Offshore Fish Farms: A Review of Standards and Guidelines for Design and Analysis

Abstract

While moving fish farms to offshore sites can be a more sustainable way to expand farmed fish production, the fish pens have to contend with a harsher environment. Thus, it is necessary to draw on offshore engineering competences for designing and analysing the offshore fish farming infrastructure. This paper reviews existing design and analysis guidance from maritime classification and national/international authorities that can be applicable for offshore fish farms. Based on the existing design guidelines, a review of design criteria for offshore fish farms under the following subtopics is provided: design life, design environmental loads, combining environmental loads, and miscellaneous load conditions. This review on the global performance analysis procedures and methods is presented based on practices used for neighbouring industries, such as offshore oil and gas and wind energy production, under the following subtopics: hydrostatic analysis, hydrodynamic analysis, and mooring system analysis with introducing theoretical background and modelling techniques. This paper also highlights limitations and cautions when using these design and analysis methods. Providing this comprehensive information, as well as commentary on their applications, will help engineers and designers to develop offshore fish farming infrastructure with confidence.

SeaFisher—A Submersible High-Density Polyethylene Offshore Fish Pen

“…The maximum von Mises stress is shown to be 12.7 MPa in the top longitudinal pipes, which is just within the permissible stress of 13 MPa, as specified in the Norwegian Standard for fish farms [33]. The Norwegian Standard is a widely recognized and commonly used guideline for assessing the structural integrity of HDPE fish pens [9].…”

“…Moreover, offshore sites offer larger water space, better water quality, cooler temperatures and better waste dispersion from deeper waters [6], less sea lice infestation [7], stronger waves, and higher current speeds [8]. Moving fish farms offshore, however, poses several challenges that include having to contend with a harsher sea environment, an uncertain environment for the farmed fish, operational requirements regarding workers' safety and support vessels, and the lack of experience and standards in designing offshore fish pens [9]. The most challenging aspect of offshore fish farming is the survivability of the fish pen and the well-being of fish during severe storms that are accompanied by huge surface waves, winds, and shear current actions.…”

Developments in Modeling Techniques for Reliability Design of Aquaculture Cages: A Review

“…where ρ air is the density of air; C h is the height coefficient to account for the increase in wind speed with elevation, and C h = 1.0 when the height of the structure above the water is less than 15.3 m; C s is the shape coefficient, which depends on the shape and orientation of the structure exposed above the water, as illustrated in Figure 3a; A e is the projected area of the exposed structure relative to the direction of the wind force, as shown in Figure 3b. The specific values for these parameters were summarized in [3].…”

“…In view of this growth trajectory, offshore fish farming is becoming an emerging innovation for providing a large and sustainable production of fish to meet the continuously growing population demands. When compared to traditional nearshore sites, offshore ones offer higher efficiency and reduced environmental impact because of the larger water column, more pristine water, cooler water temperature, and better return on investment from a larger scale of fish production [3]. However, numerous design difficulties exist within offshore fish farming that have not been clearly outlined or thoroughly investigated; consequently, fish farmers harbor reservations about transitioning to offshore fish farming due to these uncertainties [4].…”

“…Chu et al [3] categorized mooring analysis methods into the quasi-static method and the dynamic method. In the former, the tension in mooring lines is statically calculated, with the tension in each mooring line computed based on the maximum offset for each design condition [3]. The dynamic method directly simulates the frequency-domain or time-domain response of the mooring system.…”