zen801 Posted February 5, 2008 Share Posted February 5, 2008 Recently whilst fishing middle harbour i saw the biggest fish arc on my sounder. I have seen kings etc on sounder but this mid water sounding was huge. It was one of those perfect fish soundings like you see in your finders brochure. Clear and enormous. I think there must be some big noahs lurking down there. It made me nervous as he was right below my boat. About an hour before that jews and kings were down below. They cleared out and along came something big and toothy. Anyone else seen huge soundings and if so did you verify what it was? Cheers Link to comment Share on other sites More sharing options...
zen801 Posted February 5, 2008 Author Share Posted February 5, 2008 Put a hook at the end of your line with a big chunk of fish and see how you go! Yeah have caught smaller sharks there like up to 1m. Might consider doing that. In 30m of water in a small tinnie it will be interesting. Link to comment Share on other sites More sharing options...
Jiggy Posted February 5, 2008 Share Posted February 5, 2008 Hmm reminds me of an incident that happened to me a few years ago now; sometimes they don't show up as an arc. My Dad and I were fishing couple of miles north of Belambi, about 20 odd metres deep and on some gravel. I noticed a big smudge appearing on the sounder, a humminbird wide eye. I grabbed a rod to drop a jig down and mentioned to my Dad that we had a big school underneath us. He looks at the sounder and goes "No its not a school, but it's a big one." I look at the screen and on it was an almost perfect picture of a shark. You could make out it's lower jaw, all it's fins and tail; it was if someone had grabbed a pencil and drew it on while I wasn't looking. I looked over the stern and down deep was a huge shadow that disappeared. I decided that day that a 4.3 metre tri hull was just too small! About a year later trolling in roughly the same area I had another big smudge on the screen that I thought was a school until the sounder gave it a big sharky tail. I didn't stick around to see if we would get a hit! I never thought a sounder would give that sort of return image only arcs. To see it was very interesting, fascinating really, but not good on the underwear at all. Cheers Rob Link to comment Share on other sites More sharing options...
jewgaffer Posted February 6, 2008 Share Posted February 6, 2008 Hi Zenman, In that territory up there (Quo Vadis Mike), God only knows what that arc might have been. The arc could have been a big old jew or maybe even the original old Noahs after all the rain we've had Cheers jewgaffer Link to comment Share on other sites More sharing options...
frankp Posted February 6, 2008 Share Posted February 6, 2008 Noahs are referring to................ Link to comment Share on other sites More sharing options...
Jigholio Posted February 6, 2008 Share Posted February 6, 2008 Sounders work by echoing off a hollow cavity; in the case of fish, the swim bladder. A Jewfish has a very large swim bladder and will show as a disproportionately large mark. Bonito have no swim bladder and may or may not show at all. S'pose that doesn't help you much, Zenman! If you want to track a bait or downrigger bomb clearly on ur sounder try attaching a small strip of bubble wrap on the line...no sh1t this works! Link to comment Share on other sites More sharing options...
TheDiko Posted February 7, 2008 Share Posted February 7, 2008 Noahs are referring to................ Noah's Ark, a Shark IFS Link to comment Share on other sites More sharing options...
neilm Posted February 7, 2008 Share Posted February 7, 2008 But sharks don't have swim bladders and therefore wouldn't appear on a sounder normally - unless perhaps it had engulfed a large fish with a swim bladder? Can't explain jiggys observation though. Link to comment Share on other sites More sharing options...
Mondo Rock Posted February 7, 2008 Share Posted February 7, 2008 Wrecks and reefs don't have swim bladders either - yet they still show up on my sounder. I reckon it was either a shark or a big ray. Link to comment Share on other sites More sharing options...
inhlanzi Posted February 7, 2008 Share Posted February 7, 2008 What about a couple of hundred pound sea bass ??? Link to comment Share on other sites More sharing options...
Jigholio Posted February 7, 2008 Share Posted February 7, 2008 Sonar will detect sharks, but quite poorly. Also the longer an object stays within the beam, the larger it will appear on the screen. A Yakka doing happy laps under the hull would appear massive on the screen, a wahoo going full pelt on the edge of the beam would hardly register. Link to comment Share on other sites More sharing options...
choad Posted February 7, 2008 Share Posted February 7, 2008 swim bladders likely create strong echos but are not essential. seeing thermoclines is an example. Sound is reflected at the boundaries between different materials. The greater the difference in material density, the stronger the reflection ie: what you see on your screen. Sound reflects very well wherever water meets air (eg. swim bladder and fish soft tissues), or water meets sand or rock. The size of the echo depends on several factors including the time a fish is inside your transducer beam and the size of the fish. ie: big fish / slow moving = bigger echo. Colour screens tend to be better than black and white as the dynamic range in these units is better - more colours representing different echo strengths than black, white and a few shades of grey inbetween. This means you can differentiate subtle differences in density creating small echoes and displaying them on your screen. The classic example is seeing a thermocline - there are subtle differences in water density at different temperatures which create the reflected sound wave. Link to comment Share on other sites More sharing options...
Kiwi Dan Posted February 8, 2008 Share Posted February 8, 2008 I can easily tell you what that arc was Mike. It was one of Cephs rods still hooked up!! Id put money on it!! Link to comment Share on other sites More sharing options...
Robbielites Posted February 8, 2008 Share Posted February 8, 2008 I can easily tell you what that arc was Mike. It was one of Cephs rods still hooked up!! Id put money on it!! Will you ever live it down Ceph? Robbie. Link to comment Share on other sites More sharing options...
zen801 Posted February 8, 2008 Author Share Posted February 8, 2008 I'd take a big ole mulloway over a submerged Stella anyday. Link to comment Share on other sites More sharing options...
jewgaffer Posted February 8, 2008 Share Posted February 8, 2008 I'd take a big ole mulloway over a submerged Stella anyday. Mike if you leave it up to Ceph you'll more than likely get both the big ole mulloway and his next Stella back at the same time Good on ya Ceph where are you fishing next time mate ? I'll send Cungee George down, he's a Sydney Harbour diver and a real good anchor man, he'll bring up your Stellas. George is a Greek and he doesn't mind eating lightweight Sydney Harbour gastropods Cheers jewgaffer Link to comment Share on other sites More sharing options...
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