Research Report 2008

Where there’s a hole, there’s a reason

Sometimes it takes finding a lot of one thing to truly recognize just how little there really is. Coral researchers have long wondered about the effects of deep sea fishing. Researchers at Memorial set out to map the areas where fishing overlapped with known coral deposits. Near the tip of Labrador, they found a huge gaping hole — an area fishermen now avoid because the coral wreaked havoc with their nets. The results were astonishing.

This one area yielded 25 times more coral than any other area off the coast.

This was evidence for researchers like Dr. Evan Edinger, associate professor of geography and biology, that the deep-sea fishery — which intensified after the cod moratorium was imposed in 1992 — has destroyed more coldwater coral than previously thought. With more than 30 species of coldwater coral off our coasts, the push is on to protect them from trawlers and other deepwater fishing.

They come in a blend of colours: soft pink, shades of red, deep brown. Their sizes are just as varied, too. Some are long tubular shaped resembling walking canes, others are shorter stumps, while still others look like a mesh of wiry nets. They can grow up to three metres tall and can live for decades or centuries, depending on the species.

Coldwater corals are a vital part of deep-sea ecosystems and provide habitat for other invertebrates and fish. But this new study by a team of geographers and biologists at Memorial indicates that some coldwater corals are being severely damaged by fishing and other activities and that it may take centuries for these stunning marine animals to grow back, if at all.

The researchers conclude that three coldwater coral regions off this province’s coast should be protected from damage by bottom-contact fishing. In fact, they hope their extensive investigation will motivate Canada and the Northwest Atlantic Fisheries Organization (NAFO) to protect the sensitive habitats. The researchers produced a new study – Coldwater Corals off Newfoundland and Labrador: Distribution and Fisheries Impacts – for World Wildlife Fund Canada. The team amassed information from Canadian scientific surveys and the Canadian Fisheries Observer Program to show the distribution of corals and to measure coral bycatch - the accidental catch of marine life such as coral or fish in fishing gear.

“We compared the damage that different fisheries cause to deep-sea corals in the waters of our province,” said Dr. Edinger. He and his co-authors measured the impact of fishing on these fragile organisms that thrive along continental slopes, seamounts and mid-ocean ridges. “We mapped the pattern of coral bycatch according to coral type and fishery,” he added. “In those locations, coral bycatch occurred in all the fisheries operating there. Fishing in coral habitats damages corals, regardless of what gear you use, or what species you’re trying to catch.”

“We knew that corals in our region were endangered by deep-sea fishing activities before we started the mapping project, and had been for quite some time. But we didn't know just how bad things were until we started getting data from an area off the tip of northern Labrador. When we looked at the maps of fishing effort, we saw that this area was a hole, a place that the fishing industry avoided, because the rough bottoms damaged their nets too much,” explains Dr. Edinger. “Research trawls in this area collected up to 500 kg of coral in a 15-minute trawl - as high as the maximum encountered in untrawled coral habitat in Alaska or New Zealand - when the maximum we ever found anywhere else in our waters was about 20 kg per tow.” For the team, this was part of the evidence that corals were probably larger and more abundant elsewhere in the deep waters of our province before the fishing effort moved into deep water after the cod moratorium.

In addition to Dr. Edinger, the research team also included Dr. Rodolphe Devillers, assistant professor, Department of Geography; Krista Baker, a PhD student from the Department of Biology; Vonda Wareham, a master’s student in the environmental science program in the Faculty of Science; and Krista Jones, a fifth-year honours student from Geography.

The group studied the most common deep-water-fisheries off Newfoundland and Labrador, identifying three regions that potentially should be protected including the southwest slope of the Grand Banks, the Northeast Newfoundland Shelf edge, and the Hudson Strait.

Copyright © 2008 Memorial University of Newfoundland