Shetland Inshore Fish Survey (SIFS) 2023: summary of catch rates, size compositions, and spatial distributions of commercial demersal fish species

Shaun Fraser, Chevonne Angus, Mia McAllister, Louise Thomason, Sarah Ayres, Leander Harlow

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Abstract

An overview of results from the Shetland Inshore Fish Survey (SIFS) conducted by UHI
Shetland (formerly NAFC Marine Centre) from 2011 - 2023 in the coastal waters around
Shetland is presented. The purpose of the survey is to provide independent information on
the distribution, relative abundance, and population structure of fish species in local waters.
Key results from the available data are reported here with a focus on commercially important
species. This report is intended for a general audience with information presented in a concise
and non-technical format.
The survey has been carried out annually using the 12 m MFV Atlantia II (LK 502) during
August and September, using a standardised survey trawl fitted with a small-mesh (20 mm)
cod-end. The original annual inshore fish survey involves hauls from 27 pre-defined locations
within 12 nautical miles of Shetland. Since 2017, a concurrent shallow-water fish survey has
been added, with up to 25 hauls targeting potential nursery grounds around the coast of
Shetland. Catch rate results are used to investigate the relative abundance of commercial
species by considering catch per unit effort (CPUE). Length data are used to further interpret
variations in population structure and recruitment.
Results are presented for the most significant commercially important demersal fish species
sampled throughout the surveys. Key findings from the 2023 surveys include:
• Haddock (Melanogrammus aeglefinus) continues to be the main component of
catches and was characterised this year by mostly marketable size classes that were
evenly distributed across inshore grounds, with also a considerable younger age-class
present that has not yet recruited into the fishery.
• Squid (Lologi spp.) catch rate (by weight) on shallow grounds in 2023 surpassed the
record levels observed last year and were concentrated in specific nearshore areas.
• Cod (Gadus morhua) catch rate (by weight) on inshore grounds were at their highest
level since 2018 with highest cod catches mostly observed in western parts of the
study area.
• The data from shallow hauls suggests that some nearshore grounds around the
coastline of Shetland are nursery areas for a variety of commercial species including
plaice (Pleuronectes platessa) and cod; and contain important commercially
exploitable abundances of other species such as thornback ray (Raja clavata).
Final points of this report include a description of related ongoing work and the
recommendation that the annual inshore and shallow fish surveys are continued.
Original languageEnglish
Number of pages29
Publication statusPublished - 30 Nov 2023

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