Earthquakes effects on fishing?

Earthquake effects on trout fishing…?

Following the swarm of earthquakes through the central North Island on Tuesday TRM have been asked again about how this affects trout fishing?

A strong earthquake rattled central New Zealand on Tuesday afternoon.  The quake measured 6.2 in magnitude, according to geological monitoring service GeoNet.  Its epicentre was 25km south-west of the town of Taumarunui, on the central North Island, and it struck at a depth of 207km.

More than 9000 people reported feeling the quake within 10 minutes of it striking at 3.14pm.  All except me – I was enjoying a granny nap.

In New Zealand, there are dozens of minor earthquakes every day with 418 earthquakes registered by Geonet in the past week.

Many of the quakes were too small to be felt by anyone, but were still picked up Geonet.

Based on TRM inmates very unscientific results, the Tongariro River fishing was unusually erratic.

After a week of generally steady results with some delighted fishos after landing their limit of six (Hi Paddy – image on right) the pattern on Tuesday was harder and erratic.  The fish knew something was amiss.

i.e. One of our more reliable fishos, Bruce Hutchins from New Plymouth, reported landing four and losing one before the quake struck but he commented, for him it was hard work.  Then on the next day after the quake he landed five in the morning session, which indicated how quickly the trout recovered from any “quake stress”.

Bruce (image on right) also commented that any decent shake quickly becomes visually obvious from pumice flaking off the high cliffs which immediately colours up the rest of the river.  This would also affect the trout behaviour and the fishing.  For the fish, the flies would be much more difficult to identify aa they just stop feeding to wait until it clears.

Bruce was wading in the tail of Cicada Pool a couple of years ago when a huge flake peeled off the cliff and crashed into the pool.  He just avoided being swamped by the mini tsunami.

The images below illustrate the high unstable pumice cliffs up the Tongariro River that erode and crumble under the slightest hiccup.

 

The following was TRM’s report after a similar earthquake fright on May 29th 2017:

How earthquakes affect the trout fishing in Turangi?

Last week in particular the Tongariro trout fishing was described as either “hot” or “cold”.
Several regular TRM fishos could not understand it when they went home empty handed after such a long period of good catches by others.  This is serious stuff as the Tongariro has a world famous reputation to maintain.  So TRM need to come up with a simple believable explanation…
The Tongariro River often have days or periods when suddenly the hook-up pattern changes from everyone easily catching trout to suddenly no trout?  This is not unusual.  For no apparent reason suddenly for a few hours or a day or two all the trout seem to go off the bite.  Why?
We know they are resting there.  In some pools we can see them, but they refuse to even look at anything offered.  They just freeze up.  Why?
This is SWMBO’s explanation.  (She Who Must Be Obeyed is the manager who knows everything at TRM)  She has no doubt about the reason.
(But, if I may be so blunt, She may often be completely wrong, but never in doubt.) 
Of course other Tongariro anglers will have their own theories.  All are correct.  We have to believe them all.  Our guests are always right.  But you need to be warned this is all wild guess-work as, we remind you again, that nobody, not even SWMBO, have interviewed the trout yet.  But Her reason may be as plausible as any…
This volcanic region is subject to earthquake swarms that we cannot physically feel or detect but the trout are far more sensitive to tiny earth tremors.  The deep pumice sub-strata absorbs much of the shocks for humans to feel but these tremors are exaggerated in water.  Trout are far more sensitive.  The sense organs and lateral line on the trout picks up any earth tremors far more effectively so they spook and stop feeding.
Tiny earthquakes in this shaky region are a regular normal phenomena and not considered of much importance until they affect the fishing.  Then they have to be seriously considered.
So this is SWMBO’s proof to justify Her explanation:
Many wonder why the bridge pool (on right) is so successful.  On Friday and Saturday mornings there were about 9-10 anglers there each morning and trout continued to be caught most of the day just below the bridge.  (This is the closest most popular pool to TRM – just a couple of hundred metres waddling in waders…)
SWMBO applies the same loopy earthquake theory.  The trout on their spawning runs “hear” the vibrations from traffic crossing the bridge and will not continue under the bridge.  Slowly their numbers build up all day.  At night there is little traffic volume so the trout then swim under and continue their journey.  Seems a reasonable understandable explanation… as good as any.  OK?

About the Lateral Line

Trout have inner ears, which allow them to hear sounds as we do. They also have lateral lines, special sense organs used to “feel” sounds. Lateral lines allow trout to hear sounds that are too low for humans to hear. Every trout has two lateral lines, one on each side of its body. A lateral line is made of a series of U-shaped tubes. Every time the water outside the U vibrates because of a sound, a tiny hair at the base of the U wiggles, which sends a nerve signal to the brain. The trout’s brain translates the wiggle into information about where the vibration came from. Trout use lateral lines to find food, escape predators and keep away from obstacles.

Sometimes I suspect SWMBO has a lateral line too.

One scientific explanation is:

Recent animal sensory literature has been analyzed to evaluate the plausibility of reports of unusual animal behavior prior to earthquakes. Some species of fish possess remarkable sensitivity to pressure waves with frequencies below 50 Hz, which would enable them to sense earthquakes at least 1 to 3 Richter Magnitudes smaller than those detectable by human beings. Fish also have organs which can detect slight movements of water, although the available experimental data do not allow us to determine quantitatively whether they are sensing accelerations of water or variations in water displacement. Thus observations of unusual behavior of fish before earthquakes may be explained if the fish are responding to small foreshocks.

Most scientific explanations arrive after the event… I told you so…  I knew all along…  Yeah right.

Wikipedia explains:

Lateral line

From Wikipedia, the free encyclopedia

The lateral line is a system of sense organs found in aquatic vertebrates, used to detect movement, vibration, and pressure gradients in the surrounding water. The sensory ability is achieved via modified epithelial cells, known as hair cells, which respond to displacement caused by motion and transduce these signals into electrical impulses via excitatory synapses. Lateral lines serve an important role in schooling behavior, predation, and orientation. For example, fish can use their lateral line system to follow the vortices produced by fleeing prey. Lateral lines are usually visible as faint lines of pores running lengthwise down each side, from the vicinity of the gill covers to the base of the tail. In some species, the receptive organs of the lateral line have been modified to function as electroreceptors, which are organs used to detect electrical impulses, and as such, these systems remain closely linked. Most amphibian larvae and some fully aquatic adult amphibians possess mechanosensitive systems comparable to the lateral line.[1]

Function

The lateral line system allows the detection of movement, vibration, and pressure gradients in the water surrounding an animal, providing spatial awareness and the ability to navigate in the environment.

Therefore it is far more sensitive to any variances or vibrations and pressure gradients, etc.  So now you know…