Rosy bitterling
| Rosy Bitterling | |
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| Scientific classification | |
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| Genus: | Agassiz, 1832
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| Species: | R.ocellatus Kner, 1866
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| Subspecies: | R.o.ocellatus
R.o.kurumeus (=R.o.smithi)Regan, 1908
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| Binomial name | |
| Rosy Bitterling | |
Rosy bitterling (Rhodeus ocellatus) is a small fresh-water fish belonging to the family ''Cyprinidae''(carp) and genus ''Rhodeus''. Female size is about 40-50 mm length and male is about 50-80 mm. Body is flat and basically luster argent colored. However, male changes body color to reddish (sometimes purple) during the spawning season (Mar~Sep) for tempting females. Such reddish color is just like a beautiful rose flower. That is why it is called rose bitterling.[1][1]
Ecology and Reproductive system
Rosy bitterling lives in farm ponds (reservoir) where freshwater mussels live. Freshwater mussels like Dobugai are very important for rosy bitterling (especially for the reproductive system).
Every female rosy bitterling has an unique pipe for laying eggs into the specific spot of mussel easily. The pipe is about the same length as own body length. Usually 2-3 eggs are laid at once and placed at the gill. A male spawns into the gill cavity of the massele Right after a female lays eggs so eggs are safely fertilize within a mussel.[2] Normally a female repeats laying eggs at 6-9 days intervals and about 10 times in a season. Eggs grow in the mussel gill and juveniles stay inside of the mussel for approximetly 15~30 days after fertilized. Eggs are hatched about 3 days and juveniles are about 2.8 mm long in this point. The body is very unique shapes like bud of matsutake mushrooms. Juveniles swim through out from the margin of excurrent siphon. In this time juveniles are about 7.5 mm long and about same shape as adults.[3] Usually juveniles grow around 40-50 mm within one year and become as adults. Their life span is about 3 years. Especially It is very rare for R. o. kurumaeus(Nippon baratanago) living more than 3 years. [4]
Subspecies
Rhodeus ocellatus kurumaeus (Nippon baratanago) is a Japanese native species but Rhodeus ocellatus ocellatus (Tairiku baratanago) is found in China, Taiwan, as well as in Japan. Nippon baratanago was widely spread in the west side of Japan (Kyushu and western part of Honshu) before World War II. In 1942 Tairiku baratanago was accidentally introduced with grass crap (Ctenopharyngodon idellus) and silver carp (Hypophthalmichthys molitrix) from mainland China to Japan.[5]
These two subspecies are morphologically very similar but there are several different characters for distinguishing between them such as number of longitudinal scales, principal rays in the dorsal and anal fins, and shape of eggs. Also, another morphological distinguishing feature is found only in one subspecies. R. o. ocellatus (Tairiku baratanago) has a silvery-white area anteriorly (white lines) on the ventral fin but R. o. kurumaeus (Nippon baratanago) does not. The ventral fin of R. o. kurumaeus (Nippon baratanago) is entirely more dark color instead.[6] Another remarkable difference is body size. R. o. kurumaeus (Nippon baratanago) that exceeds 60mm in the body length is really rare, whereas males are larger than 80mm and females exceeds 60mm are usually found in R. o. ocellatus (Tairiku baratanago).[7]
Status
Rhodeus ocellatus kurumaeus (Nippon baratanago) was widely distributed in small ponds, reservoir, and creeks in Kyushu and the western part of Japan. However, since Rhodeus ocellatus ocellatus (Tairiku baratanago) was introduced the population of Tairiku baratanago has been dramatically increasing all over Japan. It has been seen that these subspecies coexist in many area. Also, as some individuals which identified as R. o. kurumaeus (Nippon baratanago) show white coloration on the ventral fins, it expected that hybrid populations have been increasing. In fact hybridization and subsequent gene introgression had been observing within these subspecies in Kashima and Ogori [8]
Because of this interbreeding the number of R.o.kurumaeus has dramatically declined all over Japan and now the population of R. o. kurumaeus (Nippon baratanago)) is in danger of extinction. Even though both subspecies are not on the IUCN Red List, Nippon baratanago (R. o. kurumaeus) is listed as a critically endangered species on the Japanese Red Data Book. [9]
Conservation
The numbers of Japanese native Rosy bitterling in various places have declined cased by environmental pollution, reservoirs condition, etc. Also, because the numbers of black basses and bluegills increase in such places, the number of food availability for rosy bitterling declines. Since R. o. kurumaeus (Nippon baratanago) is critically endanger non-profit organizations and study groups were established in Japan. Yao study group, one of the Japanese rose bittering conservation group, started activities for protecting endangered Nippon baratanago. For example Yao study group (Yao city, Osaka) made the protection pond in May 1999 and 41 (male) and 60 (female) Nippon baratanago were released with prawns. Also, 45 fresh-water mussels were transplanted at the same time. They had been monitoring and collecting data regularity through 2001. In 2000 they success to increase the Nippon baratanago population up to 6000 and they transferred 500 individuals to another 5 ponds from the protected pond. However, in 2001 only few individuals were collected. In this year water quality was bad compared to the previous year so the study group concluded that eutrophication affected to the reproductive system of rosy bitterling. Because of this they realized how water quality is important for protecting rosy bitterling. Since then, they started considering designing new purification system for conservation of Japanese native rosy bitterling. They also educate children as an environmental study for the next generation. [10][10]
References
- ^ 加納義彦. ニッポンバラタナゴの保護と環境保全. 第５回日本水大賞受賞活動集. 日本水大賞顕彰制度委員会. 42－45. 2003.
- ^ Kanoh, Y. 2000. Reproductive success associated with territoriality, sneaking, and grouping in male rose bitterlings, Rhodeus ocellatus (Pisces: Cyprinidae). Env. Biol. Fish. 57: 143-154
- ^ Nagata, Y. 1976. Reproductive behavior of a bitterling, Rhodeus ocellatus (Kner). Physiol. Ecol. Japan 17: 85-90 (in Japanese)
- ^ Kimura, S., and Nagata, Y. 1992. Scientific name of Nipponbaratanago, Japanese bitterling of the genus Rhodeus. Japan.J.Ichthyol. 38: 425-429
- ^ Kawamura, K., Nagata, Y., Ohtaka, H., Kanoh, Y., and Kitamura, J. 2001. Genetic diversity in the Japanese rosy bitterling, Rhodeus ocellatus kurumeus (Cyprinidae). Ichthyol Res 48: 369-378
- ^ Nagata, Y., T. Tetsukawa, T. Kobayashi and K. Numachi. 1996. Genetic markers distinguishing between the two subspecies of the rosy bitterling, Rhodeus ocellatus(Cyprinidae). Japan. J. Ichthyol. 43: 117-124
- ^ Kimura, S., and Nagata, Y. 1992. Scientific name of Nipponbaratanago, Japanese bitterling of the genus Rhodeus. Japan.J.Ichthyol. 38: 425-429
- ^ Miyake, K., Tachida, H., Oshima, Y., Arai, R., Kimura, S., Imada, N., and Honjo, T. 2000. Genetic variation of the cytochrome b gene in the rosy bitterling, Rhodeus ocellatus (Cyprinidae) in Japan. Ichthyol Res 48: 105-110
- ^ Kawamura, K., Nagata, Y., Ohtaka, H., Kanoh, Y., and Kitamura, J. 2001. Genetic diversity in the Japanese rosy bitterling, Rhodeus ocellatus kurumeus (Cyprinidae). Ichthyol Res 48: 369-378
- ^ Kanoh, Y., Yoshinaka, T., Takemoto, Y., Iwasaki, and Y., Nishino, T. (Yao study group of Japanese rose bitterling) 2002. Conservation of Japanese rose bitterling Rhodeus ocellatus kurumeus. (in Japanese) 第11期 プロ・ナトゥーラ・ファンド助成成果報告書
External links
- Genetic markers distinguishing between the two subspecies of the rosy bitterling,Rhodeus ocellatus (Cyprinidae)
- Species summary for Rhodeus ocellatus ( Rosy bitterling )
- "Rhodeus ocellatus". Integrated Taxonomic Information System.
- Tazonomy summary for R.o.kurumaeus (nippon baratanago)
- Taxonomy summary for R.o.ocellatus (tairiku baratanago)
- Japanese Red List Data 日本環境庁（現・環境省）レッドリスト
- Conservation of Nippon Baratanago 香川淡水魚研究会
- Conservation of Nippon Baratanago and its Evironment ニッポンバラタナゴの保護と環境保全