Fisheries Walkover Survey Manual

Transcription

1 1 Fisheries Walkover Survey Manual Copyright 2010 by the Westcountry Rivers Trust

2 2 Fisheries Walkover Survey Habitat Assessment Methods The objective of the walk-over survey is to gather information about the location and extent of the various physical habitat features present along and immediately surrounding the river, so that an assessment can be made about habitat quality and quantity (instream & bankside) for salmon. This should allow factors which may be limiting salmon productivity to be identified and recommendations made regarding habitat restoration techniques. The survey methodology is based upon the techniques outlined in the Environment Agency manual Restoration of Riverine Salmon Habitats A Guidance Manual (Hendry and Cragg-Hine,1997). Whilst undertaking the fisheries walk-over survey, we should aim to record the presence (where relevant field signs) and location of invasive plant species (Japanese Knotweed, Himalayan Balsam, Giant Hogweed & Montbretia), jelly lichen, otter and breeding sites for the kingfisher and dipper. See Figures 1-4 for photos of some of these plant species. Each section surveyed will consist of a 500m river section for which the appropriate map print-out should be provided beforehand to the surveyors. The boundaries of different in-channel habitat classifications (see Table 1) are drawn onto the map to represent the areas of individual habitat types using the symbols provided in the key. The features of interest (see Table 2) noted along each stretch of river are also drawn directly onto the map using the different symbols provided in a key. In this manner, a mosaic of different habitat types and features of interest can be drawn along the whole section of river (see example Maps 1 & 2). Each map will include the name of surveyor, date, upstream and downstream grid reference. Access permission from landowners should be obtained beforehand. Angling Club members who undertake survey work should be given appropriate training to ensure they are happy with the identification of different habitat types and features of interest. Strict attention should be paid to Health and Safety protocols for work near rivers (for example, it is recommended that a team of two undertakes each survey). Where possible, surveyors should be shown eg. Japanese Knotweed, Jelly Lichen etc. in the field before undertaking the survey work, and photographs/detailed descriptions provided.

3 3 Table 1. Habitat type classification system HABITAT TYPE Spawning Habitat & Silted Spawning Habitat Fry Habitat Parr Habitat Glides Pools Chute Bankside/Tunnel Vegetation Macrophyte Beds Obstructions to Migration Modified Channel DESCRIPTION Ideally stable but not compacted, easily workable with a boot without generating excessive silt release, a mean grain size of up to 80mm for salmon. ʻFinesʼ (<2mm grain size) to be less than 20% by weight. Shallow = or <20cm deep, fast-flowing (50-65 cm/s), with surface turbulence and a gravel (size range 16-64mm) and cobble (size range mm) substrate cm deep, fast-flowing (60-75 cm/s), surface turbulent, with gravel/cobble/boulder (size > 256mm) substrate. = or > 30cm deep, moderate velocity in range cm/sec, surface smooth and unbroken, relatively even substrate of cobbles with finer material. = or >40 cm deep, no visible flow, surface unbroken, substrate with a high proportion of sand and silt. Steep, fast-flowing water over bedrock; a waterfall Riparian vegetation should ideally provide a mixture of open and closed canopy throughout the reach. Tunnel vegetation forms a complete closed canopy for extensive lengths. Where this occurs, evidence of past coppicing (multistems) or standards should be recorded Extensive submerged and emergent macrophytes providing localised hydraulic diversity. Impassable falls, weirs, bridge, sills etc. shallow braided river sections preventing upstream migration during low flows. Where the bank has been artificially modified, straightened, reinforced or reprofiled, for example to accommodate flood flow (includes culverts, concrete revetment, gabions, sheet piling etc.).

4 4 Table 2. Features of Special Interest FEATURE Channel Width Access Point Bank Erosion Presence/signs Otters Presence/signs Dippers Presence/signs Kingfishers Invasive Plants Jelly Lichen Habitat DESCRIPTION Estimate the average width of channel (not water width) at one location within each 500m section. Banks trampled as a result of livestock, vehicular or human activity. Bank showing a clean earth face, overhanging turf, turf in channel, recently fallen trees, leaning fence posts. Look out for spraint (on large rocks and base of bridges) and footprints (at waterside on patches of mud or sand). Prefers fast-flowing shallow rivers with plenty of boulders and exposed tree roots. Will nest under bridges, in weirs, walls and culverts etc. Nest is domed structure of moss, grass stems and leaves with a wide entrance usually pointing down towards water. * Prefers slow-flowing, shallow rivers with branches over-hanging pools. Nests are excavated into vertical stone-free sandy soil of riverbanks, usually about 0.5m from bank top (about 6cm in diameter).* Record presence of Japanese Knotweed (JK), Himalayan Knotweed (HK), Himalayan Balsam (HB), Giant Hogweed (GH), Monbretia/Crocosmia (M). Submerged areas of bedrock. After Hendry & Cragg-Hine; 2007 * Please note, it is an offence to disturb birds close to their nest during the breeding season.

5 5 KEY. Symbols for Habitat Classification & Features of Interest S Spawning Habitat SS Silted Spawning Habitat P Pool G SS Glide Fr Fry Habitat Pr Par Habitat Ch Chute T/C Tunnel Vegetation/Abandoned Coppice T/S Tunnel Vegetation/Standards 4m Channel Width Access Point M Macrophyte Beds Mc Modified Channel O Obstruction to Migration E Bank Erosion Otter presence/signs presence/signs Dipper Kingfisher presence/signs Invasive Plants (JK/HB/GH/M) Bedrock Habitat/Jelly Lichen

6 6 Map 1. Example Field Survey Map Map 2. Example Output of Habitat & Features Map Animal AccessAnimal Access!(!( North Teign Walkover survey Manga Hill October 2010 Legend!( Notes Habitat Fry Habitat Glide Pool Animal AccessAnimal Access!(!( Par Habitat Spawning Habitat Shute Bankside - Open Moor Meters

7 7 INVASIVE PLANTS IDENTIFICATION SHEET Figure 1: Montbretia / Crocosmia Figure 2: Japanese Knotweed Copyright 2010 by the Westcountry Rivers Trust

8 8 Figure 3: Himalayan Knotweed Figure 4: Himalayan Balsam Copyright 2010 by the Westcountry Rivers Trust

9 9 EQUIPMENT CHECKLIST WRT Survey Pack (with identification sheets etc.) Relevant maps Stick (for walking, measuring depth, wading etc.) Clipboard (with plastic bag if raining) Camera * Binoculars First Aid Kit Mobile Phone Waders/Wellies Rucksack Lunch Pencils, pens and rubber Appropriate footwear & warm clothing Polaroid glasses Buoyancy Aid * To photograph important features eg. otter footprints & mark P on your map.

10 10 References Hendry K & Cragg-Hine D (1997). Restoration of riverine salmon habitats. Fisheries Technical Manual 4 Environment Agency, Bristol. Hendry K & Cragg-