Migratory smelt (Osmerus eperlanus eperlanus L.) may be perceived as a valuable indicative organism in monitoring the current environmental status and in assessment of a potential risk caused by selenium pollution. The aim of the study was to compare the selenium content in the European smelt from the Bay of Pomerania, Gdansk, and the Curonian Lagoon. The experimental material consisted of smelt samples (muscle) caught in the bays of Gdansk and Pomerania and the Curonian Lagoon (estuaries of the three largest rivers in the Baltic Sea basin: the Oder, the Vistula and the Neman). A total of 133 smelt were examined (Pomerania Bay n = 67; Gdansk Bay n = 35; Curonian Lagoon n = 31). Selenium concentrations were determined spectrofluorometrically. The data were analyzed statistically using one-way analysis of variance, calculated in Statistica PL software. The region of fish collection significantly affected the content of selenium in the examined smelts. The highest content of selenium was observed in smelt caught in the Bay of Gdansk (0.236 μg g-1 w.w.), then in smelt from the Pomeranian Bay (0.165 μg g-1 w.w.), and the lowest in smelt obtained in the Curonian Lagoon (Lithuania) (0.104 μg g-1 w.w.). The low concentrations of selenium recorded in the smelt show that there is a deficiency of this element, especially in the Curonian Lagoon (Lithuania). Geochemically, Poland and Lithuania are selenium deficient areas. Migratory smelt may serve as indicative organisms of environmental levels of selenium.
The seasonality and catching of smelt in the Pomeranian Bay were analyzed. The growth rate of this species was analyzed based on the readings of the otoliths from 230 fishes caught during the monitoring catches. The average total length and standard length as well as the weight of smelt were respectively 141.76 mm (±25.18), 120.54 mm (±21.73) and 16.41g (±11.25). Between males and females the small, statistically insignificant differences were noted. Due to the linear correlation between R and TL, the back readings were made in the variant of Rosa–Lee. The obtained empirical datas were used to theoretically increase the length by model: von Bertalanffy, Ford–Walford, polynomial of the 2nd degree and modified power function. Among the mathematical models used in the paper, the growth of the fish most suited to back readings turned out to be a modified power function. The relation between the total lengths and the weights of the smelts from the waters of the Pomeranian Bay is described by the equation for the whole material: y = 0.0015x3.4633.
PL
Przeanalizowano sezonowość i współczesne połowy stynki w Zatoce Pomorskiej. Na tym tle, na podstawie odczytów na otolitach 230 stynek złowionych w czasie połowów monitoringowych, przeanalizowano tempo wzrostu tego gatunku. Średnia długość całkowita i długość ciała oraz masa jednostkowa złowionych stynek wyniosła odpowiednio 141,76 mm (±25,18), 120,54 mm (±21,73) oraz 16,41 g (±11,25). Zanotowano niewielkie, nieistotne statystycznie różnice między samcami a samicami. Z uwagi na prostoliniową zależność między promieniem łuski (R) i całkowitą długością ciała (TL) odczyty wsteczne wykonano w wariancie Rosy–Lee. Uzyskane dane empiryczne wykorzystano do obliczenia teoretycznego wzrostu długości stynki z użyciem matematycznych modeli wzrostu: von Bertalanffy’ego, Forda–Walforda, wielomianu 2. stopnia i zmodyfikowanej funkcji potęgowej. Spośród zastosowanych modeli wzrostu ryb najbardziej dopasowanym do odczytów wstecznych okazała się zmodyfikowana funkcja potęgowa. Zależność między długością całkowitą a masą jednostkową stynki z wód Zatoki Pomorskiej opisuje równanie dla całego materiału: y = 0,0015x3,4633.