The influence of temperature on the hemolymph CO_2 solubility coefficient (αco_2, µM/L/torr) was investigated in the marine bivalves, akoya pearl oyster Pinctada fucata martensii, Pacific oyster Crassostrea gigas and noble scallop Mimachlamys nobilis. Hemolymph samples were equilibrated with standard CO_2 gas mixtures to obtain expressions for αco_2 as a function of temperature. Relationships between hemolymph αco_2 and temperature (T) were expressed as follows： αco_2 = 76.88145 − 2.62637 ･ T + 0.036203 · T^2 (for P. fucata martensii), αco_2 = 94.2109 – 3.6252 · T + 0.0554 · T^2 (for C. gigas), αco_2 = 70.4591 – 1.5253 · T + 0.0103 · T^2 (for M. nobilis). In the distribution of hemolymph αco_2 values, there was no statistical significance across an interspecies comparison of αco_2. From this result, the regression was fitted using all values of αco_2 and temperature across the species, and the relationship was expressed as follows： αco_2 = 182.3717 – 24.3932 · T + 1.6396 · T^2 – 0.0492 · T^3 + 0.000536 · T^4. This polynomial is versatile equation and would yield the hemolymph αco_2 at arbitrary temperature, even with different species.

To ensure the stable supply of the euglenophyte Eutreptiella eupharyngea in the seed production of bivalves during the winter, we evaluated the growth potential of E. eupharyngea under low water temperatures through laboratory and outdoor experiments. In laboratory experiments, no significant difference was found in the maximum yield of E. eupharyngea between water temperatures of 10 and 20℃, whereas the maximum yield of the diatom Chaetoceros neogracile known as a common diet alga for the seed production of bivalves significantly decreased at 10℃ compared with 20℃. In an outdoor experiment on a 150-L scale at a salinity of 25, furthermore, E. eupharyngea grew well in mid-winter, and reached the maximum cell density of 3.7 × 10^5 cells mL^–1. During the outdoor experiment, water temperatures ranged from 0.5 to 23.7℃, with a mean of 10.7℃. Although the water temperature in the mass-culture tank fluctuated significantly with the weather and day or night, E. eupharyngea maintained more than 2.2×10^5 cells mL^-1 for 12 days. Therefore, E. eupharyngea may contribute to the stable supply of the feed throughout seed production of bivalves in late fall and spring.

There are various types of farmers' markets； depending on the type used, the markets have both advantages and disadvantages for fishing households. In reality, fishing households utilize multiple farmers’ markets as sales channels because utilizing multiple markets offers advantages for fishing households. However, previous research on direct sales using multiple different types of farmers' markets are limited. Taking the Tabuse Fisheries Improvement Group “Shinsen Tabuse” as a case and confirming the benefits and drawbacks of direct sales using multiple farmers’ markets as sales channels, we examined the significance of direct sales using multiple sales channels. The results revealed that there were both advantages and disadvantages for fishing households, depending on the characteristics of the farmers' markets that fishing households utilized. We also found that utilizing multiple sales channels in direct sales helped avoid the accumulation of product stock, and fishing households acquired more customers.