Habitat Evaluation & Mapping
APEM have been at the forefront of habitat evaluation and mapping for many years. We have developed our own mapping methodologies specifically for
Fish Habitat Mapping (FHM). We also have extensive experience of conventional habitat mapping techniques including
River Habitat Survey (RHS) and its predecessor River Corridor Survey (RCS), which were both developed by the Environment Agency for specific purposes. Moreover
other mapping procedures are undertaken on a regular basis, for example to include conservation interests such as otter and crayfish habitat.
FHM was developed by APEM in the mid 1990's whilst evaluating salmonid habitat as part of investigations on a number of salmonid rivers, including the River Wyre (Lancashire) and Wolf (Tamar catchment). The methodology was further refined and developed for the Environment Agency Fisheries Technical Manual Series (No 4)
'Restoration of Riverine Salmon habitats - A Guidance Manual'. The technique relies on a basic knowledge of fish habitats using a combination of electric fishing expertise (fry & parr habitats) and angling knowledge (pools & glides). The methodology has also been successfully applied to trout, bullhead, lamprey, and riverine coarse fish. The technique has been used on over 30 river systems throughout the UK, from North West Scotland to the South East England. The range of projects includes abstraction studies, fish population (standing crop assessments), pollution incidents and habitat restoration projects. During 2002/3 the technique was adapted for use with a GIS system providing significant advances in spatial and data analysis. This approach was developed for the Environment Agency on the River Bollin, part of the Mersey catchment, to evaluate the required environmental/habitat improvements needed to allow development of a self-sustaining salmon population.
The APEM Fish habitat technique has been used on the following rivers for a variety of species (including salmonids and lampreys), individual surveys varying in size from 5km to cover entire catchments of 100 km or more:
APEM has externally accredited expertise in River Habitat Surveying (RHS) and its predecessor, River Corridor Surveying (RCS). This involves an assessment of flow types, physical features, vegetation structure, land use and channel vegetation types over a 500 m stretch of river channel. RHS can provide a variety of information on the habitat quality and conservation value of a watercourse and, in conjunction with fisheries or water quality monitoring, can provide an overall assessment of river quality. Specific uses include the following:
- Sites can be compared to the national reference network of sites established by the Environment Agency. This gives a national inventory of features and provides a statistically valid basis for the classification of river types. Any site in the country surveyed using RHS can therefore be categorised on the basis of river type and observed features compared with a national or regional 'norm'.
- The technique is also used to assess changes in the characteristics of a site over a number of years and determine the effects of events such as changes in flow regime or drought.
In addition to techniques described above, APEM have also developed mapping techniques for other purposes. This includes macrophyte mapping for biomass estimation prior to harvesting as part of a water plant control strategy in a RAMSAR site (
Cavendish Dock), water quality contour mapping as part of the
MSC Oxygenation Project, and erosion / sediment mapping on several studies notably the Environment Agency
Sustainable River Management Project.
Digitised map assessments provide a user-friendly, graphical method of interpreting habitat, population and water quality data. This technique, useful for identifying patterns of long-term change, has already been successfully used by APEM in a wide range of projects, and has many applications.
The technique can also be used to assess changes in the characteristics of a site over a number of years and can be used to determine the effects of events such as changes in flow regime or drought. Other examples of Habitat mapping in APEM projects include:
- Temporal changes in the distribution of wetlands
- Habitat distribution and degradation as well as barriers to migration and areas for restoration
- Macrophyte mapping to identify potential fish and invertebrate habitats
- Macrophyte density analysis in enclosed water bodies
- Population distribution mapping