When a humpback whale became entangled in a craypot line off Kaikōura last week, witnesses described it thrashing in distress for ten minutes before eventually freeing itself.

It was a fortunate outcome.

Elsewhere in New Zealand and Australia, similar cases have required complex disentanglement operations involving trained rescue teams, multiple vessels and specialist equipment.

In one recent Australian case, rescuers removed hundreds of metres of fishing line, hooks, rope and buoys from a young whale whose movement and feeding ability had already been severely compromised.

These interventions are often reported as conservation success stories. Sometimes they are.

But they also reveal a more confronting and often overlooked reality about whale and dolphin entanglements. For many animals, the real issue is not whether they escape. It is what happens afterwards.

Entanglement is an animal welfare issue

Globally, scientists estimate 300,000 whales, dolphins and porpoises are killed each year due to entanglement or incidental capture (bycatch).

Entanglements occur in all manner of marine debris including gillnets, trawl nets, longlines, pot ropes and shark nets.

The problem is so pervasive that the International Whaling Commission (IWC) leads a global entanglement response initiative which brings together leaders of established national programmes to develop best-practice........

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