Geoscience Reference
In-Depth Information
pursuit of capelin. Only this offshore habitat is productive enough and large enough to sustain northern cod
populations at historical levels.
Historically, a much smaller population of inshore spawning cod inhabited some of the larger bays around
the island of Newfoundland, the largest being Placentia Bay, and some inlets of coastal Labrador. These fish
spawned inshore and did not make long feeding migrations. They may be descendants of the original cod pop-
ulations, which predate the arrival of capelin in the northwest Atlantic. These inshore populations may be the
only hope of reseeding the larger offshore banks, where populations are so low that recovery could take many
decades, if it happens at all. Around the island of Newfoundland there is some movement between bays of
these inshore stocks, and in the past they mixed with offshore stocks on the Grand Banks during the summer,
when capelin came ashore.
Genetic differences are very small between these southern cod stocks, and dna analysis indicates that inter-
breeding has taken place. It is hoped that the inshore stocks might move offshore when the bays, where their
populations are growing, become too small to support them, and there is precedent in fisheries ecology for
such expansion. In addition, the recovery of capelin stocks on the offshore banks might lure the inshore cod to
offshore waters, where they might repopulate the banks. It remains unclear, however, whether these inshore
cod can or will expand their range and re-colonize the banks and the continental shelf.
What is known is that the welfare of the capelin is critical to the future of the cod, as it is to all of the predat-
ors at the top of the marine food chain: other fishes, such as Arctic char, Atlantic salmon, Greenland halibut,
and American plaice, as well as seabirds, whales, and seals. Capelin is a cornerstone species, meaning any
food web of the ecosystem is dominated by capelin, with capelin serving as a major food item in the diets of
most larger predators and itself acting as a major predator on smaller prey. This dependence on a single central
prey species also makes the ecosystem of Labrador and Newfoundland extremely vulnerable to natural per-
turbations like climate change as well as human activity such as overfishing.
Love on the Beach
Capelin, a small, smeltlike fish of silvery green-and-magenta coloration, has evolved the peculiar strategy of
spawning on the beaches. The capelin's spawning act is called the capelin scull in Newfoundland, where cape-
lin are said to “roll” on the beach. When they do, outport Newfoundlanders converge on the beaches with hook
and line, as well as buckets and nets, to scoop up this strange harvest of fish out of water. It is one of nature's
oddest spectacles to see the little fish throwing themselves onshore in a most unfishlike manner to deposit their
spawn in the natural incubator of beach gravel.
Male capelin are noticeably larger than females and have an exaggerated anal fin, which propels them onto
their terrestrial spawning grounds. They also have a lateral line of spawning ridges, which are actually elong-
ated scales. They look and feel hairy, like a three-day-old beard. (The capelin's Norwegian name, lodde, means
“hairy.”) These ridges are not merely attraction features, like the hooked jaws of spawning male salmon, but
have a practical function. During beach spawning, the smaller female is guided ashore by a single male—or
often between two males, like an ocean liner between two tugboats. The spawning ridges, as well as the large
pectoral and pelvic fins of the male, help to hold the female in place for the brief spawning act, which takes
place between successive waves upon the beach.
