Lamprey translocation

Introduction

Lamprey translocation refers to moving lampreys out of the way from instream works.  Translocation of is also sometimes called “fish salvage”  but is different in that translocoation is undertaken before any instream works take place and refers to the process of moving lampreys away from areas not yet disturbed by, for example, intream works or stream diversions. Lamprey salvage as opposed to translocation may be required in different habitats, for example where targeted dredging takes place and habitats are too deep or inaccessible to undertake translocation. In these circumstances lampreys could be rescued or salvaged form the dredged material.

Overall, a total of 1,250 brook lamprey ammocetes were captured and translocated downstream
Overall, a total of 1,250 brook lamprey ammocetes were captured and translocated downstream from a 100m stretch of this stream in Co Limerick

There are also some limit circumstances where an area has been already enclosed and waster has been drawn down form an enclosed are of river where “salvage” as opposed to translocoation would apply. However, with proper project panning and advice it should be possible to avoid this type of scenario.

Where possible it is recommended that lampreys (and indeed other fish and macroinvertebrates  such as white-clawed crayfish) be moved, or encouraged to move themselves, out of the affected area prior to the commencement of works. Both translocoation and salvage works need to be proceeded by a lamprey habitat survey to identify suitable receptor areas (i.e. areas with habitats suitable to receive a the translocated or salvaged juvenile lampreys.

Juvenile lamprey translocation

Translocation of Lampreys may be required during instream works where there is unavoidable habitat loss, channel diversion, water draw down or any other activity that could potentially result in lamprey mortalities. It is necessary to engage appropriately qualified fisheries ecologists to carry out lamprey removal from areas that would be directly impacted by the proposed works. It is the responsibility of both the developer and the contractor or individual working instream to ensure that appropriate permissions and authorisations are in place to undertake works affecting these species. Areas of importance to lampreys may have been previously identified in an Ecological Impact Assessment, Natura Impact Statement, or similar appraisal carried out for the site. In the absence of information on the aquatic site, it is advised that baseline sampling be carried out by suitably qualified fisheries ecologists to obtain information on the presence / absence of Lampreys, and identifying suitable receptor habitats.

Lamprey and fish translocoation and salvage on the Fergus Flood Alleviation Scheme
Lamprey and fish translocoation and salvage on the Fergus Flood Alleviation Scheme

Standard electrical fishing methods for juvenile lampreys must be followed, and it is noted that this is a different methodology than is appropriate for use with salmonids and other fish. Taking cognisance of the difficulty in extracting lamprey ammocoetes from silt, multiple passes with the anode (at least three with 15 minute breaks in between) are required to effectively ensure any area of suitable habitat is clear of juveniles lampreys prior to works taking place. Sections of the watercourse that have been cleared of lamprey must be effectively fenced off (i.e. using a stop net or fine mesh/geo-textile silt fence) to prevent recolonisation. It is recommended that any silt removal or dewatering are carried out within a short period of time to minimise the potential for recolonisation of suitable habitat. Stands of emergent vegetation over juvenile habitat should be cut down as low as possible prior to survey and removal. It is important that any vegetation clearance is undertaken without trampling or compacting suitable lamprey ammocoete habitat; all cut vegetation should be removed from the river. Efficiency should be maximised during all Lamprey removal and translocation by carrying out operations during normal to low flow, bright and calm conditions and from a boat where necessary.

Translocation and/or savage of adult lampreys has occurred before, but with proper project planning and assessment should be avoided.  Instream works should always be timed to occur outside the lamprey spawning seasons.

The proposed return point for translocated Lamprey removed from the watercourse must be determined in advance of any works taking place and specification of this relocation area is generally a prerequisite of any licencing authorisation for undertaking translocation work. All lamprey removed from the watercourse must be quantified, with species and lengths determined, and allowed to fully recover from any anaesthetic used. Fresh river water, kept oxygenated by either battery or generator operated aerators can be utilised to store juvenile lampreys in the short term prior to release at the return point. Transport of lamprey, either by hand to suitable adjacent habitat, or by vehicle to a distant release point, will need to be determined in advance of works and specified in any authorisation. lampreys should not, unless in exceptional circumstances, be moved to a different catchment.

Adult lamprey translocoation

Translocation and/or savage of adult lampreys has occurred before, but with proper project planning and assessment should be avoided.  Instream works should always be timed to occur outside the lamprey spawning seasons. This type of work should only be undertaken if there was an overriding reason why instream needed to be timed to occur during  the lamprey spawning seasons (i.e. bridge repairs or other works in rivers with an associated urgent health and safety reason).

Adult Lampetra fluvialitis and L. planeri movd out of the way of instream works
Adult Lampetra fluvialitis and L. planeri moved out of the way of instream works

Checking spoil (lamprey salvage)

During drainage works and dredging works in areas which are too deep, inaccessible, or with insufficient visibility for using the translcoation approach spoil extracted from the watercourse can be checked for the presence / absence of lampreys and these can be collected form the spoil and placed into a receptor area.  This approach is also suitable for areas where a large are of dreging may be required (i.e. on a navigation scheme) or in areas where lamprey densities are too low for translcoation procedure to be practical. Juvenile lampreys will be in the top 20cm of substrate in the river so it is recommended to first remove the top 200cm of silt using the machine bucket and spread this out on the ground for examination by a suitably qualified fisheries ecologist. Juvenile lampreys (and eels, other fish and invertebrates such as crayfish) can be collected form the spoil and moved to the predefined receptor area.

Disturbance translocation

Teleost fish and crayfish are very mobile and, with the advice of an ecologist, can be encouraged to leave an area prior to instream works commencing using disturbance methods. Because juvenile lampreys live in burrows it is more difficult to encourage them to move away form an affected area on their own accord. However, the use pre-works agitation electrical fishing may have an application here in certain cases. This would also be subject to licence and would need to be undertaken by suitably qualified fisheries ecologists.

Maintenance of Limerick City Navigation scheme
Maintenance of Limerick City Navigation scheme

Examples of translocation work

We are the most experienced team in Ireland working with lampreys in Ireland. We also work in Northern Ireland and further afield as required.

If you have any queries about lampreys (or indeed any other ecological issues associated with instream works) please do not hesitate to contact us.

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