On maximum length and weight of the stone moroco Pseudorasbora parva (Cypriniformes, Cyprinidae) in freshwaters of Ukraine

УДК 597.554.3:591.5

R. A. Novitskiy
Oles Honchar Dnіpropetrovsk National University, Dnіpropetrovsk, Ukraine

Р. А. Новицкий
Дніпропетровський національний університет ім. Олеся Гончара, Дніпропетровськ, Україна

The Stone moroco Pseudorasbora parva Temminck et Schlegel, 1846 is a widespread species in Ukraine, casual alien species that was successfully naturalised. It inhabits freshwater reservoirs, dwells in the inshore area of rivers, reservoirs, lakes, ponds, irrigation and drainage channels. Its number increased fast in some storage pools (more than 420 specimens / 100 m2). The Stone moroco is a competitor for food of many fish species (including commercial ones) which dwell in the inshore areas. Therefore, P. parva is a dangerous species which threatens ecosystem functioning by influencing sustainable development of natural fish communities. Within the limits of its new area of distribution P. parva is characterized as a plastic species that has a high rate of growth and weight gaining. Research was conducted in 2007–2012 on the water reservoirs of the Dnieper River (Kakhovske, Dniprovske (Zaporizske), Dniprodzerzhinske) as well as on the small rivers (Orel, Samara Dniprovska, Bazavluk, Mokra Sura and Kilchen), and ponds and lakes of central part of Ukraine. Ichthyologic samples were obtained from amateur catches (winter float rod) and test fishing of summer fingerlings. Sampling was made in the inshore areas by a minnow seine. 1758 fish specimens were studied. Standard length and body weight of fresh fish were measured. Literature data described the Stone moroco within its area were reviewed.

All caught specimens are deposited at the Department of Zoology and Ecology, Oles Honchar Dnipropetrovsk National University (Ukraine). In the internal reservoirs of Eastern Europe the Stone moroco dwells more than 40 years. For this period the species has passed the period of adaptation, acclimatisation and full naturalisation in different types of reservoirs. Usually a species, which adapts to a new ecosystem, differs from initial forms by increased size and weight. It is related to the species plasticity and its competition for a habitat.

The Stone moroco within the limits of natural initial area and new expanded one was characterized by the following morphological indices. According to the data of different researchers its maximal length varies within the limits of 70–110 mm. D. Karabanov et al. (2010) marked considerable sizes of the Stone moroco in the Dnieper River. In 2006 the individuals of 110 mm length were registered in the Dniprovske reservoir. A maximal index of linear growth of 120 mm was marked only in the reservoirs of Korea. Maximal weight of P. parva in the rivers and lakes of Europe does not exceed 22 grams.

Three specimens of P. parva were caught in summer in the Dniprovske reservoir (48°23’16.64″ N, 35°07’42.03″ E), in the Samara Dniprovska river (48°39’28.44″ N, 35°37’59.50″ E), and in winter of 2011 in the pond of village Nikolaevka (48°21’28.69″ N, 34°42’05.38″ E). They were one female and two males with the length of 110–115 mm and the weight of 25.5–27.0 g. The fish were 5 years old. Found size and weight of P. parva are maximal for the species caught in the freshwaters of Europe.

The largest length and weight of P. parva in the reservoirs of Ukraine are conditioned by the adequate food supply, weak competition between the Stone moroco and local aboriginal species and insignificant predation pressure.

Zoocenosis — 2013
Біорізноманіття та роль тварин в екосистемах: Матеріали VІІ Міжнародної наукової конфе ренції. – Дніпропетровськ: Адверта, 2013. – С. 108-109.