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Fish Spawning Aggregations in Sian Ka´an Biosphere Reserve

August 12 2014

We are searching for Grouper and Snapper fish spawning aggregation sites in collaboration with artisanal fishers to create no-take zones and protect fish stocks from overfishing. We train the fishers to dive and monitor the sites and will use the ROV to document the deeper sites where we can´t dive

August 12 2014


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Mission Underway

A quick update to those following this project. At the end of September, after several month of work with the fishers, the federal fisheries agency created two completely protected marine reserves to protect the fish spawning aggregations!
Thanks to everyone involved in the project. We´ll continue to explore new aggregation sites.

Wow! This is great news! I'm really eager to learn more about this. Perhaps @andrewthaler and I could interview you for the OpenExplorer Journal. Either way, exciting!

it is indeed good news. We will be back there January through March for the next grouper breeding season with the ROV.
This is the official degree in the Mexican Federal Register that created the marine reserves (in spanish)

That is awesome! :D

This is amazing! Great job.

Next stop - the Nassau grouper aggregation site! Initially things weren´t looking good. We´d taken the ROV out for 3 days but rough weather meant that the captain couldn’t keep the boat hovering over the same spot so it wouldn’t have been safe to deploy the tether. Similarly, I would have soaked my laptop from the spray. But, on the second to last day, just as the fish were getting ready to spawn we got a day with perfect weather!
Predive checks were completed and we were on our way. Controlling the ROV whilst hiding under a towel and a tarp on the boat to be able to see the laptop screen was tricky, but we quickly go the ROV down to 30 metres. The site is deep, the fish are found on top of coral spurs between 25 and 35 metres, but the ROV was doing great - then disaster! We lost control. This happens around minute 4 of the video, (just as we are being to see all the fish). I lost power to the ROV although I could still see the camera. Then after a moment we lost all power. Divers were already in the water and as you´ll see in the video the ROV was rescued by a passing scientist (thanks Will!).
Post dive diagnostic shows that the depth sensor which was glued under the back of the shell came loose and the wires got wrapped around the starboard prop, disabling the motor. The ROV seemed to get confused and shut down. Onboard repairs didn´t get it ready again for a second dive and we are back in the office checking it over.
The video is from the GoPro so we see the entire dive.

Siguiente paso – la agregación de mero! Nos tocó mal tiempo para varios días y no pudimos usar el ROV porque el capitán no pudo mantener la lancha en el mismo lugar, y se iba a mojar la compu… Pero por fin llegó un día con buen tiempo y completamos las revisiones antes del buceo para echarlo al agua. El sitio es profundo (entre 25-35 metros) pero el ROV llegó rápido a los 30 metros, todo bien, empezamos a ver los peces y…. desastre! Perdimos el control del submarino, aprox. minuto 4 del video. Unos buzos que estaban monitoreando el sitio lo rescató (gracias Will!). Lo que pasó es que el profundimetro que estaba pegado al casco se despegó y se enredó con el motor derecha. Lo subimos, intentamos repáralo en la lancha, pero sin éxito. Ya estamos en la oficina poniéndolo en marcha otra vez!
El video es del GoPro y podemos ver todo el buceo.

Wow - that water looks beautiful. Glad you were able to see the fish even if it was only briefly. Hope the repairs are going well!

We finally got the OpenROV in to the ocean on a long trip in to Sian Ka´an to study grouper spawning sites! First stop, the mangroves to check seawater bouyancy and control. Bouyancy was good, but weight was not ideally distributed. Moving the GoPro to the front corrected this. Minor leakage on the port battery tube fixed with parafin film.

Por fin echamos el OpenRov al mar, durante un viaje largo a Sian Ka´an para el estudio de agregaciones de desove de mero. Primera actividad - usarlo en el manglar para checar flotabilidad y control. Flotabilidad bien, pero tuvimos que mover el GoPro hacia el frente para compensar el peso. Se filtró un poco de agua a un tubo de pilas pero se arregló con el apoyo de Adrian Munguia!

Today is the day. Full moon is tomorrow and we are off to the field to dive on a nassau grouper aggregation site with the local fisherman - and the Open ROV is ready to go! We hope to get some good weather and get the ROV in and diving around with the spawning fish!

Wahoo! How did the dive go?

sorry for late reply! just got out of the field a few days ago - videos and reports on their way today!

Grouper spawning season is almost upon us and the OpenROV is ready to go! Only a few weeks to go and we hope to be diving on the endangered Nassau Grouper spawning sites of the Mexican Caribbean

Excellent news! Excited to see the video!

Preparation Stage

Pool testing complete! Next stop the sea and the grouper aggregations! Full control, perfect buoyancy, no leaks.

Pruebas en la alberca terminadas! Ya al mar y a las agregaciones!


After a rather long pause in activities the ROV was back in the test pool today with good buoyancy and perfectly configured controls - its easy to operate!
But.... there was a slight leak in the port battery tube. A new issue, and its not obvious which end the water sneaked in... hopefully a quick fix.

Despues de una pausa larga en las actividades, el submarino esta de regreso en el agua - ya con una buena flotabilidad y control. Pero... ya hay una pequeña fuga en el tubo de la bateria... espero que no tarda mucho en arreglar..

Freshwater test of the COBI OpenROV.
Success. So happy
No leaks, perfect bouyancy.
It works

Couldn't see the screen on the laptop for the glare!
It doesnt like going in straight lines... port motor seems stronger than the other - a lot of spiralling!

Primer prueba del mini submarino
Exitoso! Sin fugas, flotabilidad = perfects
Problemitas - no pude ver la pantalla del laptop por el sol. No le gusta ir en lineas rectas - parece que un motor es mas fuerte y hace muchas vueltas!

Glare is one of the most common issues. I usually just throw a towel over my head, but one could easily adapt a trifold onto the laptop display. Like this one:

Update the software to the most recent version a week or so ago and thought I'd killed it for a moment! No connectivity after update.
But few, all ok, some assistance from the helpful guys on the forum, a little bit of soldering and back on track! Just need to get the last few wires shrink wrapped again and we'll be good to go!

Great news! It's always a bit scary when a piece of tech doesn't boot up instantly, but these little ROVs are simple enough devices that there's always a solution!

Can't wait to see what you have planned next!

thought it was good news, but updated the software and all looked good at the start. Now I cant connect. It thinks about it for a few mins then the white lights start flashing and it seems to get stuck in a loop and never connects.

Everything seems fine, except I have the micro servo disconnected cos I think its broken. Have ordered a new one. But will take a while to get here. If thats not the problem, I have no idea...

Short video of first in-water test
Video corto de la primera prueba en agua dulce

Congratulations! Ocean testing coming up?

Yep! Hopefully soon, been crazy busy lately and haven't had time to practice my driving! Want to test again in a pool and get the hang of driving before we go to the ocean.

All watertight and looking good! Testing in deeper water coming soon

Luces prendidas y todo funcionando en la cubeta. Proximo paso - pruebas en agua profunda!


Good news! Also, nice picture!

Whoa, This is great. When is the first test dive scheduled? Good weather?

We were going to try it the other day, but the weather was/is horrible! the shore has coffee coloured water, cant see anything. Will wait a few more days

The stress test!! (for me, it was very stressful!) Doing good. Tiny filtration of water in to the starboard battery tube. Working on a fix. Camera tube and port battery tube sealed up!

La prueba de estrés (para mi, que estrés meter el submarino en el agua!) Entró un pocitito de agua a un tubo de las pilas. Lo estamos arreglando. El tubo de la cámara y el otro tubo de las pilas - todo bien!


Felicidades! Congratulations! Can't wait to see your first dive in Mexico! White tip shark territory down there right?

Any tips on sealing up the battery tube? Forum seems to suggest a bit of teflon tape under the o-ring to help with the seal. Its only a tiny amount. We sunk it for a while with the weight belt and a few drops sneaked through the end cap. Looking at the end cap, it seems the starboard acrylic disks are not as concentric as the port side. I'm guessing thats the problem.

We don't see many whitetips down where we are. Most commonly seen shark at this time of year is probably the bull shark.

A strip of Teflon tape can work, the other thing that has been a quick and dirty fix in the field the worked well was one of those tiny "ouchless" hair ties like these:

Take the O-Ring out, put two of these in first side by side, then put the o-ring over that.

Teflon tape worked great. One battery cap seems to be very slightly mis-aligned, but the tape sealed it up well

Listo para la prueba de agua! Los tres motores funcionan!

Let´s see if it´s waterproof! All motors working. Almost ready to go!


Llegaron los cargadores para las pilas - ya podemos seguir con la programación de los motores

Battery chargers arrived - time to carry on with calibrating the motors

Que Bueno, avísanos si necesitas algo mientras estas programando los esc's.

hi Erika - any advice on this problem - I think I've programmed the motors correctly but when I finish the calibration they all turn on.
whenever I switch a ESC on, and it doesnt matter which one, all motors turn on. Not sure what to do about from reprogram again

We'll just ignore that comment and pretend I didn't have my labels mixed up... duh :-)

Its alive!! Just need to programme the motors

Esta vivo! Solo le falta programar los motores.


Cuando empiezan los sonidos y luzes, hay un sentimiento de orgulloso! Estoy esperando por los expediciones con alegria! Felicidades!

When it starts beeping and the flashing lights come on for the first time, there's definitely a feeling of pride and excitement. Congrats! Looking forward to it's adventure in Mexico!

It was pretty exciting! I ran out of time today to program the motors/ESCs. To be honest, it seemed quite tricky, so am going to wait until I have enough time to do it properly and not rush.

Hey there, I am in Playa del Carmen for another 2 month maybe we can meetup at somepoint and share our ROV experience.
Looking forward to that!

Hey Nils, Are you around in the next few days? Tomorrow?? Am going away on the 27th and wont be back for a few weeks.
Would be great to meet for a coffee or something and talk about the ROV!

Did you guys end up having an ROV meet up? I love how connected we are becoming!

The electrics and the camera!

Las partes electricas y la camara!


Wow, you've made great progress! I feel like we're dragging our feet on ours. I guess I know what I'm doing this weekend.

Starting to take shape!!
The structure is done, working on the electronics!

Ya esta tomando forma. La estructura esta lista y estamos trabajando en la parte electronica


And it begins!!
Took a while to source all the materials, especially the acrylic cement, but it should be worth the wait!

Ya empezó!
Nos costó trabajo buscar algunas materiales, sobre todo un pegamento de acrílico, pero ya estamos!


So cool! I was just talking about how much I like seeing everyone's workspaces across the world.

I'm definitely looking forward to following along as you progress. Let us know how it goes!

Me gusta mucho ver todos los centros de operaciones donde se construyeron los ROVs en paises en el otro lado del mundo.

Estamos bien interesada en tu progresia. Cuentanos como va! Buena suerte!

Thanks Erika. Hope things go well, working with the acrylic is fine, working with the electrics is a whole different ball game...

Very happy today! Thanks to OpenROV and the Moore Foundation

Estamos muy contentos hoy!


Yes! Great!

I'm excited to know how things are going! Any photos from Robot building? you mentioned grouper spawing was starting this month, have you been out diving yet? Let us know if we can come together as a community to help out wiht anything!

Thanks Erika.
We are still building! Its been a very busy few months with our other projects, and we havent been able to dedicate 100% of our time to the ROV. BUT - we dont have any more field trips and we are now dedicating our time to get the ROV up and running in time for spawning season!
The december full moon falls early this year, in two days time, so our first aggregation monitoring trip will be for the full moon on the 4th of January! Can´t wait!

Very happy today!

Estamos muy contentos hoy!


Getting closer to the "mission underway" stage!
Only a month and a bit to go until grouper spawning season starts and the team is starting to get everything ready!

ROV on the way!

Good to know you are about to go deeper wit the new ROV! Congrats Stu!

Thanks Alfonso!

The Punta Herrero spawning aggregation site monitoring team! The team is made up of trained fishers from the community. They are excellent divers and have an amazing knowledge of fish behaviour in the waters around their community.

El equipo de monitoreo de agregaciones en Punta Herrero. El equipo se esta formado por pescadores de la comunidad costera. Son buzos expertos y tienen un conocimiento impresionante de las aguas alrededor de su comunidad.


Excelente trabajo que realizan los pescadores en conjunto con la AC.

Looks like a great bunch! Looking forward to following the ROV building process soon!

The fishers collecting bathymetric data in the Sian Ka´an Biosphere Reserve.

Pescadores registrando datos batimétricos en la Reserva de la Biosfera Sian Ka´an.


A short video of a small school of Cubera Snapper seen in August 2013. The video is a bit grainy as the rough seas caused low light conditions. Many of the spawning sites are multispecific, i.e the same reef area hosts the breeding grounds of several different species. August is towards the end of the spawning season for snappers and we only saw a few on this dive. However, in this region, its still not common to see a school of Cubera snappers.

Un video corto de un cardumen pequeño de pargo cubera, visto en agosto 2013. Muchos de los sitios de agregación son multi-específicos, a decir, que varias especies reproducen en el mismo sitio en diferentes épocas del año. Agosto es cerca del final de la temporada de reproducción de los pargos y no vimos muchos, pero no es común ver un cardumen de cuberas.

This would be perfect for an OpenROV! Also, love the bilingual descriptions!

I put it in spanish ´cos I´m hoping that some of the artisanal fishers we work with will come on the site to check out the videos - especially as they are the ones who took us to the sites and even did some of the filming!

Very cool collaborative project! I voted for you guys; good luck!

Thanks!! We´ll be keeping the wall up to date with more info over the next few weeks. The grouper spawning season doesn´t start until the winter so we are getting everything ready at the moment!

Nassau Grouper at spawning site. Video shot by local fisher who belongs to the biodiversity monitoring team who work with COBI. There was a strong current at the site this day as you can see by the speed the diver is going! February 2014

A school of juvenile horse-eye jacks come to check out the dive team whilst we searched for spawning aggregations last year!
The presence of jacks can sometimes signal that you are getting close to a spawning site - jacks and similar species can come to feast on the eggs released.

An example of the bathymetric maps produced by the fishers (and highly skilled captains) to help geolocate the aggregation sites. Studies by experts such as Dr. Will Heyman, suggest the sites are located near underwater promontories.
Un ejemplo de los mapas batimétricos producidos por los pescadores (y capitanes expertos) que nos ayuda ubicar los sitios de agregación. Según estudios realizado por expertos como Dr. Will Heyman, los sitios se encuentran cerca de promontorios submarinos.


A quick video of the endangered Nassau Grouper getting ready to spawn in the Sian Ka´an Biosphere Reserve filmed by a scuba diver. These fish are over 50 cm in length and many have changed colour from their normal brown to black and white which is their reproductive colour. As you can see the blue video colour was filmed deep, at about 35 meters. Our next plan is to explore the deeper waters further offshore where its looks like there are more groupers.

This is amazing! You know what the ROV needs? A red filter for deep work like this, maybe you can install one?

Dog Snapper aggregation that we saw in March - can´t wait to get back next year

Groupers only spawn a few days after the full moon of January, February and March. Snappers behave similarly, only spawning a few days after the full moon of April, May and June. This means the aggregation site can be really hard to find. We work with local fishers as they have the best knowledge of the area.

In one site we recently found over 100 Nassau Grouper getting ready to spawn. The Nassau Grouper is on the IUCN endangered species list. We found the grouper at about 35 meters depth but couldn’t stay long as we were at the limits of safe diving, and we are in a really remote place. It looked like there were more groupers in the deeper water. We hope to explore this area in January with an OpenROV.

In March 2014 we also found a site with >1000 Dog Snapper (see profile pic). It was a huge swirling mass of fish! Even the fishers who were with us had never seen anything like it!

Expedition Background

We are a Mexican NGO, Comunidad y Biodiversidad (COBI – who work to promote the sustainable use of marine resources.

We work directly with artisanal fishing communities to create no-take zones so that the fishery in that area can recover, bringing benefits to the fishers in the future. We also work closely to improve the fishers´ livelihoods, looking to increase their incomes through improving their business practices and encouraging good sustainable fishing practices that can then be certified by agencies such as the Marine Stewardship Council, so that fishers can get a better price for their catch.

Working with fishers in the Sian Ka´an Biosphere Reserve, Mexico, we were recently successful in establishing several no take zones, two of which include fish spawning aggregation sites -sites of key biological importance as these are the sites that fish such as groupers and snappers come to to breed. They are very easily overfished.
We are currently monitoring the sites but the depth of the spawning aggregations (>35 meters) means that we can only dive for short periods and the diving is potentially risky.

We hope to use an Open ROV to geolocate and document the spawning site to track its recover now that it is closed to fishing.


Spill over effect has had proven effects all over the world. I love that you are taking this on and that it has already been successful in several cases! I'd love to know more, are there links for more information about the sites you've helped establish?

Hi Erika, A lot of the information is in spanish but our website and the website of the Kanan Kay Alliance, have further info in english. The first sites were only established at the end of 2012, and another bunch less than a year ago, we are still working on the monitoring data to see the biological effects, but its still early days!
Dont hesitate to ask for more info.

This is so important, and I'm so glad you do this! Excited to see how it's going!!

This is very exciting indeed. When do you think you will be able to get back to the sites next?

Hope to be there all through the next spawning season in 2015.
Now we have some of the sites located, it makes things a lot easy to go back!

Congratulations on such a great project.

Awesome, great work! I wish I could come join you and help! Ending overfishing is something I'm pretty passionate about. I'm trying to work on Marine Protected Area efficacy in Southern California, to hopefully help increase their size.