The ICES herring assessment working group (HAWG) met online for nine days in March 2023 to assess the state of six herring (Clupea harengus) and three sprat (Sprattus sprattus) stocks. Additionally, HAWG provided advice for eight Sandeel (Ammodytes spp.) in January 2023. The working group conducted update category 1 assessments for four of the herring stocks and category 3 assessments for 2 herring stocks. An analytical assessment was performed for the combined North Sea and Division 3.a sprat, and data limited assessment (ICES category 3) was conducted for English Channel sprat (spr.27.7de). Biennial advice is given for sprat in the Celtic Seas and West of Scotland with advice provided in 2023. North Sea autumn spawning herring (her.27.3a47d). SSB in 2022 was estimated at 1.65 million tonnes while F2–6 in 2021 was estimated at 0.23, which is below FMSY. Recruitment in 2022 is at its highest since 2014, which is expected to contribute positively to SSB levels from 2024 onwards. ICES considers that the stock is still in a low productivity phase. Western Baltic spring-spawning herring (her.27.20-24). SSB in 2022 was estimated at 75,548 tonnes and is below MSY Btrigger, Bpa, and Blim. Recruitment has been low since 2007 and has been deteriorating further with time. F3- 6 has been decreasing since 2018 and is now week below FMSY (0.31) at 0.05. The stock has decreased consistently during the second half of the 2000s and given the continued low recruitments, the stock is not able to recover above Blim unless a drastic reduction in fishing effort is applied for several years. Celtic Sea autumn and winter spawning stock (her.27.irls). SSB in 2022 was estimated at 16,539 tonnes, though is increasing from its lowest level seen in 2018 (6,474 tonnes), but remains below Blim (34,000 tonnes). F(2-5 rings) in 2022 was estimated at 0.028, having decreased from a peak of 1.16 in 2017. Recruitment has been consistently below average since 2013. Irish Sea autumn spawning herring (her.27.nirs). SSB in 2022 was estimated at 25,900 tonnes and is above MSY Btrigger, Bpa, and Blim. Recruitment in 2022 is the highest on record and continues the trend of large incoming year-classes in recent years. F4- 6 has been stable between 0.22 and 0.24 since 2006 and is below FMSY (0.266). 6aN autumn spawning herring (her.27.6aN). SSB in 2022 was estimated at 33,283 tonnes using the genetically split, Malin Shelf Herring Acoustic Survey (MSHAS). Whilst SSB has increased since its lowest level in 2019, these numbers of herring are low compared to historical estimates. Indicators show that stock size is above MSY Btrigger proxy and below FMSY proxy. Herring in 6.aS/7.b, c (her.27.6aS7bc). SSB in 2022 was estimated at 147,199 tonnes using the genetically split, Malin Shelf Herring Acoustic Survey (MSHAS) and has been increasing since the lowest point in 2016 (36,707 t). Recent catches are among the lowest in the time series. Fishing pressure on the stock is below FMSY proxy (0.034) and the stock size index is well above MSY Btrigger proxy (51 390 t). Sprat in the North Sea and 3.a (spr.27.3a4). SSB in 2023 was estimated at 206,581 tonnes and is above MSY Bescapement, Bpa, and Blim. F1-2 has been decreasing since 2016, however there are high levels of fluctuation throughout the time series. Low recruitment in recent years had contributed to the stock being below MSY Bescapement, though this has been alleviated by the 2023 year-class.