Some reproductive characteristics of the Oriental River Prawn Macrobrachium nipponense in Anzali wetland

Abstract

Introduction: Some reproductive characteristics of the nonnative oriental river prawn Macrobrachium nipponense were monthly studied in Anzali Wetland.
Materials & Methods: Totally more than 2,500 prawns were caught and examined during this period.
Result: Their maximum and minimum length and weight were 97 and 10.05 mm, 0.02 to 13 grams, respectively. The average length of shrimp was 45.7±14.3 mm and the mean weight was 1.4±1.376 g. The sex ratio of females to males was 1.1±0.4 on average, which during the peak spawning months, this ratio is more inclined to females. Examining some of the reproductive factors of 244 ovigerous females within the length of 38 to 92.7 mm with an average length of 56.8±8.2 mm showed that the most frequent length and weight classes were 50 to 60 mm in length and 2 to 3 grams in weight, respectively. The minimum oviposition length was 38 mm. Total fecundity was observed 75 to 4146 oval eggs with short diameter 0.35 to 0.8 mm and long diameter 0.5 to 1.0 millimeters. The number of eggs hatched by shrimp was linearly correlated with total length and weight of shrimp. Reproductive efficiency ranged from 0.01 to 0.19.
Conclusion: Although its fecundity is lower than other economical species of Macrobrachium, other characteristics such as reasonable reproductive output and long reproduction period can make them suitable option in aquaculture.