본 연구에서는 어장환경평가가 수행된 어류가두리 양식장의 조사 결과 중 일부를 대상으로 저서동물지수(Benthic Health Index, BHI)를 이용하여 양식장의 건강도를 평가하였으며, 평가 결과로 산출된 각 등급의 양식장 환경 특성을 파악하였다. 평가대상 어류가두리 양식장은 동해, 서해, 남해에 위치한 43개 양식장으로, BHI 1등급은 8개 양식장, 2등급은 4개 양식장, 3등급은 12개 양식장, 4등급은 19개 양식장이 포함되었다. 1등급 어류가두리양식장은 사질 퇴적상, 양식강도가 낮은 양식장이 포함되었으며, 2등급 어류가두리양식장은 해수 유통이 원활한 해역에 위치한 양식장이 속하였다. 3, 4등급이 속한 어류가두리양식장은 높은 강도로 양식 활동이 진행되고 있는 대다수의 양식장이 포함되었다. 3등급과 4등급의 양식장은 총유기탄소는 큰 차이가 없었으나, 다모류 군집분석의 결과는 4등급의 양식장에서의 유 기물 농축이 더 높은 것으로 나타났다.

We investigated physicochemical properties and isotopic compositions of organic matter (δ13CTOC and δ15NTN) in the old fish farming (OFF) site after the cessation of aquaculture farming. Based on this approach, our objective is to determine the organic matter origin and their relative contributions preserved at sediments of fish farming. Temporal and spatial distribution of particulate and sinking organic matter (OFF sites: 2.0 to 3.3 mg L-1 for particulate matter concentration, 18.8 to 246.6 g m-2 day-1 for sinking organic matter rate, control sites: 2.0 to 3.5 mg L-1 for particulate matter concentration, 25.5 to 129.4 g m-2 day-1 for sinking organic matter rate) between both sites showed significant difference along seasonal precipitations. In contrast to variations of δ13CTOC and δ15NTN values at water columns, these isotopic compositions (OFF sites: -21.5‰ to - 20.4‰ for δ13CTOC, 6.0‰ to 7.6‰ for δ15NTN, control sites: - 21.6‰ to - 21.0‰ for δ13CTOC, 6.6‰ to 8.0‰ for δ15NTN) investigated at sediments have distinctive isotopic patterns (p<0.05) for seawater-derived nitrogen sources, indicating the increased input of aquaculture-derived sources (e.g., fish fecal). With respect to past fish farming activities, representative sources (e.g., fish fecal and algae) between both sites showed significant difference (p<0.05), confirming predominant contribution (55.9±4.6%) of fish fecal within OFF sites. Thus, our results may determine specific controlling factor for sustainable use of fish farming sites by estimating the discriminative contributions of organic matter between both sites.

In this paper, a pico hydro turbine employing low head circulation water at fish farms is designed and evaluated. Due to the advantages of simple structures, small head requirements, and low-cost investment, the constant thickness propeller turbine is considered as a feasible solution. The design process based on the free vortex method is presented in full detail, and a 4-blade runner is built using BladeGen. The turbine performance is analyzed both numerically and via experimental methods. Despite slight differences, the results show similar trends between CFD simulations and experiments carried out on factory test-rigs in a wide range of working conditions. At the design flow rate, the turbine achieves the best efficiency of 70 %, generating 3.5 kW power when rotating at 420 rpm. The internal flow field, as well as the turbine's behavior, are investigated through the distribution of blade streamlines, pressure, and velocity around the runner. Moreover, the pressure coefficient on the blade surface at 3 span positions is plotted while the head loss for each simulation domain is calculated and displayed by charts.

In manufacturing of flatfish skin collagen peptide (FSCP) and flatfish protein hydrolysate (FPH) by reuse of dead flatfish from fish farm in Jeju island, the industrial process was optimized with the laboratory scale research and the on-field process. Segmented unit processes from raw material incoming to shipment were established to produce commercial product of FSCP and FPH. Total plate counts of FSCP were twenty five times of FPH, but food poisoning bacteria were not detected in two samples. FSCP and FPH were safe from heavy metal such as Pb(II), Cd(II) and Hg(II). The residual contents of antibiotics and disinfection matter in FSCP and FPH were not detected. The optimized process for mass production made the one-third of the running time and two times of the yield. From economic analysis, the production cost was estimated to 22,000 and 12,000 won/kg for FSCP and FPH, respectively. Therefore the product from the reuse of dead flatfish was expected to have a considerable competitive price and high added-value functional food material compared with other commercially available fish products.