Atlantic Mackerel Spawning Has Plummeted By 41%

   According to preliminary results from the 2025 survey by the International Council for Marine Exploration (ICES) Mackerel Spawn Survey Working Group, Atlantic mackerel spawning in the northeastern Atlantic off the coast of Europe has experienced a significant decline.

Mackerel spawning has plummeted

   In 2025, total Atlantic mackerel spawning is estimated to be down by approximately 41% compared to 2022, with an estimated spawning biomass of 2.3 million tons, also down 41%, the lowest level since 1992.

   ICES divides mackerel resources into several major spawning areas, including: the main spawning and resource areas off the coast of Ireland, the west coast of the United Kingdom, and the northern coast of France, where spawning has declined by 36%; and the southern coast of the Cantabrian Sea and the Bay of Biscay, near Spain and northwestern France, a smaller spawning area, where spawning has declined by approximately 75%, the lowest level in history for this region.

   Spawning is primarily concentrated at the edge of the continental shelf, near the 200-meter isobath. Peak spawning occurs in May along the coasts of Ireland and the UK, and in March along the southern coast of the Cantabrian Sea and the Bay of Biscay.

   Overall, mackerel spawning is more concentrated and gradual in both time and space; even higher-than-usual sea surface temperatures have not resulted in wider spawning distribution.

Biomass estimates hit a record low

   Based on preliminary spawning data and analysis of reproductive capacity from the three most recent surveys, the survey team estimates total mackerel spawning biomass in the Northeast Atlantic to be approximately 2.3 million tons in 2025, compared to 3.9 million tons in 2022.

   The decline is mainly attributed to the waters off the coasts of Ireland, the UK, and northern France, with limited contribution from the southern coasts of the Cantabrian Sea and the Bay of Biscay.

The International Council for Marine Exploration emphasizes that these figures are still preliminary estimates, and final results will be released in 2026. Nevertheless, the downward trend in spawning volume and spawning biomass is already quite evident. A sharp drop in mackerel spawning means a potentially significant decrease in the number of juveniles in the next generation, and a possible decline in catchable quantities over the next 1-3 years. This reduced catch could lead to a tight supply of mackerel in the international market and higher prices.