BEN-TUVIA: IMMIGRATION OF FISHES 



MEDITERRANEAN FISHES IN 

 THE RED SEA 



The occurrence in the Red Sea of the two 

 Atlanto-Mediterranean and one cosmopolitan 

 species (Table 2) is assumed to be the result of Suez 

 Canal migration. The discovery o{ Dicentrarchus 

 punctatus in the lagoon of El Bilaiyim, situated 

 about 180 km south of the entrance to the Suez 

 Canal (Ben-Tuvia 1971a), is one of the few indis- 

 putable evidences of the immigration of a 

 Mediterranean fish into the Gulf of Suez. How- 

 ever, we have to bear in mind that the conditions of 

 El Bilaiyim differ considerably from those of the 

 Gulf proper. Salinities are much higher (50-60%o 

 according to measurements taken in June 1968) 

 and most probably the seasonal and diurnal fluc- 

 tuations are greater than those of surrounding 

 waters. In this particular biotope, less competition 

 is expected than in the open coastal waters. Dicen- 

 trarchus punctatus is known to inhabit the Bar- 

 dawil Lagoon on the northern (Mediterranean) 

 coast of Sinai, where salinities may reach 80%o. It 

 was noted already by Tillier (1902) that this fish 

 was common in the Suez Canal and reached its 

 southern entrance. Evidently, it settled in the 

 Canal soon after its opening. 



A taxonomic study of Red Sea mugilids (Ben- 

 Tuvia 1975b) revealed that another Mediterra- 

 nean immigrant, Liza durata is common in the 

 northern Red Sea. An earlier record of its presence 

 was made by Al-Hussaini (1947) who examined 

 the intestine of this mullet that was captured off 

 Ghardaqa. Liza aurata is known to be euryhaline 

 and could cross the Suez Canal or an earlier fresh- 

 water connection that was established by the an- 

 cient Egyptian pharaohs and Persian kings be- 

 tween the Mediterranean and the Red Sea using 

 an arm of the River Nile. This fish was reported in 

 the Suez Canal by Tillier (1902). I found it to be 

 common in Great Bitter Lake (Ben-Tuvia 1975a). 



Recently two specimens of a sandbar shark, 

 Carcharhinus plumbeus, were found in the Red 

 Sea. One specimen, a male, 1,600 mm total length 



was collected on 6 August 1971 in Dahab, Gulf of 

 Aqaba; the second specimen, a gravid female, 

 1,764 mm was collected on October 1975 in Ras 

 Muhammad at the entrance to the Gulf of Suez 

 (Baranes and Ben-Tuvia in press). Five additional 

 specimens varying in length between 1,500 and 

 1,800 mm have been found very recently in the 

 same region (unpubl. data). Carcharhinus plum- 

 beus (known also under the name of C milberti) is 

 common on both sides of the Atlantic and is well 

 known in the Mediterranean Sea (Tortonese 1956; 

 Ben-Tuvia 1971b; Compagno 1973). The recent 

 appearance of the sandbar shark in the northern 

 Red Sea could be due to immigration through the 

 Suez Canal although the possibility of penetration 

 from the western Indian Ocean should not be 

 excluded. 



Special consideration should be given to Ser- 

 ranus cabrilla, which is common in all parts of the 

 Mediterranean, in the Suez Canal, and also in the 

 Red Sea. However, it cannot be regarded as an 

 example of Suez Canal immigration, since a 17-cm 

 long specimen was collected by Hemprich and 

 Ehrenberg in the Red Sea before the completion of 

 the Canal (Klunzinger 1884). According to my ob- 

 servations in September 1970, S. cabrilla is com- 

 mon in the northern part of the Gulf of Suez. In- 

 dividuals were easily observed on sandy patches 

 between coral heads and rocks in the shallow coast- 

 al waters off Ras Masalla and Ras Sudar. A total of 

 10 specimens, 52-100 mm, were collected from the 

 Gulf of Suez plus 1 specimen, 70 mm standard 

 length, from the Gulf of Aqaba. The abundance of S. 

 cabrilla in the northern section of the Gulf of Suez 

 indicates the possibility that the present distribu- 

 tion might be related to the proximity of the Suez 

 Canal. However, further taxonomic and behavioral 

 studies will be needed to ascertain the relationships 

 between the Red Sea and the Mediterranean popu- 

 lations. 



Serranus cabrilla in the Mediterranean shows 

 great plasticity and adaptability to various ecolog- 

 ical conditions. This fish is found in shallow coast- 

 al waters on sandy beaches and among rocks. It is 



Table 2. — Data on Mediterranean fishes found in the Red Sea. 



' Maximum length observed in Red Sea. 



253 



