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Catching up with fish

Greater amberjack

What can we learn from this fish finder screenshot?

Greater amberjack A fish school echo breaks up, right after that we can see that the concentration has increased.

This screenshot was taken at a speed of about 0.3 knots, the left side of the screen shows echoes at 50 kHz and the right side at 200 kHz.

Fish finder screen explained

  • Water depth: 37 m
  • Bottom composition: Rocky
  • There appears to be a large school of fish 10 m above the seabed
  • Above the school of fish individual fish echoes can be seen

I caught a 35cm greater amberjack at the spot shown in the screenshot above. Greater amberjacks feast on small fish like mackerel, so utilizing live bait or jigging with lures similar to their diet are good ways to catch them.
One must when fishing for greater amberjack, is to find locations with good currents, where large schools of small fish gather. However, just because you find nice schools of baitfish, does not automatically mean that you will find greater amberjacks. Since they are a predatory fish, they are much more scarce in numbers.

A way of telling if there are greater amberjacks in the school of fish you've just found, is to look for single fish echoes on the fish finder screen. The fish finder screenshot shows a school of fish close to the seabed. With the accufish function, we can see the size of individual fish around the large school. Accufish can of course be used just for getting the size of fish, but more importantly, you can use it simply to identify whether there are any individual fish present at all.

There is one good way to identify the presence of greater amberjack, you can actually see it directly on the fish finder screenshot. That is, the sudden breakup of schools of fish, with some reservations. Since your fish finder always looks at what is straight below the boat, there will be times when the echo of schools of fish break up, such as when your boat is drifting away or when schools of fish migrate. The thing you should look for is echoes breaking up, and immediately afterwards show up with greater concentration. This tells you that a greater amberjack might be out hunting.

I've studied the feeding habits of greater amberjacks when I've been scuba diving, they attack schools of small fish, which instantly scatter upwards or downwards in the water column. The fish that scatter upwards will show up as a highly concentrated echo on your fish finder screen. When the greater amberjack has finished attacking its bait, it will withdraw for a while, observing the school of fish. Once the school of fish has become satisfactorily concentrated again, the greater amberjack will attack again and again, repeating the whole process. I was surprised to see just how efficient hunters they are.

One last reminder though, whenever you find a school of small fish, there will always be other predatory species feeding, such as amberjack, sea bream, john dory and so forth. So while you may never be entirely sure, if you fish during the late autumn towards the beginning of winter, chances are high that you'll end up with a greater amberjack on your hook.

  • Greater amberjack Greater amberjacks are excellent game fish, strong with lots of endurance.
  • Greater amberjack Greater amberjacks can be solitary as well as school together. This image shows a school of 12 greater amberjacks of about 40cm length, in the process of attacking a school of mackerel.

Writer introduction

Nobuaki Ono, FURUNO field tester.

DAIWA field tester, Writer at Boat Club, a monthly Japanese boating publication

Nobuaki is a hobby angler who travels around Japan together with his beloved car-top boat Tomoe-maru. With a keen interest in fishing as well as scuba diving, he has gained a substantial amount of knowledge in how to utilize fish finders to the fullest. Nobuaki regularly holds well-attended training courses in the use of fish finders, as well as being a proponent for proper sea manners and safety at sea. Sharing his knowledge is a passion for Nobuaki, and he manages his own homepage as well as being a sought after writer in Japanese boating publications.