HOME Catching up with fish Marbled rockfish vol.2
Catching up with fish
What can we learn from the fish finder screen?
This screenshot was taken with the boat slowly drifting due to wind and waves, at a speed of 0.3 knots. On the left side of the fish finder image, you can see what captured echoes look like at 50 kHz, and 200 kHz on the right side.
The catch of the day was marbled rockfish. Marbled rockfish tend to live in rocky reefs and wrecks, where they can pursue their crabs and shrimp. Marbled rockfish do not go out and look for its prey; they hide and wait. Once their prey comes within range, they strike. Marbled rockfish are camouflaged to look like rocks, which helps them surprise their prey.
They sometimes come up from the seabed 2-3 m for hunting, but usually they are crawling on the sea floor and hardly seen on the fish finder. This makes it difficult to find them with a fish finder; but as you may know, we can search for the places where marbled rockfish normally gather.
All you have to do is to search for places with seafloor makeup of anything except for sand and mud. In other word you will be searching for them in rocky areas or wrecks. FURUNO Fish finders, such as the GP-1870F and the FCV-587/588, which feature our unique Bottom Discrimination feature made it easier to find places rockfish may live.
When fishing for marbled rockfish, it is necessary for you to drop your bait to the bottom, however, at the point of reefs and rough stones your bait will likely get stuck. If you are drifting your boat, the likeliness of this happening is even greater. In order to avoid that as much as possible, it is very important to know the bottom contour and make up where you dropped your bait. Our recommendation is to set the frequency to 200 kHz, at which the pointing angle is narrowed, and the fishing line be hung from where the transducer is attached, so we can see the bait in the range of the angle of the transmitted ultrasonic wave.
Using heavy baits will make it easier for you to drop the line vertical to the seafloor. Control of the boat is also the key. When your bait is dropping down, it receives the effect by the sea current flow. If the sea current moves the boat in the same direction as the line flows, the line would drop straight down to the sea floor; but if the boat is moving in a different direction than the line, it will be difficult to make the line vertical to the seafloor and your bait will easily get stuck on rocks.
You need to control your boat so that the water depth depicted on a fish finder and the length of fishing reel will be almost the same. For better fishing, check the water depth and bottom configuration frequently.
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.