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Blackfising off Docks/Inlets

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hoakge12000

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3 hours ago, fish643 said:

My experience is that they start moving off the Sod Banks when surface water temp is around 57*. I have caught them around seawalls and bridges with surface water temp down near 50*. Lower than that I cant find them and believe they have moved out. Never checked what the Marine Biology experts say, but that's what I have experienced in the Back Bays and Inlets. Hope it's helpful.

In areas like the sod banks that I'm familiar with, there's lots of current and the water is turning over frequently. Is that consistent with your sod bank spots? Lots of current, lots of water changing each tide, this homogenizes the water greatly...the bottom temperature in these situations is generally not too far from the surface temp. As these spots get deeper, I believe there's more separation between the dense, colder water...and lighter, warmer water.  But the 50F mark certainly seems like a reasonable surface temp for blackfish to vacate an inshore area - the bottom temps have to be in the 40s at that point...and they stop feeding in the very low 40's on the bottom.

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1 hour ago, TimS said:

In areas like the sod banks that I'm familiar with, there's lots of current and the water is turning over frequently. Is that consistent with your sod bank spots? Lots of current, lots of water changing each tide, this homogenizes the water greatly...the bottom temperature in these situations is generally not too far from the surface temp. As these spots get deeper, I believe there's more separation between the dense, colder water...and lighter, warmer water.  But the 50F mark certainly seems like a reasonable surface temp for blackfish to vacate an inshore area - the bottom temps have to be in the 40s at that point...and they stop feeding in the very low 40's on the bottom.

Tim, my favorite sod bank is literally just inside the Inlet. I suspect that up to this point the surface and bottom temps are within a degree or two of each other. This year I have had no wild swings in surface temps and have similar readings on both the Incoming and Outgoing tides. Proximity to the inlet and almost 30' of water heightens the erosion and helps minimize temperature swings. Been fishing the same area for almost 50 years but I pay a lot of attention to water temp and changing conditions - especially with Tog. The patterns of the movement of the Tog that I described, as it relates to changing water temps, is only from my experience. I think the only place our experiences may differ is the low end of their temperature range in the Back Bay. I have found that they migrate in mass over a very short period of time, and I have yet to catch one in the back with water temp below 50*.

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3 hours ago, fish643 said:

The patterns of the movement of the Tog that I described, as it relates to changing water temps, is only from my experience. I think the only place our experiences may differ is the low end of their temperature range in the Back Bay. I have found that they migrate in mass over a very short period of time, and I have yet to catch one in the back with water temp below 50*.

:th: Personal experience is, without question, the most reliable information source available to any of us :)  I've seen a whole lotta stuff fishing all these years...my personal experience is where I draw from entirely. Too many people these days are "internet smart"...they only know what they've read, they haven't experienced anything yet :o

 

Your experience in the back bay makes sense to me...I don't have much experience in the big bays, mine is in a small estuary that turns over about 60-75% of it's water every tide cycle. That makes it kind of unique...shallow and dark bottomed, it warms up quickly in the sunshine...but incoming tide replaces the majority of the water with ocean water. The places in that estuary where I blackfish are very close to the same as the ocean water temps during the incoming tide...and can be 4 or 5 degrees warmer on a sunny afternoon outgoing. By the time the water gets anywhere near 50 on the surface, I'm fishing for blackfish a few miles off shore...I have no idea if they are still in my estuary or not. This year I'm gonna try to keep track of when they leave my river - last week week we had half a dozen in the 4-5# class in an hour...in the river :b: I'm gonna see if I can check on them tomorrow afternoon and see if they are still around :)

 

 

TimS

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16 hours ago, TimS said:

It kinda does...you can't establish their optimum temperature range by catching one - all you can tell from that is that they can tolerate whatever temperature it was on the bottom...where you caught that fish. That might have been the only one. It might have been one second from leaving...it might have been amazingly tolerant to warmer/colder water. If you caught 40 fish you could at least establish that more than one fish was tolerating that bottom temp.

 

The relationship between ocean height (I'm guessing you mean depth) and water temp at the given depth is somewhere between exponential...and inverse? I'm trying my absolute best to understand what this means. So if it's 80ft deep, the inverse would be 1/80th - so in 80 feet of water the temperature is 1/80th of what it is on the surface? "Exponential" - assuming the exponent is larger than zero - we can start with 1 - this means in 80ft of water the temperature on the bottom is 80(1) = or 80? I'm struggling to understand what you are saying...how did you arrive at the bottom temp in 65ft of water being 58F degrees when the surface is 70F - and the bottom temp in 30ft of water being 62F when the surface is 65F. I'm not doubting your math...I'm trying to understand what math we are talking about. I'm all for learning new stuff...I'd love to be able to figure out the bottom temp based on the surface temp and water depth - enlighten me :)

 

TimS

In your example of 80ft water using inverse relationship, its not 1/80th. It's k/80th and even then it's k/80th + surfacetemp/80.

Inverse relation is easy to calculate on the go [h*t=k+i] (there are more missing variables that i dont know of) . Continuous exponential depression [t=i*e^(-k*h)] is more accurate as i would like to think, but heck do i know i haven't been 100ft under. h= height below surface, t=temp (any unit [C,F, or Kelvin] as long k is derived from that unit) at a given h, k = derived constant from two data points, i = surface temperature.

Need two data points. At h = 0, t = 70 and at h = 3, t = ~69. Of course you can take a thermometer and send it down via a string and measure the length of the submerged string, but it doesn't really matter as the first say 5 ft of water under the surface are influenced by many factors that are not hindering temps at say 100ft deep. In summer months, and in the fall, from experience, and from dipping my hand in the water, i can say that there is maybe 1 or 2 degrees at most of temp difference between the tip of my finger and the surface. Why is this the case? That's up for another topic, but i'm pretty sure its not that drastic of a degree difference.

 

Anyway, say we use exponential relationship. We have two points (0,70) and (3,69).

1. Plug In: 

70=70*e^-k*0  --->  70 = 70 good job, we didnt derive k yet, so this is useless.

69=70*e^-k*3  --->   69/70 = e^-k/3  --->  -ln ( 69/70 ) /3 = k = 0.00479624581 (google calculator)

Now we have the following:

t=70*e^(-0.00479624581*h)
so at 70 ft below surface, temp would be:

t=70*e^(-0.00479624581 * 70) = 50.0367650061 F

 

You might be skeptical so, say you measure out 69.5F at 3ft below surface:

-ln ( 69.5/70 ) /3 = k = 0.00479624581 (google calculator)

t=70*e^(-0.00238949649 * 70) = 59.2182924204 F

If you have a thermometer that can be sent down just underneath the boat, then you can stick to one, but if you dont know and are guessing like i am, putting hard limits of 0.5 degree difference of 3ft (very realistic), then that pattern would yield in such temps.

 

Using 67F@Surface and 0.5F drop@3ft below surface to predict temp@30ft under.

-ln ( 66.5/67 ) /3 = k = 0.00249689057 (google calculator)

t=67*e^(-0.00249689057 * 30) = 62.1646122089 F

You can do inverse in same fashion, but I like exponential better :) It also helps to have a thermometer or some heat measuring tool at hand. If I was desperate I'd probably lower my transducer via its cable, but not going to happen for my concerns.
 

Edited by hoakge12000
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I hate to be overly critical...but you know you can't calculate things properly when you are uses guesses in place of the measurements, right?

 

It's also pretty likely that the transducer on your kayak is likely further below the surface than your fingertips...and it's pretty unlikely that you can tell a 1/2 a degree temperature change at your fingertips by shoving your hand underwater. 

 

Lastly, estimating bottom temps based on surface temp and depth requires an area with current or wind driven turn over. The reality is, the only way you can have any idea what the temp is on the bottom on either shore of Long Island is by dropping a thermometer to the bottom. They are cheap, but one...attach it to a string...lower it down :)

 

TimS

 

Show someone how to catch striped bass and they'll be ready to fish anywhere.
Show someone where to go striped bass fishing and you'll have a desperate report chaser with loose lips.

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1 hour ago, TimS said:

I hate to be overly critical...but you know you can't calculate things properly when you are uses guesses in place of the measurements, right?

 

It's also pretty likely that the transducer on your kayak is likely further below the surface than your fingertips...and it's pretty unlikely that you can tell a 1/2 a degree temperature change at your fingertips by shoving your hand underwater. 

 

Lastly, estimating bottom temps based on surface temp and depth requires an area with current or wind driven turn over. The reality is, the only way you can have any idea what the temp is on the bottom on either shore of Long Island is by dropping a thermometer to the bottom. They are cheap, but one...attach it to a string...lower it down :)

 

TimS

 

Yeah its only a very rough estimate, there's no way to know without having a thermometer at hand.

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21 hours ago, hoakge12000 said:

In your example of 80ft water using inverse relationship, its not 1/80th. It's k/80th and even then it's k/80th + surfacetemp/80.

Inverse relation is easy to calculate on the go [h*t=k+i] (there are more missing variables that i dont know of) . Continuous exponential depression [t=i*e^(-k*h)] is more accurate as i would like to think, but heck do i know i haven't been 100ft under. h= height below surface, t=temp (any unit [C,F, or Kelvin] as long k is derived from that unit) at a given h, k = derived constant from two data points, i = surface temperature.

Need two data points. At h = 0, t = 70 and at h = 3, t = ~69. Of course you can take a thermometer and send it down via a string and measure the length of the submerged string, but it doesn't really matter as the first say 5 ft of water under the surface are influenced by many factors that are not hindering temps at say 100ft deep. In summer months, and in the fall, from experience, and from dipping my hand in the water, i can say that there is maybe 1 or 2 degrees at most of temp difference between the tip of my finger and the surface. Why is this the case? That's up for another topic, but i'm pretty sure its not that drastic of a degree difference.

 

Anyway, say we use exponential relationship. We have two points (0,70) and (3,69).

1. Plug In: 

70=70*e^-k*0  --->  70 = 70 good job, we didnt derive k yet, so this is useless.

69=70*e^-k*3  --->   69/70 = e^-k/3  --->  -ln ( 69/70 ) /3 = k = 0.00479624581 (google calculator)

Now we have the following:

t=70*e^(-0.00479624581*h)
so at 70 ft below surface, temp would be:

t=70*e^(-0.00479624581 * 70) = 50.0367650061 F

 

You might be skeptical so, say you measure out 69.5F at 3ft below surface:

-ln ( 69.5/70 ) /3 = k = 0.00479624581 (google calculator)

t=70*e^(-0.00238949649 * 70) = 59.2182924204 F

If you have a thermometer that can be sent down just underneath the boat, then you can stick to one, but if you dont know and are guessing like i am, putting hard limits of 0.5 degree difference of 3ft (very realistic), then that pattern would yield in such temps.

 

Using 67F@Surface and 0.5F drop@3ft below surface to predict temp@30ft under.

-ln ( 66.5/67 ) /3 = k = 0.00249689057 (google calculator)

t=67*e^(-0.00249689057 * 30) = 62.1646122089 F

You can do inverse in same fashion, but I like exponential better :) It also helps to have a thermometer or some heat measuring tool at hand. If I was desperate I'd probably lower my transducer via its cable, but not going to happen for my concerns.
 

LOL! I can't stop laughing. Thank you guys!

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Remembering a spring several years ago and the fluke bite was very poor in the intercoastal waters. I noticed my fishfinder actually showed what I believe was a thermocline which to me explained the poor fishing. My understanding is that the two different temperatures also change the characteristics of the water as to speed and in some cases even the direction during the weakest part of the tide. This effect I read is amplified offshore, remembering feeling a cold sinker just retrieved from the depths while the surface temperature was comfortable. A well respected charter captain and scuba diver and author of many articles wrote an article about reef fishing where the surface water was clear but the bottom visibly was very poor from recent swells. A really involved puzzle when you try to figure it out, give the water temp on your fishfinder very little credence in my opinion.

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1 hour ago, squidder 329 said:

Remembering a spring several years ago and the fluke bite was very poor in the intercoastal waters. I noticed my fishfinder actually showed what I believe was a thermocline which to me explained the poor fishing. My understanding is that the two different temperatures also change the characteristics of the water as to speed and in some cases even the direction during the weakest part of the tide. This effect I read is amplified offshore, remembering feeling a cold sinker just retrieved from the depths while the surface temperature was comfortable. A well respected charter captain and scuba diver and author of many articles wrote an article about reef fishing where the surface water was clear but the bottom visibly was very poor from recent swells. A really involved puzzle when you try to figure it out, give the water temp on your fishfinder very little credence in my opinion.

On the topic of 'Back Bays', IMO the phenomena described above is true in the very early Spring and late Fall.

In the Summer and the six or so weeks either side of it, I believe the shallow water ( < 30' ) negates any appreciable difference between top and bottom water temp. Where I am, from Mid May to the end of October, Wind has a more significant impact but it is throughout the water column. For example, I have seen a South wind cool water by as much as 10* in 72 hours. 

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3 mins ago, fish643 said:

On the topic of 'Back Bays', IMO the phenomena described above is true in the very early Spring and late Fall.

I will add that In the Summer and the six or so weeks either side of it, I believe the shallow water ( < 30' ) negates any appreciable difference between top and bottom water temp. Where I am, from Mid May to the end of October, Wind has a more significant impact but it is throughout the water column. For example, I have seen a South wind cool water by as much as 10* in 72 hours. 

 

Edited by fish643
Trying to delete duplicate post
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