How species rarity is judged

Every species this site tracks carries a rarity label — Daily, Regular, Uncommon, Very rare, and so on. Those labels decide which sightings get flagged as notable on the homepage, so they need to mean something more than a guess. This page shows the working.

The short version: "rare" here means rare in the published record for the Southern California Bight — the stretch of coast from Point Conception to the Mexican border — as measured by line-transect surveys, passive acoustic monitoring, and federal stock assessments. It does not mean "the boats haven't seen one this week."

The easiest mistake in whale-watching copy is to rank species by how impressive they are rather than how likely you are to see one. A blue whale is the largest animal that has ever lived, so it feels like a once-in-a-lifetime encounter. In the Southern California Bight in August, it isn't — it is the most seasonally predictable large whale in the water.

The clearest evidence comes from Campbell et al. (2015), who analysed 37 quarterly line-transect cruises run across the Bight between July 2004 and November 2013. Of 79 on-effort blue whale sightings in that decade, 62 fell in summer. Across those same ten years of survey effort, blue whales were recorded once in winter and once in spring. Expressed as density, the survey found roughly forty times as many blue whales per unit area in summer as in winter.

So the honest label for a blue whale is not "rare visitor" but "Reliable in summer — June to October, peak July–September." Reliable is not the same as guaranteed: densities were higher in the early and mid-1990s, part of the population appears to have shifted north and offshore since the late 1990s, and two years in the middle of the survey decade were notably poor. But a blue whale off Long Beach in August is a species behaving exactly as expected.

The ladder used across the site runs, loosely, from most to least expected:

• Daily — you would be unlucky to miss it. Common dolphin only.
• Regular — present across the year, with seasonal peaks. Bottlenose and Risso's dolphins, humpback and fin whales.
• Common in season / Reliable in summer — near-certain inside a window, near-absent outside it. Gray whale, blue whale.
• Uncommon — a real part of the fauna, but not on most trips. Pacific white-sided dolphin, Dall's porpoise, northern right whale dolphin, striped dolphin, minke whale.
• Rare — a handful of days in a year. Orca.
• Very rare — worth telling people about. Sperm, sei, Bryde's, false killer, pygmy and dwarf sperm whales, short-finned pilot whale, and the beaked whales.
• Exceptional — a record, not a sighting. North Pacific right whale.

Four kinds of evidence sit behind the labels, and they answer different questions.

Line-transect surveys answer "how many animals are in this water, in this season?" Campbell et al. 2015 (Deep-Sea Research II 112:143–157) is the backbone: ten years of quarterly CalCOFI cruises covering the Bight specifically, rather than the whole US West Coast. It is the reason the seasonal labels have shape.

Federal stock assessments answer "how many exist at all, and is that changing?" NOAA's U.S. Pacific Marine Mammal Stock Assessments give abundance estimates and, importantly, say plainly when the data cannot support a trend claim.

Passive acoustic monitoring answers "were they here when nobody was looking?" Alksne et al. 2024 (Diversity and Distributions 30(9)) draws on recordings from 14 sites between 2005 and 2021 — continuous coverage a ship survey cannot match.

Shore-based census and operator logs answer "what actually happened this season?" The ACS/LA gray whale census at Point Vicente has counted the migration from land for decades, and operators' own long-run trip reports are the only record of how often a day boat encounters a given species.

Gray whale — common in season, but a much smaller population

This is the most consequential number on the site, because the gray whale is the winter mainstay: anyone booking a December-to-April trip is booking to see this species. The eastern North Pacific population peaked at roughly 27,000 animals around 2016, two decades after being removed from the Endangered Species list in 1994. NOAA's July 2026 estimate is about 17,750, with a range of 15,930–20,530. NOAA cautions that the apparent increase from the prior estimate may reflect survey and modelling assumptions as well as population change.

An Unusual Mortality Event ran from 17 December 2018 to 9 November 2023, with 690 strandings recorded — 347 in the United States, 316 in Mexico and 27 in Canada. The new estimate does not establish a confirmed population rebound; NOAA says the reasons for the apparent increase remain open. Calf production remains a concern: the 2025 count was roughly 85, the lowest on record.

The shore-based record from Southern California is consistent with that picture, though it measures a different thing. The ACS/LA census at Point Vicente counts whales passing one headland; in 2024–25 it logged 130 southbound whales with zero southbound calves, and 485 northbound with 8 calves — 1.6% of northbound migrants. Against ACS's own published historical ranges — southbound has varied between 293 and 1,902, northbound between 521 and 3,412 — that season sits below the bottom of both.

These two sets of figures are not the same quantity and must not be read as one series. NOAA's ~13,000 is a model-based abundance estimate for the entire eastern North Pacific population. The ACS numbers are a count — an index of how many whales passed a single point of coastline while observers were watching. They agree in direction; they are not interchangeable.

None of this makes a winter trip a poor bet. The migration is still the most dependable whale-watching event of the Southern California year, which is why the label reads "Common in season — late Dec to mid-Apr." But "abundant" is no longer an honest word for it, so the site does not use one.

Pacific white-sided dolphin — a range shift, not a collapse

This is the species where the survey data is most dramatic and the honest conclusion is most restrained. Campbell et al. found it was the only one of six study species with a statistically significant trend inside the Bight: density fell from 138 animals per 1,000 km² in 2004 to 4.6 by 2012, a decline of roughly 22.5% a year. The acoustic record shows a step change after the 2014–16 marine heatwave.

But the stock as a whole — estimated at about 34,999 animals in 2018 — shows no long-term trend. The dolphins moved; they did not disappear. So the label is "Uncommon — winter and spring; much scarcer than 20 years ago", and this site does not describe them as a declining species.

Risso's dolphin — no evidence of decline, and a correction on our part

Risso's are often assumed to be in decline here. NOAA's 2023 assessment does not support that: it describes them as commonly seen on the shelf in the Southern California Bight, on an estimated stock of about 6,336 animals, and states plainly that "no long-term trends have been identified."

This page previously ran a striking story about Santa Catalina Island here — a resident population disappearing after the 1982–83 El Niño, with Risso's dolphins moving in from 1987 onward to fill the gap. On re-checking the primary source, that story is real, but it is not about Risso's dolphins. It is NOAA's short-finned pilot whale stock assessment that describes a resident population around Catalina virtually disappearing after the 1982–83 El Niño — nothing in that document, or in Risso's own section, says Risso's dolphins increased there afterward. We had misattributed the pilot whale's story to Risso's dolphin and invented a claim NOAA never made about Risso's replacing them; both errors are corrected here. The pilot whale's real, correctly-sourced story is why that species — one people assume is a local fixture — carries a "Very rare" label today.

One correction that follows from the same reading: a "peak in fall" for Risso's is not supported by the literature, which points to cooler months generally. The label reads "Regular — year-round, more often in cooler months."

Bryde's whale — rarer than "rare", and easily mistaken

Only two Bryde's whales were confirmed off southern California in five decades (Smultea et al. 2012, Aquatic Mammals 38(1):92–97). The January 1963 animal off La Jolla was originally identified as a fin whale, and five further survey records could only ever be logged as "sei or Bryde's" — the two species are frequently inseparable at sea. NOAA's 2023 assessment counts seven or more in southern and central California across 1991–2014.

Acoustics add a twist: Bryde's calls were absent from Southern California recordings in 2000–01, then detected in every year from 2003 to 2010, from summer through early winter — consistent with a northward range expansion. The label is "Very rare — celebrate."

The identification problem is also why this site's scraper refuses to resolve an operator's "sei or Bryde's" entry to either species. It goes to a review queue instead of quietly becoming the rarest baleen record of the year. See the methodology page for how that queue works.

Sperm whale — regionally regular, but not from a day boat

Sperm whales are present in California waters year-round, on a stock estimated at about 2,606 animals in 2018, and the region has real history with them: 176 were Discovery-tagged off southern California in the winters of 1962–1970. On paper, that is not a rare animal.

In practice they work the deep basins and the slope, while day boats work the shelf. Operator records make the point better than any density figure: a Dana Point operator logged sperm whales in 2023, 2024, 2025 and 2026 — and before that, not since 2014. A San Diego sighting in September 2025 was reported as the first since 2011. Because this site describes what a day-boat passenger can expect, the label is "Very rare — celebrate."

North Pacific right whale — exceptional means exceptional

There are thought to be around 30 North Pacific right whales in the eastern North Pacific. Southern California has two records from 2017, off La Jolla and off Malibu — and the La Jolla animal was initially logged as a gray whale. A single confirmed sighting would be the most significant cetacean record in the region in years, which is why its label is "Exceptional — once in a generation" and why it outranks everything else in the site's alert logic regardless of how many animals were counted.

The everyday end of the ladder

Common dolphins earn the "Daily" label on volume: roughly 168,000 animals in the CalCOFI study area alone, present in every season the surveys covered. Bottlenose dolphins are labelled "Regular — year-round, close inshore" for a geographic reason: the California coastal stock spends 99% of its time within 500 m of the beach and 90% within 250 m — which is precisely where the boats run. Humpbacks are "Regular" and improving: the California/Oregon population of roughly 5,000 has grown at about 7–8% a year since the late 1980s. Fin whales likewise show higher densities in the Bight than surveys recorded across 1991–2008.

Some labels rest on far less than others. Rather than dress those up, here is where the confidence drops:

• Orca. There is no published encounter rate for orcas in Southern California. The label — "Rare — a handful of days a year, no reliable season" — reflects sightings databases and operator logs rather than a survey estimate, and deliberately claims no season at all.
• Sperm whale seasonality. The only citable seasonal description dates to 1974 and points to peaks in spring and in late summer through autumn. It is coarse and fifty years old, so this site sets no sperm whale season.
• Sperm whale demographics. There is no data on whether the animals passing Southern California are lone bulls or family groups. This site makes no claim either way.
• Minke whale site fidelity. There are only about 915 minke whales in the whole California/Oregon/Washington stock, so "Uncommon — year-round" is well supported. What is not well supported is the follow-on claim that individuals hold reliable coastal home ranges here: stock assessments describe "apparent coastal home ranges", but the strongest work on minke site fidelity was done in Washington State, and applying it to Southern California is inference. The label promises no dependable spot.

The site recognises a fixed allowlist of 23 species. Some plausible-sounding omissions are deliberate:

• Harbour porpoise. Point Conception is the documented southern limit of its range. A "harbor porpoise" in an Orange County trip report is far more likely to be a misidentified Dall's porpoise, so leaving it off the list is a feature, not a gap.
• Rough-toothed dolphin and melon-headed whale. No credible modern Southern California record.
• Pygmy killer whale, spinner dolphin, pantropical spotted dolphin. Their stocks in the federal assessments are Hawaiian or eastern tropical Pacific, not Californian.

The allowlist is not a filter that throws away surprises. A species string outside it — including a genuine first record — is captured in a review queue for a human to read, rather than being force-fitted to the nearest known species or silently discarded. It simply does not enter the published counts until someone confirms it.

Every figure on this page is decadal. Survey densities, stock estimates and trend rates describe the Southern California Bight averaged over years — in some cases over half a century. The numbers on the homepage describe what boats reported today.

These two things must never be read as one. A rarity label cannot tell you whether the animals are out there this afternoon, and a day's sighting count cannot tell you whether a species is common in the region. A blank week for gray whales in February is weather and luck; a decade of survey data is what makes "common in season" true anyway. Conversely, an exceptional day for Pacific white-sided dolphins does not undo a 22.5%-a-year decline in the survey record.

For how today's counts are gathered and scored, see the methodology page.

Population figures on this page were verified against the cited sources on2 August 2026. NOAA stock assessments are republished annually — if that date is more than a year old, treat the numbers as indicative and follow the links for current figures.

• Campbell, G.S. et al. (2015) — "Inter-annual and seasonal trends in cetacean distribution, density and abundance off southern California", Deep-Sea Research II 112:143–157.
• NOAA Fisheries — U.S. Pacific Marine Mammal Stock Assessments, 2023 (final, December 2024).
• NOAA Fisheries — Sperm Whale, California/Oregon/Washington stock assessment (rev. May 2024).
• NOAA Fisheries — Pacific White-sided Dolphin stock assessment (rev. March 2022).
• Alksne, M. et al. (2024) — Diversity and Distributions 30(9), passive acoustic monitoring across 14 sites, 2005–2021.
• Smultea, M.A. et al. (2012) — "Bryde's whale sightings in the Southern California Bight", Aquatic Mammals 38(1):92–97.
• Kerosky, S.M. et al. (2012) — Bryde's whale acoustic occurrence off southern California, Deep-Sea Research I.
• NOAA Fisheries — "Eastern North Pacific Gray Whales Continue Decline After Downturn During Unusual Mortality Event".
• NOAA Fisheries — Gray Whale Population Abundance.
• American Cetacean Society / Los Angeles — Gray Whale Census, 2024–25 summary (shore-based count, not an abundance estimate).
• Cascadia Research Collective — humpback whale programme.
• OBIS-SEAMAP and NOAA ship-based cetacean and ecosystem assessment surveys — underlying sightings data.

If you think a label is wrong, or you have a published source that contradicts one, please get in touch. Corrections are welcome and will be made.