Unexplainable bat ray death.. twice..

[eelman]

Thinking back, I’ve had about a 50% mortality rate with these in the first 30 days. I don’t recall any sudden deaths like your though. They often come in thin and in poor condition.

One thing - on the dead rays, did you happen to notice any green staining under the skin in the belly?

This is top and bottom about 30 minutes after he passed.

What’s so odd, it’s really no frantic swimming, nothing alarming. No disorientation or running into walls, he seemed great, until he wasn’t. There were literally 0 cues until the jolting/twitching back and fourth. Even then he’d stop and lay at bottom and then quite literally just turned off.

 

[Jay Hemdal Verified Community Expert]

This is top and bottom about 30 minutes after he passed.

What’s so odd, it’s really no frantic swimming, nothing alarming. No disorientation or running into walls, he seemed great, until he wasn’t. There were literally 0 cues until the jolting/twitching back and fourth. Even then he’d stop and lay at bottom and then quite literally just turned off.

I don't see the green bile staining that I mentioned - that would have been on the belly, where the gill slits point to, right where there is a little red spot.

I do see a LOT of sand stuck in the ray's mucus - that's unusual to me, but your sand is very fine, more so than I use, so I don't think that is diagnostic of anything....

 

[sjfishguy]

I was thinking water is too cold. The things are fine during shipping with water in the 70s and then die when the water is in the 60s? I can tell you when fishing in Jersey I have only ever seen or caught bat rays when the water is 75+. In Florida they are everywhere on water 75-80+. 60s seems low. Especially for one that spent days in the 70s and to me explains acute death. And then it happened again within hours again.

 

[Jay Hemdal Verified Community Expert]

I was thinking water is too cold. The things are fine during shipping with water in the 70s and then die when the water is in the 60s? I can tell you when fishing in Jersey I have only ever seen or caught bat rays when the water is 75+. In Florida they are everywhere on water 75-80+. 60s seems low. Especially for one that spent days in the 70s and to me explains acute death. And then it happened again within hours again.

I think you’re mixing up cownose rays with this species of bat ray. This is a temperate water species from the eastern Pacific, San Francisco down into Baja Mexico - maybe even further north.

 

[sjfishguy]

That could be the case. Either way, the temperature swing to me is the only thing that makes logical sense given it happened so fast and the same way twice. And everything else is fine