Chapter 4: Healthy and Biologically Diverse

The spatial variation in Species Richness of demersal fish in waters around Scotland, averaged over the period 1999 to 2009.

This dataset is part of the larger Spatial Variation of Demersal Fish in Waters Around Scotland Dataset, which includes three layers that show the spatial variation of Demersal fish (generally living on or near the seabed) in waters around Scotland (averaged over the period 1999 to 2008) for:

• Size Composition (Large Fish Indicator) (defined as the proportion of fish (by weight) in the community that is greater than 40 cm in length). The higher the value (varying between 0 and 1), the greater the proportion of large fish in the community.
• Species Richness (a count of the number of demersal fish species recorded in any survey sample).
• Species Diversity (indices that also take account of the relative abundance of each species in the sample).

All three datasets are based on surveys carried out by ICES set up to provide fisheries independent information to support stock assessments.

The spatial variation in Species Diversity of Demersal fish in waters around Scotland, averaged over the period 1999 to 2010

This dataset is part of the larger Spatial Variation of Demersal Fish in Waters Around Scotland Dataset, which includes three layers that show the spatial variation of Demersal fish (generally living on or near the seabed) in waters around Scotland (averaged over the period 1999 to 2008) for:

• Size Composition (Large Fish Indicator) (defined as the proportion of fish (by weight) in the community that is greater than 40 cm in length). The higher the value (varying between 0 and 1), the greater the proportion of large fish in the community.
• Species Richness (a count of the number of Demersal fish species recorded in any survey sample).
• Species Diversity (indices that also take account of the relative abundance of each species in the sample).

All three datasets are based on surveys carried out by ICES set up to provide fisheries independent information to support stock assessments.

The spatial variation in size composition (Large Fish Indicator) of Demersal fish in waters around Scotland, averaged over the period 1999 to 2008.

This dataset is part of the larger Spatial Variation of Demersal Fish in Waters Around Scotland Dataset, which includes three layers that show the spatial variation of Demersal fish (generally living on or near the seabed) in waters around Scotland (averaged over the period 1999 to 2008) for:

• Size Composition (Large Fish Indicator) (defined as the proportion of fish (by weight) in the community that is greater than 40 cm in length). The higher the value (varying between 0 and 1), the greater the proportion of large fish in the community.
• Species Richness (a count of the number of demersal fish species recorded in any survey sample).
• Species Diversity (indices that also take account of the relative abundance of each species in the sample).

All three datasets are based on surveys carried out by ICES set up to provide fisheries independent information to support stock assessments.

Scottish underwater TV surveys to estimate Nephrops burrow distribution and abundance, from Nephrops Functional Units of significance to Scotland. Underwater TV footage is taken at specified stations within Functional Units. The underwater camera is mounted on a towed sledge and tow duration is 10 minutes. Records of Nephrops burrows, Nephrops and other benthic fauna is recorded onto DVD for analysis and review. At each station, a custom built sledge is towed along the sea bed and all Nephrops burrow complexes are counted and used to derive density estimates. These estimates are shown in this data layer.