How Process Safety can Improve Fish Welfare

Did you know that onshore fish farming facilities are advanced process facilities and that focus on process safety can reduce fish mortality and improve fish welfare?

Feeding a growing population

During the last decades, the fish farming industry has developed into a key provider of protein-based food for a growing global population. Fish farming involves raising multiple species of fish and includes a range of different facility types. The focus of this insight is on onshore farming of Atlantic salmon, but the principles apply for all fish farming involving advanced process facilities.

Moving fish farms onshore

Atlantic salmon develops in different life stages. The initial stage is carried out in the hatchery and smolt process, which includes growing salmon from roe to smolt (juvenile salmon) in freshwater conditions. This stage is always performed in onshore facilities. Once the salmon leaves the smolt stage it is adapted to sea water conditions and is normally transported to sea water cages for further growth, until it is ready for butchery and transport to the consumer market. Some asset owners are now also developing onshore facilities for all life stages, from roe to final product.

As the industry is growing, several large-scale onshore facilities are currently being engineered and constructed, and more new projects are expected.

A RAS facility is an advanced process facility

Modern onshore facilities are developed as Recirculating Aquaculture Systems (RASs). This means that the facilities are closed and have process systems for recirculation and water treatment, unlike flow-through facilities. A standard set-up is to have a water treatment package that processes and monitors a slip stream from a fish tank. The package then includes mechanical filtering, biofiltering, chemical dosing, oxygenation, temperature control, cleaning systems and various pump arrangements.

In addition, onshore fish farms include process-based systems for other purposes, such as pumps and pipe work dedicated for fish transport.

Process deviations can lead to fish mortality

The growth and welfare of salmon is strongly correlated with water quality. To ensure low fish mortality, high fish welfare and optimal fish growth, it is important to closely control key parameters such as temperature, composition (ammonia, hydrogen sulfide, carbon dioxide, oxygen), pH, solids, microbes, illumination and noise. A sudden drop/increase in one of these parameters can cause a stressful environment for the fish, and quickly develop into fish mortality. As fish have limited tolerance for deviating parameters, the operational envelope is limited, which adds complexity to design and operation of RAS-based systems.

There are multiple recent examples in the industry of process safety incidents leading to fish mortality, including mortality of the entire population in a fish tank.

Process safety studies for RAS

Industries such as oil and gas, chemical and renewables have used process safety tools for decades as an integral part of asset engineering and operation. An onshore fish farming facility is a process facility with live animals. A single accident can have major consequences for fish welfare, finance, environment and reputation. It is therefore evident that focus on process safety is key for all stakeholders.

The following main process safety steps are recommended to develop safe and reliable onshore fish farming facilities:

• Conduct a Hazard and Operability (HAZOP) study covering critical process systems. A HAZOP aims to identify scenarios that can lead to deviating process parameters, which can potentially cause fish mortality or negative fish welfare. The HAZOP will map and evaluate safeguarding of such accidents, and propose means for further improvements. A HAZOP is a robust and well-proven method for risk-based design improvements.

• Instrumented functions are used to warn operators, or take automatic actions, in case of loss of control of a process parameter (e.g. too high temperature, too low oxygen level). Evaluate the most severe scenarios (from the HAZOP) in a Layers of Protection Analysis (LOPA) to determine the need for performance requirements of the instrumented functions based on the company’s acceptance criteria. Such requirements are, among others, important input for procurement of equipment.

• Incidents in smolt facilities can quickly develop and give significant consequences. Focus on alarm rationalization and categorization to ensure correct and timely executed actions during critical incidents. An excess of alarms can lead to wrong decisions in a stressful situation.

• Develop an asset-specific barrier management plan. The asset owner should have a barrier management philosophy —an overview of main barrier functions (preventive and mitigating) — and ensure that these barriers are tested and maintained throughout the lifetime of the facility. In addition to process safety accidents and related barriers, there are also other types of barriers that need to be considered, such as barriers against fish escape and internal/external biosecurity barriers. See for example this ORS Consulting webinar on barrier management for aquaculture systems focusing on offshore systems: https://youtu.be/cmG0FiSphOU?si=5k0NVHapGnDJYGFh

• Develop proof test procedures for safety critical barriers and implement a regime for statistical analysis of barrier performance.

ORS has a wide range of experience with fish farming, both from offshore and onshore facilities. Do not hesitate to contact one of our experts if you would like to discuss this further.