The annual gray whale migration from the Arctic to Baja is at its peak right now. It's an ideal time to go whale watching off San Diego's coastline. And that's just what Environmental Reporter Ed Joyce did recently.

It's estimated that about 20,000 gray whales pass by San Diego on their migration from their feeding grounds in the Arctic to the breeding lagoons of Baja California. As our boat headed west off Point Loma, Birch Aquarium Naturalist Chelsea Rochman told us how to spot the whales.

Rochman: So after the swimming you will see a fluke or a sounding when that whale is going to dive all the way down below the surface usually 20 feet or so and stay down there for maybe three to five minutes. And then he'll come up and do the swimming and breathing again hopefully with another round of sounding.

She also tells us about one unusual behavior called spy-hopping.

Rochman: The gray whale has one eye on either side of its head. So it has monocular vision, one eye at a time, just like a cow. And when it comes up it's going to spy-hop so that it can get a look at its surroundings. So it might come up, do a ballerina spin, take a look at us and head back down.

A few moments later, we see our first whale.

Rochman:  So that's our first gray whale sighting, it seems to be just one whale. So look for those characteristics, see if you can see the dorsal knuckles. Notice it doesn't have a dorsal fin.

Later we see several whales at the same time as Rochman tells us how the whales feed.

Rochman: Look at that blow it's a heart-shaped blow. This is a baleen whale meaning that it does not have teeth instead it has baleen, which is made out of what your fingernails are made out of. It looks sort of like a broom or a moustache hanging from their upper jaw and it's used for filter feeding. All baleen whales have two blow holes which gives it that heart shaped blow right there, right there at 11 o'clock. And then you just got a good shot at those dorsal knuckles.

She says the gray whale migrates farther than any other mammal.

Rochman: So this whale is going to travel 10 to 14,000 miles per year, that's round-trip. The reason they do this is because they are such a large animal and they eat such small food. And if you weigh 70 to 80,000 pounds and you're 45 feet long, which is about half the size of the boat, you're going to need a lot of small food in order to sustain you for the long migration.

Rochman:  That did look like a dive though. So this whale seems to breathe four times and then maybe stay down for about three minutes. So, if we could time you can actually kind of see that regularity. Which is nice, it's good for whale watching.

The whales are so close to shore you don't have to take a boat to see them. Some of the best land spots include Cabrillo Monument, Torrey Pines State Park, and any high cliff points above the ocean.

Rochman: So take a look right now at how close we are to the shore. This is the reason why the gray whale is such a good whale for whale watching and it was such a good whale for hunting.

They're very accessible to humans.

Birch Aquarium Naturalist Chelsea Rochman says most of the whales finish passing San Diego at the end of March. The trip was courtesy of the Birch Aquarium.