Histopathology Laboratory, Regional Science Research Center, Office of the Vice Chancellor for Research and Extension, Mindanao State University General Santos
Corresponding author
johnchristianentia12@gmail.com
,
Glennville A. Castrence2,
Blessie Justine G. Arellano1 ,
Red Arthur Duke A. Amoncio1 ,
James T. Wetzel3, Edna P. Guevarra4
The structural configuration of oogonial and spermatogonial models in oviparous species are key determinants of reproductive biological parameters, as these factors also determine gonadogenesis and spawning lengths. This study systematically characterized frigate tuna (Auxis thazard) collected from the southern Philippine waters, including Sarangani Bay, Davao Gulf, Moro Gulf, and the Sulawesi Sea. Characterization involved a comprehensive analysis of gross gonadal features, aided by gross morphological identification and histological profiling utilizing Hematoxylin and Eosin (H&E) staining. Samples were caught and categorized into four size classes: Size 1 (≤ 20 cm), Size 2 (20.1–30 cm), Size 3 (30.1–40 cm), and Size 4 (>40 cm). Histological evaluation of gonads indicated asynchronous ovarian strategy, which undergoes six stages: Immature, Onset Maturation, Developing or Maturing, Spawning (during which active release of gametes occurs), Spent, and Recovering. At the spawning stage, ovaries were characterized by their prominent blood arteries, orange or pink color, and large, transparent ovum; testes were characterized as creamy-white full lobes prone to discharge under pressure. Histoanatomy of this stage showed yolk granules in the cytoplasm and mature follicles (in females); for males, the occurrence of the sperm duct, main sperm duct, and spermatozoa. Females at the spawning stage were 25.10–42.00 cm (FL), while males were 42.00–48.70 cm (FL). The size of sexual maturation of A. thazard occurred at 30.10–40.0 cm (Size 3). Notably, our study represents the first association between gonadal development and fish sexual maturity length in A. thazard within the Philippines.