The Canadian Department of Fisheries and Oceans (DFO 2002) indicates that early southern British Columbia harvesters targeted populations of this species in areas close to the harbour, where diving was easy and the resource abundant. Researchers and managers felt that only a small proportion of the stock was being harvested, and that many sea cucumbers were left untouched in these areas. The fishery therefore expanded to more remote northern areas, but remained targeted on very accessible locations. Still today, large areas of the coast have not been visited by the commercial sea cucumber fleet. Surveys conducted in various areas of the coast indicate that sea cucumber population densities vary considerably with habitat type. Density estimates from almost all surveys are significantly higher than the conservative estimate of 5.08 sea cucumbers per meter of shoreline. This species' populations extend below the safe diving depth of 20m where extensive harvesting cannot be conducted (DFO 2002). In British Columbia, the densities are estimated at less than 0.25ind*mâ2 (Bruckner 2006). The CPUE values supplied by Muse (1998) for this species in British Columbia are in kg per diver per hour: 372 in 1983, 347 in 1987 and 617 in 1992.
Woodby et al. (2000) investigated the depth distribution of this species in the vicinity of Sitka Sound, Alaska and found that sea cucumber densities were greatest in shallower waters with ca. 70 percent of the sea cucumbers observed above 15m. Average densities were 0.03ind*mâ2 in deeper water and 0.3ind*mâ2 at SCUBA diving depths. The deepest sea cucumber was observed at 87m. In Southeast Alaska, Zhou and Shirley (1996) used a submersible to measure densities which varied from 0 to 267ind*haâ1. The highest density recorded was 0.23ind*mâ2. Bruckner (2006) reported that harvested sites in California showed densities that were 50â80% lower than in the non-fished areas. For instance, at an established reserve in northern California, densities averaged 2200ind*haâ1. Another set of data from a newly established reserve (Punta Gorda Ecological Reserve) ranged from 250 to 790ind*haâ1, taking into account the large size classes of sea cucumbers exclusively (Rogers-Bennett and Ono 2001, Bruckner 2006). Until 1996, an average of 75 percent of the annual catch came from the trawl fishery in southern California. Between 1997 and 1999, the dive fishery accounted for 80 percent of the take. Recent surveys showed a 50â60 percent decline in abundance between 1994 and 1998, but no correlation was noted between decline in abundance and data on landings. The only increase in abundance (39 percent) was noted at two no-take reserves (Rogers-Bennett and Ono 2001; Schroeter et al. 2001). In California, between 1983 and 1990 annual landings fluctuated between about 20,000 and 60,000kg. In 1991, over 261,871kg were harvested. Combined trawl and dive harvest peaked in 1996 at 380,703kg with an ex-vessel value of USD 582,370 (Rogers-Bennett and Ono 2001).
In Washington State, CPUE from 1983 show that the minimum in those days was around 75kg*diver-1hâ1 and the maximum around 130kg*diver-1hâ1 (Bradbury 1994). Data recorded in this state at the time clearly demonstrates the impact of the fishery on the stock of sea cucumbers with a decline of up to 70%: sea cucumber densities were around 0.35ind*mâ2 before the fishery opened and dropped to 0.1ind*mâ2 just after (Bradbury 1994). In Oregon, densities of this species are between 0.1 to 0.22ind*mâ2 at depths of 80 to 130m (Bruckner 2006). In Washington, the CPUE between 1995 and 1998 (Bradbury 1999) varied from 56 to a maximum of 80kg*diver-1hâ1.
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