Week 31. John Odenkirk: VDGIF Snakehead Expert
The word “snakehead” once stoked fears around on the Mid-Atlantic of some toothy invasive monster intent on devouring the local native fishery. The Washington Post even wrote an editorial warning that the snakehead “could harm the Potomac, by for example, competing with he river’s prized largemouth bass … and do worse damage elsewhere.”
Fifteen years after the Northern snakehead first arrived, it turns out largemouth populations are increasing and anglers are so hooked on snakehead that many are asking for limits to protect it!
John Odenkirk has been on the front lines of snakehead management since day one as district biologist for Virginia Department of Game and Inland Fisheries, and is one of the nation’s foremost expert on the species. He’s monitored and managed the snakehead population for 15 years, watching it peak in some places and expand in others.
Through the years, snakehead have won over some fans. The Asian native is now featured on the menu of some of Washington’s best restaurants, and anglers have realized they can be as fun to catch as some of the region’s other top sportfish like largemouth, smallmouth, and brown trout – which, by the way, are all also non-native.
John has years of observing their feeding, migrating, and reproduction habits. I caught up with John recently to learn more about the lifecycle of this species, how to catch them, and of course, his favorite snakehead recipe. Below are my questions in bold, followed by his answers.
What is your role at VDGIF?
I’m a district biologist at Game and Inland Fisheries and manage the waters of 12 counties stretching from as far south as Lake Anna, and from mountain headwaters to the tidewater. It’s me and another biologist and an assistant covering all 12 counties, so we have a lot of water to cover. We don’t get bored!
You cover ground zero of snakehead territory and known as a snakehead expert. What’s the ideal habitat for snakehead?
Snakehead love freshwater tidal systems and like aquatic vegetation, such as macrophytes or shore vegetation like arrowheads or cattails, and are almost always found in in very shallow water. The shallow water gives them the competitive advantage because it’s probably water that other fish don’t want to be in, but they’re air breathers and can thrive there. They prefer to be in vegetation and seem to require it for reproduction.
They try to stay away from the high velocity water and prefer very sluggish water. They like silty, muddy bottoms in very sedentary water. The only exception -- this is an annual thing -- is when a subset leaves during the pre-spawn and heads upstream. April is the big month when they start moving upstream.
They seem to know when to move, and when they disperse they go upstream. They’ll go upstream until they get to a barrier, and try to get around it. If they can’t get around it, they fall back. If there’s a flood event with rising waters, some may ride on the floodwaters downstream. But if they’re going to move pre-spawn, they usually go upstream.
They are a bad ass migrant!
Why they are moving upstream?
We don’t really know. Not sure if they are looking for mates, looking for food, or occupying new habitat if there’s too many in certain creek and they need to spread out.
But we do know they move upstream, and if you live in an area where you know they are present and have a barrier of some kinds like a dam or a fall line, you can see them stack up to get around it. On the Rapidan or Rappahannock -- or, the Occoquan is a great example below the dam. People come down at lunch time and hunt them with a bow and arrow by the dozen.
How to do you track the numbers?
Fifteen years of tagging, radio, sampling and observation, and talking to anglers.
Where’s the best place to find snakehead habitat in our region? Where are they thriving?
They continue to increase their range and are constantly colonizing new areas and spreading. Where they’ve been the longest, they seem to be declining. There seems to be a decline for example around Mt. Vernon where they’ve been for a long time. In Aquia Creek, which they colonized three years after Mt. Vernon, it’s a little further behind on the curve. They’ve peaked in those areas and are stable now if not declining.
The further down [south], we’re still on upper trajectory of curve, and in the newly colonized area, they’re building momentum and in certain spots have a higher density.
Assimilation seems to be based on two things. First, the areas they’ve been in longer and where they’ve assimilated, they reach an equilibrium in habitat. In general, when a new organism comes into a novel environment, it may increase rapidly but then typically falls back and stabilizes at a reduced level. That’s part of it.
The second is that in the established areas, the fishermen -- bow fishermen, commercial, and recreational -- cause more mortality. Without the exploitation, we don’t know if would decline. At $20/pound and getting served in restaurants, it’s in high demand. Some people are upset and want me to put limits on it!
What’s a yearly lifecycle for snakehead?
Starting in the dead of winter in February, the ice and cold temperatures has most of the fish hibernating. Most of them are buried in the mud, or in the mouth of a creek in 4-8 feet on a channel drop-off. They are effectively shut down and living on air in their swim bladder.
When it’s in the 50s for a fair amount of time, they’ll start emerging from the mud. They’ll head to the mud flats and soak up the heat. Not really feeding but getting warm.
The first thing they want to do is find cover -- they’re a very cover-oriented fish -- but there there’s no aquatic vegetation in March. So they look for natural wood or docks -- the same places that bass and crappie hang out.
On the spring tides when there’s higher water, they might head for emerging vegetation or cattail stubs and last year’s growth. On flood tides or a flood moon, they may be up in 2-3 inches of water in shoreline growth.
In mid-April, the spatterdocks (lily pads) start to emerge, and you’ll find them in the spatterdocks. They’ll hang in there until the submerged aquatic vegetation starts to come up. When it comes up, it’s hard to find them anywhere else.
They’ll be in the native plants like coon-tail or the non-native like hydrilla. They love hydrilla more than anything -- that’s their native habitat and where they are going to be during spawning.
When it gets close to 60, they’ll start feeding pretty well and once we’re in the pre-spawn, they’ll start moving.
The peak of spawning is early June. Spawning was late this year with the cold spring, and they just spawned [mid July] in Aquia Creek.
When they’re spawning, they don’t eat. They’ll strike if they feel a threat and it’s an aggressive strike, but it’s a quick hit and you can’t hook the fish that way. We know they usually don’t eat because we’ve killed a number and they had nothing in their stomach.
The bite is before the spawn and after the spawn. People complain about lock-jaw during spawning and they just don’t want to eat. I had two anglers call me this week that they had the best spring in years but they just can’t buy a bite now.
They actually do spawn twice each summer, and the peak is June and then again in mid-August -- at least that's our best guess now.
It tappers off in the fall, and they’re guarding their young fish until they get big. The grass is going to peak in early September, and they’ll be pretty well hidden in there.
What do snakehead feed on and is there a "peak" season?
Snakehead are extreme opportunists and will eat whatever is in their face when hungry. By numbers, they mostly eat killifish, and by weight, they mostly eat bluegills.
They operate like a flounder and lay and wait to ambush until something comes by, and then will have a vertical thrust. They’ll stay in a holding pattern and expend very little energy until something comes along.
One of the best times to fish for them is in May. The ones that are going to move have moved or come back, and they haven’t started spawning yet. The grass is not fully established yet too. There’s a lot of fish in May, and a lot post-spawn in July. But if I had to pick the best time, I’d pick May.
It seems that snakehead habitat is somewhat similar to largemouth. How are snakehead habits and behaviors different than largemouth?
Certain times you can find them right next to each other, but that’s a relatively short period of time in early to mid-spring. Once the bass are done spawning, they move to deeper water.
In later May, there is a habitat transition. The snakehead will stay in shallow water, maybe 1-2 feet, which heats up and has lower oxygen. Most bass are going to move into deeper water, in 3-6 feet of water with hardwoods.
So they don’t compete with each others?
They’re both piscivorous (both feed on fish), and there’s no question that at the same time of the year, they’re eating the same thing. In a farm-pond, bluegills eat the insects, and bass eat the bluegill. Snakehead rely on bluegill as their number one dietary source for weight, and so during a certain time of year, there is that dietary overlap. However, for competition to occur, there needs to be a limitation on forage, and we don't think that's happened. At least not at the densities of snakeheads we've seen.
In the system we monitor, it’s important to look at the relative abundance. We look at fish per hour in shocking, and during a standard survey, we observe maybe 50-100 bass/hour. We may see 8-10 snakehead at Mt. Vernon where they’ve been for a long time and have stabilized. So you add that level of predator to the Potomac, which is a very productive system, and that amount of predatory impact is meaningless.
If they were equal to bass it would be a problem. But the fact that it’s going down, makes me thing it’s much less of a concern.
Any favorite recipes?
It’s an Asian recipe compliments of a critic of Jeremy Wade.
You steam the fish filets in a steam pot. You sauté it with sesame oil and soy sauce, and cover it with chili powder and chopping scallions and shaved ginger. You serve it with white rice and sautéed spinach and garlic.
Any particularly memorable snakehead fishing experiences?
My first one was my most exciting one. It was 2005, and in 2004, only 20 were caught nationwide by all state and federal officials and all anglers. I was working in Dogue Creek, and decided to take a couple of casts along a hydrilla edge and hooked up with one. I was so excited, I was shaking. You would have thought I shot my first buck! I mounted it and still have it in my office today.