Offshore Fish Farm Research Articles

Numerical investigation of the hydrodynamics of a submersible steel-frame offshore fish farm in regular waves using CFD

The hydrodynamics and non-linear interaction between the submersible steel-frame offshore fish farm “ShenLan 1” and regular waves are investigated using the open-source CFD toolbox REEF3D. The effects of the regular wave parameters, different net sheets, and structural variations on the motion responses and mooring forces of the fish farm system are studied. The numerical framework consists of a moored-floating body motion solver for the frame structure coupled to a fluid dynamics solver to simulate the two-phase propagation of the waves. The momentum loss of the flow over fixed net sheets is included in the solver. First, the chosen model is validated for a coupled rigid body motion and net hydrodynamics. Then, the solver is applied to the offshore fish farm “ShenLan 1”. It is shown that the surge motions are more sensitive to the wave parameters compared to the heave and pitch motions due to the restrain from the mooring system. In contrast to the vertical components, the horizontal loadings positively correlate with the wave heights and periods. The nets show minor influence on the motion responses, but the percentage of horizontal forces attributed to nets decreases from 55% to 10% in larger wave periods. The translational motions, as well as mooring restoring tensions, are particularly sensitive to shifts of the draught. Finally, the increase of the aspect ratio of “ShenLan 1” through enlarging the overall diameters results in declined motions and mooring forces. Thus, this study provides the first indications towards a systemic evaluation of the dependencies of different structural parts of a submersible steel-frame offshore fish farm for hydrodynamics.

Test based finite element analysis of wire meshes

As fish farming is becoming more and more important worldwide, this ongoing project aims at the simulation and test-based analysis of highly stressed wire contacts, as they are found in off-shore fish farm cages in order to make them more reliable. The quasi-static tensile test of a wire mesh provides data for the construction of a finite element model to get a better understanding of the behavior of high-strength stainless steel from which the cages are made. Fatigue tests provide new insights that are used for an adjustment of the finite element model in order to predict the probability of possible damage caused by heavy mechanical loads (waves, storms, predators (sharks)).

A frequency domain approach for analyzing motion responses of integrated offshore fish cage and wind turbine under wind and wave actions

This paper presents a frequency domain (FD) approach for analyzing wind and wave coupling effect on motion responses of an integrated offshore fish cage and wind turbine named COSPAR. FD analysis was performed by ANSYS AQWA to obtain response amplitude operators (RAOs) for surge, pitch and heave motions as well as mooring tension RAOs. Wind thrust was estimated by using a linearization method based on the pre-defined thrust coefficients determined from a fixed-bottom wind turbine. In AQWA, wind force coefficients were specified to incorporate the thrust force and moment in the hydrodynamic response analysis of a floating structure. The present FD method was applied to a DeepCwind floating wind turbine problem for its validation. It was found that the AQWA-FD approach can furnish wind and wave induced motion responses that are comparable with published experimental and numerical results. Thereby, this approach can be used to readily obtain a preliminary design for subsequent refinements for an optimal design. Based on the FD analysis results, DeepCwind and COSPAR have a pronounced the coupling effect only in the pitch motion. Moreover, COSPAR shows not only moderate coupling effect, but steadier and less RAOs in surge, heave, pitch and mooring tension than those of DeepCwind. In addition, it is evident that COSPAR can provide a stable working platform for offshore fish farms from wind, wave and current loads, and has acceptable pitch angles for a steady wind turbine operation.

Инновационный вектор развития морской промышленности Норвегии

According to the updated Norwegian maritime strategy, its further economic growth will be closely linked with the maritime industry development, which is focused on satisfying the world economy's growing demand for food, energy, and transportation services. Along with supporting the traditional sectors of its maritime industry (offshore hydrocarbon production, fishing, coastal aquaculture, shipping, etc.), Oslo plans to develop some innovative areas of the industry, such as offshore aquaculture, offshore renewable energy and “green” shipping, which are the main research objects of this work. The author presents an analysis of the main innovative projects implemented by Norway in various sectors of its maritime economy. Amid the international community's concern over the global environmental situation, Oslo is actively developing and implementing advanced technological solutions in its maritime industry, which can not only reduce the level of negative impact on the environment, but also significantly improve its economic performance. A key feature of Norway's maritime industry development is the deepening of intersectoral collaboration, which enabled it to implement oil and gas technologies into offshore aquaculture and offshore wind energy, as well as traditional net-pen aquaculture technologies into offshore solar energy projects. Particular attention in the article is paid to the digitalization of Norway's maritime industry, aimed at ensuring automation or, in some projects, complete autonomy of the utilization of different floating and fixed maritime constructions (vessels, offshore fish farms and power plants).Moreover, the author assesses the Norwegian government's efforts in facilitating further maritime industry development, which includes educating specialists in information and communication technologies, expanding international cooperation, implementing public-private partnership programs, searching for new sales markets and revising the state investment system. In conclusion, the author suggests that in the future the global demand for environmentally friendly innovative technologies produced by Norway will increase, thereby providing for new employment opportunities, development of the national maritime industry and, as a result, the country's sustainable economic growth.

An improved screen force model based on CFD simulations of the hydrodynamic loads on knotless net panels

Knotless net panels are widely-adopted for traditional fish cages and offshore fish farms. A new screen force model based on numerical simulations of a portion of knotless net panels is proposed in this paper. At first, the hydrodynamic loads on knotless smooth and textile twisted net panels are studied using Improved Delayed Detached Eddy Simulations while varying the incoming velocity as well as the diameter and length of the net twines. The accuracy of the simulations is validated through a computational grid and domain independence study for the mean hydrodynamic loads on full-size net panels. The comparison of the hydrodynamic loads on a circular cylinder, cruciform and net panel reveals the unique hydrodynamics around net panels which emphasises the importance of studying complete panels. Then, a Kriging metamodel is established from the simulation-based data to generate response surfaces for the hydrodynamic load coefficients for a large range of flow and geometrical properties. Hence, this combination of high-fidelity CFD and Kriging metamodelling provides a more flexible approach than the common theoretical or experimental variations of screen force models. The metamodel predicts well the non-linear relation between drag coefficient, twine diameter and length of the twines. A second-order regression fitting is applied to generate a closed polynomial which is compared to existing approaches and physical measurements for validation. The proposed approach outperforms previous screen force models for the prediction of the drag and lift coefficients for a wide range of nets and inflow velocities due to the inclusion of different roughnesses and more geometrical properties of the net in the derivation. Finally, the proposed formula for the drag force coefficients is applied to a two-way coupled CFD method which is based on screen force models to determine the hydrodynamic loads. It can be shown that the new approach is superior to previously used screen force models for the simulation of the drag forces on and the velocity reduction behind net panels.

A Numerical Study of the Hydrodynamics of an Offshore Fish Farm Using REEF3D

Abstract In this article, the hydrodynamics of and nonlinear interaction between the large offshore fish farm “ShenLan 1” and regular waves are investigated using the open-source computational fluid dynamics (CFD) toolbox REEF3D. The framework consists of a rigid body dynamics solver for the frame structure coupled to a fluid solver including the shielding effects of the nets. The solver and grid independence are validated using a 2D numerical wave tank, a free decay test, and a study of the wave loads on a rigid net panel. Then, the effects of regular wave parameters, the thickness of the vertical outer columns of the structure, and the variations of the aspect ratios on the loads, responses, and maximum mooring tension forces are studied. It is concluded that the response motion is sensitive to the wave period rather than the wave height due to the longer duration of unidirectional wave loads acting on the frame. The frequent events of partial submersions and wave overtopping in rather steep waves are confirmed through the capturing of the free surface. The net system accounts for about 30% of the total drag but does not influence the structural response to a larger extend. The effect of the aspect ratio on the hydrodynamics is more distinct than that of the frame thickness. As a result of the study, the first step toward a systemic evaluation of the importance of different structural parts of an offshore fish cage for the expected responses is provided.

The environmental effect on the seabed of an offshore marine fish farm in the tropical Pacific

Marine aquaculture is expanding offshore, where the environmental interactions are not yet fully understood. We performed a benthic environmental assessment of an offshore fish farm on unconsolidated sediment. The physicochemical variables showed marked changes just under the fish farm, although the structure of the community and its bioturbation potential were not influenced. Under no or minimum influence from the fish farm, the physicochemical variables, including acid-volatile sulphides and redox, were notably different to those found in unaffected coastal areas. For this reason, classifications of the environmental status based on physicochemical variables should be adapted to offshore areas. Despite the low degree of impact detected, the organic matter carrying capacity should be carefully determined to avoid environmental drawbacks in terms of fine-grained offshore sediments. Offshore aquaculture could have a lower environmental impact than other types of aquaculture located closer to the coast, but further research is needed to obtain conclusive results.

Nonlinear vertical accelerations and mooring loads of a semi-submersible offshore fish farm under extreme conditions

Semi-submersible offshore fish farm has been considered a step forward to the new aquaculture era. To make it more durable to the excitations caused by waves and current, this paper examines the nonlinear vertical accelerations and mooring loads of a semi-submersible offshore fish farm model under extreme conditions. The steady-state non-dimensional first- and second-order harmonic accelerations at five different positions along the frame and the mooring tensions are obtained via experimental measurements and numerical simulations. The results show that both the first- and second-order harmonic accelerations are independent of the positions on the model but dependent on the wave period. Under wave-only conditions, when H≤0.15m, there is little difference between the experimental measurements and the numerical predictions on the accelerations. When H≥0.20m, the increasement of acceleration amplitude is 0.5 %–4.1 % for experiment, while the value is 3.3 %–19.0 % for numerical simulation. Under combined waves and current conditions, compared with H≤0.15m, the second-order harmonic acceleration increases exponentially under larger wave height, and most of the experimental results are larger than the numerical predictions when the current velocity V2=0.2m/s. The damping from the net enhances the nonlinearity of the second-order acceleration but it has little effect on the first-order. The current has a pronounced effect on the mooring tensions. When T=1.39s, the mean values of front mooring load at V2=0.2m/s are 6.4 times of that at V1=0.1m/s in maximum, but when the wave height reaches H=0.25m, the increase rate of mooring force gradually decreases. The free surface effect is also assessed in this paper.

The selection of aquaculture site based on chlorophyll-a concentration at Sidoasri Bay, Sendang Biru, Malang regency, East Java

Currently, offshore fish farms are using floating net cages or offshore aquaculture is one alternative to support the fisheries sector in Indonesia. Several requirement parameters must be met before the installation of floating cages for the sustainability of the fish culture. One of which is the distribution of chlorophyll-a in the waters. In this paper, Landsat 8 satellite imagery was collected to evaluate the chlorophyll-a concentration in the waters of Sidoasri Bay, Sendang Biru, Malang regency, East Java. The concentration of chlorophyll-a will be used as indicators to select a suitable location for offshore aquaculture. Based on the satellite image observations indicated that at Sidoasri Bay, there are two locations appropriate for floating cages. The location is generally suitable for floating cages installments with an average score of 2.26 on a scale of 3.

A review on transient stability of land-sea networked fishery microgrids

The islands and offshore fish farming platforms in the deep sea can form a land-sea networked fishery microgrids to realize the complementary supply of energy. The fishery microgrid contains a high proportion of renewable energy sources such as wind, solar and waves, and mixed AC and DC loads such as feed machine, energy storage, and fishery robot. Due to the harsh operating environment, the possibility of equipment damage increases, and the requirements for system stability are higher. In this paper, firstly, the definition of transient stability of land-sea networked fishery microgrids is given. Then, the key features of the fishery microgrid is introduced, and the influence of the microsource interface type, control strategy, current limiting mechanism and load characteristics on the transient stability is expounded. The definition of power Angle of fishery microgrid and the characterization of instability system are given. Next, the research trends of transient stability are sorted out, evaluated and discussed from two aspects: approaches of transient stability analysis and methods to improve transient stability. Finally, the key issues that need to be solved urgently in the research on the transient stability of the land-sea networked fishery microgrids are summarized, and the relevant research directions are prospected.

Growth performance, hematological and biochemical parameters, and hepatic antioxidant status of spotted knifejaw Oplegnathus punctatus in an offshore aquaculture net pen

Spotted knifejaw (Oplegnathus punctatus) is a promising species for aquaculture production because of its high commercial value and limited supply. The growth performance, hematological and biochemical parameters, and hepatic antioxidant status of spotted knifejaw reared in an offshore aquaculture net pen system (OANPS) were examined to evaluate the potential development of offshore fish farming on the north coast of China. Results showed that 50, 000 juveniles spotted knifejaw (initial mean body weight 392.73 ± 58 g) were transferred to OANPS and had a survival rate of 98%, final mean body weight of 790.05 ± 12.83 g, body weight gain of 101.2%, feed conversion ratio (FCR) of 1.52, and specific growth rate (SGR) of 0.59% d−1 after 120 days. The hepatosomatic and the viscerosomatic indices (HSI and VSI) of the spotted knifejaw did not change significantly. The plasma albumin and globulin contents of the spotted knifejaw reared in the OANPS increased significantly. In contrast, the plasma alkaline aminotransferase and aspartate aminotransferase activities significantly decreased at the end of the experiment. However, the plasma glucose, cholesterol, triglyceride contents and albumin/globulin levels, white blood and red blood cell numbers, hemoglobin, and hematocrit contents showed no significant differences throughout the experimental period. Hepatic superoxide dismutase and glutathione peroxidase activities were significantly increased, and the catalase activity and malondialdehyde levels remained unchanged. In addition, the low hepatic lipid droplet number was observed in the spotted knifejaw reared in the OANPS. These results indicated that juveniles spotted knifejaw reared in an OANPS can show a high survival rate and high growth performance and physiological status through short-term culture. The OANPS opens a new door for spotted knifejaw culture. These findings enhance our understanding of spotted knifejaw aquaculture and contribute to offshore fish farming in China.

Experimental and numerical study of a semi-submersible offshore fish farm under waves

The interaction between the semi-submersible offshore fish farm (SOFF) and waves was investigated by numerical simulations and dedicated model tests. The SOFF generally consists of three main components, such as large pontoon, frame system, and net system. And the hydrodynamic forces cannot be calculated by the same method due to the big difference in the main dimensions of them. Therefore, a hybrid numerical method of direct time domain and indirect time domain for the SOFF was proposed in this paper, and the calculation program was originally developed. In the present numerical method, the three dimensional potential theory was used to calculate the hydrodynamic loads on the large pontoon through indirect time domain, and the Morison equation and screen model were used to calculate the hydrodynamic loads on the frame system and net system, respectively. Then the total hydrodynamic loads on the SOFF at each time step can be obtained, and the motion responses of the SOFF were calculated in the time domain. The model tests were carried out in the wave basin, and the heave and pitch motions with wave periods were obtained. The numerical results were verified by the experimental results. A good agreement exists between the numerical results and experimental results. Then the effects of some key parameters on the motion responses were investigated by the present numerical model, such as draft, wave height and net solidity ratio. The results show that the draught of SOFF has an obvious influence on the heave and pitch motion. In addition, heave and pitch response amplitudes are positively correlated with wave amplitude. And the change of net solidity ratio has a notable effect on the heave motion and pitch motion.

Development of a Hydropower Turbine Using Seawater from a Fish Farm

Discharge water from fish farms is a clean, renewable, and abundant energy source that has been used to obtain renewable energy via small hydropower plants. Small hydropower plants may be installed at offshore fish farms where suitable water is obtained throughout the year. It is necessary to meet the challenges of developing small hydropower systems, including sustainability and turbine efficiency. The main objective of this study was to investigate the possibility of constructing a small hydropower plant and develop 100 kW class propeller-type turbines in a fish farm with a permanent magnet synchronous generator (PMSG). The turbine was optimized using a computer simulation, and an experiment was conducted to obtain performance data. Simulation results were then validated with experimental results. Results revealed that streamlining the designed shape of the guide vane reduced the flow separation and improved the efficiency of the turbine. Optimizing the shape of the runner vane decreased the flow rate, reducing the water power and increasing the efficiency by about 5.57%. Also, results revealed that tubular or cross-flow turbines could be suitable for use in fish farm power plants, and the generator used should be waterproofed to avoid exposure to seawater.

Examination of net volume reduction of gravity-type open-net fish cages under sea currents

Owing to heavy criticisms of nearshore fish farming for causing environmental pollution and encroaching on sea space used for shipping, boating, recreational sea activities and marine eco-tourism, offshore fish farming has now being seriously considered. Moreover an offshore site provides more pristine water and greater space for increased fish production. However, offshore fish farming poses challenges such as a more energetic sea environment. A higher sea current can lead to large deformation of fish net and hence a net volume reduction which compromises fish welfare. With the view to identifying the effects of various important parameters on net volume reduction of a gravity-type open-net fish cage, this paper adopts a mass-spring model for the dynamic analysis of current-induced net deformations of cylindrical fish nets with discrete weights hanging at the bottom edge of the nets. In this model, the net mesh comprises knot nodes and bar nodes connected by tension-only massless springs. The spring stiffness is determined from the net bar diameters and material properties. The current-induced loads are applied to each node and calculated based on Morrison’s equation. The governing equation system for nodal motions can be established according to Newton’s second law, and solved by using the Runge-Kutta method for the real-time net deformations. The effects of net string reinforcements, weight distributions and net shapes on the net volume reduction are studied with the view to shed insights into how one may improve fish cage designs to effectively mitigate net deformation under high sea current speeds in offshore fish farming sites.

Design of a Practical Underwater Sensor Network for Offshore Fish Farm Cages.

In this paper, we present the design of a practical underwater sensor network for offshore fish farm cages. An overview of the current structure of an offshore fish farm, applied sensor network solutions, and their weaknesses are given. A mixed wireless–wired approach is proposed to mitigate the problem of wire breakage in underwater wired sensor networks. The approach is based on the serial arrangement of identical sections with wired and wireless interconnections areas. Wireless section alleviates underwater maintenance operations when cages are damaged. The analytical model of the proposed solution is studied in terms of maximum power transfer efficiency and the general formulas of the current in their transmitting antennas and sensor nodes are provided. Subsequently, based on simulations, the effects of parasitic resistance across the network are evaluated. A practical underwater sensor network to reach the 30 m depth with sensor nodes distanced 6 m is used to determine the proposal compliance with the ISO 11784/11785 HDX standard in its normal operation. Taking into account the cable breakage scenario, the results from experiments demonstrate the robustness of the proposed approach to keep running the sensor nodes that are located before the short circuit. Sensor node run time is reduced only 4.07% at most using standard values when a cable breakage occurs at the second deepest section.

Hydrodynamic Response Analysis of Combined Spar Wind Turbine and Fish Cage for Offshore Fish Farms

This paper is concerned with the hydrodynamic response of a novel offshore fish farm that combines a floating spar wind turbine and a fish cage (named as COSPAR for brevity). The open net steel cage is octagonal in shape with a partially porous wave fence at its top end to attenuate wave energy for a calm fish farming environment as well as to keep predators out. The deep draught spar is made from concrete for its bottom half and from steel for its top half. The spar carries a control unit and a 1[Formula: see text]MW wind turbine that provides the required power to operate the offshore salmon fish farm. The COSPAR fish cage has four catenary chains as mooring lines attached to mid length of the spar (outside the fish cage) so as to mitigate tension force in the mooring lines and to reduce the benthic footprint. ANSYS Design Modeler and Aqwa are used to perform the hydrodynamic response analysis of free-floating condition of COSPAR in the frequency domain and coupled analysis involving COSPAR and the mooring lines in the frequency domain and time domain. Environmental conditions, representing 5-year, 20-year and 50-year wave return periods with a constant current flow at an exposed fish farming site in Storm Bay of Tasmania, Australia, are adopted for the analyses. A comparison study is made against having a floating fish cage only (i.e. without the bottom half concrete of the spar) with four catenary chains attached to side vertical columns of the cage so that the fish cage behaves like a semi-submersible cage. Based on the comparison study, the COSPAR fish cage shows enhanced hydrodynamic responses in the following respects: (1) more stable motion responses in heave and pitch against wave and current forces, (2) less susceptible to the viscous damping when it is assumed by a linearized drag force of Morison elements in the frequency domain and (3) reduction of tension forces in the mooring lines. Interestingly, the pitch motion response of COSPAR fish cage in the frequency domain is in close agreement with the time domain result due to its greater pitching stiffness that reduces nonlinear effects from viscous drag and mooring interaction.

Potential for offshore aquaculture development in North Korea: Focusing on Atlantic salmon farming

This study investigated the potential for Atlantic salmon farming in North Korea. Farmed Atlantic salmon (Salmo salar) are aquaculture products commonly consumed in East Asia, but they are not commercially produced in large quantities. One barrier to Atlantic salmon farming is that the marine environmental conditions (i.e., water temperatures) in much of East Asia are unsuitable. North Korea has recently initiated Atlantic salmon farming assuming it has appropriate locations for it. If North Korea indeed has suitable locations for successful Atlantic salmon aquaculture and the United Nations' sanctions were lifted, the country's Atlantic salmon farming project might have potential for successful inter-Korean economic collaborations. The current study analyzed North Korea's possible farming sites using remote sensing data, and it used those findings to evaluate the feasibility of inter-Korean Atlantic salmon fishery collaborations and to propose policy implications. Remote sensing information estimated sea surface temperatures and hydrodynamic modeling extended that to estimate the sea temperatures at various depths to precisely propose appropriate farming locations in North Korea. The results indicated that most of North Korea's sea surface temperatures were below 20 °C in January through June. However, the surface temperatures in July and August exceeded 20 °C, indicating unsuitability for Atlantic salmon farming during that period. The water temperatures at the 25-m depth were below 20 °C year round, and Atlantic salmon farming would be possible there using submersible farming technologies, such as plant-type offshore fish farming systems.

Hydrodynamic performance of a semi-submersible offshore fish farm with a single point mooring system in pure waves and current

A physical model of a semi-submersible offshore fish farm with a scale of 1:30 has been tested in a wave-current tank. The mooring force of the fish farm in waves was measured and compared for different single-point mooring arrangements, and henceforth, a safe and reliable mooring form is chosen as the mooring system for the fish farm. On this basis, the tested results for the mooring force, heave, pitch and roll of the fish farm in waves and current are presented, in which the effect of drought was discussed. The performance of blocking water flow for the fish farm in pure current was also evaluated. It has been found that increasing the anchor chain length and adding a sinker suspending from the chain could reduce the mooring force significantly despite the fluctuations in the mooring force. During the experiments, the tested value for the heave and pitch as well as the roll has been small, which indicates that the fish farm has a good stability. The mooring force has become larger, while the heave became smaller as the drought increased. Furthermore, the current velocity inside the fish farm is significantly lower than that of its outside. According to the field test results obtained in the fish farm, the farm exhibited good adaptability and it formed a suitable environment for growing cultured fish.

Environmental quality assessment of the fish farms' impact in the Monastir Bay (eastern of Tunisia, Central Mediterranean): a benthic foraminiferal perspective.

Offshore fish farms have been active inside the Monastir Bay, Hammemet Gulf for over 10years, but their environmental impact is still unknown. This study focuses on the evaluation of the fish farming activity impact in the Monastir Bay as revealed by geochemical and benthic foraminiferal data. Samples were collected around three fish cages at different water depths. Total organic carbon (TOC) and total phosphate (TP) in the sediment show higher values beneath the fish cages and decrease proportionally with distance from the cages. Living foraminiferal assemblages around fish farms are dominated by stress-tolerant species with higher abundances of Ammonia tepida, Rosalina bradyi, Elphidium crispum, and Peneroplis planatus. On the basis of our results, A. tepida and Quinqueloculina seminula are confirmed to be tolerant to elevated nutriment content, while Ammonia parkinsoniana seems to be more sensitive to organic enrichment. We also test the Foram-AMBI that is revealed to be a very promising tool by which evaluating the ecological quality status of marine sediment. The results of the present study confirm the suitability of living benthic foraminifera as bioindicators of organic enrichment induced by aquaculture activities.

Determining potential conflicts between small-scale fisheries and sea-cage fish farms in the Aegean Sea

Background. Fish farms attract both juvenile and adult wild fishes in great numbers and diversity. These wild fishes also become an easy target stock for local fishers, both professional and recreational. There are three groups of interest in this study, the fish farmers, small-scale fishermen (professional), and recreational fishers (mostly anglers but also spear fishers). This study was intended to determine conflicts derived from the adverse social and bioecological interactions from the perspective of both local fishermen and fish farmers and to determine the observed incidence of predators. Materials and methods. In this study, 48 randomly selected fish farms, 28 fishery cooperatives, and 33 fishing ports located close to aquaculture areas were visited for face-to-face interviews with the fishermen of small-scale fisheries (SSF) between July 2015 and July 2017. The main purpose of the survey questionnaire was to ask SSF fishermen for their opinion about offshore aquaculture and vice versa—ask the fish farmers about SSF, emphasizing issues potentially creating problems. Data were collected mainly on sociodemographic profiles, current problems, reciprocal conflict issues, the impact of offshore fish farming on SSF activities, and on bioecological interactions such as predator attacks and problems with farm fish escapes. Results. Approximately 77% of fishermen in Izmir and 71% of fishermen in Muğla declared that they had problems with the sea-cage fish farms. On the other hand, 40% of fish farmers in Izmir and 54% of fish farmers in Muğla reported problems with local SSF. The fishermen believe that in recent years, Mediterranean monk seal (Monachus monachus), sea turtle (Caretta caretta), and invasive fish (pufferfish, etc.) populations have been increasing in Muğla. Additionally, 46% of Muğla fish farmers and 60% of Izmir fish farmers acknowledged cases of fishes escaping from sea-cages. In terms of the predators, 84% of Muğla and 75% of Izmir’s fishermen expressed their concerns regarding predator attacks on the sea-cage farms. Conclusion. Further studies, based on socioeconomic issues, are needed for better understanding the dimensions of incomes and economic losses of SSF and cooperation issues in the area where the interaction is high. We suggest that all stakeholders, small-scale fishermen, in particular, must be integrated with a management plan, and the cooperation among both fishing groups should be encouraged.