (three adults and one calf) occurred here in recent times. Most cases involved single adult individuals, but one included a mother‐calf pair that was temporarily resident in a port for several months, a behaviour atypical for this species. Photo‐identification showed that the presumed mother had previously been sighted in the Ionian Sea in Greece, over 1,000 km from the Gulf of Trieste, making this the longest documented movement for this species worldwide.
5. At present, the common dolphin continues to be rare in the region.

中文翻译：

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的里雅斯特湾和北亚得里亚海常见的海豚（Delphinus delphis）发生

1. 地中海海豚（Delphinus delphis）过去被认为是非常普遍的，但到1970年代末，整个海盆的大部分地区都经历了急剧下降。在亚得里亚海北部，这是历史信息最丰富的地区之一，普通海豚被认为是整个20世纪大部分时间里最常见，数量最多的鲸类。但是，到1970年代末，它实际上已从该地区消失了，现在被认为整个亚得里亚海普遍不存在。
2. 该文稿总结了的里雅斯特湾常见海豚的发生，并简要回顾了亚得里亚海其他地区的已出版记录。
3. 在2002年至2019年期间，对的里雅斯特湾的更广泛区域进行的系统船调查证实，普通的宽吻海豚（Tursiops truncatus）是该地区唯一定期出现的鲸类物种。尽管如此，2009年至2012年间，通过目睹活体动物或死去的滞留动物的恢复，在的里雅斯特海湾记录了几只普通海豚的记录。
4. 背鳍标记可以对其中一些进行光识别，这表明最近至少有四个不同的活体个体（三只成年人和一头小牛）出现在这里。大多数病例涉及单身成年个体，但其中一例包括一头母小牛对，它们暂时在港口居住了几个月，这是该物种的典型行为。照片鉴定表明，这名推测的母亲此前曾在希腊的爱奥尼亚海被发现，该岛距离的里雅斯特湾超过1000公里，这是该物种在全世界记录得最长的一次运动。
5. 目前，普通海豚在该地区仍然很少见。