The Abalone Dive Team has been busy for the past five years trying to discover the habits and behaviour of the Northern Abalone stocks, M. Hearne writes. Having been overfished since 1972, with 274 tonnes alone taken in l976, abalone are now on the 'threatened' species list. A recovery plan is underway, but what to do and how to do it is a first priority. Bart DeFreitas, program biologist for CHN and a team of three divers have spent up to 24 days a year for the past five years underwater, setting up transect lines, developing artificial mini-reefs, counting and tagging these 'marine snails' in an effort to encourage their recovery to pre-harvesting levels.
"Abalone," Bart explained to the small but interested group at the Green Church, Masset, Monday night, " are sedentary, aggregate to spawn, have sporadic recruitment and a short larval period. They are slow-growing and long lived. Their predators were sea otters, sea stars, octopus, crab, reef fish, and latterly scuba gear commercial fishermen. Abalone can hide from natural predators either by moving out of their way or in rock crevices, but there's no hiding place from the scuba gear fishers. It has been illegal to take abalone since 1990, however there is no sign of recovery of the Haida Gwaii populations. Where they once flourished, grazing on kelp reefs, they now face a fairly uncertain future. They are listed as a 'threatened' species (likely to become 'endangered' if limiting factors are not reversed) under COSEWIC. They are the first Canadian marine invertebrate to be so listed.
"We are developing a Community Action Plan to try and return abalone populations to historical levels that will support a food fishery," Bart continued. "We are working at two sites, Northwest Graham Island (near Langara Island) and Juan Perez Sound, Gwaii Haanas. These places had, historically, a huge abundance of abalone but the commercial fishery totally removed them. Part of our work includes running transect lines from deep to shallow water and counting and measuring every abalone found along the line. We are trying to determine their age, distribution and abundance. It's underwater work and includes ecological surveys of the habitat, i.e. what seaweeds are around, what other marine species inhabit the same area. In our five-year survey we tagged 3,295 abalone and measured growth, survival and mobility. We had 8 'test plots' where, in May 2002 we gathered 200 abalone in a 100 sq. m. area and tagged them to see if they would stay together in the same general area. We rechecked the sites in July and found that the density remained high, however, the following year the numbers in the 'test plots' had reverted to their original levels. We are learning that abalone are extremely mobile. Tagged abalone moved 50 sq m. from where we had put them - 5% had died (from natural mortality); we found the empty tagged shells. We also created 'shelters' for abalone using old, abandoned crab traps in which we placed broken pieces of cement. We left the shelters to weather and allow algae to attach, then rechecked them. Interestingly we found quite a few abalone in these 'condos'; mostly small, larger ones didn't seem to stay there.
"Our next steps include an annual population survey, continued monitoring of research sites, expanding the use of artificial habitats and exploring habitat enhancement strategies. Our partnership group wants to finalise a community action plan and begin conservation education. Other plans are to develop a stewardship program, do applied research and have an 'abalone watch' program to prevent illegal harvest."
To find out more about the Northern Abalone and the work of the HG Northern Abalone Community Action Plan contact Bart at 626 3302 or browse the excellent and informative leaflets now available.