Mariene mollusken uit het oostelijk deel van de Middellandse Zee 15. Invasie van rugschilden van Sepia pharaonis langs de kust van Israel

In the period of 20-24 April 2003 large numbers of cuttlebones belonging to the species Sepia pharaonis Ehrenberg, 1831 were found in the flood-line on the Mediterranean coast of Israel. Hundreds of specimens, but still larger numbers of Sepia officinalis Linnaeus, 1758 and a few specimens of Sepia orbignyana De Férussac, 1824 and Sepia elegans D’Orbigny, 1826, were laying also at high watermark. Most of these cuttlebones were in perfect condition and all were tree of any epibionts. All other floating objects found in the same driftline were densely covered with two species of Goose-barnacles (Lepas species). Sepia pharaonis is a squid commonly encountered in the Indo-Pacific. It was originally described from the Red Sea and is being exploited by Egyptian fishermen as a commercial species in the Suez Canal. The find of so many large numbers of Sepia pharaonis raises several questions. How can we explain the sudden invasion of it on the Mediterranean coast? Are they unpalatable left-overs of squids consumed on ocean-going vessels? Did these cuttlebones have their origin in the Suez Canal? Or has Sepia pharaonis to be considered another Lessepsian migrant? Due to the large numbers in which they washed ashore, accompanied by three typical Mediterranean-Atlantic species, I reject the possibility that they had their origin in the Suez Canal. The numbers in which the cuttlebones covered large stretches of the beach (respectively 23 km near Tel Aviv and 13 km near Haifa) makes it also impossible to consider them leftovers of meals. The fact that they were not covered with any epibionts, in particular Goose-barnacles, shows that they did not float around for a long time. This leaves in my opinion only one possibility: Sepia pharaonis has most probably managed to get a foothold in the Eastern Mediterranean. However, this assumption still has to be confirmed by the finds of living specimens.