Top shelf bottom feeders

If you are in Jervis Bay and see someone knee deep surrounded by rays or alternatively sitting staring at rays for hours on end then chances are you are looking at the “mother of rays”  otherwise known as  Joni  – the driving force behind the Stingray Diaries. She’s studying smooth stingrays throughout the Jervis Bay Marine park, in conjunction with Fisheries NSW and gives us a rundown on her research in her guest blog below…

Learning to swim by getting thrown off the end of a busy public wharf on the Hawkesbury River in nothing but a pair of hot pink floaties… Living in a swimsuit and covered in sand every single day of the year… Chucking tantrums when told to come inside after playing on the beach all day because it was dark… At the age of 4, saying with great certainty, “Mum, when I grow up I’m going to be a Marine Biologist.”

My name is Joni, and this little water-baby was, and pretty much still is, me. These days I am just as much a thalassophile as I was back then, but now I get to actually study the creatures that live in our oceans. I am a Masters of Research candidate at Macquarie University in the BEEF Lab, working under A/Prof Culum Brown. I also have a Masters of Marine Science and Management and a Bachelors of Marine Science (Biology) under my belt…so I guess you could say I was pretty serious back in ‘94.

I am interested in the conservation biology of sharks and rays. My goal is to get people as fascinated with these species as I am and try to fill the important knowledge gaps regarding the basic biology and life histories of these misunderstood and poorly studied animals.

Currently, I am studying the movements, behaviour and social networks of short-tail stingrays (Bathytoshia brevicaudata) in Jervis Bay, NSW, Australia. I think short-tail stingrays are the gr-RAY-test. They are the biggest species of marine stingray, growing to over 2.2m wide and 350kg… Yep, you read that right. They are incredibly docile, but they aren’t without their defences. They are usually packing up to 2 serrated barbs that will probably ruin your day should you get up close and personal with one of them. Check out this girls’ weaponry:

Short-tail stingrays are really common in shallow, coastal areas along the southern coast of Australia, as well as New Zealand and South Africa. If you dive or snorkel regularly, you have likely even seen one. Surprisingly though, we know almost nothing about them. Significant knowledge gaps exist regarding their movements throughout their range and some of their basic life history, especially with regard to reproduction.

In Jervis Bay there has been a 30 year history of short-tail stingrays coming to a boat ramp in the area to feed on fish scraps discarded by fishermen. To date, no assessment of the behavioural and ecological implications of this phenomenon has been made. That’s what I am here to do.

You may think, “The stingrays have a pretty good deal there though… Why should we care?”  Well, any human activity that has the potential to influence any aspect of another species biology, ecology, behaviour or environment should be properly assessed to ensure any negative impacts are identified and appropriately mitigated or managed.

Some significant impacts to stingray behaviour have been noted in places where stingray feeding is a highly popular tourism attraction. These include Moorea, French Polynesia, Stingray City, Cayman Islands and Hamelin Bay, Western Australia. The impacts have included changes to natural behaviours, such as reversed diel movements and unnatural grouping, increased tolerance to humans leading to increased risk to stingrays and the public, increased aggression towards conspecifics and people, improper nutrition and overfeeding, health implications, increased parasite loads and transmission, changes to population structure and trophic balance, as well as water fouling from excess fish scraps entering the system.

Stingray City, Grand Cayman, Cayman Islands

Now, I know what you’re thinking… a few stingrays hoovering up some scraps they happen across in Jervis Bay isn’t really a comparison to the above examples, right? Well, the short-tail stingrays in Jervis Bay provide a really cool opportunity to investigate this phenomenon at the earliest stages. With the exception of the Moorea stingrays, the above examples plus other unstudied occurrences have stemmed from the stingrays learning the association between boats and fishermen discarding fish scraps in the shallows and a free meal. It appear that this is what is happening in Jervis Bay.

My research involves assessing the links between stingray visitation to the provisioning site (who is visiting and how often?), the amount of fish cleaning occurring (how much free food are they getting?) and the intensity of boating activity (are they using boats as a cue for their next free meal?).

We are currently inviting the locals and visitors of Jervis Bay to get involved in this research. We are asking for anyone who sees, or thinks they have seen, a short-tail stingray in Jervis Bay or surrounds to report it to us. If you do see one, take note of where you saw it and at what time, what it was doing and any distinguishing marks. If you can, snap a photo to send through to us too. You can read more about what to look for and how you can help here.

These data will give us a bigger picture of what areas the rays are using throughout the bay. In the future, we hope to use this data to acoustically track a number of short-tail stingrays, providing us with information on seasonal trends of movement, potential diel movements and shed light on key habitats in the bay for this species.

If you would like to get involved in this research, head over to the project website.

You can also follow myself, as well as our lab and other research on Facebook and Twitter.

Twitter:

@MotherOfRays

@FishLab_MQ

Facebook:

https://www.facebook.com/theBEEFlab

Websites:

The Fish Lab

Stingray diaries