Pre-spawning herring shoals attract whales and other wildlife to coastal waters
Posted: Thursday 8 May, 2025 @ 14:05:10
One of Scotlands biggest (in kg) coastal wildlife events?
Wester Ross spring spawning herring report_8may25.pdf
This report describes observations of marine wildlife thought to be associated with shoals of maturing herring in coastal waters near Gairloch, Wester Ross, between February and early April 2025; and subsequent spawning of herring verified by the discovery of herring eggs on the seabed nearby.
Marine mammal sightings within 2km of the shore included up to 40 dolphins (assumed to be mostly common), 60 porpoises, 50 grey seals, 3 minke whales (perhaps 5 in the area) and one or perhaps two humpback whales. Up to 120 gannets were seen in the main feeding area and 300+ gulls (several spp.). Observations possibly amounted (in kg) to one of Scotland’s biggest springtime coastal wildlife events.
On 20th March 2025, a drop-down video survey of the seabed to the northwest of Loch Gairloch failed to identify and record herring eggs in the area where much sea mammal activity was observed on 9th March 2025 and where herring eggs were recorded in March 2024. However, on 3rd April 2025, herring eggs were found on maerl gravel and sugar kelp fronds on the seabed about 800m west of the shore at Opinan (southwest of Gairloch) in water depths of 10m to 15m. High densities of recently hatched herring larvae were taken with a plankton net in the water column on the same day demonstrating successful spawning by herring. Eggs collected from this location on 4th April 2025 were mostly eyed.
Observations and seabed surveys demonstrate successful spawning of herring to the southwest of Gairloch in 2025, with a herring spawning event around 20th March to 23rd March. With additional support in future years, associated marine wildlife and spawning grounds could be monitored and mapped in more detail.
Thank you to the West of Scotland Herring Hunt project, Seabed and Seashore Loch Ewe, Little Loch Broom Marine Life, Blue Hope Alliance, Dry Island Shellfish Safaris, Nature Scot and many people within the local community for support with finding herring spawn and recoding associated wildlife in 2025.
The report can be found here:
