. The Canadian field-naturalist. 1989 Jamieson: Status of the Northern Abalone 155 Otters, live abalone are larger in size and abundant outside crevices on open rock faces (Hines and Pearse 1982). Sea Otters have been re-introduced on the west coast of Vancouver Island and as their distribution spreads (MacAskie 1987), it can be expected that Northern Abalone abundance will be depressed to a lower level, as is the current situation in central California where Sea Otters are abundant (Bissell and Hubbard 1968). Following the eradication of the Sea Otter in the nineteenth century and before the
. The Canadian field-naturalist. 1989 Jamieson: Status of the Northern Abalone 155 Otters, live abalone are larger in size and abundant outside crevices on open rock faces (Hines and Pearse 1982). Sea Otters have been re-introduced on the west coast of Vancouver Island and as their distribution spreads (MacAskie 1987), it can be expected that Northern Abalone abundance will be depressed to a lower level, as is the current situation in central California where Sea Otters are abundant (Bissell and Hubbard 1968). Following the eradication of the Sea Otter in the nineteenth century and before the development and widespread use of underwater breathing equipment by commercial fishermen in the early 1970s, abalone mortality rate was probably reduced, causing their abundance to increase. Large, older abalone were particularly abundant (Quayle 1971). Intensive commercial exploitation began in 1976 (Figure 3) and although efforts were made to manage the fishery to a sustainable level of production, there were little data to indicate what the sustainable annual level of production might actually be (Breen 1980; Bernard 1982). Early landings were high and the abundance of legal-size abalone may have declined by as much as 80% by 1978 (Breen 1980). Annual production was initially assumed to be substantial because of the large initial biomass (Breen 1980), but recent data indicate that annual recruitment has been less than expected (Boutillier et al. 1984, 1985). Abalone reach the legal size for exploitation at about six to eight years of age (Quayle 1971), and so it has only been in the last few years that the consequences of fishing on recruitment (entry rate of individuals into the legally exploited size range) could be investigated. Monitoring of recruitment began with the establishment of a fishery, and in the first decade following major exploitation, recruitment was low even though the abundance of adult animals was high at the time of spawning, since the current intensive
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Keywords: ., bookauthorottawafi, bookcentury1900, bookdecade1910, bookyear1919
