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Terrafin Sea Surface Water Temperature (SST) Maps


Sea Surface Temperature (SST) water temperature map for East Cape, Baja California Sur, Mexico.

A Terrafin sea surface temperature (SST) map, reduced in size to fit on this page, for East Cape, Baja California Sur, Mexico. Note waer temperature "pinch" at Los Frailes. Reprinted with permission from Terrafin Software.


Aug. 14, 2000, by Gene Kira, Western Outdoor News:

One of the most important characteristics of "fishing water," in Baja California or any place else, is its temperature, and that's still true even if you're only swimming in it.

Personally, I'm very species-specific when it comes to the swimming part; if the water is less than 80 degrees, you can have it, amigo. I ain't goin' for a swim unless the boat sinks or mermaids show up.

Fish, too, have their species-specific preferences, with each species seeking out its particular comfort zone, and all along Baja's Pacific and Sea of Cortez coasts the fantastic range of water temperatures available makes life good for an equally fantastic variety of fish.

If you circled Baja with a thermometer on any given midsummer day, the chances are pretty good that your readings would have a temperature range of 25, or even more, degrees -- from about 90 at both ends of the Sea of Cortez, down to about 65 somewhere between Ensenada and San Quintin.

And if you threw bait or lures into that range of water, you might catch anything from frigid-dwelling lingcod, up through medium-water bonito and tunas, then the warm-water jacks and groupers, and finally "hot-water" lovers such as dorado, sailfish, and blue marlin. (All "hot-water" fish are not big and glamorous. In many years of getting my elbows wet, the highest temperature preference I've ever noticed was for the lowly ribera cabrilla, or Panamic graysby, which hits best at 85 degrees and up. Just below that is the cornetfish, and just below that the giant needlefish.)

There is, of course, considerable fuzziness to these preferences, but they are nevertheless real and predictable. You aren't going to catch a lot of true bonito in 85-degree water, and if you catch a sailfish in 65-degree water, you've just experienced a medium-sized miracle.

Over the reefs, the temperature of the water is important because it tells you pretty much what kinds of fish you can expect to catch. But in offshore fishing this all-important characteristic takes on even greater significance, because it can tell you not only what kinds of fish to expect, but also where they can be expected.

Why is this so? Well, let's say that you're an average sailfish, swimming along comfortably in 82-degree water, and suddenly you hit a wall of water that is several degrees cooler. Naturally, you do what comes naturally. You make a left or right turn and you swim along the edge of the warm water, feeding and feeling good about life. Pretty soon, all your fellow sailfish are doing the same thing and before you know it, there's a sailfish party going on, all along the interface between the two temperature zones.

Naturally, this is where we anglers want to troll our lures, and when we do so, we are doing what is called "fishing the temperature breaks."

So... how do you know where the temperature breaks are? There are two basic methods. Method 1: troll your brains out while keeping one eye on the sea temperatire gauge. Method 2: use a current Sea Surface Temperature (SST) map.

Discarding "Method 1" as too Neanderthal for modern times, that leaves "Method 2," the SST map, generally compiled from satellite data, and readily available for free on the internet.

The problem with the free government maps is that they are relatively useless for planning your day of fishing. Their scale is so large that you're looking at half the Eastern Pacific Ocean, for instance, and the temperature breaks indicated are so big and broad that you could cross them only if you were trolling in an airplane. At normal boat speeds, you could die of old age before you crossed from one temperature into another.

Enter Jeff Gammon of Vista, California.

Jeff is a sportfishing enthusiast who also happens to be a computer programmer. Last November, he got fed up with the government maps and he started massaging them with graphics software. It took him about two hours of "tinkering" per map to turn the government product into something you could actually fish with.

Pretty soon, Jeff's friends started pounding on him for more maps, and that got old too, so he sat down and wrote some custom software that can crank out a map in about 15 minutes. What Jeff's software does is read the digital satellite data, break it down into small zones (2 degrees x 2 degrees), bump the resolution to 1.1 km/pixel, increase the temperature resolution to about 1 degree per pixel, overlay latitude, longitude, shore outline, offshore banks, and key geographic features, and then spit the whole thing out in the form of an attractive color map. Simple, right?

Anyway, that was the birth of Terrafin Software, which has become a full-time occupation for Jeff, and part-time for his wife, Lorrie. On a daily basis (usually, depending on cloud cover), Terrafin processes 21 areas ranging from Oregon, to Cabo San Lucas, and up Mexico's Sea of Cortez as far as Mulege.

These daily water temperature maps are downloadable online from the Terrafin website on an annual subscription basis, so once you sign up you can grab and print the current map you want at any time. Terrafin's website: www.terrafin.com.

For the present, the areas covered in Baja are: Southern California/Northern Baja, Magdalena Bay, Todos Santos, Los Cabos/San Jose del Cabo, East Cape, La Paz, Loreto, and Mulege. The Midriff and Gonzaga Bay areas are scheduled to be added soon.

Once I started using these maps, I quickly became a fan of them. I receive a lot of Baja fishing reports, and it is fascinating to compare the reports to what you see on Terrafin's maps. For instance, the last two weeks' East Cape reports talk about a good tuna bite south of Buena Vista, down near Los Frailes. One quick glance at the Terrafin map for this period (see above) instantly shows what's going on down there. The sea temperature gradient pinches in close to shore right at Los Frailes, compressing the fish there, and that's where they are being caught, right now.

To the north, you see the temperature gradient going farther and farther from shore, and in fact, the boats going north from East Cape are having their best luck about 20 miles out, right now. That's hot stuff, and it's great fun to watch this happening all over Baja as the reports come in.

A couple of interesting notes on interpreting sea surface water temperature (SST) data obtained from satellites:

First, the water temperature data is read in two narrow bands of the infrared spectrum. It can't see through clouds. So sometimes you will have white spots or blotches that indicate cloud cover.

Second, with satellite data what you are seeing literally is the sea SURFACE water temperature, not the temperature, say, a foot below the surface. Satellites read the temperature of perhaps only the top millimeter of the ocean. This can cause higher than expected readings at times when the water is very calm and the sun is strong. According to Jeff, on some days you can actually watch the sea's "skin" temperature rise as the day progresses. Fascinating!

Jeff and Lorrie Gammon, of Terrafin Sea Surface Temperature (SST) water temperature maps for Mexico.

Jeff and Lorrie Gammon of Terrafin Software, with daughter Meg.

(Related Baja California, Mexico, articles and reports may be found at Mexfish.com's main Baja California information page. See weekly fishing news, photos, and reports from the major sportfishing vacation areas of Mexico including the Baja California area in "Mexico Fishing News.")