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"Begging" dolphins at risk
Murdoch University Cetacean Research Unit   
Friday, 07 December 2012
edin_dolphins_istock
Researchers found that dolphins that "beg" for food are at greater risk of entanglement and boat strikes.This may have a negative impact in the dolphin population of Western Australia, where feeding dolphins is illegal.
Image: edin/iStockphoto

The Coastal and Estuarine Dolphin Project (CEDP) collects photo-identification, behavioural, and longitudinalal data to support the long-term conservation of bottlenose dolphins in metropolitan waters of Perth, Western Australia.

The illegal feeding of dolphins is a key conservation issue for dolphins in the Perth area. Finn et al. (2008) reported 14 dolphins resident in Cockburn Sound exhibiting behaviours indicative of being conditioned to human interaction by food reinforcement (e.g., approaching and remaining in close proximity to the research boat). Analysis of scarring rates found that dolphins that interacted with humans for food (i.e., “beggars”) are at greater risk of entanglement and boat strikes than other dolphins (Donaldson et al 2010). Donaldson et al (2012) also found that social learning influenced whether dolphins learnt to interact  with humans for food, particularly among male associates.

In our winter 2012 season, the adult male Backpack – not previously known as a beggar – has approached close our research boat on three different occasions (once in Cockburn Sound and twice in the Swan Canning Riverpark).

Backpack is an old male (first seen in 1993), resident in Cockburn Sound and recently observed up to Freshwater Bay in the Swan Canning Riverpark. He mainly associates with Fingers, another old male (first seen in 1993) who has also shown similar ‘begging’ behaviour. This apparent change in their behaviour has two components:

1. The recent exhibition of ‘begging’ behaviour by both dolphins (neither was reported as a “beggar” dolphins during previous studies dating back to 1993); and

2. The recent expansion of their home range with observations of the two in the middle sections of the Swan Canning Riverpark.

During our winter 2012 season, we encountered 31 groups of dolphins (compared to 24 during our previous winter season) in 5 cycles (a cycle is completed when the four areas – Cockburn Sound, Owen Anchorage, Gage Road, and the Swan Canning Riverpark – are surveyed). Group encountered doubled in winter 2012 (n = 6 in winter 2011 and n = 13 in winter 2012). However, we identified more individuals in winter 2011 (n = 182) than in winter 2012 (n= 127).

In addition, we surveyed the Swan Canning Riverpark 4 more times (i.e., not part of a cycle) and encountered 13 dolphin groups.

Among the dolphin we observed within the Swan Canning Riverpark were: Blackwall; Tworakes and her calf Zari; Print and Extreme (a suspected male alliance); Tupac and her calf Gizmo (who has recovered well from his entanglement); and Resource and her calf Product .

This research is made possible through the support of a variety of corporate, government, and community partners including volunteers from the Dolphin Watch project, Fremantle Ports, and the Swan River Trust.

Editor's Note: Original news release can be found here.
 

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