UK Biodiversity Indicator D1a, Fish size classes in the North Sea

• Published by: Joint Nature Conservation Committee
• Last updated: 17 May 2018
• Topic: Environment
• Licence: Open Government Licence ; View licence information

Summary

This spreadsheet is the underlying data for the biodiversity indicator D1a, Fish size classes in the North Sea.

Change in relative abundance of large fishes is likely to affect marine ecosystems in a number of ways. Fewer large fishes will reduce the amount of predation on smaller prey species and allow increases in their abundance and biomass. In turn this will affect the structure and stability of the ecosystem. The indicator responds to fishing impacts on the fish community because larger fish are more likely to be caught by trawls and because larger species of fish are more likely to decline in number for a given rate of fishing. When fish communities are more heavily fished, the proportion of large fish is expected to fall and, when fishing is reduced, the proportion of large fish is expected to rise. Some variation in the proportion of large fish will be driven by environmental variation, but available evidence suggests environmental effects on this indicator are relatively small in relation to fishing effects over periods of a few years.

The indicator shows changes in the proportion, by weight, of large individuals equal to or over 40cm in length in fish populations in the North-western part of the North Sea. The indicator is based on standardised annual research survey trawls. During the 1980s, large fish in the North Sea fish community included cod (Gadus morhua), haddock (Melanogrammus aeglefinus), saithe (Pollachius virens), ling (Molva molva), anglerfish (Lophius piscatorius) and rays (Batoidea). Recently, haddock have formed a substantial part of the large fish catches in the North-western North Sea, along with cod and saithe.

This is one of a suite of 24 UK biodiversity indicators published by JNCC on behalf of Defra; the latest publication date was 19 January 2016 - for indicator D1a the latest data are for 2014. The supporting technical document details the methodology used to create the indicator.

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Related datasets

• 2006 - 2007 Centre for Environment, Fisheries & Aquaculture Science (Cefas) Northern North Sea saithe, cod and haddock 2003/04 - Fisheries Science Partnership
• 2001 Strategic Environmental Assessment SEA2 Technical report - North sea fish and fisheries
• UK Biodiversity Indicator B2, Sustainable fisheries
• 2001 Strategic Environmental Assessment SEA2 Technical report - A review of pockmarks in the UK part of the North Sea, with particular respect to their biology

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Data links

Link to the data	Format	File added	Data preview
page-4248	N/A	17 May 2018	Not available

Additional information

View additional metadata

• Added to data.gov.uk: 2018-05-17
• Access contraints: No limitations
• Harvest GUID: 3742a2e5-361d-43cc-8c98-d42bdbf3215a
• Extent: Latitude: 61.0° to 49.77°
• Extent: Longitude: -8.65° to 2.0°
• Dataset reference date: 2016-01-19 (publication)
• Responsible party: Digital and Data Solutions, JNCC (distributor)
• ISO 19139 resource type: dataset
• Metadata language: eng
• Source Metadata: XML
• Source Metadata: HTML

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Licence information

Released under the Open Government Licence v3.0. Attribution statement "Contains public sector information from the Centre for Environment, Fisheries and Aquaculture Science and Marine Scotland, licenced under the Open Government Licence v3.0"