Fish ID

HOW EX­PERTS IDEN­TIFY SPECIES THEY MARK ON A FISH FINDER

Saltwater Sportsman - - Table Of Contents / Departments - JIM HEN­DRICKS

“Get your bait close to bot­tom,” he said. I promptly dropped a live squid on a lead-head into the depths. Within sec­onds, I was hooked up. A se­ries of vi­o­lent head shakes were all I needed to as­sume that Wisch was cor­rect.

Five min­utes later, the cap­tain sunk the gaff in a sil­very 45-pound white seabass, a glory fish that lo­cals call a tanker. So­phis­ti­cated fish find­ers and sonar sys­tems from brands such as Fu­runo, Garmin, Hum­min­bird, Lowrance, Ray­ma­rine and Sim­rad make it pretty easy to dis­tin­guish fish from other un­der­wa­ter el­e­ments such as wrecks or the seabed.

How­ever, there’s one thing th­ese ad­vanced echo-sound­ing de­vices can­not do: iden­tify a par­tic­u­lar species of fish or any other sea crea­ture. Yet skip­pers such as Wisch and oth­ers have learned how to ID species they see on fish find­ers. How do they do it?

Keys to Learn­ing

One of the steps in rec­og­niz­ing species is de­vel­op­ing an un­der­stand­ing of how echo sounders work. To sim­plify things, think in terms of bounc­ing a ten­nis ball. On dense sur­faces, it bounces well. On softer sur­faces, it does not.

Sim­i­larly, fish-finder sig­nals bounce strongly off cer­tain parts of a fish, in­clud­ing the skele­ton and air blad­ders, Wisch ex­plains. So it’s also im­por­tant to un­der­stand the anatomy and habits of dif­fer­ent fish. This can lead you to iden­tify a par­tic­u­lar species you mark.

“For ex­am­ple, croak­ers like white seabass have heavy bone struc­tures and large swim blad­ders,” says Wisch, “so the croak­ers gen­er­ate rel­a­tively large marks on a fish finder.

“White seabass also move slowly, and so on a sta­tion­ary boat, they tend to stay in­side the sonar beam an­gle longer,” he adds. This re­sults in elon­gated re­turns, some­times called “worms,” on the fish-finder dis­play. On the other hand, Cal­i­for­nia yel­low­tail, a species of am­ber­jack that of­ten feeds in the com­pany of white seabass, tends to move through the beam an­gle quickly, so the re­turns are more like di­ag­o­nal streaks.

Study the Re­turns

One of the eas­i­est ways to ac­quire species-id skills lies in cor­re­lat­ing re­turns on the fish finder to the fish you are catch­ing, says Capt. Tom Pi­tasi, who guided trips in eastern Long Is­land Sound for 19 years and now man­ages the pro staff for Ray­ma­rine.

“Af­ter years of com­par­ing fish marks to what’s bit­ing, I’ve learned to dis­tin­guish striped bass from blue­fish re­turns,” says Pi­tasi. Striped bass tend to ap­pear as pro­nounced

arches (“boomerangs,” as they are called), Pi­tasi says.

Striped bass are rel­a­tively thick, en­dowed with heavy bone struc­tures and large swim blad­ders. They gen­er­ate larger, more elon­gated marks than the slim­mer blue­fish, Pi­tasi says. “Blue­fish show as shorter, rounder marks.”

Pi­tasi fishes with the Ray­ma­rine CP470 CHIRP sounder with an Air­mar B175H trans­ducer aboard his 205 Tri­ton 26-foot cen­ter con­sole, tar­get­ing striped bass and blue­fish along the rips and reefs off Rhode Is­land.

“Most of the time, we’re af­ter striped bass,” he ex­plains. “So it is help­ful to know how to dis­tin­guish schools of stripers from blue­fish, which of­ten feed in the same wa­ters.”

Bait School

It’s not al­ways about find­ing the right tar­get fish. Some­times it’s more im­por­tant to first find the right bait. For in­stance, when opales­cent squid mi­grate off Cal­i­for­nia, a host of game fish fol­low, in­clud­ing Cal­i­for­nia hal­ibut, white seabass and yel­low­tail.

Dis­tin­guish­ing squid from an­chovies and sar­dines be­comes mis­sion crit­i­cal. “You need to re­mem­ber how fish find­ers work in re­la­tion to anatomy,” says Wisch. “Squid are soft-bod­ied, with no bones or swim blad­der, and barely mark on a fish finder.”

On many color fish find­ers, all you see is blue fuzz when a school of squid passes un­der the boat, as op­posed to the dis­tinc­tive red blob from a school of sar­dines. “When you see the weaker marks, you know you’ve found squid,” Wisch says.

Re­tain the Set­tings

Another key to ex­pert iden­ti­fi­ca­tion is us­ing iden­ti­cal set­tings all the time, then care­fully com­par­ing the marks, says Capt. Mark Cole­man, who char­ters in Wash­ing­ton State and Costa Rica.

Cole­man’s boats are also equipped with Ray­ma­rine CP470 CHIRP sonar sys­tems with Air­mar B175M trans­duc­ers. “The 85 to 135 khz band­width (of the B175M trans­ducer) of­fers good al­laround ver­sa­til­ity for find­ing bot­tom­fish as well as pelagic species when off­shore fishing,” he says.

Iden­ti­fy­ing species is par­tic­u­larly help­ful when pur­su­ing al­ba­core in the Pa­cific North­west, Cole­man dis­cov­ered. “We ba­si­cally mark two species when fishing off­shore — schools of tuna (al­ba­core) and groups of blue sharks, but we are in­ter­ested only in tuna,” he says.

“Af­ter care­fully study­ing the marks, we found that the slow-mov­ing blue sharks look like blobs, while the fast-mov­ing tuna show up as ex­ag­ger­ated streaks. We learned that when we stopped to fish the blobs, all we caught were sharks, but the streaks pro­duced tuna. So now we don’t stop on the blobs.”

In order to make this dis­tinc­tion, it’s im­por­tant to main­tain the same fishfinder set­tings all the time. Changes in the sen­si­tiv­ity, for ex­am­ple, al­ter the char­ac­ter­is­tics of the marks. That means you might not learn to rec­og­nize the species un­less you main­tain con­sis­tent set­tings.

With the in­tro­duc­tion of fea­tures such as chirp tech­nol­ogy and side-look­ing sonar, fish find­ers have pro­gressed might­ily in the past few years. Yet, ul­ti­mately, the ef­fec­tive­ness of th­ese sys­tems hinges on your ded­i­ca­tion to learn­ing how to use the tech­nol­ogy and study­ing what’s on the screen. Put in your time and you can learn to trans­late the marks and ID the species.

LONG AND SHORT: Striped bass tend to make more elon­gated marks on a fish finder than do blue­fish.

“Those are white seabass,” said Capt. Mark Wisch, peer­ing at the fish-finder dis­play in the dark of night as we bobbed in 120 feet of wa­ter on the back­side of Santa Catalina Is­land off South­ern Cal­i­for­nia.

STRIPED BASS BLUE­FISH

BASS MARKS: Th­ese longer re­turns show striped bass on the edge of a reef.

SCHOOL ZONE: Marks stretch­ing side­ways in­di­cate a school of stripers, be­low.

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