Fish Exclusion
Fish exclusion is the process of safely removing fish from in-water work areas and relocating them elsewhere, out of harm’s way.
Projects such as culvert replacement, pipeline burial/reburial, or in-water stream restoration/enhancement will likely require fish exclusion if located in fish-bearing waters. This process is often a required first step by both state and federal regulatory agencies before in-water construction can commence.
Regulatory agencies may request a Fish Exclusion Plan be submitted as part of the construction permitting process. This plan describes the equipment needed, methods, and sequencing surrounding safely removing fish from the in-water work area prior to construction, where fish will be relocated once captured, and more importantly, how they will be kept from re-entering the exclusion zone.
Although a formal plan is not always required by permitting agencies, having an informal approach or onsite discussion between the biologist and general contractor before in-water construction starts can help guide the fish removal process from creating unduly delays to the project. This meeting will outline the specific construction sequence where fish impacts could possibly occur and identify who will be responsible for what tasks, on what schedule, and in what order.
A site meeting at the beginning of construction is helpful for all of those involved to understand the site, potential hazards, and any project constraints. The Plan is Not Real Life. Not surprisingly, methods described in the Fish Exclusion Plan or accompanied permit are not always practical or feasible. For example, there may be too much debris in a stream or too many tree snags to effectively seine that portion of the stream. The plan is meant to be adaptive to the on-site field conditions.
At the start of the in-water construction, the fish exclusion subcontractor and general contractor will closely coordinate to collect and remove fish safely, as well as section off and dewater or direct flow away from the in-water construction area. If dewatering is not possible, fish removal will be conducted to the best extent possible and block nets will be placed up- and downstream of the work area to exclude fish from entering or re-entering the area.
In small bodies of water, fish exclusion typically consists of three possible methods – seining, dip netting, and electrofishing. In larger systems, such as lakes or large rivers, an electrofishing boat may be utilized.
In a stream, biologists will begin the fish exclusion process by sectioning off a stream reach with block nets and then sweeping the area with seine nets or dip nets. These are the least invasive method of fish removal and are usually the preferred method recommended by permitting agencies. Electrofishing is another method biologists can use, either as a standalone method or after non-invasive netting methods have been utilized. An electrofisher is an electronic device that sends electric currents of various wave forms and intensities through the water to temporarily stun fish. With electric currents flowing through the water, biologists need to be aware of not only the safety of the fish, but their personal safety as well. The electrofisher settings are optimized based on the water temperature, conductivity, fish size, and fish species present.
Once a fish is stunned, biologists will use nets to quickly move them to a transfer bucket, out of the in-water construction area, and into a holding cooler. To minimize stress to the fish, holding coolers should be set up beforehand on a nearby streambank. These holding coolers have lids, ample cold, fresh water, and an aerator, and are monitored regularly to ensure the fish have recovered and are healthy. Stunned fish recover very quickly, and mortality is extremely rare. Once the fish have recovered, they are released to a safe site where they will not be able to re-enter the in-water work area. This is usually downstream, but the release location can vary depending on the complexities of the construction site.
Ultimately, the aim of fish exclusion is to remove fish from an area that is unsafe, utilizing the least intrusive method for the fish, while also minimizing impact to the aquatic habitat. 48 NORTH’s fisheries staff are well-versed in performing these tasks, including developing and executing both formal and informal Fish Exclusion Plans. In addition to trained fisheries staff, 48 NORTH has an electrofishing unit, and block, dip, and seine nets ready to deploy.
Please contact 48 NORTH’s Senior Fisheries Biologist, Bill Mavros, if you have any questions about fish exclusion, our expertise, or how we can support your next in-water construction project
Projects such as culvert replacement, pipeline burial/reburial, or in-water stream restoration/enhancement will likely require fish exclusion if located in fish-bearing waters. This process is often a required first step by both state and federal regulatory agencies before in-water construction can commence.
Regulatory agencies may request a Fish Exclusion Plan be submitted as part of the construction permitting process. This plan describes the equipment needed, methods, and sequencing surrounding safely removing fish from the in-water work area prior to construction, where fish will be relocated once captured, and more importantly, how they will be kept from re-entering the exclusion zone.
Although a formal plan is not always required by permitting agencies, having an informal approach or onsite discussion between the biologist and general contractor before in-water construction starts can help guide the fish removal process from creating unduly delays to the project. This meeting will outline the specific construction sequence where fish impacts could possibly occur and identify who will be responsible for what tasks, on what schedule, and in what order.
A site meeting at the beginning of construction is helpful for all of those involved to understand the site, potential hazards, and any project constraints. The Plan is Not Real Life. Not surprisingly, methods described in the Fish Exclusion Plan or accompanied permit are not always practical or feasible. For example, there may be too much debris in a stream or too many tree snags to effectively seine that portion of the stream. The plan is meant to be adaptive to the on-site field conditions.
At the start of the in-water construction, the fish exclusion subcontractor and general contractor will closely coordinate to collect and remove fish safely, as well as section off and dewater or direct flow away from the in-water construction area. If dewatering is not possible, fish removal will be conducted to the best extent possible and block nets will be placed up- and downstream of the work area to exclude fish from entering or re-entering the area.
In small bodies of water, fish exclusion typically consists of three possible methods – seining, dip netting, and electrofishing. In larger systems, such as lakes or large rivers, an electrofishing boat may be utilized.
In a stream, biologists will begin the fish exclusion process by sectioning off a stream reach with block nets and then sweeping the area with seine nets or dip nets. These are the least invasive method of fish removal and are usually the preferred method recommended by permitting agencies. Electrofishing is another method biologists can use, either as a standalone method or after non-invasive netting methods have been utilized. An electrofisher is an electronic device that sends electric currents of various wave forms and intensities through the water to temporarily stun fish. With electric currents flowing through the water, biologists need to be aware of not only the safety of the fish, but their personal safety as well. The electrofisher settings are optimized based on the water temperature, conductivity, fish size, and fish species present.
Once a fish is stunned, biologists will use nets to quickly move them to a transfer bucket, out of the in-water construction area, and into a holding cooler. To minimize stress to the fish, holding coolers should be set up beforehand on a nearby streambank. These holding coolers have lids, ample cold, fresh water, and an aerator, and are monitored regularly to ensure the fish have recovered and are healthy. Stunned fish recover very quickly, and mortality is extremely rare. Once the fish have recovered, they are released to a safe site where they will not be able to re-enter the in-water work area. This is usually downstream, but the release location can vary depending on the complexities of the construction site.
Ultimately, the aim of fish exclusion is to remove fish from an area that is unsafe, utilizing the least intrusive method for the fish, while also minimizing impact to the aquatic habitat. 48 NORTH’s fisheries staff are well-versed in performing these tasks, including developing and executing both formal and informal Fish Exclusion Plans. In addition to trained fisheries staff, 48 NORTH has an electrofishing unit, and block, dip, and seine nets ready to deploy.
Please contact 48 NORTH’s Senior Fisheries Biologist, Bill Mavros, if you have any questions about fish exclusion, our expertise, or how we can support your next in-water construction project
