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UK Biodiversity Indicators 2021. Indicator D1a – Fish size classes 2021

Corporate UK Biodiversity


These documents support indicator D1a – Fish size classes. The documents include a datasheet. Technical documentation for the indicator is available at:

There has been no update since the previous publication.

The indicator shows changes in the proportion, by weight, of large individuals equal to or over 50 cm in length in demersal (bottom-dwelling) fish populations in the North Sea. Changes in the size structure of fish populations and communities reflect changes in the state of the fish community. Fluctuations in values between years are expected given inter-annual fluctuations in the distribution and abundance of North Sea fish populations and sampling variation.

These resources may not be fully accessible for all users. If you need a copy of any of these resources in a different or more accessible format, please get in touch.

Resource type Publication

Topic category Environment

Reference date 2021·10·20

Department for Environment, Food and Rural Affairs, UK. 2021. UK Biodiversity Indicators 2021.

The UK Biodiversity Indicators were first published in 2007. They were created to provide a measure for reporting on the UK’s progress towards meeting international biodiversity goals and targets. The indicators were comprehensively reviewed during 2011 and 2012 to ensure they continued to be based on the most robust and reliable available data, and remained relevant to the new international goals and targets developed in 2010 and 2011.

Responsible organisation
Communications, JNCC distributor

Limitations on public access No limitations

Use constraints Released under the Open Government Licence v3.0. Attribution statement "Contains public sector information from Defra, licenced under the Open Government Licence v3.0"

Metadata date 2021·10·20

Metadata point of contact
Communications, JNCC

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