Work

At the Onset of Gonadogenesis: The First Description of Ovarian and Testicular Macro and Microanatomical Maturation of Bullet Tuna (Auxis rochei) in Southern Philippines

Year: 2024

Type: article

Abstract: Structural and functional maturation in gametogenesis through comprehensive histoarchitectural and gross morphological analyses can serve as a powerful tool for gauging population health and resilience within gonochoristic fish populations. The Philippines boasts a robust neritic tuna fishery, with Bullet Tuna (Auxis rochei) being a significant species. Nonetheless, our understanding of reproductive parameters in neritic tunas remains deficient, hampering sustainable management strategies. In this study, 975 fish samples were collected from Sarangani Bay, Davao Gulf, Moro Gulf, and Sulawesi Sea. Samples were then classified and grouped into four size classes: Size 1 (≤ 15 cm), Size 2 (15.1 – 25 cm), Size 3 (25.1 – 35 cm), and Size 4 (>35 cm). Six reproductive maturity stages were profiled: Immature, Onset Maturation, Developing/Maturing, Spawning/Mature, Spent, and Recovering. In Spawning/Mature, the testis appears opaque white, with full lobes discharging contents.At the same stage, the ovary is orange/pink in color, with noticeably visible venation. Examination of histoanatomy shows viable spermatozoa in testes, along with lobular lamina, secondary and primary spermatocytes, and spermatids. Ovaries at this stage show secondary vitellogenic oocytes and prominent yolk granules, with distinguishable follicular epithelium at the border of the follicle. Our data show that A. rochei gonad strategy is asynchronous and spawns at 25.1–35.0cm (Size 3). Our study is the first description of the gonadal maturity on the gross and histological aspects of Auxis rochei concerning its fish body length in the waters of Sarangani Bay, Davao Gulf, Moro Gulf, and Sulawesi Sea.

Source: The Philippine Journal of Fisheries

DOI: 10.31398/tpjf/31.1.2023-0028