Using molecular pedigree reconstruction to evaluate the long-term survival of outplanted hatchery-reared larval and juvenile northern abalone (Haliotis kamtschatkana)

Abstract

The restoration of abalone (Haliotis spp.) populations through supplementation with the offspring of hatchery-spawned wild parents has been attempted in several species, with variable results. Between 2002 and 2005, the Bamfield Huu-ay-aht Community Abalone Project released 4.5 million larvae and 152,000 juveniles of the northern abalone (Haliotis kamtschatkana) into Barkley Sound, BC. The purpose of this study was to estimate the long-term survival of outplanted abalone 3-7 years after their release and thus determine their contribution to local population densities at three different outplanting sites. We identified outplanted abalone by genotyping epipodal tentacles sampled from wild-caught abalone for seven microsatellite loci. We then used three different pedigree reconstruction programs: one that used genotypes from hatchery-reared siblings (PEDIGREE 2.2), one that used the wild parent genotypes that were available (CERVUS 3.0), and one that used both sources of information (COLONY 2.0). Each program identified different but partially overlapping subsets of hatchery-outplanted offspring. From this we inferred that up to 26% of the individuals sampled at the main outplanting site were from hatchery spawnings. Despite this large contribution of hatchery-reared stock, the density of mature abalone at each site was below the level required for successful fertilization. More intensive outplanting efforts might increase population densities of this broadcast spawner above this minimum sustainable level. However, for supplementation to be successful, other factors that could reduce outplanted juvenile survival, including the low genetic diversity of hatchery-produced offspring and the low habitat quality of some outplanting sites, need to be monitored.

Contribution of genetics to ecological restoration

“…For example, long‐term survival of out‐planted abalone ( Haliotis kamtschatkana ; Read et al . ) and reproductive success in Pacific salmon ( Oncorhynchus spp. ; Baumsteiger et al .…”

Movement and home range of pink abalone Haliotis corrugata: implications for restoration and population recovery

“…Schiel & Welden 1987, Tegner & Butler 1985, Tegner 2000, James et al 2007, Roberts et al 2007, Hamasaki & Kitada 2008. Long-term survival of hatchery released larvae and juveniles was recently assessed by Read et al (2012), who found that up to 26% of emergent adults were from hatcheries. While this is encouraging, the overall density was still considered to be low.…”

Are hatchery-reared abalone naïve of predators? Comparing the behaviours of wild and hatchery-reared northern abalone,Haliotis kamtschatkana(Jonas, 1845)

“…This suggests restoration efforts are needed if abalone populations are to recover. One potential solution, the outplanting of hatchery-reared H. kamtschatkana, has so far been limited by high mortality rates of hatchery abalone when released into the wild (Read, Lemay, Acheson & Boulding 2012;Hansen & Gosselin 2013;Read, Lessard & Boulding 2013). For H. kamtschatkana, the mortality rate of recently outplanted juveniles has been estimated at 66% over 2 weeks (Hansen & Gosselin 2013), while the mortality rate of wild individuals of the same age in the same region is <1% over the same duration (Breen 1980(Breen , 1986Fournier & Breen 1983;Sloan & Breen 1988).…”