Ovarian histology and reproductive health of short mackerel, Rastrelliger brachysoma (Bleeker, 1851), as threatened marine fish in Thailand

Abstract

The ovarian structure and reproductive health of short mackerel, Rastrelliger brachysoma in the upper Gulf of Thailand from non-breeding (October to November 2013) and breeding seasons (December 2013 to February 2014), were examined by histological and histochemical techniques. The results revealed that the ovary in this species was enclosed by the tunica albuginea. It was considered as an asynchronous type, which could be classified into seven stages based on its histological characteristics. These seven stages were oogonium, chromatin nucleolar, perinucleolar, oil droplet and cortical alveolar, early, late and post vitellogenic stages. During the oogenic processes, the change and characterization of inclusions including lipids, cortical alveoli and yolk granules were detected by histolochemical techniques. The ovarian histopathology in R brachysoma was detected. This includes ovarian degeneration, ovarian atrophy and atresia in different stages (oogonia, previtellogenic stages and vitellogenic stages) as well as melano-magcrophage centers. Atretic follicles and ovarian atrophy were also observed and could negatively affect the reproductive health of the species, which could lead to population declines in R. brachysoma as well as threaten other marine fishes connected through the food web in Thailand.

Keywords

• ovary
• histopathology
• Rastrelliger brachysoma
• reproductive failure