BBC The Blue Planet Disc 3: Seasonal Seas (2002)

Just when the weather is at its worst, 100,000 grey seals haul themselves up through the surf on to Sable Island off Nova Scotia. This is the world's largest colony of grey seals and perversely they've come to breed in winter. Within 18 days the pups are abandoned, but spring is on its way with plenty of food.

An eight-tonne basking shark filters 1,000 tonnes of seawater through its gills every hour to sieve out plankton, and large numbers are attracted to plankton blooms. On the seafloor, seaweed stretches towards the sunlight, and off the coast of California, underwater forests of giant kelp grow up to 100 metres high. Massive schools of fish shelter here and sea otters snooze at the surface winding strands of kelp around themselves as anchors.

By July, the seasonal seas are warming up fast. On the coast of Nova Scotia large female lobsters are marching 150km from cold, deep waters where they spent the winter, to warm shallows where they can incubate their eggs. In August, pacific salmon return to the coast of Alaska and are hunted down by huge salmon sharks.

By early autumn, Pacific white-sided dolphin are turning up in British Columbia in great numbers. Rather than fish for herring they like to play - engaging in a dolphin's version of tag, as they pass a strand of seaweed from flipper to flipper.

As fast as winter approaches in the north, spring is coming back at the opposite end of the world. Strange handfish walk across the bottom of the sea using their fins like hands. There is also a beautiful courtship ballet performed by Australian squid that change colour as they dance. A male leafy seadragon is a devoted parent, carrying dozens of eggs on his belly and relying on his perfect leafy camouflage to hide them from other hungry fish.
Peter's DVD rating: 4.5 stars
Great scenes in this portrait of the seas through the seasons include huge swarms of jellyfish, a Herring bait ball being hunted to the last individual in a feeding frenzy from several predator species, and the hilarious Handfish. The Sea Slug chase scene shows clearly how Navanax follows the slime trail left by Janulus. The only weak segments are the Sea Otter and the Pacific Salmon (which species?), which should go a bit more in depth on the ecology of these animals.
2:50 Gray Seal pup in winter (Sable Island, Nova Scotia) 4:50Phytoplankton: Volvox, Diatoms (Scotland) 5:55 Jellyfish medusae budding from polyps
6:55 Copepod leaves feeding trails 8:00 Sea Nettle (up to 30 kg) and Moon Jelly (Common Jellyfish) feed on Copepods 11:25 Basking Shark filters plankton
12:10Anemones, Sea Squirts, Gorgonians on the sea floor 13:25 Bull Kelp (British Columbia) 14:10 Giant Kelp (California)
15:10 Blacksmith Fish feed on plankton in Kelp forest 15:45 Californian Sea Otter feeds on shellfish and are guardians of the kelp forest 17:20 Garibaldi Fish feed on Bryozoans
18:00 Bryozoans open at night to feed 18:25 Amphipod mother produce silk to form nest in kelp 19:45 Harbor Seal males establish dominance in Eelgrass
21:50 Bat Ray digs in sand to feed 22:45 Kelp Bass stealing scraps 23:15 Fan-tailed Sole hunts Manta Shrimp
23:55Sea Slug Navanax? stalks Janulus by following trail of slime 25:20 Atlantic Lobsters migrate 150 km to spawning ground, fight for nest site (Nova Scotia) 28:40Baby Crab feeds on Sea Lettuce , sensors in feet of adult
29:55 Common Octopus preys on crab 30:50 Pacific Salmon feed on Mysid Shrimp (Alaska) 31:50 Salmon Shark preys on Pacific Salmon by sensing electrical signals
32:40Vancouver Island: Atlantic Herring? bait ball decimated by Gulls, Auklets, Murres, and Yellow-tailed Rockfish 35:40 Pacific White-sided Dolphin playing "pass the seaweed" (British Columbia) 36:45 Dogfish embryo develops from spring to autumn
38:00 Hooded Sea Slug swims and feeds on plankton (British Columbia) 40:00 Handfish walking among Kelp (Tasmania) 41:10Australian Squid ? mating by passing sperm packet
42:40Australian Squid ? baby swimming 43:10 Leafy Sea Dragon male carrying eggs 44:20 Killer Whale hunt North Atlantic Herring (5 billion individuals) by echolocation and stun the fish with their tails (Norway)
2:50 Gray Seal pup
5:55 Jellyfish
6:55 Copepod
8:00 Sea Nettle
8:00 Moon Jelly
11:25 Basking Shark
13:25 Bull Kelp
14:10 Giant Kelp
15:10 Blacksmith Fish
15:45 Californian Sea Otter
17:20 Garibaldi Fish
18:00 Bryozoans
18:25 Amphipod
19:45 Harbor Seal males
19:45 Eelgrass
21:50 Bat Ray
22:45 Kelp Bass
23:15 Fan-tailed Sole
23:15 Manta Shrimp
23:55 Navanax?
23:55 Janulus
25:20 Atlantic Lobsters
28:40 Crab
28:40 Sea Lettuce
29:55 Common Octopus
30:50 Pacific Salmon
30:50 Mysid Shrimp
31:50 Salmon Shark
32:40 Atlantic Herring?
32:40 Yellow-tailed Rockfish
35:40 Pacific White-sided Dolphin
36:45 Dogfish
38:00 Hooded Sea Slug
40:00 Handfish
41:10 Squid ?
42:40 Squid ?
43:10 Leafy Sea Dragon male
44:20 Killer Whale
44:20 Atlantic Herring
Index Dec 24, 2005 copyleft Peter Chen