​Where and When to Find Bluefin in Southern California

 

Pacific bluefin migrate north from Mexican waters beginning in late spring and can be found off San Diego, the Coronado Islands, the Channel Islands, and along the Southern California coast through fall. The best months are typically June through October, though warm-water years can extend the season in both directions. Some years the fish show up early in April or May. Other years, they push later into November.

 

Bluefin in Southern California are often found pushing bait in open water, sometimes within sight of the coast but more commonly 20 to 60 miles offshore. They're frequently spotted on the surface chasing bait — look for diving birds, surface boils, and foaming water. Sonar and fish-finding electronics on the boat are essential for locating schools below the surface. When the fish are deep and not showing on top, metering marks on the sounder may be your only clue.

 

The best encounters tend to happen at first light or in the last hour or two before sunset. Bluefin are more active and more willing to approach divers during these low-light windows. Midday encounters happen, but the odds are stacked in your favor early and late in the day.

 

Water temperature matters. Bluefin prefer water in the 60 to 68 degree range in our area, and they'll follow temperature breaks and current edges where bait concentrates. When you find a sharp temperature change on the surface — even just a two or three degree shift — pay attention. That edge is likely holding bait, and bluefin won't be far behind.

 

How Moon Phases Affect Bluefin Behavior

 

This is a topic that generates a lot of debate among divers and fishermen, but there's enough consistent experience out there to take it seriously when planning your trips.

 

The moon affects tidal movement. Full moons and new moons create the strongest tidal swings — bigger highs, lower lows, and faster-moving currents in between. Quarter moons produce the weakest tides with less current movement. This matters because current directly affects how bluefin feed and where they position themselves in the water column.

 

New Moon and Bluefin

 

Many experienced bluewater divers and tuna fishermen in Southern California prefer the new moon phase for bluefin. The theory is straightforward: weaker tides mean less current, which means bait moves less. When bait is holding still or drifting slowly, bluefin don't have to expend as much energy to feed. They get comfortable. They slow down. And slower, more relaxed bluefin are easier to approach on a breath-hold.

 

There's also a visibility factor at play. During the new moon, nights are darker. Bluefin that have been feeding at night under a dark sky tend to be hungrier and more actively feeding in the early morning hours. The combination of reduced current and active morning feeding makes the new moon period — and the days immediately surrounding it — a prime window for bluewater divers.

 

Full Moon and Bluefin

 

Full moon periods bring stronger tides and faster currents. Bait gets pushed around more aggressively, and bluefin have to work harder to feed. The fish are often deeper, more scattered, and moving faster. That makes them harder to locate and harder to approach. Many divers report that bluefin are more skittish and less willing to come within range during full moon periods.

 

That said, full moons aren't a total washout. Slack tide — that brief window when the current stops between tidal changes — can still produce quality encounters even during a full moon. When the current pauses, the bait pauses with it, and bluefin take advantage. If you're diving during a full moon phase, time your dives around the slack. Check tide charts for your area and plan to be in the water during those transition windows.

 

Putting It Into Practice

 

The moon phase isn't a magic switch that turns the bite on or off. Bluefin feed during every phase of the moon. But if you have flexibility in your schedule and you're choosing between weekends, lean toward the new moon period. Plan your trip for the three or four days on either side of the new moon, get in the water at first light, and you're stacking the odds in your favor.

 

Gear for Spearfishing Pacific Bluefin

 

Bluefin tuna demand serious bluewater gear. This is not a species you can target with a standard reef gun. Everything about your setup needs to be scaled up — your gun, your shaft, your rigging, and your float system.

 

Spearguns

 

A bluewater tuna gun is typically 60 to 70 inches long with four to five power bands. You need the length for range and the band power to drive a heavy shaft through a fish that may weigh more than you do. Multi-band railguns from dedicated bluewater manufacturers are the standard. Whether you prefer a roller gun or a traditional band gun comes down to personal preference, but either way, you need enough power to penetrate deep into a fast-moving fish at realistic shooting distances of 10 to 20 feet.

 

Shafts and Tips

 

Use a minimum 8mm shaft — many experienced bluewater divers prefer 9mm or even 9.5mm for large bluefin. A thicker shaft reduces the leverage the fish can use to work the shaft free. Slip tips are the gold standard for tuna because they toggle inside the fish after penetration, making it nearly impossible for the fish to throw the shaft. Double-flopper shafts are an alternative, but slip tips offer superior holding power on large, powerful fish.

 

Float Line and Float System

 

This is where bluefin gear differs most from standard spearfishing. You need a breakaway rig — the shaft and shooting line connect to a float line and one or two high-pressure inflatable floats rather than attaching to the gun via a reel. When you hit a bluefin, that fish is going to run hard and dive deep. A reel attached to your gun would pull you under or rip the gun from your hands. The breakaway system lets the fish fight the floats while you stay safe at the surface.

 

A typical rig uses 75 to 150 feet of float line (PVC or Spectra core) with a bungee section to absorb the initial shock of the run. Connect this to one or two high-pressure floats rated for the depths you're diving. The bungee is critical — without it, the initial hit can snap your line or pull your slip tip through the fish.

 

Additional Gear

 

A quality low-volume mask, long carbon or fiberglass freediving fins, a sharp knife accessible with either hand, and a wetsuit appropriate for Southern California water temps — typically 3mm to 5mm during summer and early fall when the bluefin are here. A weight belt with a quick-release buckle is essential. If something goes wrong during a fight, you need to be able to ditch weight and get to the surface immediately.

 

How to Approach and Shoot Bluefin Tuna

 

Finding and Approaching the School

 

Bluefin tuna are typically located from the boat first using electronics, visual sighting of surface activity, or by following bird life. Once a school is located, positioning is everything. The fish are usually pushing bait up-current, so determine the direction the school is traveling and get the boat ahead of them. Shut down the engines well before the school reaches you — bluefin are boat-shy and engine noise will push them down or send them off in another direction.

 

Divers enter the water quietly and position themselves in the path of the approaching school. Speed matters here — have your gear ready, guns loaded, and divers in the water quickly. Bluefin schools move fast, and you may only get one chance before they pass. Every second between "fish spotted" and "divers in the water" counts.

 

The Shot

 

Bluefin tuna move faster underwater than most divers expect. You need to give the fish lead — aim ahead of the fish's direction of travel, not at the fish itself. The most effective shot placement is behind the pectoral fin into the body cavity, or a spine shot if you can get above the fish. Avoid head-on shots and tail shots — the skull is incredibly hard, and a tail shot gives the fish maximum leverage to throw the shaft.

 

A heavy shaft moving at high speed is critical. These fish are dense and muscular, and a weak shot will either bounce off or fail to penetrate deep enough for the slip tip to toggle. Commit to the shot and let the bands do the work. Don't rush it — a clean, well-placed shot on a closer fish beats a hail-Mary at maximum range every time.

 

After the Shot

 

Once you've hit a bluefin, get out of the way. The fish will run immediately and violently. Your float line should be paying out freely — make sure nothing is tangled around your body, your gun, or your fins. The fish will tow the floats, sometimes for hundreds of yards and to significant depth. Your job is to stay at the surface, keep visual contact with the floats, and let the fish tire itself out.

 

The boat follows the floats. When the fish slows, a diver can go down the float line to place a second shot or dispatch the fish with a kill shot to the brain. Never rush this process — a green bluefin at close range is dangerous and can injure or drown a diver. Wait until the fish is clearly exhausted before approaching.

 

Regulations for Pacific Bluefin in California

 

There is no closed season for bluefin tuna in California — you can spearfish for them year-round. The daily bag limit is 2 bluefin tuna per person, and this is in addition to the general daily bag limit of 20 finfish. There is currently no minimum size requirement for recreational take in California.

 

That said, always check the most current regulations from the California Department of Fish and Wildlife before your trip. Bluefin regulations can change mid-season based on quota management and international agreements. NOAA also manages Pacific bluefin at the federal level, so keep an eye on any federal updates that could affect recreational take.

 

You need a valid California fishing license and an ocean enhancement stamp. If you're diving from a charter or private boat, make sure the vessel is in compliance as well.

 

Safety Considerations

 

Bluewater spearfishing for bluefin tuna is an advanced activity that carries real risk. This is not a beginner species. The open ocean off Southern California demands respect.

 

Freediving fitness:   You need strong breath-hold capability and comfort at depth. Bluefin encounters often happen at 30 to 60 feet, and you need to be relaxed and in control at those depths while simultaneously managing a loaded speargun and reading the behavior of a fast-moving school. If you're not confident in your freediving skills, take a course before attempting bluewater tuna. I recommend the free freediving safety course at freedivingsafety.com as a starting point — it covers the essential rescue skills every diver needs.

 

Shallow water blackout risk:   Extended dive sessions in open water with adrenaline pumping is a recipe for pushing your limits. Always dive with a dedicated safety diver who watches you on every descent and ascent. Download our free Emergency Procedures checklist at SpearFactor.com and make sure everyone on the boat knows the protocol before anyone gets in the water.

 

Boat coordination:   Communication between divers and the boat captain is critical. Establish clear signals before anyone enters the water. The boat needs to stay close enough to assist but far enough to avoid running over divers or spooking the fish.

 

Entanglement:   Float lines, shooting lines, and bungee cords create entanglement hazards, especially when a fish is running. Keep your knife accessible at all times and stay clear of the line when a fish is on.

 

Never dive alone.    Bluewater spearfishing requires a team — divers, a safety diver, and a capable boat captain who understands what's happening below the surface.

 

Ready to Chase Bluefin?

 

Spearfishing Pacific bluefin tuna off Southern California is the pinnacle of West Coast diving. It demands peak freediving fitness, serious gear investment, open-ocean experience, and a team you trust. But when everything comes together — when you're floating in blue water and a wall of bluefin materializes out of the haze — there is nothing else like it.

 

If you're working toward your first bluewater hunt, start by building a strong foundation. The SpearFactor Master Class at spearfactor.com covers the core skills every diver needs, from breath-hold technique to underwater positioning. And make sure your safety fundamentals are solid — take the free course at freedivingsafety.com and download our Emergency Procedures checklist. The ocean rewards those who prepare.

 

I'll see you out there.