Shetland Inshore Fish Survey (SIFS) 2025: summary of catch rates, size compositions, and spatial distributions of commercial demersal fish species

An overview of results from the Shetland Inshore Fish Survey (SIFS) conducted by UHI Shetland (formerly NAFC Marine Centre) from 2011 - 2025 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 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 additional 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) through time and space. Length data are used to further interpret variations in population structure and recruitment.

Results are presented with a focus on the most significant commercially important demersal fish species sampled throughout the surveys. Key findings from the 2025 surveys include:
• Record high squid (Loligo forbesii) catches surpassed the high levels observed in recent years and were concentrated in specific nearshore areas.
• Average catch rates for several other key commercial species were at the lower end of observed values, e.g. haddock (Melanogrammus aeglefinus), cod (Gadus morhua), whiting (Merlangius merlangus) and plaice (Pleuronectes platessa), while some other species were particularly widespread and/or abundant this year, e.g. John Dory (Zeus faber), megrim (Lepidorhombus whiffiagonis) and hake (Merluccius merluccius).
• Two fish species that were recorded for the first time in 2024 in the SIFS dataset, scaldfish (Arnoglossus laterna) and imperial scaldfish (Arnoglossus imperialis), were observed again in 2025 and more widespread than the previous year suggesting that SIFS can provide an early warning of species shifts and changes to fish assemblages.
• Even in a year characterised by low relative abundances for some species, the 2025 data continue to show that specific nearshore grounds around the coastline of Shetland are consistently used as nursery areas for key commercial species including plaice, haddock, whiting, 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, opportunities for further research, and the recommendation that the annual inshore and shallow fish surveys are continued.