California Halibut Have Tripled Since 2019 — Here's What the Data Shows

California halibut are booming. That is not a hot take or a wishful guess — it is what 12,503 halibut logged in CDFW Commercial Passenger Fishing Vessel (CPFV) logbooks between 2019 and 2025 tell us. What the data reveals about population growth, temperature triggers, timing, and moon phase should change how every diver in California approaches halibut hunting.

The Population Explosion Nobody Is Talking About

In 2019, CPFV boats logged 541 California halibut. In 2025, that number was 5,171. That is nearly a tenfold increase in raw catch — but raw catch alone does not prove a population boom. More boats could have gone out, or more anglers could have targeted halibut.

So we looked at Catch Per Unit Effort (CPUE) — the number of halibut caught per angler-trip. CPUE tripled over the same period, with a correlation coefficient of r=0.85 between year and CPUE. That is a strong, statistically meaningful trend. The halibut are not just being caught more — there are genuinely more of them.

This is arguably the biggest California spearfishing story that nobody is covering. While debates rage about marine protected areas and declining kelp forests, halibut have quietly staged one of the most impressive comebacks in recent California fishery history.

The 61°F Sweet Spot

We paired CPFV logbook data with sea surface temperature (SST) records to find the optimal halibut temperature. The answer was surprisingly precise: 61°F.

At 61°F, the CPUE was 0.24 fish per angler — four to five times higher than any other temperature band. This is tighter than most temperature windows for other species. It is not a wide comfort range; it is a specific trigger point.

For divers, the practical takeaway is clear: when your dive computer or water temp gauge reads 61°F, you should be hunting halibut. That temperature correlates with peak halibut activity, feeding behavior, and accessibility in the water column where divers operate.

Spring Is King — Not Summer

Ask most people when halibut season peaks and they will say summer. The CPFV data says otherwise.

The hook-and-line fishery peaks in March and April. April CPUE is 0.63 fish per angler — double March at 0.31, and dramatically higher than any summer month. The CPFV fleet catches the majority of its halibut during spring, not during the warm-water months most people associate with flatfish.

This lines up with the 61°F sweet spot. Southern California coastal waters typically hit that temperature window during spring before warming past it in summer.

But Grunion Changes Everything for Divers

Here is where the CPFV data diverges from the diver experience, and this is a critical distinction.

Party boats fish offshore in deeper water. They do not fish the surf zone. But divers operate in 5 to 30 feet of water — and that is exactly where grunion runs stack halibut during spawning season.

Photo: CDFW 2026

Grunion season runs from March through August, with spawning runs peaking from April through June. During active grunion runs, halibut move into the surf zone at 5 to 20 feet to ambush the spawning fish. This creates the best shallow-water halibut hunting opportunities of the year — conditions that CPFV logbooks simply do not capture because party boats are not working those depths.

For divers, grunion season is halibut season. The two datasets tell complementary stories: CPFV data shows when halibut are most active broadly (spring), and grunion data shows when they are most accessible to divers specifically (spring through early summer in shallow water).

Moon Phase: Neap Tides Win on CPFV, but Divers Should Think Differently

The moon phase data from CPFV logbooks revealed a clear pattern: quarter moons (neap tides) produced a CPUE of 0.10, while new and full moons (spring tides) dropped to 0.04. That is a significant difference — neap tides outperform spring tides by roughly 2.5 times in the hook-and-line fishery.

But for divers targeting halibut, moon phase is nearly neutral when it comes to halibut presence. California halibut are ambush predators. They bury in the sand and wait for prey to pass overhead. They do not migrate or reposition based on tidal flow the way pelagic species do.

The CPFV moon phase effect likely reflects bait fish behavior and current conditions rather than halibut movement. For divers, the more important moon phase consideration is grunion — grunion runs are triggered by spring tides following new and full moons. So while the hook-and-line data favors neap tides, divers benefit from tracking spring tides because they trigger grunion, which in turn stacks halibut shallow.

How to Hunt Halibut: They Do Not Chase

California halibut are ambush predators, and understanding this fundamentally changes how you should approach them compared to other species.

They bury themselves in sandy substrate near structure and wait. They are patient, camouflaged, and explosive when they strike — but they do not chase prey over long distances. This means your approach needs to be low and slow over sandy bottom in 5 to 30 feet of water.

Dawn, dusk, and night are the best hunting windows. Halibut are more active during low-light conditions when their ambush strategy gives them the greatest advantage. Many experienced divers consider night diving one of the most productive methods for targeting large halibut.

Sand Is King — Not Kelp, Not Rock

For almost every other target species in California, divers look for kelp forests, rocky reefs, or structure. Halibut flip that playbook entirely.

Sandy bottom is the primary habitat. Halibut need sand to bury in — that is non-negotiable for their ambush hunting strategy. But they are not sitting in the middle of featureless sand flats. The sweet spots are transition zones where sand meets rock, reef edges that border sandy expanses, and sandy channels running between structure.

These transition zones concentrate bait fish moving between habitats, and halibut position themselves along these edges to intercept prey. If you are diving a rocky reef, do not skip the sandy perimeter — that is where the halibut are waiting.

What the Trend Means for the Future

The tripling of California halibut CPUE from 2019 to 2025 is not a blip. The r=0.85 correlation suggests a sustained, meaningful population trend. Multiple factors likely contribute: improved water quality in some coastal areas, warming waters extending halibut range, and possibly the lingering effects of marine protected area spillover.

If this trend continues — and the data currently gives us no reason to think it will not — California halibut spearfishing is going to get even better in coming years. Divers who dial in the temperature triggers, timing patterns, and habitat preferences now will be well positioned as the population continues to grow.

The Quick Reference

• Best temperature: 61°F SST (0.24 CPUE — 4-5x better than any other temp)

• Best months (CPFV): March-April, with April CPUE at 0.63

• Best months (divers): April-June, during peak grunion runs

• Best habitat: Sandy bottom near structure — transition zones between sand and rock

• Best depth: 5-30 feet for divers

• Best time of day: Dawn, dusk, or night

• Approach: Low and slow — halibut are ambush predators, not chasers

• Population trend: CPUE tripled 2019-2025 (r=0.85), and still climbing

Check Today's Halibut Conditions

Want to know if conditions are right for halibut right now? Our California Diving & Fishing Conditions Tool integrates real-time SST, swell, wind, visibility, moon phase, and grunion data to score halibut conditions at dive sites across California. It takes the data findings above and applies them automatically so you know whether today is a halibut day before you load the truck.

Data source: CDFW CPFV logbook data, 2019-2025. 12,503 halibut total. SST data paired from NOAA buoy records. Grunion run schedules from CDFW Grunion Research Program.

Cover photo: California halibut (Paralichthys californicus) at OdySea Aquarium. Photo by RatioTile, Wikimedia Commons, CC BY-SA 4.0.