Moon jellyfish

Global warming and overfishing. And any good news we can dig up.
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Matt Flynn
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Moon jellyfish

Post by Matt Flynn »

A very common species. A few being seen around Darwin, but they are found everywhere, including Tasmania, and in brackish water.

They have recently caused problems in Tasmania, killing farmed salmon. I see in the Wiki entry that they thrive with slightly hypoxic conditions near the sea floor, I guess this would make some fish farm locations ideal, under the pens.

Increasing warmth and hypoxia-loving jellyfish - tough gig for salmon farmers, same deal with a different species in Scotland ... https://www.bbc.com/news/uk-scotland-hi ... s-30493457

Anyone reckon jellyfish numbers are increasing in their patch?


NinjaFish
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Re: Moon jellyfish

Post by NinjaFish »

By the thousands last weekend.

Thought my settings had changed on the sounder and started trying to fix the view on Saturday. It wasn't till we hit the shallows that we saw the Jellyfish as big as or bigger than soccer balls everywhere and fishing was slow to non existent where they were.

Same thing late Feb early March last year at Shady mouth - no bites, almost as if they annoy the fish enough that fish go elsewhere?

Plenty of sharks around in places that I don't usually get them though - 4 different species in 15 minutes.

I usually run the sensitivity at A-4 which showed them as near perfect teardrops but screenshot taken while I was trying to clear it up. :bonk:

I never thought a sounder would pick up Jellyfish.
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al57
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Re: Moon jellyfish

Post by al57 »

thats a cool sounder pic NF,i have never thought of doing that here in the bay .on many occasions we have an absolute boom in those blue blubber jellyfish ,come into the bay by the millions,
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Re: Moon jellyfish

Post by slug »

I wonder if we'll see an increase in turtles coming in for some fine dining??
NinjaFish wrote: I never thought a sounder would pick up Jellyfish.
This sort of stuff always interests me, and I here so many conflicting opions.
I can't see why jellies won't give a sonar return?
I hear all time that only fish with swim bladders will return echos - doesn't cut the mustard with me?

You can't tell me that you'll get no return from a 5 foot bull shark swimming through the transducer cone (no swim bladder in sharks), but there is a return from a 5ml diameter twig floating through the water column??

Perhaps Theo could enlighten us a bit on the science - I think he's the guru in all things radar/sonar/xray ??
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