Auswahl der wissenschaftlichen Literatur zum Thema „Pike-factory“

A description of biotechnical methods of harvesting pike perch in natural reservoirs, methods of catching pike perch spawners, keeping in adaptation cages and transporting pike perch from fishing sites to the farm is given. Pike perch breeders were caught from the reservoirs with fixed and floating nets during the period: in the Kapshagai reservoir from 10 to 20 April; in the Syrdarya river — from April 20 to May 5. The adaptation was carried out in cages located in the coastal zone. Transportation to the fish farm was carried out in live fish tanks with a volume of 1 and 3 m³ with water aeration. The reproduction of pike perch was carried out in two fish farms of the Republic of Kazakhstan. The data on spawning of pike perch in two ways are given: in cages on nests; as well as the receipt of reproduction products by the factory method from “flowing” producers. In the first case, females and males were placed in cages in a ratio of 1:1 and 1:2; a spawning nest was installed in each cage and spawning was monitored. In the second case, from the “flowing” pike perch breeders ready for spawning, reproductive products (eggs and sperm) were obtained, fertilization and degluing were carried out with a suspension of white clay. The monitoring of hydrochemical indicators was constantly carried out, the dates of the beginning and end of spawning of pike perch were determined. The article presents the fish-breeding and biological characteristics of pike perch producers participating in spawning. The mass of spawned pike perch females in LLP “Halyk Balyk” ranged from 2 kg to 2.5 kg, males — 1.5–2.5 kg; females weighing 2.1–2.6 kg were used in the Republican State Enterprise “Kamyshly-Bashsky Fish Hatchery”; males — from 1.2 kg to 2.4 kg. Based on the results of the research, biotechnical standards were developed for the preparation of pike perch producers in water bodies, for transportation to fish farms, standards for spawning of pike perch in various ways.

The article presents data on the capture of pikeperch producers from natural reservoirs, the placement of males and females in pairs for spawning in cages on nests; spawning and sexually obtained products by the factory method, incubation of pike perch eggs in the grass carp incubation apparatus, and hatching of larvae. As a result of the studies, the dates of the beginning and end of spawning, the duration of incubation of eggs and hatching of pikeperch larvae were determined. The conclusion is the optimal dates for the spawning campaign of zander; optimal sizes of manufacturers. The principal opportunity of the artificial is reproduction of zander in the conditions of fish farming in the south of Kazakhstan.

The central massif of the Lake District around Great Langdale and Scafell Pike was one of the major locations for the production of Neolithic, polished stone axes. In response to the continuing erosion of the axe production sites a field survey was undertaken in 1984 and 1985. 566 distinct working sites were identified, within 35 groups; each site was recorded and the site data and high-scale survey plans are presented in microfiche. A fourfold categorization of the working sites is suggested which relates production methods to significant geological, topographic and geomorphic elements of the landscape. The quantity of axe waste, particularly in the Langdale area, confirms that production was on a massive scale and the variations in strategy and methods of extraction suggest a development through time towards greater sophistication and organization. Estimates of relative flake quantities for each group of sites have been used to compare the varying levels of activity at each group. A similar analysis was used to estimate the extent to which differing strategies were used at the two main production areas. Petrographic analysis of the outcrops which were exploited and the debitage associated with axe manufacture suggest that it may be possible to attribute dispersed products to specific production areas.

The pollution of surface waters has be-come rampant, which has led to the degrada-tion of many fishery reservoirs. The variety of toxicants entering water bodies in various ways is extremely large and is constantly being replenished with new substances. Their impact on aquatic organisms is associ-ated with the development of pathological processes, degradation of populations up to their death. This is especially evident in the main object of the use and protection of fish-ery reservoirs - fish. First of all, the most valuable species of whitefishes and salmon-ids suffered in the North-West region. The paper considers one of the main problems of fisheries in the North-Western region of Russia – the decrease in fish stocks and catches in natural reservoirs, and reveals the main reason for this ongoing process - the violation of natural and factory reproduction of fish and invertebrates due to the influence of a toxicological factor. This primarily affected the most valuable fish species - salmonids, white-fishes, pike perch. It has been shown that in recent years in Lake Ladoga (especially in its southern shallow zone, the main breeding and feeding zone of many fish species) and other reservoirs of the region, the negative situation of violation of repro-duction of fish and invertebrates (fish food supply) has significantly worsened, which has had a very negative impact, including the decline in the catch of especially valuable fish resources. Measures to prevent negative events are in-dicated. The need to take urgent measures to reduce the flow of pollutants into Europe's largest Lake Ladoga and other important fisheries reservoirs in the North-West region is emphasized.

Distributional movements of subpopulations may act as a buffer to prevent the loss of a species in a certain area. However, within subpopulations adaptations may evolve that makes the inhabitants of a certain habitat to better cope with prevailing environmental conditions. If such traits are related to reproduction, they may reduce the opportunity of gene exchange between other subpopulations. Also, a lack of adaptations to a specific habitat may be what prevents a group of individuals, arriving from an adjacent habitat, to successfully colonize an area where a previous subpopulation has been lost.This is the report from a field study conducted in the wetland Lake Långsjön, that in 2018 was restored in order to promote the recruitment of anadromous pike (Esox lucius) to the Baltic Sea. Commonly, wetlands that are restored to promote anadromous pike recruitment, are constructed so that they enable spawning migration from the sea towards the wetland and juvenile emigration towards the sea only. In that sense Lake Långsjön is different, from other wetlands restored for the same purpose, due to that it is connected to both the Baltic Sea and an upstream located freshwater lake. By quantifying the migration of pike (spawners and juveniles) in both directions I explore the consequences that the regained connectivity between the Lake Långsjön and the coast may have on the population dynamics within this wetland; (i) whether it is potentially influenced by allowing mixture between pike with different migratory strategies for spawning (anadromous and potamodromous), (ii) what drivers there are of pike fry emigration and how they may influence the pike fry emigration route and (iii) whether or not the pike of potamodromous origin, resident in the upstream located lake, may work as a source, providing the Baltic Sea with pike juveniles. Pike spawners arriving in the wetland were caught in traps between March - April. Pike fry were caught withing the wetland with fyke nets and by netting. Emigrating pike fry were caught in fyke nets. Findings suggest that spawning migration patterns do not differ between anadromous and potamodromous pike. However, the spawners arriving from the Baltic Sea I suggested are to be composed by offspring of potamodromous origin, possibly hatched during the previous season, and that they as juveniles swam downstream. This, in turn, indicates that the potamodromous stock can help establish an anadromous stock in the Baltic Sea. Still, due to the observation of pike fry displaying an emigration behaviour upstream, origin is identified as a factor that may influence the pike fry emigration route. Also, this emigration pattern seems to indicate a heritable trait that has not been described before among pike, that of downstream spawning. The restoration of the wetland and the regained connectivity is key, both for the ability to restock the Baltic Sea with pike juveniles but also to ensure the conservation of a fascinating stock of pike exhibiting a unique spawning strategy