Ideas about using OpenROV to eliminate lionfish?



Hi all,

I'm curious if folks have any thoughts on a payload that can be used to collect lionfish? The problem I keep running into when discussing the possibility of using an ROV to eradicate invasive lionfish is the challenge of rearming some kind of speargun device. I thought that you could have an rov descend with a mousetrap type spring in the 'armed' position. The idea is that a spear could be attached to the spring and a solenoid would trip the spring and shoot the spear forward. Problem is that once you release the spring you can't rearm the tension spring. It's just an idea I've been kicking around but I'm up for any and all ideas.

Thanks everyone and happy 2013!

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You could use a "slurp gun" to collect them. It might be able to get two of them together live, but it would be pretty heavy. You might also have a robotic arm with a small spear or knife attached.


I like the idea of a slurp gun!

My understand of the Lionfish issue is that they're wanted "dead or alive" but that they carry real value for culinary purposes. It seems like the only way to make the ROV a useful tool for helping with Lionfish problem is to make sure the economics work (i.e. one dive can get mulitple Lionfish, they are recoverable (for cooking), it doesn't destroy the ROV, etc.).


What if you used a small net attached to a self-inflating balloon? That way you could "send" the fish to the surface to be collected. Not sure how you'd do this multiple times in a single trip, though.


CAn't you use sound or airpressure to knock the fish unconcious just like a pistol-shrimp? After that, scewer them to collect, charge up for the next and repeat?


I have a design idea for a re-loadable spear gun and have added a picture of it. The few comments I have had are that size may be a factor on a small ROV and the air propulsion may change buoyancy after multiple shots. Also, it may not be clear, but the caught lion fish get pulled back onto the spear shaft housing, where they are lined up to free the spear for the next shot. I think a spring stop and the end of the shaft housing would be better than trying to design an air cushion to absorb the shock when the spear hits the stop. Otherwise, I would be happy to hear comments on it. I do not have the facilities to machine all of the parts for the controller, but could make the shaft housing with spear to test shoot & reload capabilities.

1964-LionFishSpear.jpg (691 KB)


I really like the concept here!! I think you're right that with such as mall ROV, air displacement issues may have a noticeable effect, not to mention performance reduction due to an accumulating mass of lionfish! All the same the direction of thought is really good. Let us know if you build any hardware!



Thanks! another thought would be to use a magnetic coil with a positive charge to shoot and negative to retract the spear, but electricity has never mixed well with water so it would probably require embedded coils and some other fancy engineering beyond my capability. Other suggestions involved zapping or stunning the fish and then using an arm to place them in a net for retrieve, but that is also some fancy engineering. Any engineers out there have an opinion?


I love where this is going. I agree that the buoyancy change from the bottle would be an issue. However, existing pneumatic operate without expending the air supply in the gun. It could be possible to "borrow" that sort of mechanism instead of rigging up a constant loss system.

I think something along the lines of a hawaiian sling could potentially be a easier method of using OpenROV to hunt lionfish, since they have a stationary "handle" that the shaft slides through but doesn't leave. The spears I've seen online that are designed for lionfish are quite short, and appear to not be all that powerful (conjecture), since the fish do not flee from divers.

Something similar in concept to this maybe?


Hey Jeff, I like your idea as well. If the ROV is fitted with a something similar to the acuspear, but with a close fitting shaft housing extending in the front (to collect the fish) and the spring loaded spear tip, a robotic arm of the ROV could be the way to re-arm the spear. All that is left to work out is the effects of the 'wiggle factor' of speared Lion fish that do not die. This should be fairly easy to machine, but would be dependent on robotic arm assemblies. I have attached another file with the design concept. The first diagram shows the spear armed, the second having being shot and the third is the same as the first from above. The spear shaft would have teeth or ridges similar to a calking gun and the robotic wheel would have corresponding teeth with a low gear reduction motor and actuated arm that would lift (to shoot) and lower (to reload) the wheel. This style would not be able to incorporate a spring, but other ideas might be able to incorporate a spring for propulsion. Whatever is used would have to be powerful enough to push the spear tip through the fish to allow the spear tip to pull the fish back onto the spear shaft housing.

More feedback?...

1963-LFspear2.jpg (187 KB)


Brilliant, I was also thinking about a wheel and teeth set up like the second file. I hadn't gotten around to thinking about how to release the shaft yet, I like the idea of raising the cog. I like your design much better than the AcuSpear because it would be the perfect way to incorporate rubber shooting bands like most spearguns, spear poles and hawaiian slings use. Band material is cheap, durable and they would be much easier to rig up. The red lines/string(?) in your second file would be how I'd probably try to rig up the bands.

As far as the spear tip I don't think a spring loaded tip will be necessary, there are double flopper tips like you've drawn but many, including myself, prefer single floppers for spearfishing a single flopper is very reliable. Either styles would work. The double floppers have a retaining ring that keeps them closed until it contacts the fish and a compressed piece of rubber helps spread them.

Double flopper:

Single flopper:

It would be easier for the fish to slide down the shaft with the single flopper that is riveted to the shaft like the picture so that would also be a plus.

As far as dealing with live fish on the shaft, I'm not really sure what would be best. Personally since they are a devastating/invasive species I might even consider forgoing the flopper so that the fish are not retained. But I don't really care for wasting perfectly good meat so... maybe not.

I think I'll grab my speargun and pole spear and ponder this with a beer tonight.


Can one eat Lionfish meat? And don't they have poisonous spines? I'd rather fire a projectile and not worry about recovery.



I was just about to post that same video.


You can eat Lionfish, here are some videos showing how to remove spines and prepare them.

Lionfish Cleaning and Filleting, San Pedro, Belize

How to filet a Lionfish


DANGER! You first.


Thanks again for the feedback Jeff - I think we are close to a great solution! The red lines do represent rubber bungy and the spear tip idea is me reinventing the wheel, as I have never used a spear to fish before (I actually did not fish or eat fish before getting involved with the Lion fish issue) - so your suggestion of a single flopper makes sense. The idea of a weak spring (or other material) to open it is based on the idea that the force of the shot, and penetration of the fish allows the flopper to lay flat, but opens the tip on the other side of the fish to ensure the fish can be pulled back onto the shaft.

Just need to hear from a robotics/ROV expert to see if they have suggestions on how to make something like the 'wheel' work, or if there is a better way to do the same thing.



Lionfish is VERY tasty. I tried it in Key Largo back in March.


Happy to weigh in, glad you found it useful. It seems like all that needs to be worked out now is the mechanism for "loading" the spear, I'm sure somebody will have a good solution.


Please view this video that shows just how easy it is to spear a Lionfish. I have a Lionfish specific trap designed using a combination of ROV and ancient trap technology. I am President of Traditional Fisheries, the world's only commerial supplier of Lionfish for consumption. I have contacts throughout the Caribbean and east coast where a successful Lionfish capture device has great income potential. Please let me know your thoughts.