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David Ross, PhD (Woods Hole Oceanographic Institute, WHOI), Effect of barometric pressure on fish.

Radio show from 04/09/18, Ben Ball Host, WTKF 107.1 FM, 1240 AM.


Dr. Bogus: I have from time to time talked about what I call my library club, my book club, and one of my favorite books on the shelf is called the Fisherman’s Ocean, subtitled How Marine Science can help you find and catch more fish. That sounds like something I’d be interested in…right? So we have David Ross who is Emeritus Professor at Woods Hole Oceanographic Institute, Good Morning David.

David Ross: Good morning how are you? We’re doing great this morning, what’s the weather like on Cape Cod? It’s still pretty cool out here, but the snow is gone, and it’s starting to warm up so I’m getting optimistic. Hearing your fishing report kind of gets me even more itchy. Could be worse, could be better.

Dr. Bogus: This has been a trying winter and spring and one of the reasons why your book has been one that I have used a lot and is on my bookshelf, we’re both scientists and I’ve always had the thought, and this is what I do on the radio show, “know thy fish…catch more fish” is my approach to fishing coming from the background that we have both come from. What is your background Dave?

David Ross: I’m actually an oceanographer and most of my research has been in the Middle East, but I took some early retirement that’s why I’m emeritus, still working at the institution. And decided to use my marine science knowledge and combine it with my fishing interest, I’m a fisherman, I catch fish, I eat fish, I catch them on fly rods, on catch them on spin I catch them trolling. So I started writing a bunch of articles about science and fishing. I started writing for a magazine called Saltwater Fly Fishing. I wrote about 60 articles and it turns out at that time I was the only guy doing that, and there really isn’t that much science on fishing, on the kind of fishing you and I like to do. Then I combined it into this book, which is in its eight printing, to my amazement. I still write things and more recently I wrote an article, which I think caught your attention about barometric pressure is it important for fishing or not. So I still give talks and fish a lot, I live on the water. I have a boat that came from Morehead City; I have a Jones Brother’s boat that I use. I fact I visited MHC in 1965 coming up on a cruise, a research cruise and ended up judging the Miss Bluefin Marlin Festival…which itself is a story which we don’t have enough time probably to cover, but it was kind of an amazing experience.

Ben Ball:  It’s the Big Rock Blue Marlin Tournament now!

David Ross: If they need another judge just let me know.

Dr. Bogus: We have David Ross from WHOI on Cape Cod; we’re talking about environmental factors that influence fish. We’re going to get to barometric pressure momentarily, but what are some of the other environmental factors that when the fish are who they are? Of course one of my favorites is water temperature, decided who and when but are some of the other ones that really decide that?

David Ross: Up here on the Cape, water temperature certainly is important, but probably tides and tidal currents are the most important thing up here. Fish are opportunistic as you know and magnificent creatures, I’m a big fan fish. I think they are wonderfully evolved, that have things that they can do much better than humans. Their sense of smell for example is about 1,000 times better than the dog and the dog is about 1,000 times better than a human so fish can smell about a million times better than us. But tide is very important, temperature is important, presence of bait, time of day can actually be important, turbulence as it may affect oxygen content in the water. I see fish as being very opportunistic creatures and if there is food, of if there is the right structure which can trap or trap bait, they are going to take advantage of it. Fish have been around for about 450 million years or so, we have found fish that old, and they have evolved to the environment superbly. The only problem is that they haven’t learned anything about electronic devices or nets, so in that respect it’s our advantage. On the Cape, we get pretty much have similar fish that you do but not all the same, stripers, bluefish, false albacore, bonito, offshore tuna. Bottom fish like tautogs, black sea bass…by the way, climate change is affecting us up here.

Dr. Bogus: How are you noticing that?

David Ross: Well several ways, we see fish species coming a little bit earlier, we see black sea bass is a wonderful example of this. Black sea bass really wasn’t an important fishery until a few years ago, it was more of a middle-Atlantic fishery, now because of the warmer temperatures the black sea bass have moved up here and it’s a big cash fishery up here last couple of years and beautiful fish and a lot of them. We see lobsters who like cool water moving farther north, so their range is changing. A lot of fish of course can tolerate a decent range of temperatures, but there are temperatures that they prefer. But the sea bass and their presence is certainly a good example of how changing temperatures is affected the fisheries here.

Dr. Bogus: One of the claims that you always hear from fishermen is that…boy you know that there is a storm coming, the fish know it and I’m going to have a great day as that front, hurricane or Nor’easter or something comes up the coast. And that’s the claims Dave, but what is the reality? How can you determine, decide whether what side of that log you’re on? Does barometric pressure really influence fish or doesn’t it? We know that they have their air bladders…sooooo

David Ross: A hundred questions, first of all fish cannot predict the future. Humans cannot predict the future, so let’s not give fish too much credit, they can’t do that. When we talk about barometric pressure we’re talking about the marine environment, and I’m not talking about fish that live in the top one or two feet of water. Let me make a strong statement, barometric pressure has NO effect on marine fish, no effect. And let me explain why. The barometric pressure is the result of the 160 miles or so of atmosphere bearing down on the land and ocean, and we call that one-atmosphere right about sea level. But because water weighs so much more, and is so much denser than the atmosphere, you only have to go down 32.8 feet in the ocean to have another atmosphere of pressure. In other words, 32.8-feet of water equals the entire pressure of the atmosphere. So what if for example a fish is swimming along nicely and a 3-foot wave not a big wave, comes along every 3 or 4 or 6-seconds, that change in pressure that that fish is experiencing is equivalent to the change in pressure for a hurricane like Katrina, which took 2-days. So in the space of 6-seconds our fish is experiencing a change in pressure equal to Katrina…every 6-seconds. Suppose the fish goes ups and downs, to take a lure goes up 3-feet same thing! A tide goes 3-feet, same thing. Basically it’s like this, you and I are talking, but as we’re talking, there’s also some lady talking in Miami, do you hear her?

Dr. Bogus: Not yet!

David Ross: That’s the point. Now barometric pressure when it changes and it changes very slowly, brings other things, changes in cloud cover, maybe wind direction, maybe changes in temperature, maybe changes in turbulence…what have you. Now those things might influence fishing. And coming back to fish and their bladders, fish can tolerate an awful lot of things, like human beings. When you swim in the water you can dive down quite a bit, fish are even better at this, so a change in barometric pressure and neat as it sounds, is really some change in the weather pattern that’s happening and some fishermen think that this is great and they’re going to catch more fish. And I’m of the opinion that is you really think you are going to catch fish, and you go out there and you are intense about it you are usually going to do better than if you go out and just be casual about it.

Ben Ball: That’s Dr. Bogus’ feeling too!

Dr. Bogus: Absolutely!

David Ross: You try harder, you change your lures if nothing is working, you move around, you’re more enthusiastic and usually you do better. But barometric pressure I’m sorry to say, the physics just aren’t there, just doesn’t make a bloody difference to the fish.

Dr. Bogus: I‘ve been trying to convince people that for years and you always get a lot of blow-back on that because people have their experiences that they say…“look well see this, I did great that day”.

David Ross: Ask them what color underwear they had, that may have just as much an effect. 

Dr. Bogus: David, one of the things you mentioned in your article that I read, is a term I use a lot, “east is least and west is best,” why don’t you tell us why.

David Ross: Well, I wish I completely knew. I my case it’s the wind direction and where it comes from and I think that’s always important when you’re fishing and you have a tide or moving current, where the water comes from. And if the water comes from the east it’s really not going to have much bait in it and it’s not going to be as attractive as water that is coming from the west. We also have a lot of protective areas, a lee area so a west breeze, the water coming from the west is preferable. But fish got to be somewhere, they are not going away, so you can still catch fish when the wind is bad, you just got to know where to go and you got to do it a little differently. Like I say, fish are great creatures, they don’t stop eating because the wind isn’t blowing in the right direction and if they see something that’s good to eat they’re going to take it. You just have to be there and take advantage of different conditions. But you’re right, and we have another expression up here, “it’s no use if it’s not chartreuse”.

Dr. Bogus: Absolutely.

David Ross: And that to me is an amazing one, because as an oceanographer I can tell you that there is nothing, nothing natural in the ocean that’s chartreuse, nothing!

Ben Ball:  I know, isn’t that interesting.

David Ross: There’s a reason, chartreuse is a color that is seen further away than most other colors, so it’s visible, so that’s why if everything else is equal, somebody has chartreuse it’s more visible for a fish than most other colors.

Dr. Bogus: Most fish are sight feeders so that really makes a big difference.

David Ross: Well, I might not 100% in agreement with that, they are sight feeders at the last moment.

Dr. Bogus: Right.

David Ross: But often they are attracted by noise, and by smell. I remember some experiences fishing on some of our flats area where nothing was biting at all and a friend of mine pulled out the ugliest fly you’d ever seen, but it had a rattle in it, he threw it out and boy you can see the fish just change direction the first time that rattle and go attack that ugly, ugly fly. So different things, different times and whatever.

Ben Ball: You said your book is in its eighth printing.

David Ross: Yah, much to my amazement. If I may, I make pennies on the book, but I love to recommend the book, and I’ve written a lot of books on oceanography, so this is not my source of income. The book has in my opinion a really good section on tides and tides are one of the most complex things in the ocean, it’s really a complex phenomenon. So I think if you read this the average fisherman may might have a better feeling or understanding for tides and that in itself might be worth the price of the book.

Ben Ball: And here with our tides, again similar to you only we have a south facing beach.

Dr. Bogus: We have a south facing beach we have Bogue Sound and we have the ocean and a barrier island.

David Ross: I understand, I would be complicated. In fact if I was down fishing down there, which I haven’t done for a long time, I think the first thing I would do is get in touch with a charted guy or go to a fishing store just trying to learn about the tides.

Ben Ball: I imagine you get that question about barometric pressure all the time, just like Dr. Bogus does. But it’s the ancillary things that are happening around it.

David Ross: That’s really the case

Dr. Bogus: They are associated with a lot of changes that the fish can key in on.


Check out The Fisherman’s Ocean, How marine science can help you find and catch more fish. By David A Ross, PhD.


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