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Papers by Benjamin Gonzales

Dragonets are one of the dominant species in Tosa Bay, Southwestern Japan. However, until now, t... more Dragonets are one of the dominant species in Tosa Bay,
Southwestern Japan. However, until now, there is no baseline
information on the conservation status of its species and
populations. This study gathered genetic and ecological data
and information to analyze and measure the historical
conservation status of dragonets in the Bay. Quantitative
values were converted into qualitative ranges to measures the
conservation status of dragonet species. Eight dragonet
species/populations were found to be in stable condition in the
early 1990s, namely: Callionymus planus Ochiai, 1955;
Callionymus lunatus Temminck and Schlegel, 1845;
Callionymus curvicornis Valenciennes, 1837; Callionymus
japonicus Houttuyn, 1782; Callionymus enneactis Bleeker,
1879; Synchiropus altivelis (Temminck and Schlegel, 1845);
Repomucenus virgis (Jordan and Fowler, 1903); and
Repomucenus huguenini Bleeker, 1858. Others were globally
endangered and rare (Callionymus draconis Nakabo, 1977),
locally highly vulnerable (Callionymus valenciennei
Temminck and Schlegel, 1845; Callionymus beniteguri
(Jordan and Snyder, 1900), locally vulnerable (Callionymus
formosanus Fricke, 1981; Bathycallionymus kaianus
(Günther, 1981)), and globally highly vulnerable (Callionymus
sokonumeri Kamohara, 1936). The information gained in this
study provided baseline knowledge on the historical species
risk status of dragonets in Tosa Bay, which can be used as a
basis for future studies. It also provided some scientifically-
based options for managing biodiversity in a defined spatial
management unit, which is applicable to e.g., marine protected
areas, parks, bays, islands, lakes, etc.

Science of the total environment, Feb 1, 2024

Tropical oceans are among the first places to exhibit climate change signals, affecting the habit... more Tropical oceans are among the first places to exhibit climate change signals, affecting the habitat distribution and abundance of marine fish. These changes to stocks, and subsequent impacts on fisheries production, may have considerable implications for coastal communities dependent on fisheries for food security and livelihoods.
Understanding the impacts of climate change on tropical marine fisheries is therefore an important step towards developing sustainable, climate-ready fisheries management measures. We apply an established method of spatial meta-analysis to assess species distribution modelling datasets for key species targeted by the Philippines capture fisheries. We analysed datasets under two global emissions scenarios (RCP4.5 and RCP8.5) and varying degrees of fishing pressure to quantify potential climate vulnerability of the target community. We found widespread responses to climate change in pelagic species in particular, with abundances projected to decline across much of the case study area, highlighting the challenges of maintaining food security in the face of a rapidly changing climate. We argue that sustainable fisheries management in the Philippines in the face of climate change can only be achieved through management strategies that allow for the mitigation of, and adaptation to, pressures already locked into the climate system for the near term. Our analysis may support this, providing fisheries managers with the means to identify potential climate change hotspots, bright spots and refugia, thereby supporting the development of climate-ready management plans.

Fisheries Science, 1997

The spawning cycle of Calliurichthys japonicus and Repomucenus huguenini was investigated from Ma... more The spawning cycle of Calliurichthys japonicus and Repomucenus huguenini was investigated from March 1992 to February 1993 in a wild population in Tosa Bay, Kochi Prefecture. Calliurichthys japonicus is an annual spawner, having high reproductive activity in summer. The species appears to spawn mainly between 90-120m water depth and extends its spawning ground to shallower waters of the Bay during the peak reproductive period in July. Maturity of females occurs at 12.5cm in SL and 17.7 cmSL in male. Repomucenus huguenini is a biannual spawner, spawning within its normal distri bution range of 15-30m water depth during spring (May) and autumn (October to December with a peak in November). This species matures and reproduces from an early age with maturity estimated to occur at 4.5cm SL in both sexes. The temperature in 45-120m when the GI of C. japonicus samples was at its peak in July, ranged from 17.4-21.6•Ž and salinity from 34.6-35.0. During the peak reproductive season of R. huguenini in November, the temperature ranged from 22.4-22.8•Ž and salini ty from 34.4-34.6in 15 to 30m water depth.

Aacl Bioflux, 2016

Coral Bay is the main source of marine-based food to the people of Bataraza, Palawan. Rio Tuba be... more Coral Bay is the main source of marine-based food to the people of Bataraza, Palawan. Rio Tuba being one of the most populated barangays of Palawan has the challenge to balance the utilization and protection of bay's resources. Hence, the author analyzed results of socioeconomic studies conducted in the area and the 3-year coral and fish assessments results to form as basis for its future EAFM/coastal management plan. In order to discern possible impacts of developments, the bay was divided into two zones according to distance from development sites: landward and seaward zones. Fishers of Coral Bay averaged 46 years-old with 4.25 average number of children. Trading/vending of dried and fresh fishes was dominated by women, while aquaculture and capture fisheries by men. From 2007 to 2009, all fish indicators in stations at Landward Zone either remained the same or have improved conditions, except for decreased in fish biomass in two stations, while in seaward zone fishes have generally decreased in abundance and biomass. The live coral cover trend increased in landward zone at 1.0%/year, while 4.4%/year decreased in seaward zone. The fish density (abundance) in landward zone has increased to 25% from previous average density in three years, while has decreased to 39% in the seaward zone. The average fish biomass per year in the landward zone (3.53 kg/250 m 2) was more than three times than that in the seaward zone (1.15 kg/250 m 2) in 2009. This may be because the seaward zone was open to any kind of fishing, including destructive means. While the landward zone has an in-placed security systems provided by private sectors that prevented destructive fishing and therefore might have protected coral and fish resources. In addition, the landward zone has viable population of crocodiles known to enrich estuarine waters that enhances primary productivity and growth of resources. This situations showed that in Coral Bay, proper protection of coastal fishing grounds and resources is a must, whether located near or far settlement/development areas. This study manifests that natural resources adjacent to heavy human population are not necessarily at risk as long as the protection mechanisms are properly in-placed. Hence, the local government must jointly plan with private sectors on how to institutionalize and perpetuate the protection of the bay's resources and more studies like siltation and chemical analysis shall be conducted to augment the results of this study. Information gaps for appropriate management of the bay were recommended in this paper.

Japanese Journal of Ichthyology, 1994

... Shen, S. С and С H. Lee. 1981. Study on sole fishes (Family Soleidae) from Taiwan. Bull. Inst... more ... Shen, S. С and С H. Lee. 1981. Study on sole fishes (Family Soleidae) from Taiwan. Bull. Inst. Zool. Acade-mia Sinica, 20: 29-39. 493 Page 4. В. J. Gonzales et al. 7t>5i/;y^ BenjaminGonzales Piti К ФН'Й.Ш ' "ШШ ■VV <У > J > 9 ЩМ.Ш, V -t V ■> > У > ? ...

SPCP-IMS Research Journal, 1995

Bathycallionymus formusanus, considered a rare dragonet in Tosa Bay, was caught by trawling in 90... more Bathycallionymus formusanus, considered a rare dragonet in Tosa Bay, was caught by trawling in 90-120 m depth of the Bay. Descriptions of the specimens agreed with the previously reported specimens from other localities, Bottom water temperature where the species was collected ranged from 14.00-19.90 C and salinity 34.91-35.33. The diet composition of the examined specimens were similar to its confamilial species and seemed to show more preference on amphipods than polychaetes. The recent trawl survey recorded fourteen species of five genera of the Family Callionymidae in Tosa Bay and Uranouchi Inlet. Ranges of the depth distributions of these species were likewise provided.

Regional Studies in Marine Science

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The LRF in the Philippines started in the 1970s. The influx of traders and fishers to the Calamia... more The LRF in the Philippines started in the 1970s. The influx of traders and fishers to the Calamianes Islands contributed to the overharvest of groupers in the area. While LRF in the southwest of the Sulu Sea started in Talakanen Island, Taytay Bay, in 1997, the “Boom and Bust” trend in fisheries threatens the populations of target valuable species due to overharvesting. Survey studies are essential for fisheries management, but only a few studies were conducted in the West Sulu Sea. This study aimed to document the LRF of the Northwest Sulu Sea and use fisheries dependent and non-fisheries dependent methods to assess the population of P. leopardus in the area. Fisheries dependent and non-fisheries dependent methods were used to determine CPUE, population size structure, abundance, and composition of grouper LRF species. The fishing grounds of LRF were in the inner portion of the bay during Northeast Monsoon, while extended to outer portions during Southwest Monsoon. Three kinds of h...