Akahiretabira, an undescribed subspecies of Acheilognathus tabira, known as subsp. (a) sensu Nakamura (1969), has been reported to lay oval shaped eggs. The juveniles generally do not have a dark spot on the dorsal fin, unlike seboshitabira, A. tabira subsp. (b) sensu Nakamura. We collected several adult and juvenile akahiretabira from a small agricultural stream in Natori Basin, Miyagi Prefecture. With gentle pressure applied to her belly, a mature female laid elliptical eggs (2.50±0.063mm x 1.22±0.085mm in diameters). Juvenile dorsal fins did not have a small dark spot, but visually appeared a solid gray, and melanocytes were found to be more or less uniformly distributed. Morphological variation within species and also within subspecies of A. tabira is more variable than previously recognized.

We rediscovered Acheilognathus typus in Lake Izunuma-Uchinuma basin in autumn 2006. This species is designated an Endangered species in the Red list of Japan. A. typus had not been captured in Lake Izunuma-Uchinuma basin since 2000.To protect A. typus in this area, the following research of the distribution of the population needs to be conducted.

The emergence periods of larvae from the adult mussel in an endangered bitterling Acheilognathus typus and invasive bitterling Rodeus ocellatus were investigated in a sympatric habitat. The emergence period of A. typus was from late May to late June. The peak of emergence in A. typus was late May when the mean water temperature was at 18.6℃. The emergence period of R. ocellatus was from early-June to late October. The peak of emergence in R. ocellatus occurred from late June to mid July. The period and the peak of the emergence in A. typus was earlier than R. ocellatus. The emergence of A. typus was concentrated during one month.These results indicate that the investigation of A. typus larvae should be conducted within a few weeks after the beginning of larvae emergence.

In Lake Izunuma-Uchinuma, Japan, the invasive species: bluegill, Lepomis macrochirus, have been rarely caught, and there is a small possibility they have spawned. A population of bluegill was discovered in an irrigation pond in the Lake Izunuma-Uchinuma basin in autumn 2006. In the pond, we captured several 0+ juveniles (29.4-46.3mm in standard length) and an adult fish (118.8mm), indicating that the bluegill population has reproduced in the pond. Moreover, in the creek which connected the pond with Lake Izunuma, we captured a 0+ juvenile (28.6mm). It is highly likely that this 0+ juvenile dispersed from the pond. There is continually a risk that bluegill will disperse into the lake, and establish a population, causing serious damage to the lake’s ecosystem. To stop dispersion of the bluegill into the lake, they must be exterminated from the pond.

Habitat selection of Greater White-fronted Geese Anser albifrons and Whooper Swans Cygnus cygnus was studied in rice fields (30ha) adjacent to Lake Izunuma-Uchinuma from November to February in the 2004/05 wintering season. Greater White-fronted Geese arrived at the study sites from distant rice fields north of the lake after 10:00 A.M. The number of Whooper Swans gradually increased during the morning. Through out the season the main behaviors of both species were foraging and resting. The density of foraging geese was higher in rice fields harvested by combine than in other kinds of rice fields (e.g. fields harvested by reaper machinery, unharvested, or fallow fields). It was similar to foraging densities on levees. In contrast to the geese, swans foraged in winter-flooded rice fields and levees. Differences of habitat selection between both species result from the differences of foraging methods; the geese are picking, while the swans are filtering.

Artificial spawning nests (ASN) were experimented with and developed in order to prevent successful reproduction of largemouth bass Micropterus salmoides. A total of 128 ASN of 15 types were set on the natural spawning grounds along the south coast of Lake Izunuma (sand zone, 40-140 cm in depth). Eight ASN were set so deep, 110-140 cm, that it was impossible to observe spawning, and 14 ASN were broken mainly by bass anglers. Largemouth bass spawned in 32 ASN from early May to late June. ASN that used plastic net trays for spawning boxes showed higher spawning rates than those with plastic containers. ASN spawn boxes that were graveled with macadam showed significantly higher spawning rates. The most appropriate shielding to set up on the ASN was one that blocked three sides. Five improved ASN composed of plastic net boxes, graveled with macadam (4-5cm in diameter) inside, and plastic net screens (35cm in height) blocking up three sides were made. These were set in the natural spawning grounds and 100 percent of them were used as spawning nests by largemouth bass.

Dwarf topmouth gudgeon Pseudorasbora pumila pumila is listed as an endangered species in the Red List of Ministry of the Environment, Japan. It is endangered because of hybridization with Topmouth gudgeon Pseudorasbora parva, and the influence of alien fish such as Largemouth bass Micropterus salmoides. The Society for Shinaimotsugo Conservation study group is engaged in increasing and reestablishing Dwarf topmouth gudgeon populations in ecosystems by developing successful artificial breeding, and determining the proper timing for transplanting spawns. As a spawning substrate, we used plastic pots instead of conventional chloroethylene pipes, and obtained excellent results (spawning rate = 100%). Experiments examining the timing to transplant the spawns found that transplanting at the eyed-egg stage had the highest hatch success. These results brought marked improvement in artificial breeding success of Dwarf topmouth gudgeon, and consequently in methods for restoration of ecological systems.

The spawning area for largemouth bass was surveyed with the Side scan sonar in Lake Izunuma. Individual spawning spot for largemouth bass was not able to be distinguished in a sound image of the Side scan sonar alone. However, it was possible to estimate the influence of waves on the spawning area by identifying the ripple besides the division of the sediment and the structures. The range where the artificial spawning beds were installed and that was the main spawning area in Lake Izunuma was chiefly composed the sediment of sand only, and the influence of waves was weak. On the other hand, it was chiefly composed the sediment of sand and mud outside of the range where the artificial spawning beds were installed. It was guessed that the range composed of sand was under the influence of waves from the situation of a surrounding ripple. If it was 1m or more in depth, even in case of the turbid water, it was shown to be able to select the spawning area of largemouth bass and the smallmouth bass, and to become one of the effective methods to control the alien fishes.