Description of the mackerel

Biology and morphology

• Morphology: The mackerel is a fusiform, highly hydrodynamic fish, capable of reaching speeds of 10 km/h. It is recognizable by its blue-green back marked with 23 to 33 sinuous dark chevrons, contrasting with a silvery belly. It possesses two widely spaced dorsal fins and, a major distinctive feature, five finlets (small plume-like fins) before the caudal fin on both the dorsal and ventral sides.

• Physiological peculiarity: Unlike the Atlantic chub mackerel (Scomber colias), the common mackerel does not possess a swim bladder; it is therefore forced to swim constantly to avoid sinking.

• Life cycle and feeding: Gregarious, it forms compact schools. It alternates between a demersal phase (near the bottom) in winter, where it fasts, and a pelagic phase (in open water) from spring to autumn, dedicated to feeding (primarily on zooplankton and small fish) and reproduction. It can live up to 20 years, reaching sexual maturity around age 3 (approximately 30 cm).

Current status and threats

Information cross-referenced between scientific reports (such as the one from the Ministry of Ecology in "Maquerau 2.pdf") and recent articles reveals a worrying situation:

• Disturbed distribution: Climate change is causing populations to shift toward colder areas, rendering old quota allocation agreements obsolete.

• Geopolitical crisis and overfishing: The absence of a robust international agreement (especially since Brexit) has led to unilateral quota setting by certain countries. This uncoordinated management has generated fishing pressure that exceeds scientific recommendations.

• Biological consequences: There is a marked collapse in spawning biomass and a worrying decrease in the recruitment of young individuals. The stock is now considered overexploited, which has forced drastic reductions in fishing quotas for the years 2024–2026 in an attempt to preserve the future of the species.

Interest for humans

• Health: It is an oily fish recognized for its richness in omega-3 fatty acids, which are beneficial for the prevention of cardiovascular diseases and proper immune function.

• Regulations: Its fishing is strictly regulated, with minimum catch sizes set by decree (generally 20 cm, except in the North Sea where it is increased to 30 cm) and mandatory marking for recreational fishing (removal of a portion of the caudal fin).

In summary, the mackerel perfectly illustrates the current challenges of marine management: a species that is biologically well-understood, but whose survival and exploitation are being severely tested by a combination of environmental factors and deficiencies in international ocean governance.