Bluefin tuna are back in the Bay of Biscay. After decades of decline, the fishery is experiencing a major revival. Roscoff in Brittany is the main departure port, with fish over 440 lbs landed regularly. The season runs June through November, driven by summer stratification that creates warm surface layers where tuna feed. Combined with Brittany's established bass fishing on the Cote d'Armor and the Basque coast's traditional bonito and swordfish fisheries, the Bay of Biscay has become one of Europe's most exciting saltwater destinations.
Species and Seasons
Bluefin tuna: The emerging European sport fishery. Brittany season June through November (no-kill early June to mid-November, harvest July 11 through October 10). Roscoff and Brest are the main ports. Fish average exceptional size, with specimens over 440 lbs regular. Topwater lures, spinning, and trolling. Water 59-66°F when fish are present.
European sea bass: Brittany's Cote d'Armor is famous for bass. Best April through October. Lure fishing from shore and boat. 55-62°F.
Albacore tuna: Traditional Bay of Biscay pole-and-line fishery with long commercial history. Summer and autumn in offshore waters.
Atlantic bonito: Summer species, often encountered while targeting tuna. Trolling 5-25 miles offshore. Basque coast is the traditional bonito fishery.
Swordfish: Deeper offshore waters, especially the southern Bay off the Basque coast. A specialty species.
Pollack: Rocky reefs and wrecks along the Brittany coast. Year-round, best spring and summer.
Why SST and Chlorophyll Matter
Summer stratification creates the warm surface layer that bluefin tuna feed in. SST imagery shows exactly where the warm patches are. Charter captains track these daily to locate feeding schools. Temperature breaks between 59-66°F are the key targets.
The southern Bay receives influence from the Iberian upwelling system. Cooler, nutrient-rich water upwells along the Spanish coast in summer, visible on SST as cool tongues. This drives the productivity that feeds the entire Bay food chain. River plumes from the Loire, Gironde, and Adour create distinct chlorophyll signatures.
Strong tidal currents around Brittany (especially the Ouessant/Ushant passage) create nutrient mixing visible as elevated chlorophyll, similar to the English Channel.
Calendar
Apr-May: Bass season ramps. Pollack on reefs. 50-59°F. Jun-Jul: Bluefin arrive (no-kill from early June). Bass peak. Bonito and albacore offshore. 59-66°F. Aug-Sep: Peak bluefin, largest fish. Best water temps. 62-72°F. Oct-Nov: Late bluefin (season closes mid-November). Cooling. 57-66°F. Dec-Mar: Winter. Offshore closed. 48-54°F.
Fishing nearby waters too? UK English Channel and Western Med are the closest covered regions. See pricing for what a plan covering Bay of Biscay / W France costs.