Agata Korzelecka-Orkisz

Salmonid fish only reproduce in habitats that meet specific environmental requirements, including appropriate gravel–cobble substrate, suitable flow velocity, and adequate oxygenation. Long-term drainage practices and river channel regulation have led to substantial alterations of river systems, particularly affecting bed structure. The aim of this study was to assess habitat conditions in the Ina river catchment and to restore spawning grounds for salmon and sea trout through the construction of artificial redds, as well as to evaluate the effectiveness of these measures over subsequent years. The number of fish nests recorded prior to the implementation of the restoration project in 2011 was significantly lower (3 ± 1, mean ± SD) compared to post-restoration periods in 2013 (23 ± 11) and 2015 (21 ± 14). Spawning nests were predominantly located in areas characterized by high flow velocity and elevated water conductivity, hardness, and alkalinity. During the spawning migrations in 2013–2015, a total of 4593 individuals were recorded using a fish scanner. Despite a gradual decline in water levels from pre-restoration to post-restoration periods, the number of nests remained consistently high. The results indicate that ongoing environmental and climatic changes necessitate continued efforts to improve spawning conditions for anadromous salmonids. Currently (2024–2025), the potential for natural reproduction in the Ina River catchment remains comparable to the study period (89 redds), largely determined by the availability of gravel habitats and river discharge enabling upstream migration.

The aim of this study was to determine the influence of static magnetic fields with intensities of 1 mT, 3 mT, and 5 mT on the embryonic and postembryonic development of the rainbow cichlid ( Herotilapia multispinosa ). The experiments were conducted using eggs obtained from sexually mature, actively spawning pairs of this species. Analysis of the results showed that the applied magnetic fields significantly affected the rate of embryogenesis, which, depending on the intensity, could be either accelerated or slowed down. In particular, exposure to a 5 mT field accelerated development and produced larger hatchlings with smaller yolk sacs but lower subsequent growth, whereas exposure to a 3 mT field prolonged embryogenesis, resulting in smaller hatchlings with relatively larger yolk sacs and faster posthatching growth. The findings suggest that appropriately selected magnetic field parameters may positively influence the development of eggs and larvae of the rainbow cichlid, indicating the potential application of this method in ornamental fish aquaculture to reduce breeding losses.

The objective of the study was to trace directional reactions of the fry of Siberian sturgeon ( Acipenser baeri , Brandt, 1869) to magnetic field of 0.2 and 0.9 mT superimposed on geomagnetic field according to the geomagnetic force lines. In the experimental setup the fish could enter chambers...

This article has examined the effects of magnetic fields with intensities of 1 mT, 3 mT, and 5 mT on two species of cichlid fish (family Cichlidae). This study focused specifically on assessing the influence of these magnetic fields on larval development, the survival rate, and the occurrence of deformities in the larvae of the jaguar cichlid (Parachromis managuensis) and the green terror (Andinoacara rivulatus). The analysis of the study results indicates that the effects of magnetic field exposure depend both on its intensity and on the fish species being studied. Magnetic fields, depending on the applied intensity, can influence changes in body size as well as the size of the yolk sac. In jaguar cichlid larvae, increased survival was observed in the groups exposed to the magnetic field; however, this was accompanied by a higher number of deformities compared with the control group. In the case of the green terror, the highest survival rates were recorded in the control group and in the group exposed to a magnetic field of 3 mT, while increased numbers of deformities were also noted in the exposed groups. The obtained results may be of significant importance for ornamental fish aquaculture, where appropriately selected magnetic field parameters could support larval growth and survival, reducing losses in breeding.

Low and poor-quality water resources in Poland require rational and responsible use of them also in aquaculture. In recent years, there has been an increase in fish consumption, but also a change in consumer preferences. The development of innovative aquaculture methods leads to a reduction in water consumption, even by 20%, as is the case with recirculation aquaculture systems with salmonid fish production. In turn, sewage sludge generated in the purification process should be directed to the third stage of their purification, i.e. a hydrophyte lagoon. High requirements for the discharge of post-production water into aquatic ecosystems call for even more restrictive water management at every stage of fish production. The use of phytoremediation based on knowledge about the adaptation of aquatic and wetland plants to development in artificial aquatic ecosystems is an important element supporting the improvement of surface water quality. Thanks to the processes of rhizofiltration, phytoextraction and phytodegradation, hydrophytes effectively participate in reducing the concentration of nutrients and additionally metal ions. In turn, in fish farms focused on intensive carp production, part of the water drained from ponds in autumn can be subjected to phytoremediation in channels with an ecotone zone, thus improving the quality of these ecosystems. The key here is the selection of plants for the proposed solutions using phytoremediation and guaranteeing the effectiveness of this technology

In 2022–2023 specimens of A. fallax are recorded for the first time in approximately 17 years in Szczecin Lagoon. We collected 11 specimens of juveniles, 9 premature and mature females, and 9 premature and mature males (20.3–40.7 cm of total length, aged from 1+ to 4+). The 2+ aged fish was slightly dominated (34.5% of the whole sample). Females in the Szczecin Lagoon were ready to spawn in the age of 3+ and 4+ years, while males partly in 2+, and in the age of 3+ and 4+. Fulton’s condition factor of this fish was 0.93±0.14 and Clark’s 0.78±0.14. Analysis of correlations between the total length and individual weight of fish revealed that the growth of A. fallax was allometric (b < 3.0). The range of gonadosomatic index (GSI) was 0.12–26.59%, while the mean of the absolute and relative fecundity was 58,756 eggs per female and 139,650 eggs per kilogram of body weight. The obtained results indicate the occurrence of an anadromous population of Alosa fallax in the studied water areas. However, there is still a need to obtain detailed information on the population status and the biology of A. fallax in these areas in order to designate special conservation areas (SACs) for their protection, especially taking into account spawning habitats.

The paper discusses the current prognoses of aquaculture development worldwide putting an emphasis on its effect on the environment and the issue of the protection of water reservoirs in different countries. Water consumption in diversified aquaculture systems is presented herein as well as the characteristics of the mechanical and biological water treatment methods in fish farms, with particular attention paid to the recirculating water systems. New aquaculture technologies using post-production waters are presented. The paper provides a discussion on the contribution of aquaculture to the global greenhouse gas emissions and the means of limiting this emission. The effect of climate change on aquatic ecosystems is presented in the context of the changes of the aquaculture production profile. The paper includes a brief presentation of the methods of mitigating the changes with respect to contamination of aquatic ecosystems as well as climate change. Reducing the water footprint can be achieved through selective breeding, species diversification and implementation of more technologically advanced aquaculture systems such as: integrated multi-trophic aquaculture, aquaponics and recirculation systems in aquaculture. The need for certification of fish farms with water recirculation systems is justified in the paper. The issues addressed herein are summarised and the main areas for extending the research promoting preservation of aquatic ecosystems in aquaculture are presented.