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Top shelf bottom feeders

New research shows stingray feeding is affecting their behaviour

 Photo credit: Joanna Stephan, Macquarie University

Photo credit: Joanna Stephan, Macquarie University

Last month we introduced you to one of our favourite elasmobranchs - the smooth stingray! Well, maybe one of my favourite elasmobranchs... And if you joined us for our Shark-Themed Movie Night, you would have learnt all about these beauties from me, the stingray lady.

If you don't know me yet, my name is Joni Pini-Fitzsimmons, and I am elasmo's resident marine biologist. In a nutshell, I am a PhD researcher at Macquarie University, and I study stingray behaviour.

Earlier this week, my very first research paper was published in the Marine Ecology Progress Series. This research shows that the common practice of throwing fish scraps back in the water after fishing is actually have a potentially negative effect on smooth stingrays and it is influencing their behaviour.

If you've ever been fishing, odds are that you've thrown your left over bait in the water, or when you've cleaned your catch you've thrown the scraps in. This practice is typically viewed as ecologically benign, or even doing the animals that feed on it a favour! But feeding wildlife has actually been shown to have a range of negative impacts on the animals' wellbeing, from altering their behaviour, causing shifts in the food chain, and even reducing overall health.

 Raylene the smooth stingray waiting patiently for a feed of fish scraps.

Raylene the smooth stingray waiting patiently for a feed of fish scraps.

Smooth stingrays are common scavengers of fish scraps throughout southern Australia. Surprisingly though, the effects of feeding scraps to these rays hadn't been assessed. This is important because fish cleaning stations and facilities for recreational fishing are being built in the absence of this important environmental impact data.

In this project, we focussed our observations on a population of smooth stingrays being fed fish scraps at a small, but popular boat ramp on the south NSW coast by fishermen and the public for over 30 years.

While considered small scale, we actually found that feeding the scraps to the rays strongly influenced their behaviour and use of the area. The rays would even arrive in anticipation of a feed. This anticipation is concerning because it may indicate that the stingrays are either developing dependency on the discard fish waste or that they are at a heightened risk of developing dependency. This could have potential repercussions for their survival.

Fish scraps are discarded at boat ramps and from boats all around Australia, therefore it is important that the effects are identified and considered in management. Through my continued research, we hope to identify the long-term impacts of this feeding on smooth stingrays and other species. 

The paper is now available on the Marine Ecology Progress Series. If you don't have access to this journal and would like to read the full article, please send me an email: joni.pini-fitzsimmons@hdr.mq.edu.au.

Check out the video summary below:

If you would like to follow my research or learn more about stingrays and their importance in our oceans, check out my Instagram, Twitter and the Project Website.

Joni Pini-Fitzsimmons