Introduction: China is responsible for more than 60\% of global aquaculture production. As the frontiers of food production have expanded, the cultivation of marine organisms in coastal zones and the open ocean has grown rapidly. The dominant mariculture industry in China is suspended mariculture, which uses net cages, ropes, or other structures suspended in the water column to cultivate aquatic organisms. This systematic, quantitative review provides a clear and comprehensive account of research that has investigated the adverse impacts of suspended mariculture in China and reviews research that has applied Integrated Multi-Trophic Aquaculture (IMTA) systems for mitigating impacts. This work builds on 218 peer reviewed papers that have been published in English-language journals. Outcomes: Eighteen impacts were identified, including chemical, ecological, physical, and socioeconomic impacts. Eighteen measures for improving suspended mariculture were recommended consisting of government department, farm management, and ecological engineering measures. IMTA was the most frequently recommended measure. The capabilities of IMTA for bioremediation and increased farm production were the most frequently studied advantages. Seven other benefits have been explored but remain understudied. The current challenges facing the expansion of commercial IMTA include limited use of new technology, limited skills development, decreasing production of low trophic-level species, biogeographic and temporal barriers, and negative system feedbacks. Conclusion: Despite challenges, implementing commercial IMTA is a promising measure for reducing the impacts of suspended mariculture because it presents a range of secondary benefits that can improve the overall sustainability of aquaculture in the coastal zone
Pilot studies are used to assess different sampling and monitoring protocols when developing long-term monitoring programs (LTMPs). Considering that the ultimate goal of LTMPs is preservation-orientated, non-destructive sampling methods are favoured. For coral reef fishes, underwater visual censuses (UVCs) have become the method of choice for surveying shallow, highly-diverse reefs. This study assessed three different UVC transect types to monitor highlatitude western Indian Ocean coral reefs; these were slate, photo and video transects. Slate data were analysed with CountN (all fish observed), while footage from reviewable photo and video transects was analysed by both CountN and MaxN (a single frame with the most fish per species), resulting in an assessment of five transect-type analysis technique combinations; slate, photo-CountN, video-CountN, photo-MaxN and video-MaxN. Video-CountN transects had the highest estimates of richness and abundance, the lowest variability, and the most representative diversity. Video-CountN transects were also the most efficient in that the time taken to analyse footage was comparable to the other combinations considered, the proportion of unidentifiable individuals was low, and it required the lowest sample size to achieve an acceptable statistical power. Video-CountN transecting is therefore recommended as the most appropriate method for conducting UVCs of high-latitude coral reef fishes in the southwestern Indian Ocean.
It has been suggested that the invasive, omnivorous Clarias garipienus is capable of rapid invasions and long-term persistence in recently inhabited freshwater systems. To test this hypothesis, the life history of the established, extralimital Darlington Dam (33°10'31"S, 25°09'13"E) population was investigated. By counting post-fluorescent mark increments on otoliths from 21 chemically tagged wild fish recaptured 244-537 days later, the deposition of growth zones, comprising alternating opaque and translucent bands, was validated as annual. Examination of sectioned otoliths from 175 fish revealed that the oldest fish, two males of 840 and 1074 mm total length (TL), were 25 years old -10 years older than previously described for any C. gariepinus population. The oldest female was 885 mm TL and 21 years old. Lengthat-age was subsequently described using the von Bertalanffy growth model. Combined-sex growth was best described as L t = 931.7 ( 1 -exp(-0.15(t +2.43))) mm TL. Total mortality (Z) was calculated using catch curve analysis and the Chapman & Robson estimator to be 0.35/yr. The presence of specimens 15 years and older indicates that these fish established quickly and supports the finding that mortality rates are low, which, in turn, suggests likely long-term population persistence.
It has been suggested that the invasive, omnivorous Clarias garipienus is capable of rapid invasions and long-term persistence in recently inhabited freshwater systems. To test this hypothesis, the life history of the established, extralimital Darlington Dam (33°10'31"S, 25°09'13"E) population was investigated. By counting post-fluorescent mark increments on otoliths from 21 chemically tagged wild fish recaptured 244-537 days later, the deposition of growth zones, comprising alternating opaque and translucent bands, was validated as annual. Examination of sectioned otoliths from 175 fish revealed that the oldest fish, two males of 840 and 1074 mm total length (TL), were 25 years old -10 years older than previously described for any C. gariepinus population. The oldest female was 885 mm TL and 21 years old. Lengthat-age was subsequently described using the von Bertalanffy growth model. Combined-sex growth was best described as L t = 931.7 ( 1 -exp(-0.15(t +2.43))) mm TL. Total mortality (Z) was calculated using catch curve analysis and the Chapman & Robson estimator to be 0.35/yr. The presence of specimens 15 years and older indicates that these fish established quickly and supports the finding that mortality rates are low, which, in turn, suggests likely long-term population persistence.
The environmental implications of integrated multitrophic aquaculture have been well studied in China, but few investigations have empirically explored potential economic benefits. This study investigated the technical and economic feasibility of physically integrating the noble scallop Mimachlamys nobilis (Reeve, 1852) with existing fish monoculture farms in Hong Kong. Scallops were grown for 201 days from June to December in lantern nets hung directly from fish farm platforms at treatment depths of 1, 3.5, and 6 m. Only the 1-m treatment attained the target mean height-at-harvest of 80 mm. Fitted von Bertalanffy growth functions showed significant differences in growth performance between depths. The von Bertalanffy growth function projected that the 3.5-and 6-m treatments would require an additional 26 and 59 days of culture to reach 80 mm. Mortality was significantly lower at 1 m (53% ± 12.5%) compared with those at 3.5 m (70% ± 9.0%) and 6 m (83% ± 4.5%). The slower growth and higher mortality at 3.5 and 6 m were probably due to periodically low oxygen which dropped to 4.96, 3.08, and 1.73 mg L -1 at 1, 3.5, and 6 m, respectively, in midsummer. A bioeconomic assessments of two typical farm sizes was conducted; small (45 m 2 ) and large (315 m 2 ). The initial investment, discounted payback time, and 10-y net present value of the projects was US$5,485.51, 3 y, and US$20,211.33, respectively, for the small farm and US$27,659.03, 2 y, and US$227,406.49, respectively, for the large farm. Sensitivity analysis revealed that the profitability of operations was sensitive to changes in mortality and sales price. This study has confirmed that physically integrating M. nobilis at existing fish farms is technically and economically feasible.
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