Distribution and conservation of Acipenser sturio L., 1758 and related species in Greek waters

Four sturgeon species have been reported to exist in Greek waters: the Atlantic sturgeon, the great sturgeon, the stellate sturgeon and the Adriatic sturgeon. The Atlantic sturgeon Acipenser sturio L., 1758 has an almost regular presence in the Evros River (Aegean Sea), and is rather rare in the Pinios and Acheloos Rivers. The great sturgeon or beluga Huso huso L., 1758 is suspected to be an occasional visitor in Greek waters, or it is a case of undocumented information. The presence of the stellate sturgeon Acipenser stellatus Pallas, 1771 has been recently verified by a specimen caught close to the Thracian shore. The Adriatic sturgeon Acipenser naccarii Bonaparte, 1836 is supposed to have its southern distribution limits in the waters around the island of Corfu, although this information has never been confirmed. The distribution of these species is obviously related to salinity, probably prohibiting the extension of other sturgeon species to the Mediterranean, except for A. sturio. The discontinuous distribution of H. huso and A. stellatus may be a result of sea-level changes, while salinity played some role in the last period of glaciation. In the marine area of the Evros River A. sturio has been economically significant until 1975, supporting a small black caviar industry. Since then, the species has become rare mainly because of overfishing, and the reduction and pollution of the Evros River, in the upstream of which some important sturgeon spawning sites have been located.Cuatro especies de esturiones han sido citadas en las aguas griegas: el esturión atlántico Acipenser sturio L., 1758, el beluga Huso huso (L., 1758), el esturión estrellado Acipenser stellatus Pallas, 1771 y el esturión del Adriático Acipenser naccarii Bonaparte, 1836. El esturión atlántico A. sturio tiene una casi regular presencia en el río Evros (mar Egeo), y es bastante raro en los ríos Pinios y Acheloos. El beluga H. huso se sospecha que es un visitante ocasional de las aguas griegas, o es un caso de información indocumentada. La presencia de esturión estrellado A. stellatus ha sido recientemente verificada con un ejemplar capturado cerca de la costa tracia. El esturión del Adriático A. naccarii se supone que tiene sus límites meridionales de distribución en las aguas alrededor de la isla de Corfú, aunque esta información nunca ha sido confirmada. La distribución de estas especies está obviamente relacionada con la salinidad, impidiendo, probablemente, la extensión de otras especies de esturiones en el Mediterráneo, con excepción de A. sturio. La distribución discontinua de H. huso y A. stellatus puede ser el resultado de cambios en el nivel del mar, mientras que la salinidad desempeñó algún papel en el último periodo glacial. En el área marina del río Evros, A. sturio ha sido económicamente significativo hasta 1975, soportando una pequeña industria de caviar. Desde entonces, la especie ha llegado a ser rara, principalmente a causa de la sobrepesca y la reducción y contaminación del río Evros, en cuya parte superior se localizaban importantes lugares de freza para el esturión.Instituto Español de Oceanografí

SHAD SPECIES IN GREEK WATERS – AN HISTORICAL OVERVIEW AND PRESENT STATUS.

An historical overview of the shad species in Greek waters and the present status of these species are given. The species Alosa fallax (Lacépède, 1803), Alosa macedonica (Vinciguerra, 1921) and Alosa vistonica (Economidis and Sinis, 1986), are the three kinds of shad thriving in Greek waters. The Alosa fallax regularly occurs across coastal zones, mainly near estuaries, and enters the rivers such as Evros, Nestos, Strymon (Thrace and Macedonia), Pinios (Thessaly), Acheloos and Thyamis (western Greece), during the spawning period. Its presence is also confirmed in lake Vistonis, which is connected with the Thracian Sea and there is also strong evidence that it enters some other rivers such as Loudias (Macedonia), Louros and Arachthos (western Greece). Alosa macedonica is a landlocked species endemic to lake Volvi, whereas Alosa vistonica is also endemic and landlocked in the lacustrine part of the lagoon Vistonis

Relationship between morphologic and genetic variation in red mullet (Mullus barbatus) populations from Greek Seas

Data derived from morphometric, allozymes and RAPD analyses were compared, in order to investigate the possible relationships between morphologic and genetic variation observed in seven Mediterranean red muller (Mullus barbatus) populations. An absence of correlation between morphological and genetical variability patterns was found, at least for the part of the genome screened by allozymes and RAPD markers. However, heterozygotes for four allozyme loci showed a tendency towards lower morphological variance than homozygotes

The spawning behaviour of the endangered freshwater fish Ladigesocypris ghigii (Gianferrari, 1927)

peer reviewedLadigesocypris ghigii (Gianferrari, 1927), commonly called gizani, is an endangered freshwater fish endemic to the Greek island of Rhodes. The spawning behaviour of gizani was studied in aquaria, to develop an artificial breeding technique for this endangered species. Spawning in captivity was recorded over 41 spawning days between 15 February and 14 July 2001, under constant temperature (18 or 21 degrees C) and photoperiod 14L/10D. The number of spawning acts in a day was 82 +/- 28. No aggressiveness and no territoriality were developed. The mating system of the fish was polygamous, with females spawning more than once. In captivity, eggs are laid either on aquatic plants or on gravel, while in nature fish spawn mainly on algae and plants. The latter suggests that, as far as breeding substrate is concerned, gizani is an opportunistic species using different substrates when necessary