Trichiurus lepturus is a species that is highly valuable in the commercial fishing industry along the Babuyan Channel, a significant fishing ground in the Philippines. Data was collected from April 2018 to March 2020 at the established National Stock Assessment Program (NSAP) fish landing centers along the Babuyan Channel. The population parameters and gonadosomatic index were analyzed using FAO-ICLARM Fisheries Stock Assessment Tools II software and a five-point scale maturity index, respectively. A total of 2,597 fish samples were collected, with a higher number of female individuals. The mean fecundity observed was 48,576 eggs, with spawning occurring mainly in May (1st peak) and October to November (2nd peak). Majority of the observed females were at Stages IV and V, indicating that the Babuyan Channel is a spawning area.
The province of Cebu is endowed with rich fisheries resources and is one of the known milkfish fry-producing areas in the Philippines. Milkfish fry fishery is one of the most critical industries in the country, and it provides livelihood to many coastal communities. However, with the global climate change threat, coastal areas serving as milkfish fry grounds are at risk. This study assessed milkfish fry fishery sites in Argao and Bantayan using a Fisheries Vulnerability Assessment Tool (FishVool). Vulnerability assessment tools aid in identifying risks, impacts, and possible climate change adaptation strategies..
The number of non-native fish species introduced into the Philippines has steadily increased over the last decades, similar to other Southeast Asian countries. This trend of non-native species introductions is of high concern for the conservation of the native aquatic biota of the country, as invasive fishes are known to be responsible for a wide range of detrimental effects. In this study, the 13 non-native freshwater fish species recently reported for Ramsar-listed Lake Naujan (Province of Oriental Mindoro) were screened for their invasiveness risk under current and predicted climate change scenarios. Of the screened species, 23.1% and 61.5% were ranked as high risk under current and future climate conditions, respectively. The higher-risk species were redbelly tilapia Coptodon zillii, Nile tilapia Oreochromis niloticus, and guppy Poecilia reticulata.
Consuming scombroid fish containing high histamine levels can lead to histamine fish poisoning caused by the proliferation of histamine-forming bacteria (HFB). Interestingly, some HFB strains have developed resistance to antibiotics. This complicates efforts to control their populations in fish and aquatic environments. As these bacteria become harder to eliminate, the risk of histamine fish poisoning may increase, highlighting a concerning link between antibiotic resistance and food safety. In this study, the histamine concentration levels and the presence and antibiotic resistance of isolated HFB in bullet tuna were investigated. The fluorometric method (AOAC 977.13) showed that the average amount of histamine was 39 ppm, which was below the local regulatory limit (< 200 ppm). Ten (10) presumptive HFBs were isolated using modified Niven’s agar. However, only five of the 10 isolates were identified at the species level by molecular methods. These isolates were then identified as Proteus mirabilis (Hfb_5, Hfb_8, and Hfb_13) and Klebsiella pneumoniae (Hfb_6, and Hfb_10). These potential HFBs were subjected to antibiotic susceptibility testing.
The Philippines is the second biggest source of skipjack tuna (Katsuwonus pelamis), contributing to the country’s economic development. However, its sustainability faces challenges due to overfishing and a lack of proper management practices. Otoliths are important tools for managing fish stocks, but their analysis is time-consuming and requires a high level of expertise. In this paper, we explored the use of convolutional neural networks (CNNs) to recognize patterns and classify them according to developmental stages.
This study aims to identify microplastic pollutants of four important commercial fish (Johnius borneensis, J. macropterus, Osteomugil engeli, and Sardinella fimbriata) in the east coast of North Sumatra Province, Indonesia. The study was conducted from May to December 2022 in Langkat, Deli Serdang, Serdang Begadai and Batu Bara Regency, Indonesia. Microplastic analysis was conducted at the Biology Laboratory, Faculty of Mathematics and Natural Sciences, Universitas Negeri Medan, Indonesia. The microplastic extraction process was started by inserting the target fish organs into 10% KOH solution (1:10 ratio), then incubated for 12 hours at 60°C. Furthermore, the decomposed fish organs were filtered using Whatman No. 540, assisted by a vacuum machine; then the filter results were incubated at 50°C for 5 hours so that the liquid on the filter paper evaporated.
A. vaigiensis is one of the top ten aquarium reef fish in the world, but the supply of this ornamental fish species is mainly from the collection of wild populations. This current study investigated some aspects of the reproductive biology of Indo-Pacific sergeant A. vaigiensis (Quoy and Gaimard 1825) from Iligan Bay, Southern Philippines from August 2021 to August 2022. Monthly samples of 35 to 45 individuals per class size with a range of 6.8 to 15.3 cm (TL) were collected to examine the sex ratio, maturity stages and spawning period, gonado-somatic index (GSI), length at first maturity (L50), and the batch fecundity (BF) of the species. The sex ratio showed female dominance (1:1.09) among size classes and across months.
The abundance and population size structure of two populations of the crown-of-thorns seastar (COTS), Acanthaster sp., were investigated as part of removal activities of the seastar due to population outbreaks in two areas of Camiguin Island, Northern Mindanao. Abundances reached 75 and 160 individuals/hectare for Pasil Reef and San Roque, respectively. Mean weights and diameters were 302.64g and 340.89g, and 21.37cm and 24.09cm for Pasil and San Roque, respectively. Size frequency distribution of the diameters and weights of the seastars indicate that the populations in both areas were composed of different cohorts. The COTS population in San Roque had characteristics of a relatively more mature population compared to that in Pasil Reef.
Otoliths, crucial tools for understanding fish biology and ecology, offer valuable insights into fisheries science in Southeast Asia. Traditionally used for age identification through shape analysis and growth ring counting, otolith studies have evolved to encompass broader ecological investigations. This review synthesizes literature on fish otoliths in Southeast Asia to identify research gaps and suggest future directions. Utilizing targeted keywords, we mined data from scientific search engines, focusing on peer-reviewed articles. Our analysis spans 1988 to 2021 and collated 129 publications, which were trimmed to 91 reviewed scientific articles. Otolith microstructure emerged as a primary research area of interest, with a focus on catadromous fishes from the Anguillidae family.
Frigate tuna (Auxis thazard, Lacepede, 1800) is a commercially valuable food fish thriving in tropical marine waters. In the Philippines, despite its abundance, information on its estimated age and growth patterns is lacking. This study reported the relationship between the size (fork length, FL) and age (otolith growth increment) of frigate tuna using the sagittal otoliths. Sampling was conducted in the Celebes Sea, including the inner bay and gulfs within it (e.g., Moro Gulf, Sarangani Bay, and Davao Gulf) from November 2020 to September 2022. A total of 1,046 frigate tuna samples with sizes ranging from 14.5 cmFL to 44.7 cmFL, caught using ring nets, hand lines, and purse seine nets, were examined.
Organogenetic alterations described over the stages of gonadogenesis at the gross and microscopic scale can be used to determine spawning behavior in iteroparous fishes and provide finer details of the reproductive functions of commercially important species. This information can be used as the basis for stock assessment and maintenance of wild populations. In this study, the gross morphology of Eastern Little Tuna (Euthynnus affinis) gonads from Sarangani Bay, Davao Gulf, Moro Gulf, and Sulawesi Sea collected in 2020–2022 was investigated along with its microanatomy through histotechniques.
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.
T he 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.