Transplant/release captive-bred or hatchery-reared species in predator exclusion cages

How is the evidence assessed?
  • Effectiveness
  • Certainty
  • Harms

Study locations

Key messages

  • One study examined the effects of transplanting or releasing hatchery-reared species in predator exclusion cages on their wild populations. The study was in the North Pacific Ocean (Canada).




  • Survival (1 study): One replicated, controlled study the North Pacific Ocean found that hatchery-reared abalone transplanted in predator exclusion cages had similar survivorship following release compared to those transplanted directly onto the seabed.

About key messages

Key messages provide a descriptive index to studies we have found that test this intervention.

Studies are not directly comparable or of equal value. When making decisions based on this evidence, you should consider factors such as study size, study design, reported metrics and relevance of the study to your situation, rather than simply counting the number of studies that support a particular interpretation.

Supporting evidence from individual studies

  1. A replicated, controlled study in 2009 in one area of seabed off Vancouver Island, North Pacific Ocean, Canada (Hansen & Gosselin 2013) found that hatchery-reared northern abalone Haliotis kamtschatkana transplanted into the wild in predator exclusion cages did not have higher survivorship following release compared to those transplanted directly onto the seabed. For the first seven days after transplantation, abalone in predator cages (not yet released) had higher survivorship (96%) than those not transplanted in cages (57%). However, seven days after being released from their cages, survivorship of abalone had decreased (42%) and was similar to those directly transplanted onto the seabed (34%). In addition, transplanting abalone in cages 1 m above the seabed or in cages onto the seabed led to similar survivorship, both before release (after 7 days; 96% vs 96%) and after release (after 14 days; 38% vs 46%). In 2009 a total of 1,680 hatchery-raised abalone (4.2–6.5 cm shell length) were used in a project assessing the survivorship of transplanted abalone. Three groups of 20 tagged abalone were transplanted at each of seven locations 10 m apart (9 m water depth). Each group corresponded to one of three treatments: 1) abalone placed in predator exclusion cages suspended 1 m above the seabed, 2) abalone placed in predator exclusion cages onto the seabed, 3) abalone transplanted directly onto the seabed (no cage). Seven days after transplanting, abalone in predator exclusion cages were released and allowed to disperse. On day 7 and 14 following transplanting, surviving abalone were searched for and counted inside all cages and during circular surveys (5 m radius around each of the transplantation locations).

    Study and other actions tested
Please cite as:

Lemasson, A.J., Pettit, L.R., Smith, R.K. & Sutherland, W.J. (2020) Subtidal Benthic Invertebrate Conservation. Pages 635-732 in: W.J. Sutherland, L.V. Dicks, S.O. Petrovan & R.K. Smith (eds) What Works in Conservation 2020. Open Book Publishers, Cambridge, UK.

Where has this evidence come from?

List of journals searched by synopsis

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Subtidal Benthic Invertebrate Conservation

This Action forms part of the Action Synopsis:

Subtidal Benthic Invertebrate Conservation
Subtidal Benthic Invertebrate Conservation

Subtidal Benthic Invertebrate Conservation - Published 2020

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