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Recovery strategy for the Northern Abalone

1.4 Needs of the Northern Abalone

1.4.1 Habitat and biological needs

Northern abalone are normally found on firm substrates, such as rocks, boulders, or bedrock, and in areas of moderate to high sea water exchange, such as in exposed or semi-exposed coastlines.  Most of the adult northern abalone occur in near shore, exposed or semi-exposed coastal waters at <10 m depth (Breen and Sloan, 1988). 

Currently, there is ample habitat available for the northern abalone population on the coast of B.C.  Although the abalone population has declined, there has been no known significant reduction in available habitat.  Therefore, habitat loss is not a major concern in the recovery of northern abalone at this time in comparison with the identified threats.

Northern abalone growth can vary considerably between areas depending on the extent of exposure to wave action and availability and quality of food.  Growth of adults tends to be stunted in highly exposed outer coastal areas where food may be limited because of strong wave action and water currents (referred as ‘surf abalone’).  Feeding opportunities may be reduced because abalone would be less able to catch and hold onto drift algae.  When “surf” abalone were transplanted to calmer, kelp abundant habitats, growth rates were higher than for abalone in high-energy areas (Emmett and Jamieson 1988).  Abalone growth was more rapid in moderately exposed areas with giant kelp, Macrocystis integrifolia, or bull kelp, Nereocystis luetkeana, kelp forests than at highly exposed areas with Pterygophora californica kelp forests (Sloan and Breen 1988).      

Adult northern abalone aggregate in warm shallow water areas to broadcast their gametes simultaneously (Breen and Adkins 1980).  Spawning off B.C. generally occurs between April and July.  Large female northern abalone (> 100 mm SL) contribute substantially more to population fecundity than small mature abalone (Campbell et al. 1992; Campbell et al. 2003).  Cues that cause mass spawning in Haliotis spp. can include environmental factors such as temperature changes (Sloan and Breen 1988), and minor storms and typhoons (Sasaki and Shepherd 1995).  Studies on Haliotis spp. (Clavier 1992; McShane 1995a,b; Shepherd and Partington 1995; Babcock and Keesing 1999) and sea urchins (Levitan et al. 1992) have emphasized reduced fertilization success can be caused by dilution of gametes through reduced adult spawner densities (Levitan and Sewell 1998).  Since fertilization success depends on the aggregation density of abalone, exploitation rates and high natural mortality on abalone aggregations are likely important in influencing egg production (Campbell 1997). 

Within 48 hours after fertilization, the planktonic trochophore larvae emerge from their egg membranes. The planktonic phase of northern abalone is short and temperature dependent (12 days at 14 degrees Celsius, 13 days at 17.5 degrees Celsius)(Standley 1987).  Larvae settle on crustose algae (Sloan and Breen 1988).  Small juvenile (<10 mm SL) northern abalone are hard to find.  Juvenile northern abalone (10-70 mm SL) are found under and on exposed areas of rocks, whereas the majority of adults (≥ 70 mm SL) are found on exposed rock surfaces.  More juvenile abalone emerge on to exposed rock surfaces at night than in the day.  Densities of juvenile abalone (≤ 30 mm SL) surveyed at study sites in the Pacific Rim National Park Reserve were significantly higher (by a factor of 15.74) at night than in the day (H. Holmes, Parks Canada Agency, Pacific Rim National Park Reserve, Ucluelet, BC VOR 3A0, pers. comm.).  As the juveniles develop to maturity, their diet changes from benthic diatoms and micro-algae by moving to shallower, more exposed areas to feed on drift macro-algae.  The general habitat areas of the adults and their juvenile offspring could be within close proximity of each other.  Studies have suggested that larval dispersal in some Haliotis spp. may occur in small geographic areas, on a scale of hundreds of meters to several kilometres (Tegner and Butler 1985a; Prince et al. 1987; McShane 1992, 1995a,b; McShane et al. 1988). 

1.4.2 Ecological role

Within the near shore, exposed or semi-exposed coastal waters, northern abalone play the role of herbivore and are prey of many species.  Recovery of northern abalone may be related to the abundance and health of kelp forests in certain areas.   Northern abalone compete with other species (e.g., red sea urchins, Strongylocentrotus franciscanus) for food and space.  Northern abalone are prey for sea otter, Enhydra lutris; river otter, Lutra canadensis; mink, Mustela vison; crab, Cancer species; sea stars, Pycnopodia helianthoides; octopus, Octopus dofleini; wolf eel, Anarrhichthys ocellatus cabezon, Scorpaenichthys marmoratus; and other sculpin fish species, Cottidae spp.  The role of sea otters in shaping the nearshore kelp forest ecosystem likely has a significant impact on the structure of the northern abalone population where the two species co-exist.  Studies have shown that abalone, in areas where sea otters are present, are restricted to crevices and other cryptic habitats where they are inaccessible or hidden from sea otters (Watson 2000). 

1.4.3 Limiting factors

The northern abalone is vulnerable to harvest because this species has a patchy distribution, a short larval period, is slow growing, relatively long-lived, and has low or sporadic recruitment. Also, mature individuals, which tend to accumulate in shallow water, are easily accessible to harvesters.

The appropriate size and distribution of the northern abalone population required to provide effective reproduction and subsequent sufficient recruitment are unknown.  Current knowledge of abalone species, in general, suggests there needs to be sufficient densities within patches of large mature abalone close enough together to successfully spawn and produce viable offspring (Babcock and Keesing 1999). 

Recruitment is defined as the number of juveniles growing and surviving to the adult population.  Generally, high densities of adult northern abalone are required to ensure sufficient recruitment.  Shepherd and Partington (1995), using a Ricker stock recruitment curve, suggested that there was a critical stock density threshold (0.15 per m2) for the H. laevigata in Waterloo Bay, South Australia, below which the risk of recruitment failure was high.  Later studies by Shepherd and Rodda (S. Shepherd, SARDI Aquatic Sciences, Henley Beach, South Australia, pers. comm.) have shown higher thresholds at around 0.3 per m2.  Shepherd and Brown (1993) found that a “minimum viable population” of more than 800 individuals of H. laevigata was required at West Island, Australia; anything less caused recruitment failure.  Shepherd and Baker (1998) suggested that recruitment to an abalone fishery could be relatively lower and more variable in small abalone populations than in larger populations.  In this case, small populations would need to have more egg production to prevent depletion.  These studies supported the influence of the Allee effect or depensation (Allee et al. 1949) in which low abalone densities and few aggregations reduced reproductive success due to low fertilization of gametes. 

Recent modelsimulations suggested that mortality would have to decrease in order for northern abalone populations to increase (Lessard et al. 2006).

1.5 Socio-economic value

Long harvested by coastal First Nations, abalone (Haliotis spp.) meat was consumed as food and the shells or pieces of shell of northern abalone or red abalone (H. rufescens) traded from California were used in B.C. as fishing lures, in jewelry and as an inlay for carvings (Stewart 1977, Sloan 2003).  Abalone buttons on a ceremonial blanket were a sign of wealth to the Tsimshian (Reece 2000).  Harvest was generally restricted to the lowest tides, although some, such as the Haida, also used a three-pronged spear to access abalone in subtidal areas, 2 m below the lowest tide (Jones 2000).  B.C.’s coastal First Nations express continued concern that the northern abalone population is threatened, which results in food, social and ceremonial fisheries being closed[1]. Interest in food, social and ceremonial fisheries for abalone has provided an incentive for northern abalone rebuilding programs in some areas.  Some of these programs go beyond the objectives of the recovery strategy, but nonetheless support northern abalone recovery.

In addition to the concerns of First Nations, the closures of B.C.’s commercial and recreational abalone fisheries represented significant economic and recreational loss to participants, associated industries and coastal communities.  While small recreational and commercial fisheries for northern abalone occurred in B.C. as early as 1900, a commercial dive fishery directed on northern abalone began in earnest in 1972.  Developing through the 1970s, B.C.’s commercial fishery peaked in 1977 with landings of 481 t.  The majority of harvest occurred in the north and central coast of B.C. and in the Queen Charlotte Islands (Adkins 2000; Campbell 2000b).  The value of the commercial fishery peaked at $1.86M (landed value) in 1978 (Sloan and Breen 1988).  Northern abalone were also regarded as a gourmet food and recreational divers were known to have had a keen interest in northern abalone harvest.  Conservation concerns led to the complete closure of all northern abalone fisheries in B.C. in 1990, including recreational, commercial and First Nations’ food, social and ceremonial fisheries. 

There is no other abalone species occurring within Canada’s Pacific Coast with sufficient abundance to directly replace the northern abalone fisheries.  Recreational and commercial dive fisheries and First Nations’ food, social and ceremonial fisheries continue for other invertebrate species (the value of commercial invertebrate fisheries in B.C. is significant, currently estimated at $122.1M) (2005 British Columbia Seafood Industry Year in Review). 

There is currently no commercial harvest of northern abalone.  There has never been a commercial fishery for northern abalone in Washington State, and Alaska's commercial fishery was closed in 1996.  The recreational fishery in Washington also closed in 1994, but there is currently an Alaskan sport/subsistence fishery.  Other species of abalone (e.g., red abalone, H. rufescens) from aquaculture and commercial fisheries in other jurisdictions (including Australia, Mexico, China, Chile, and the U.S.) are still available in B.C.

Pilot projects were initiated in 2000 under the abalone rebuilding strategy (Dovetail 1999) to develop aquaculture techniques for northern abalone in B.C.  The Bamfield Huu-ay-aht Community Abalone Project (BHCAP) continues to provide support to the abalone recovery strategy (including population rebuilding by out-planting hatchery-raised northern abalone to the wild) and also has the goal of providing economic opportunity in the community.  The BHCAP’s operations are authorized under section 73 of SARA.  The first sales of cultured northern abalone were made by BHCAP in 2006. 

Recreational diving and tourism associations have expressed an interest in maintaining healthy aquatic environments, including healthy and abundant invertebrate communities, which generally support abalone recovery efforts.  The general public also has an interest in addressing species at risk and maintaining a healthy environment.

[1] In the event abalone populations are recovered to sufficient levels, priorities will be given to First Nations’ food, social, ceremonial fisheries pursuant to Section 35(1) of the Canadian Constitution.