Mako's and The Thermocline -- Archive

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Subject: Mako's and The Thermocline

Author:
ED

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Date Posted: 923677710PDT

Posted by Jim Day on April 08, 1999 at SharkTagger

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Posted by Dave Teufel on April 08, 1999
I just finished reading "movement of the Mako" on this site and have a few questions for Keith or anyone else with some insight..... the waters off Maine, being as cold as they are, would result in makos staying above the thermocline. What do you think? Thanks in advance. ........
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Like most things having to do with Mako's I've thought about this a lot. (too much time on my hands )I don't have any scientific studies to back this up but based on my experience I'd say it works like this. Mako's like most big fish are all about effeciency, it's about energy expended vrs food taken in. When trolling: Mako's will almost always hit the closest biggest bait. I.E. most food for the effort. It's really rare to catch a big Mako trolling (over 150 pds) its just not worth their effort. Chasing down a little skirted Mack thats hauling butt at three knots is just not efficient for a big fish. It's all about energy spent vrs energy gained, calories in vrs calories burnt. It's the same with the thermocline. Mako's feed mostly on surface fish Macks bones berry's tuna etc. bait fish are usaully up on the surface because they prefer warmer water. So a mako needs to be near the surface most of the time, to find dinner. Got all that? O.K. now comes the tricky part. Cold water is denser than warm water. thats why cold water sinks and warm water comes to the top. The thing about density is: the denser the water the more bouyent any given object is thats within it. I could explain it on a molecular level but take my word for it. It has to do with mass: theres more molecules per square inch in dense cold water than in the light warm water, more molecules means more weight. Cold deeper water weighs more per square inch. Bouancy works on a displacement weight ratio. How much your shark weighs vrs the weight of the water its displacing. In other words the shark is effectively lighter (weighs less) in the cold dense water than in the warmer water where the bait hangs out. Got that OK put the two things together. Sharks are about efficiancy, colder water is more dense so a shark effectively weighs less in colder denser water. Add to this that sharks are not naturally boyent, they have no swim bladder so if the stop swimming they sink. So it takes less effort for a shark to swim in the colder denser water below the thermocline than above. Sharks constantly expend energy to maintain their depth in the water column. So it's just less work to swim below the thermocline. So put it all together and what do you get. Sharks cruise along in the top layer of the cold water looking their food source up in the warm water: because; it takes less effort than swimming in the warm water above. When they see somthing up there worth the effort they charge up and nail it. They like big baits downrigged to the thermocline because it takes less effort to chase something down thats right next to you, than to charge 100 feet up to the surface to get a meal. Like I said I don't have any scientific studies to back this up but it just makes common sense. I can tell you this: 90% of the big sharks we've caught trolling have hit baits down rigged on the thermocline. So thats my theory , unproved by scientific method. Let's just call it a hypothosys ( an eduacated guess).

Tight lines Jim

P.s. of coarse this only describes one possible situation, I'm not suggesting this is always the case.

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Subject	Author	Date
Re: Mako's and The Thermocline	ED	924118332PDT