Cod’s Journey Back Home—From Birth to Nursery

Adult cod swim hundreds of kilometers away from home to release their eggs into the ocean water. After some days, tiny larvae hatch from the eggs. At first, the larvae have a small food reserve to sustain them during their first days of life. Soon after emptying the yolk-sac, the larvae must find food on their own. Both eggs and larvae are carried by the ocean currents and they experience large changes in conditions as they drift back to the nursery areas where their parents came from, where the larvae grow up to become adult fish. Our research on cod indicates that the number and location of cod larvae are associated with the size of the spawning adults; and that the number of larvae influences how many cod will grow to be recruits. So, it is important to also know the living conditions of the parents before they spawn, which will be important for the survival of their offspring.

WATER BIOLOGICAL RESOURCES OF THE REPUBLIC OF MORDOVIA: THE MOKSHA RIVER

The article is focused on the problem of biological resources of the Republic of Mordovia. The Moksha River is traditionally the main fishery water body in the Republic of Mordovia. There have been presented the results of comprehensive fisheries research for 2009-2015 carried out on the segment of the Moksha within the Republic of Mordovia. Analysis of the food supply has shown a significant underutilization of zoobenthos, phytoplankton and macrophytes. Using the data, which are the average indicators of the food reserve over the years, the river’s production capabilities were calculated and made 418.6 tons or 186.9 kg/ha. According to the results of research catches with fixed nets and minnow seines, the composition of the fishing ichthyofauna was determined, where roach, perch, goldfish dominated in number, roach, crucian carp, bream, perch dominated in biomass. There were recorded in total 29 fish species, mainly carp species. There has been defined the ichthyomass of fish aged two years and older, which varies from year to year within 141.3-180.2 tons or 63-81 kg/ha, and taking into account juvenile species it will make 108 kg/ha. As for the most significant species in the fish ichthyofauna (roach and silver carp) the increase in fish production was calculated (8.6 and 14.9, correspondingly) and the total catch quotas were determined. Under the constant value of the average catch per year effort, they amount to 50-60 tons. Taking into account the free food reserve due to the reproduction and protective measures carried out at the expense of compensation funds for the damage caused to aquatic biological resources, the catch of marketable fish species in the Moksha River can be in-creased in 2.0-2.5 times.

ASSESSMENT OF PHYTOPLANKTON AS FOOD RESERVE IN MIDDLE CASPIAN

The paper considers the specific features of development of the qualitative composition and ecological groups of plankton algae in the Middle Caspian in the summer of 2019. The yearly dynamics of biomass and the number of algae in the sections of Makhachkala - Cape Sagyn-dyk, Derbent - Cape Peschanny, Divichi - Kenderly Bay has been examined. During the study period 109 samples were collected and examined and 110 taxonomic units of algae were found, with diatoms always prevailing. The structure-forming role belonged to freshwater algae (37 %), which became characteristic of this part of the sea. The biomass and number of phytoplankton in the Middle Caspian made 12.9 million copies/m3 and 166.56 mg/m3, respectively. The layer-by-layer distribution of biomass was determined by the intensity of development of the diatomaceous alga Pseudosolenia calcar-avis. The most favorable conditions for vegetation of dinophytic feed organisms were formed in the western (sections of Makhachkala - Cape Sagyndyk, Derbent - Cape Peschanny) and central (Divichi - Kenderly Bay) parts of the section in a layer of 0-25 m, which presumably has a positive effect on the development of planktonic organisms. Small-cell forms of algae dominated, which is an important aspect in the formation of the fish food reserve.

Effects of Stockholding Policy on Maize Prices: Evidence from Zambia

Many countries in the developing world use public stockholding programs to stabilize prices for both farmers and consumers. Governments directly purchase and store staple grains, and then sell them to processors or consumers, often at heavily subsidized prices. Despite the substantial costs of these stockholding programs, little is known about their effectiveness in mitigating retail price swings. This paper estimates the effects of purchase and sales activities of the Zambian Food Reserve Agency (FRA) on monthly maize market prices across more than thirty markets in Zambia from 2003 to 2008. To deal with the endogeneity in purchases and sales, we use predicted FRA purchase and sales targets as instrumental variables. Controlling for other policies, we find evidence that FRA activities stabilize retail prices in major district markets within the cropping year. Results show that FRA purchases raise local prices for surplus maize producers about 5 % on average at the time of harvest, and that FRA sales help lower the prices to consumers during the lean season up to 7 %. However, we find limited evidence that the FRA is able to reduce price volatility between years.