4f4c4942-4343-5764-6473-313031383334 English NRW_DS116344 Master Reference Data Team Natural Resources Wales, Maes y Fynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW enquiries@naturalresourceswales.gov.uk http://naturalresourceswales.gov.uk/splash?orig=/ 2026-09-29T13:49:00.998Z NRW 1.0 wel utf8 British National Grid (EPSG::27700) Llyn Tegid Hydroacoustic Surveys and Gwyniad Translocations 2004-2009 Llyn Tegid Hydroacoustic Surveys and Gwyniad Translocations 2004-2009 Arolygon Hydroacwstig a Thrawsleoli Gwyniaid Llyn Tegid 2004 - 2009 Gwyniad Hydroacoustic Survey 2003 - 2009 - CCW Science Report 903 - Countryside Coucil for Wales CCW000800000000C Gwyniad Hydroacoustic and Gill netting survey of Llyn Arenig Fawr 2009 - CCW Science Report 904 CCW000800000000D Llyn Arenig Fawr Hydroacoustic Gwyniad Surveys 2009-12-31 NRW_DS101834 http://naturalresources.wales/ The gwyniad (Coregonus lavaretus) population of Llyn Tegid has been considered, for a number of years, to be threatened by deteriorating environmental conditions, particularly those associated with eutrophication. This dataset contains the results of a project established in 2004 to carry out translocations, hydroacoustic surveys, and the measurement of environmental variables. The purpose of this data collection was to assess the implications for the status of gwyniad (Coregonus lavaretus) and its habitat in Llyn Tegid. The objectives of the project included both conservation actions and further research, including the establishment of a refuge population in Llyn Arenig Fawr. Surveys were carried out annually from 2004 to 2009. Following an unsuccessful translocation attempt in 2003, three successful translocations took place in early 2005, 2006, and 2007. A full fish population survey of the recipient site, Llyn Arenig Fawr, was undertaken in 2009. The gwyniad (Coregonus lavaretus) population of Llyn Tegid has been considered, for a number of years, to be threatened by deteriorating environmental conditions, particularly those associated with eutrophication. This dataset contains the results of a project established in 2004 to carry out translocations, hydroacoustic surveys, and the measurement of environmental variables. The purpose of this data collection was to assess the implications for the status of gwyniad (Coregonus lavaretus) and its habitat in Llyn Tegid. The objectives of the project included both conservation actions and further research, including the establishment of a refuge population in Llyn Arenig Fawr. Surveys were carried out annually from 2004 to 2009. Following an unsuccessful translocation attempt in 2003, three successful translocations took place in early 2005, 2006, and 2007. A full fish population survey of the recipient site, Llyn Arenig Fawr, was undertaken in 2009. Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Centre for Ecology and Hydrology (CEH) Environment Centre Wales, Deiniol Road, Bangor, Gwynedd, LL57 2UW, Wales enquiries@ceh.ac.uk http://www.ceh.ac.uk/ Natural Resources Wales (NRW) Maes-y-Ffynnon, Penrhosgarnedd, Bangor, Gwynedd, LL57 2DW, Wales enquiries@naturalresourceswales.gov.uk http://naturalresources.wales/?lang=en Species distribution GEMET - INSPIRE themes, version 1.0 2008-06-01 geonetwork.thesaurus.external.theme.httpinspireeceuropaeutheme-theme oxygen profile marine and freshwater inventory gwyniad (freshwater whitefish) hydroacoustic Llyn Tegid coregonus lavaretus temperature profile Llyn Arenig Fawr secchi depth NRW Thesaurus 2026-08-27 geonetwork.thesaurus.local.theme.converted_nrw-keywords There are no access restrictions to this data. NRW may release, publish or disseminate it freely. no limitations © CNC/NRW 2008. There are no use restrictions on this data. Recipients may re-use, reproduce, disseminate this data free of charge in any format or medium, provided they do so accurately, acknowledging both the source and NRW's copyright, and do not use it in a misleading context. It is the recipient's responsibility to ensure the data is fit for the intended purpose, that dissemination or publishing does not result in duplication, and that it is fairly interpreted. Advice on interpretation should be sought where required. To avoid re-using old data, users should periodically obtain the latest version from the original source. Contains Natural Resources Wales information © Natural Resources Wales and Database Right. All rights Reserved. Open Government Licence English biota SeaVoX Vertical Co-ordinate Coverages 2021-01-06 Wales (WLS) GWYNEDD - GWYNEDD -3.66161429 -3.58302308 52.85964672 52.91223083 2004-08-05 2009-07-31 Rivers Ecologist, Marine and Freshwater Science Group, NRW Data collected under project number FC 73-02-304. The species records which form part of this dataset are available to download from the NBN Gateway as part of a larger packaged species dataset. Gwyniad translocation project 2004-05 : hydroacoustic survey of Llyn Tegid Llyn Tegid hydroacoustic surveys 2005 Llyn Tegid hydroacoustic surveys 2006 Llyn Tegid hydroacoustic surveys 2007 Llyn Tegid hydroacoustic survey 2008 Gwyniad translocation project 2004-05 : translocation attempt Llyn Tegid gwyniad translocation advice 2005-2006 Llyn Tegid gwyniad translocation advice 2006-2007 Delimited Unknown Echoview analysis data (*.csv); lake level data (2005 survey). Binary Unknown Raw echo sounder data (*.dt4 format). Text or Plaintext Unknown Oxygen and temperature profiles; Secchi depth measurements; hydroacoustic transect lengths; back-calculated under-yearling gwyniad lengths. Documents Unknown CCW Contract Science Reports 903 and 904 (PDF and Microsoft Word formats). Image Unknown Translocation photographs. Movie Unknown Translocation video clips. Database Unknown Archived survey and translocation data held under Project Numbers 29, 154, 194, 200, 226 and 227; Media Numbers 169, 232, 468, 539, 595 and 952. Species data also stored in Recorder 6. Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services 2010-12-08 This dataset has not been assessed for conformance to the referenced INSPIRE regulation. false Hydroacoustic surveys and measurements of environmental variables, including temperature, oxygen profiles, and Secchi disk readings, have been carried out annually since 2004 (with the exception of Secchi disk readings in the 2008 survey). In 2005, an analysis of historic lake data in the context of gwyniad spawning requirements was also undertaken. The methodology followed the standardised survey and monitoring protocol for the assessment of whitefish (Bean, 2003; JNCC, 2005), with two minor deviations. Firstly, rather than using the target strength-to-fish-length relationship described by Foote (1987), the relationship given by Love (1971) was used to allow wider comparison. Secondly, a vessel speed of 2.0 m s⁻¹ was adopted as the general target mean speed rather than as an absolute upper limit. Translocation attempts involved seine netting conducted after dark. Stripping was performed on the morning following sampling, and the volume of eggs was determined. Viable gwyniad were returned alive to the lake. Eggs were transported to Llyn Arenig Fawr and introduced into incubation boxes. A fish population survey at the recipient site was undertaken using hydroacoustic methods and gill netting. Hydroacoustic surveys and measurements of environmental variables, including temperature, oxygen profiles, and Secchi disk readings, have been carried out annually since 2004 (with the exception of Secchi disk readings in the 2008 survey). In 2005, an analysis of historic lake data in the context of gwyniad spawning requirements was also undertaken. The methodology followed the standardised survey and monitoring protocol for the assessment of whitefish (Bean, 2003; JNCC, 2005), with two minor deviations. Firstly, rather than using the target strength-to-fish-length relationship described by Foote (1987), the relationship given by Love (1971) was used to allow wider comparison. Secondly, a vessel speed of 2.0 m s⁻¹ was adopted as the general target mean speed rather than as an absolute upper limit. Translocation attempts involved seine netting conducted after dark. Stripping was performed on the morning following sampling, and the volume of eggs was determined. Viable gwyniad were returned alive to the lake. Eggs were transported to Llyn Arenig Fawr and introduced into incubation boxes. A fish population survey at the recipient site was undertaken using hydroacoustic methods and gill netting.