Breeding Strategy of Nannothrissa stewarti POLL and ROBERTS 1976 (Clupeidae) in Lake Mai-Ndombe, Democratic Republic of Congo

Sammanfattning

The clupeid, Nannothrissa stewarti (Poll and Roberts 1976), endemic to Lake Mai-Ndombe, is one of the most heavily fished fish species using practices and nets not allowed by the country's legislation. The objective of this study was to determine some aspects of the reproductive biology of N. stewarti in Lake Mai-Ndombe. Fish were monthly sampled from November 2020 to October 2021. Breeding parameters were determined: gonado-somatic index (GSI), size at first sexual maturity, absolute fecundity and the relationship between total weight (TW) and total length (TL). Results obtained showed that the sex ratio was in favor of females (1: 0.8). Estimated absolute fecundity was between 227 and 4080 oocytes for females of total length between 23 and 35mm, with an average of 923 ± 664g oocytes and a relative fecundity varying between 25120 and 155460 oocytes kg-1. The average oocyte diameter was 0.20 ± 0.14mm. Distribution of oocyte diameters observed in the population as well as monthly variations of the Somatic Gonado Index (SGI) indicates that the species has two main clutches during the year. LT50 size at first sexual maturity is 27.6mm for males and 25.5mm for females. N. stewarti from Lake Mai-Ndombe has multiple reproductions throughout the year, with two maximum peaks at the beginning of the peak rainfall (February-March and September-October).

Nyckelord

Fecundity; First sexual maturity size; Gonado-somatic index; Lake Mai-Ndombe; Maturity stage; Oocyte diameter; Sex ratio

Publicerad i

Egyptian Journal of Aquatic Biology and Fisheries
2023, volym: 27, nummer: 1, sidor: 27-45
Utgivare: Egyptian Society for the Development of Fisheries and Human Health

SLU författare

• Wilander, Anders

  • Institutionen för vatten och miljö, Sveriges lantbruksuniversitet
    

UKÄ forskningsämne

Zoologi
Ekologi

Publikationens identifierare

• DOI: https://doi.org/10.21608/ejabf.2023.280234

Permanent länk till denna sida (URI)

https://res.slu.se/id/publ/129492