Study

Measurement, management and mitigation of operational interactions between the South Australian Sardine Fishery and short-beaked common dolphins (Delphinus delphis)

  • Published source details Hamer D.J., Ward T.M. & McGarvey R. (2008) Measurement, management and mitigation of operational interactions between the South Australian Sardine Fishery and short-beaked common dolphins (Delphinus delphis). Biological Conservation, 141, 2865-2878

Actions

This study is summarised as evidence for the following.

Action Category

Establish handling and release protocols for mammals captured by fisheries

Action Link
Marine and Freshwater Mammal Conservation

Establish ‘move-on rules’ for fishing vessels if mammals are encountered

Action Link
Marine and Freshwater Mammal Conservation
  1. Establish handling and release protocols for mammals captured by fisheries

    A before-and-after study in 2004–2006 of a pelagic area in the Great Australian Bight, Australia (Hamer et al. 2008) found that introducing a code of practice for releasing dolphins trapped in fishing nets, along with avoiding dolphins during fishing, resulted in fewer deaths of short-beaked common dolphins Delphinus delphis. The study did not distinguish between the effects of releasing and avoiding dolphins. Mortality rates of dolphins in purse-seine nets were lower after the code of conduct was put in place (0.01 dolphins killed/net) than before (0.4 dolphins killed/net). The code of practice was introduced to a sardine Sardinops sagax fishery in September 2005. At least one crew member/vessel was required to observe for dolphins. Fishing was delayed or relocated if dolphins were present. Release procedures for encircled dolphins included opening the net or a dolphin gate within the net, using weights to submerge the float line, physical removal of dolphins or stopping fishing. An independent observer recorded dolphin encirclements and deaths during 49 fishing events by eight vessels in November–June 2004/2005 (before the code of conduct) and 89 fishing events by 12 vessels in November–June 2005/2006 (after).

    (Summarised by: Anna Berthinussen)

  2. Establish ‘move-on rules’ for fishing vessels if mammals are encountered

    A before-and-after study in 2004–2006 of a pelagic area in the Great Australian Bight, Australia (Hamer et al. 2008) found that introducing measures to delay or relocate fishing if dolphins were encountered, along with releasing dolphins trapped in nets, resulted in fewer short-beaked common dolphins Delphinus delphis being encircled and killed. The study did not distinguish between the effects of delaying/relocating fishing and releasing dolphins. Encirclement and mortality rates of dolphins in purse-seine nets were lower after the measures were put in place (0.2 dolphins encircled/net; 0.01 dolphins killed/net) than before (1.8 dolphins encircled/net; 0.4 dolphins killed/net). The measures were introduced to a sardine Sardinops sagax fishery in September 2005. At least one crew member/vessel was required to observe for dolphins. Fishing was delayed or relocated if dolphins were encountered. Release procedures included opening the net or a dolphin gate within the net, using weights to submerge the float line, physical removal of dolphins or stopping fishing. An independent observer recorded dolphin encirclements and deaths during 49 fishing events by eight vessels in November–June 2004/2005 (before the measures) and 89 fishing events by 12 vessels in November–June 2005/2006 (after).

    (Summarised by: Anna Berthinussen)

Output references

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