Full Moon and Bite Activity

[Benni3]

Everything has a factor,,,, but food supply and when they are hungry,,,, that's the best place to be,,,,,,

As usual, you hit the nail on the head, Bennie.  You must go fishing a lot. 

If you only get to eat what you can catch with your mouth, you better hang out with the food.  And unless you are absolutely too plugged to eat any more, don't turn down a meal.

This is the key to the whole full moon and feeding thing, and why the "tuna are harder to catch during a full moon because they feed all night" is not a very strong theory.

But there are  feeding patterns that correspond  to moon phases  for some species, just not for the reasons that we read in the fishing magazines.  And  the actual moon  phase  and  change in feeding varies by specie.

I will try to write this next part up soon for the final installment.

-J

One factor I came up with is oxygen,,,, I see trout coming up to get air for there blatter I,,,,,? and marlo said no Benny they need oxygen in the water that's where they go not a food source,,,,,,,

[DougK]

I thought that at least common carp feed all day and usually all night, but feed more when the water temps were just right, so more active early/late feeding occurs in some locales in the summer, but not maybe not in other seasons. Probably depends on the water temp variations  where the food is at.

this is correct.. carp are mostly feeding by senses other than sight, so light conditions aren't that important. Clear water and bright light of course will send them into the deeps like any other fish, and may produce more nocturnal feeding.
Last week I was trying to flyfish for some carp, could see the mud plumes from their feeding but not the fish. What surprised me was several groups of pelicans hanging out around the carp, but not feeding on the carp, nor did the carp seem at all perturbed by the nearby predators.

[jurelometer]

I thought that at least common carp feed all day and usually all night, but feed more when the water temps were just right, so more active early/late feeding occurs in some locales in the summer, but not maybe not in other seasons. Probably depends on the water temp variations  where the food is at.

this is correct.. carp are mostly feeding by senses other than sight, so light conditions aren't that important. Clear water and bright light of course will send them into the deeps like any other fish, and may produce more nocturnal feeding.
Last week I was trying to flyfish for some carp, could see the mud plumes from their feeding but not the fish. What surprised me was several groups of pelicans hanging out around the carp, but not feeding on the carp, nor did the carp seem at all perturbed by the nearby predators.

Ooh, interesting.


Only caught one carp on a fly rod.  The guy I was with said that they don't take flies easily, so of course the first carp  that I cast to ran down that critter fly like  a starving bonefish .  I read somewhere that carp will focus on either  a grazing vegetarian mode or more actively hunting invertebrates,  so it might pay to watch how a particular group  is feeding.

Do  you think the mudding is from grazing, or hunting mode?  I know that in saltwater, there are often gamefish trailing rays around, looking to snatch any stray critters that the ray rooted up.  Maybe the muds are from  rooting for invertebrates, and the pelicans were hanging around for a similar reason. Dunno.

If moon phase affects shallow freshwater invertebrate behavior, that might be of interest to fly fishers targeting carp. Maybe not so much for the bait guys.

-J

[Gfish]

Everything has a factor,,,, but food supply and when they are hungry,,,, that's the best place to be,,,,,,

As usual, you hit the nail on the head, Bennie.  You must go fishing a lot. 

If you only get to eat what you can catch with your mouth, you better hang out with the food.  And unless you are absolutely too plugged to eat any more, don't turn down a meal.

This is the key to the whole full moon and feeding thing, and why the "tuna are harder to catch during a full moon because they feed all night" is not a very strong theory.

But there are  feeding patterns that correspond  to moon phases  for some species, just not for the reasons that we read in the fishing magazines.  And  the actual moon  phase  and  change in feeding varies by specie.

I will try to write this next part up soon for the final installment.

-J

One factor I came up with is oxygen,,,, I see trout coming up to get air for there blatter I,,,,,? and marlo said no Benny they need oxygen in the water that's where they go not a food source,,,,,,,

True dat. When the dissolved oxygen decreases towards a lower threshold for a species(I ?think? about 5ppm for trout), they head for where the O2 is. Maybe a plunge-pool ina river? Deeper colder water in a lake?... the surface to gulp air when it get's really bad?

[jurelometer]

Full moon, full moon!   Hopefully we can mostly stay on topic.

If we divert on every environmental factor that might affect the bite, the discussion will get too unwieldy.

[Gfish]

Alright, alright, Dave. I got practically nothin for this'n. But it is real interesting. My experience with no real empirical data, is trolling the reef in the dark with the full-moon in the west and it "seems" not as good'a fishin.

[Benni3]

Full moon, full moon!   Hopefully we can mostly stay on topic.

If we divert on every environmental factor that might affect the bite, the discussion will get too unwieldy.

Ok let's stay on topic,,,,, full moon is a thing but some other things has factors on it,,,,, oxygen,,,food source,,,water temperature,,,lighting storms,,,,biosphere,,,cloud cover,,,polushion,,,,,predators,,,what fly to use on the hatch,,,,,, where to fish when to fish,,,,, moonshine is good and one day we can figure it out add all the factors then in maybe we got a better grasp on it,,,,,,,

[philaroman]

Full moon, full moon!  Hopefully we can mostly stay on topic.

If we divert on every environmental factor that might affect the bite, the discussion will get too unwieldy.

I don't chuck moons anymore...  neither full, nor partial
when I did, I wasn't looking for a bite 

[jurelometer]

Part 3. Vertical Migration vs. Thermoregulation

In the end, yes, the moon phase (independent of tides) affects the bite on the ocean, but not as strongly as key environmental factors such as temperature, current strength, visibility, and salinity (Boon's point).  And  not all species, and not at the same phase.  So if you are worried about the full moon affecting your fishing... meh.

I am covering the open ocean here, but there is probably some useful stuff to glean for inshore salt and freshwater environments.

First of all, lets talk about plankton and vertical migration.

There are two general categories of plankton.  Phytoplankton- the plant stuff – relies on photosynthesis- so it lives near the surface where sunlight penetrates well.  Zooplankton- the critter stuff- often feeds on the phytoplankton.  Baitfish (this is shorthand, also includes important prey like  squid and argonauts) diet often consists of zooplankton, and those little buggers are not very fast or agile, so they are pretty easy to run down in the daylight - being in deeper (and therefor darker) water makes it harder to be seen.  So the zooplankton slowly (remember that they are not very speedy) migrate daily up and down through the water column between the surface (night)  and down 300 feet or more (day). [Update:  the complete story is a bit more complicated: This migration works more like a complex nutrient conveyor belt that extends several thousand feet, with the participating species having different ranges of daily migrations]. 

When the moon is full, the zooplankton, and therefore the baitfish don't migrate quite as high in the water column.  Presumably this is due to the extra light from a full moon.  In the arctic winter where there is next to no sunlight, this vertical migration still happens, but reversed from sunlight driven to moonlight driven- the zooplankton migrate downward as the moon rises.

Now let's talk about thermoregulation.

  Most fish species are ectotherms (cold blooded) with their internal temperature matching the surrounding water.  There is an ideal temperature for a specie, where its internal bodily functions perform optimally (warmer is better within limits), but water temperature drops with depth.  So when a baitfish is cold, it is not seeing as well, or capable of moving as fast, but ectotherms are very efficient in terms of not burning off calories to warm themselves.

An adaption that has evolved independently in some predatory fish species (billfish, tunas, opahs, some sharks) uses heat energy from muscle contraction to warm the blood in some areas of the body, making them endotherms (warm blooded), at least for parts of the body.  This burns off a lot of calories, but gives them an advantage over prey in colder water. How predators thermoregulate determines how and when they can take advantage of the vertical baitfish migration.

Tuna are the most extreme endotherms, and the larger the individual, the more extreme the thermoregulation.  So the tuna have a greater speed advantage over prey at depth, and have no problem following the baitfish on the vertical migration.  During a full moon, the tuna are feeding all day where the bait is hanging out, which might be a bit deeper than normal. This is especially true of bluefin and bigeye tunas.  But the tuna are not out of reach for the sportfishers, just possibly shifted a little lower than normal.

Marlin just warm the region around the eyes and brain, improving their already strong low light vision.  This saves some calories compared to tuna. Marlin spend most of their time near the surface, diving to as deep as around 250 ft to feed, and then back to the surface to warm up.  There is some sportfishing catch/effort data that shows better success in the full moon (but not always), and it is attributed to marlin being more hungry/willing to bite in the full moon when the prey is deeper.  But the sportfishing studies data set is not really complete enough to inspire my confidence.

Now at the other extreme, mahi mahi are ectotherms (cold blooded). They also thermoregulate, but have to do it behaviorally.  They like to stick to a narrow temperature band, usually staying near the surface with a bit of deep diving, but not as often or as deep as the marlin.  Mahi have excellent day vision, but not as good night vision as marlin, so they feed more during the day.  But mahi can't really follow the vertical migration.  Maybe this is why they are such enthusiastic daytime feeders once we find them.  There is some pretty good evidence that mahi  will spend more time at relatively greater depth at night if the water temps are warm enough, so it may be that they are taking advantage of the peak  of the vertical migration that they are able to reach.  It could also be to avoid billfish predation, or some combination of the two..

I will post one more followup with links to some of the scientific papers that are available without subscription.  They are worth taking a look at, especially the one on smart-tagged mahi (dolphinfish) behavior.

Hope you folk found this useful. 

-J

[DougK]

Only caught one carp on a fly rod.  The guy I was with said that they don't take flies easily, so of course the first carp  that I cast to ran down that critter fly like  a starving bonefish .  I read somewhere that carp will focus on either  a grazing vegetarian mode or more actively hunting invertebrates,  so it might pay to watch how a particular group  is feeding.

Do  you think the mudding is from grazing, or hunting mode?  I know that in saltwater, there are often gamefish trailing rays around, looking to snatch any stray critters that the ray rooted up. 

about one day in a hundred fly fishing for them, I find carp actively hunting.. typically it's a crawfish bite, though I have heard of them taking young shad in the shallows, never seen it.

mudding is definitely browsing/grazing. A couple of times I've caught smallmouth bass while trying to present a fly to the mudding carp, suspect the bass might be following them around..

fascinating detail in your post on the temp regulation evolutions in saltwater, thank you. I knew about the warm-blooded tuna, not the marlin and mahi-mahi..

[jurelometer]

Many of the references are behind paywalls, but these are useful and free:
——-
Remote Predictions of Mahi-Mahi (Coryphaena hippurus) Spawning in the Open Ocean Using Summarized Accelerometry Data.

Don't let the title fool you.  Lots of good data about mahi movement and water temps.

https://www.frontiersin.org/articles/10.3389/fmars.2021.626082/full
——-
Lunar landings—Relationship between lunar phase and catch rates for an Australian gamefish-tournament fishery

Almost 400 tournament-days worth of catch/effort data by moon phase.  Way too many variables at play to take the results as gospel, but still very interesting.

https://moscow.sci-
hub.se/1657/03b96a4ffc6b350f8e83222b530eb66c/lowry2007.pdf
——-
 
Moonlight Drives Ocean-Scale Mass Vertical Migration of Zooplankton during the Arctic Winter

Stuff on vertical migration of Zooplankton and how it changes in the arctic winter
https://www.cell.com/current-biology/fulltext/S0960-9822(15)01432-3

[Benni3]

Ok but when and where to fish that's the question we all have,,,,,,

[jurelometer]

Ok but when and where to fish that's the question we all have,,,,,,

That's easy. Go whenever you can, wherever you can.  But you already knew this

-J

[Midway Tommy]

Ok but when and where to fish that's the question we all have,,,,,,

That's easy. Go whenever you can, wherever you can.  But you already knew this

-J

So true! I've never caught much, other than boredom, sittin' on the couch watchin' TV.      

[Brewcrafter]

Benni has the street cred of not just once, but a few times tuning in for the Saturday Zoom and then catching a fish on air.  And I want to say there was also a bunch of young ladies on the bike path cheering for him? - john