72 JUNE 2024 • WORLD AQUACULTURE • WWW.WAS.ORG by Young et al. (2021b) and Dickson (2022), culture technology support and environmental factors have spurred the growth of Asian sea bass, gilt-head bream, Sabaki tilapia, and snubnose pompano farming in Saudi Arabia since the 2010s. Nonetheless, many marine finfish producers still depend on fingerlings imported from Bahrain, Turkey, and other Mediterranean countries, resulting in limited species diversity and product development opportunities. Saudi Arabia is uniquely positioned to develop mariculture, leveraging its warmer waters to enhance productivity, especially during winter months. Sobaity seabream, commonly found in tropical regions, thrives in brackish and marine waters with optimal temperatures ranging from 28° to 30° C. High water temperatures ranging from 17.5° C to a maximum of 35° C have posed challenges for Saudi producers, limiting both suitable culture species and the seasonality of cultivation periods (Young and AlMoutiri 2022, Young and Shaikhi 2022). Additionally, seawater along the Saudi Arabian coast typically exhibits salinity levels of 42–45‰. Therefore, most sobaity seabream farms are in northern Saudi Arabia to avoid high water temperatures (Figure 7). In Saudi Arabia, sobaity seabream are generally stocked from juveniles with an initial size of approximately 1–2 g in local hatcheries using imported eggs, and then grown to marketable size (400 g) in cages for 13–14 months (Young et al. 2022). Most producing countries have cultured sobaity seabream at lower temperatures (22.0–29°C) and little information exists on farming this species at higher temperatures. As a result, we are trying to better understand its culture potential under local high-temperature conditions (28-32° C). Sobaity Seabream Farming Trials in High-temperature Conditions Survival, growth performance, feed intake and feed conversion ratio of juvenile sobaity seabream (99 g average body weight) in temperatures of 24° C, 28° C, and 32° C were evaluated in our study. Our results indicated that survival and growth of juvenile sobaity seabream were significantly affected by temperature. Total weight gain was significantly higher in the 32°C group followed by the 28°C group, and the lowest weight gain was observed in the 24°C group. The feed conversion ratio (1.62) was significantly lower in the 32° C group than in the 28° C (1.80) and 24° C (1.85) groups. Feed intake was significantly higher in the 32° C and 28° C groups than in the 24° C group. Specific growth rates (SGR) did not differ significantly across all groups (0.82-0.99). Notably, in the 32° C group, the survival rate was considerably lower. Similar results have been observed in other Mediterranean finfish species under the same culture conditions in terms of lower survival rates after three months of high temperature (Young and Shaikhi 2023). Our findings suggest a temperature range of ~24–32° C is appropriate for sobaity seabream farming. This species can be found in tropical areas in both brackish and marine environments, with preferred temperatures ranging from 28–30° C (Abu-Rezq et al. 2002, Torfi Mozanzadeh et al. 2017). Our findings show that sobaity seabream grew fastest at 32° C, slightly higher than the temperature conditions it prefers in the wild. Although the final body weight gain of sobaity seabream was significantly higher at 32° C, our findings revealed that the fish’s SGR did not differ significantly among the three temperature conditions tested. As a result of this finding, sobaity seabream seems to have a broad temperature range for farming. Future Development of Sobaity Seabream Aquaculture in Saudi Arabia The reliability of fingerling sources, whether from local landbased hatcheries or imports, is crucial for expansion of sobaity seabream aquaculture. Hence, it is imperative to prioritize the artificial propagation of the species. Given the limited availability of local hatcheries supplying fry, expanding fry production and establishing additional fingerling sources is necessary (Figure 8). Moreover, most sobaity seabream hatcheries in Saudi Arabia lack capacity for broodstock maintenance. Current coastal hatchery policies are focused on limiting the number of discharge canals, preventing problems resulting from alien invasive species and biosecurity. Also, most marine fish hatcheries lack live food production sections. Nonetheless, sustainability strategies can be developed to support sobaity seabream culture, including establishing a national broodstock center for the private sector, enhancing live food production from hatchery sites, and investing in human resource development. Although sobaity seabream are generally stocked from juveniles with an initial size of 1–2 g and then grown to marketable size (400 g) in cages for over a year, the ideal weight of sobaity seabream broodstock averages around 3 kg, which requires longterm cultivation and incurs additional operational costs. Based on our results, using larger juveniles may shorten the farming period FIGURE 7. Water temperature ranges of aquaculture regions in Saudi Arabia, with black circles showing the locations of sobaity seabream farming locations. Source: Benjamin C. Young. FIGURE 8. A private marine fish hatchery in Saudi Arabia. Source: Benjamin C. Young.
RkJQdWJsaXNoZXIy MjExNDY=