Atlantic bluefin tuna larvae face heat risk in Balearic waters

An international multidisciplinary team published a study on 19 August 2026 finding that Atlantic bluefin tuna larvae in the Balearic Islands, the principal breeding area for the species in the western Mediterranean, have little room before sea temperatures reach their upper survival limit. The Spanish Institute of Oceanography said current waters there are only three point six degrees below that threshold.

The study places the larvae’s average upper thermal limit at thirty-one point seven degrees Celsius and its lower limit at seventeen point nine degrees Celsius. This narrow range leaves the early life stage particularly exposed to ocean warming and helps explain why the species does not breed in colder seasons or waters.

Atlantic bluefin tuna reproduce during summer, when marine heatwaves can raise water temperatures rapidly to levels that threaten larval survival. Researchers expect ocean warming to make such episodes more frequent and intense, further reducing the available margin.

The team said the larvae’s sensitivity also makes controlled research on this open-sea species difficult. The findings add to thermal-limit data for young fish and improve understanding of a top predator that is important to marine ecosystems.

Source: Europa Press / Mallorca.com