The Mysterious Mullet

Flyfishers have a notable desire to catch mullet.  A small number even succeed, but few seem to understand how they did it. Catching one mullet is okay, but catching two in a row seems just about impossible. There are few answers and even more questions. I don’t think there is anyone anywhere who has truly figured them out. It’s a species that may well be a mystery fish forever.

And do not be fooled by the many European anglers who will tell you they catch mullet all the time. The fish they are fishing for is a different species of mullet – the thick-lipped mullet. We do not have this species in New Zealand. Our grey mullet exists in European waters as well, but they hate it and declare it ‘uncatchable’.

The problem with our grey mullet (Mugil cephalus) is that they mostly feed on algae and detritus that is sucked off mud and sand. To do this they possess strange mouth parts and transparent coverings that protect their eyes when grubbing in the mud. Equally odd is an unusual gizzard stomach that sits just behind the gills. Here mud and sand is processed and separated from food items. Nutritional elements are removed and clean mud and sand is ejected back out though the gills. It’s an odd way of feeding that involves ingesting large quantities of mud and sand, but not a lot of chewing on any sort of bait that you might try and cast their way. 

They do eat some micro-plankton as well – mostly as juveniles, but also occasionally as adults. This is probably why they will occasionally take a very small fly. And yet they are the least predacious fish you will ever meet. They don’t run down and catch any sort of food item. Most of the time they won’t even notice your fly. What they really want to do is just eat mud, cruise around in circles, jump occasionally, push each other around, and eat more mud. They really are a totally crazy fish.

And you have to fish for these mud grubbers in shallow water, in an environment where they’ll hear every footstep, and flee every time you flick your fly in the water. Getting close to them without having them tear off to another ocean somewhere is a very big part of the battle. 
So the more mullet you find, the greater your chances of success will be.

Same species, but different
This is where the whole discussion takes an interesting turn. It appears there are different populations of grey mullet in different environments that do different things and focus their attention on slightly different food sources. 

Our river running mullet might be a separate population from our harbour mullet, which might be a separate population from our surf and open coast mullet.  

The genetic basis for these different mullet populations was uncovered in some recent overseas scientific work which identified numerous different ‘haplogroups’ of grey mullet. Each haplogroup was adapted to a different environment and a slightly different food source. Effectively there were different ‘tribes’ of Mugil cephalus in one geographical area. Only genetics could tell the different tribes part. 

This has had, and will have, profound implications for mullet fishery management now and in the future. Some haplogroups of mullet are obviously being overfished, while some are not.

An early fisheries scientist in New Zealand by the name of Sir James Hector ran across this reality many many years ago when asked to investigate the declining catch rates of mullet in northern New Zealand. Large mullet canning factories that had been set up in the 1800s had, in combination with massive deforestation and general environmental destruction, effectively wiped-out many harbour stocks of mullet in only a few short years. And yet, there were still plenty of mullet in the surf and on the open coast. Sir James was given the task of finding out why.

With genetic science still being one hundred years away, Sir James could only scratch his head at the mystery. A very interesting paper that details the work that Sir James did and the continuing problem of mullet management today is freely available on the internet. It is entitled The Kaipara mullet fishery: nineteenth century management issues revisited and was written by Chris D. Paulin and Larry J. Paul. It is a fascinating read.
Even back then Sir James was finding evidence of different populations of mullet, and the more he looked, the more mysterious the whole species became. Not a lot has changed today.

Our harbour waters still only carry a tiny fraction of the mullet stocks that existed in pre-European times. And because of the ease at which harbour mullet can be netted, they are still caught more commonly in this environment than they are in the surf or on the open coast. This may be severely denting the viability of all harbour swimming mullet. Where once there were vast numbers of mullet feeding over the harbour flats, today there are bugger all. One can only guess at the changes in coastal ecology that have happened as a result.  

This reality is reflected in the places I choose to go mullet fishing. Most of the local harbour flats now seem to be a dead loss. Instead, I have found some good mullet schools off clean ocean beaches and along protected areas of rocky shoreline where the rocks are festooned with oysters. Both are places that the netters rarely go.

In these locations, I stalk the mullet with a light fly rod and cast a tiny sparkly green fly on a floating line in amongst them. A medium speed retrieve follows – one that occurs with no slack in the line, the rod tip touching the water and no pauses being allowed in the retrieve. The trick is to stay as totally connected to your fly as possible. Mullet takes are feeble at best. There needs to be some resistance felt by the fish if it mouths the fly. A constant medium speed motion going forward is the best way to achieve this.

Having done this, you then proceed to find out that mullet will absolutely ignore the fly most of the time. There is no mullet body language that tells you whether or not they like your fly. All that happens is that very occasionally you will catch one, and you will be left with absolutely no understanding of why that cast was successful. 

The last mullet I caught was my biggest so far and was taken after only three or four casts. This was very unusual. It encouraged me to try a few more times. And then a few more. Eventually I became totally discouraged. I gave up mullet fishing completely. Again!

This is fairly much the true reality of life for any mullet fisherman. I think I have caught a total of five mullet over the years and maybe lost a couple more. Each mullet represents days of trying.
Every time I declare that I am never going to cast to mullet ever again, and every time I slowly get drawn back into the madness. Mullet are like that. Fascinating and maddening all at the same time.