Spawning seasons of Rasbora tawarensis (Pisces: Cyprinidae) in Lake Laut Tawar, Aceh Province, Indonesia

Abstract

BackgroundRasbora tawarensis is an endemic freshwater fish in Lake Laut Tawar, Aceh Province, Indonesia. Unfortunately, its status is regarded as critical endangered with populations decreasing in recent years. To date no information on the spawning activities of the fish are available. Therefore, this study provides a contribution to the knowledge on reproductive biology of R. tawarensis especially on spawning seasons as well as basic information for conservation of the species.MethodsMonthly sampling was conducted from April 2008 to March 2009 by using selective gillnets. The gonadosomatic index, size composition and sex ratio were assessed. The gonadal development was evaluated based on macroscopic and microscopic examinations of the gonads.ResultsThe gonadosomatic index (GSI) varied between 6.65 to 18.16 in female and 4.94 to 8.56 for male. GSI of the female R. tawarensis was higher in March, September and December indicating the onset of reproductive seasons, the GSI and oocyte size being directly correlated with gonadal development stages. Although, a greater proportion of mature male than female was detected during the study, the sex ratio showed that the overall number of female was higher than male. The ovaries had multiple oocyte size classes at every stage of gonadal development, thus R. tawarensis can be classified as a group synchronous spawner or a fractional multiple spawner.ConclusionThe spawning seasons of R. tawarensis were three times a year and September being the peak of the reproductive season and the female was the predominant sex. This species is classified as a group synchronous spawner.

Genetic variation and taxonomy of Rasbora group (Cyprinidae) from Lake Laut Tawar, Indonesia

“…However, R. tawarensis occurs only in Lake Laut Tawar being an endemic of this lake. Studies on the some biological aspects of this endemic species have been reported by Muchlisin et al (2010aMuchlisin et al ( , 2010bMuchlisin et al ( , 2011aMuchlisin et al ( , 2011b.…”

Distribution, Composition, and Abiotic Environment of Silver Rasbora (Rasbora argyrotaenia Blkr) Fish in Upstream Areas of Barito Watershed, South Kalimantan

“…Difference color of water firmly relates to water turbidity level, otherwise, water turbidity level affects an existence of R. argyrotaenia fish. Muchlisin et al (2010) asserts that the existence of fish belonging to one genus with R. argyrotaenia, i.e. R. tawerensis when gonadal maturity stage is reached, it always lives in an area with high transparency value.…”

“…It belongs to one of primary commodities giving the greatest contribution to inflation in South Kalimantan in January-October, 2011 (Central Agency on Statistics of South Antara News Agency, 2011). High demand on a fish species may trigger high exploitation activity and exploitation intensity to fish resources affecting degradation of the resources itself (Allan, et al, 2005;Alonso et al, 2008;Dudgeon, 2000Dudgeon, , 2005Triyanto, et al, 2009;Muchlisin, et al, 2010). Exploitation activity of R. argyrotaenia is dominantly executed in upstream areas of Barito watershed, tributary, and surrounding marshes (Rosadi, 2009;Chairuddin, et al, 2011) by reaching 80% of R. argyrotaenia total production in South Sulawesi (Fisheries and Marine Services of Barito Kuala Regency, 2011).…”

Reproductive performance of asian catfish (Hemibagrus wyckii Bagridae), a candidate species for aquaculture

“…Please cite these references to enhance your methods: Muchlisin  et al ., 2010 1 Muchlisin  et al,  2011 2 …”