Rhithropanopeus harrisii (Gould, 1841) is an estuarine crab native to the East Coast of North America. This species has invaded both the West Coast of the United States and several European countries since the late 1800s where it has reportedly altered native ecosystems. This crab can tolerate a broad range of salinities and temperatures, which probably contributes to its success as an invader. In 1969, five specimens of R. harrisii were recorded in Panama, but subsequent surveys suggest it was not established. Here, evidence is reported of an established, reproducing population of R. harrisii in the Panama Canal. The crab's entire distribution within this waterway remains to be determined and potential changes in its ecology, especially given the imminent expansion of the Canal, need to be evaluated.

No abstract

The article presents the research materials of pike perch r. Volga and the Kuibyshev reservoir and noted the changes that have occurred in its population. Prior to the creation of the reservoir in the conditions of the Middle Volga, male zander matured at the age of 5–6 years, females at 6–7 years. In the Kuibyshev reservoir, pike perch becomes sexually mature at the age of 4–5 years, and a small part of it matures at the age of three. In the reservoir, due to ecological plasticity and the ability to lay eggs in a wide temperature range, regardless of the level regime of the reservoir and the spawning substrate, a gradual increase in its biological indicators, abundance and reserves began to be noted. Improving the feeding conditions of zander in the reservoir contributed to earlier puberty, an increase in the absolute fecundity of fish and its abundance in the reservoir. This contributed to an increase in zander catches since 1974, which in 1985 reached a maximum of 517 tons (9,2% of the total fish catch in the reservoir). Sufficiently high catches of zander over the past 10–15 years indicate the stability of its stocks in the Kuibyshev reservoir, which currently tend to increase. The multi-age sizeweight composition of zander in the Kuibyshev reservoir is represented by both young and older individuals, and confirms that the population is in good condition.

No abstract

The article analyzes the data of long-term studies of sterlet growth in the Kuibyshev Reservoir (watershed of the Volga River) conducted by researchers of the Tatar branch of the All-Russian Research Institute of Fisheries and Oceanography. Significant variations in sterlet length were found not only from year to year, but also in different parts of the reservoir. There have been stated the changes in sterlet population. In recent years, the reservoir has seen an improvement in the growth of sterlet yearlings in comparison with that of fish in the Volga river and in the first years of the reservoir's existence, and a decrease in the growth rate and size of older individuals. It has been found that starlet species in Kama Reaches grow better than in other parts of the reservoir. Fish with fast linear growth is found to increase its percentage, while the part of slow-growing fish decreases.