Entrapment of harbour porpoises (Phocoena phocoena) in herring weirs in the Bay of Fundy, Canada

  • Published source details Neimanis A.S., Koopman H.N., Westgate A.J., Murison L.D. & Read A.J. (2004) Entrapment of harbour porpoises (Phocoena phocoena) in herring weirs in the Bay of Fundy, Canada. Journal of Cetacean Research and Management, 6, 7-18.


This study is summarised as evidence for the following.

Action Category

Use ‘mammal-safe’ nets to capture and release mammals trapped in fishing structures

Action Link
Marine and Freshwater Mammal Conservation
  1. Use ‘mammal-safe’ nets to capture and release mammals trapped in fishing structures

    A controlled study in 1992–2001 at coastal fishing sites in the Bay of Fundy, Canada (Neimanis et al. 2004) found that using specialised ‘marine mammal nets’ with a large mesh size to release harbour porpoises Phocoena phocoena from herring weirs resulted in lower porpoise mortality compared to when conventional nets were used. Overall porpoise mortality rates were lower when released from weirs with ‘marine mammal nets’ (6 of 240 porpoises, 3%) than with conventional herring nets (44 of 239 porpoises, 18%). Porpoises trapped in herring weirs were captured and released using two types of purse-seine net: ‘marine mammal nets’ (buoyant polypropylene with mesh size 7.5 cm; 240 porpoises) and conventional herring nets (mesh size 0.75–1.25 cm; 239 porpoises). Herring weirs (comprising 1-cm nylon mesh strung between wooden stakes in a kidney-shape, 3–20 m deep) were built near the shore to catch Atlantic herring Clupea harengus. Trapped porpoises were enclosed within the purse-seine nets, transferred to boats and released outside of the weirs. Researchers recorded porpoise deaths during each of the 479 release attempts in 1992–2001.

    (Summarised by: Anna Berthinussen)

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