Getting the most from trout stocking – Part 1

In the first of two parts, Steve navigates a confusing but crucial topic. 

This is a wander through the issue of fish stocking, with a focus on trout. I’ve had a bit of practical and policy level experience, and in the following two articles, I’ll try to offer a balanced view on some sensitive topics, touch on a few myths, burst a few bubbles, and ask (if not entirely answer) a few questions about whether, where, what and when we should be stocking.

But first. As a child I read two of Henry Williamson’s many books. One was our family favourite, ‘Tarka the Otter’, the other my personal favourite, ‘Salar the Salmon’. Williamson’s ability to anthropomorphically observe and describe nature, took the reader on a journey as close to virtual reality as a mind can imagine. I was that salmon; the one in ten thousand that survived to return and complete my lifecycle, despite man’s best endeavours to engineer a different ending.

Williamson and a stocking parable

It’s not enough to describe Williamson as a keen angler. In his writings, I see the same obsessions I’ve had my whole life; right from the first time I held a fishing line, then a rod, then a fly rod. Williamson wrote ‘Salar the Salmon’ in 1935. A few years after, he had taken the lease on Shallowford Cottage on the River Bray in Devon (coincidentally the same year as the NSW Fisheries and Oyster Farms Act 1935, which ensconced the NSW Trout Acclimatisation Societies into legislation, and which I later helped rewrite).

The lease for Shallowford Cottage came with fishing rights thrown in. Williamson’s diaries from that period in his life refer to fish stocking (which is how I can work him into this article!). In 1931, Williamson acquired some brown trout from Loch Leven in Scotland to stock the River Bray. By 1933, he is noting these Loch Leven trout catches in his diary, distinguishing them from local brown trout due to their distinct markings.

To move trout from Loch Leven to Devon in 1931 would have been a significant logistical challenge, involving a trip of around 800 kilometres. There seems to have already been plenty of local brown trout but Loch Leven trout (which are of course just brownies) have an almost mythical reputation for size and power. So, there would have been no doubt in the author’s mind that their introduction would result in better fishing. Two years after the stocking, we see Williamson justifying the decision (and no doubt the expense) by attributing a part of his catch to the stocking. “Fished in afternoon with Peter Elmington and his cousin. Caught nil but had fun stoning empty cans. Fished in evening in Bridge Pool, and got 2 Loch Leven trout, 11 and 8 ounces, and 2 brown, ¼ lb each.”

Then the doubt; the stocking strategy appears to backfire as the stocked fish seem to outgrow the locals and become predators. Williamson became convinced a Loch Leven trout had become a cannibal, preying on smaller fish. He wrote, “Saw the big trout in Bridge Pool take a trout across his mouth, sink down, and hold it there.” And, “Again I saw that damned cannibal fish take trout back in Bridge Pool.” “We must get him out!”

Whether he was successful in getting ‘him’ out is not mentioned but I love the example, because this is what fish stocking does to the mind – creating uncertainty and contentious debate. Preying on the willingness of the angler-mind to leap to conclusions with almost no real evidence. Williamson was an educated naturalist. He stocked brown trout into a brown trout river, he convinced himself the bigger fish in his catch were the stocked brown trout, and even attributed gender to the cannibal.

The English influence

A very English scene in the land of stocking.

England is truly the land of stocking. There would be very few trout rivers in England which haven’t been stocked at some point. Fishery improvement by stocking is an obsession. It is common for angling clubs to stock their ‘beat’ on a river, and for the adjacent beat to proudly advertise that they don’t stock – as if the fish you’ll catch in the latter are going to be unaffected wild fish. Even seemingly intelligent people engage in this thinking. There are literally thousands of man-made trout stocked lakes where you can pay to fish in England – even those ubiquitous brown signs on the roadside have a special symbol for them (one of 93 symbols). So always carry your rods. Feel like a bit of a break, turn off the phone, and there’s a good spot!

Moving along almost half a century from Williamson, it’s 1981 and I’m fishing a dam on a small creek, privately stocked with rainbow trout. The creek eventually runs into the River Wye in South Wales. On the way down the steep valley, a picturesque waterfall dives into a plunge pool in the forest below. Inaccessible, surrounded by a tangle of bramble bushes; observable but unfishable. One summer’s day in 1982, convinced that pool offered a potential fishing Nirvana, I decided to hack my way in. Sweating and bloodied, I made it. The rainbows were abundant and massive – my first double-figure fish. The salmonids of the River Wye and its tributaries are brown trout and Atlantic salmon, so the awe of finding very large rainbow trout, the quest for an explanation (ignoring the obvious), and the denial of the evidence, led to a great debate in the local newspaper – as if aliens had perchance landed!

Fishing here – pay-to-fish stocked waters are common in the UK.

Australian beginnings

Given our modern Anglo heritage, it’s not surprising we’re partial to a bit of stocking in Australia. I don’t know when Australian natives first featured in fish stocking, but certainly there was a big upturn from the late 1970s as hatchery breeding was improved and governments made a decision to invest. Translocations had occurred at least a hundred years before.

I can be a bit more certain about our salmonid stocking. The first brown trout were hatched from eggs in 1864, 86 years after the first European settlement. The eggs had been shipped by sea from England. Then later, we see those famous Loch Leven brown trout coming to New South Wales and Victoria during the 1890s, after first being introduced to New Zealand. The first rainbow trout came to Australia in 1894, also from New Zealand. In this case, the original Californian fish had been shipped to New Zealand in 1877.

Atlantic salmon were the original salmonid introduced into Tasmania with the goal to re-create the great migratory fisheries of the Northern Hemisphere. However, once released, the fish were never seen again. Still, Atlantics have made their mark and are the foundation of an aquaculture industry worth around a billion dollars a year to the Tasmanian economy; making a significant contribution to a fishing industry that creates more than 9,000 direct and indirect jobs. (We still haven’t quite figured out how to recreate a river-run recreational fishery for Atlantic salmon, and probably never will – some things aren’t meant to be!)

Australian stocking today

Today, every State and Territory runs a fish stocking program and they all operate hatcheries. The annual investment in fish stocking by governments runs into many millions of dollars. That’s a back of the envelope estimate because no one really says exactly what’s spent on hatcheries and stocking. Add that guess to the not-insignificant amount spent on private stocking, and we’re talking some fairly big numbers. But we don’t know how big because there’s no centralised record of private stockings. I’d say $100 million wouldn’t be an exaggeration.

Trout fry in trays at the Victoria’s Snobs Creek Hatchery.

We do know that, just for trout, there are government and private hatcheries in Western Australia, South Australia, Tasmania, Victoria, and New South Wales. The most northerly trout hatchery in Australia is at Ebor, about 80 kilometres as the crow flies west of Coffs Harbour, bordering the Guy Fawkes National Park. If that seems like it might be a bit warm (salmonids don’t do at all well in warm water) there are plenty of hatcheries in warmer places a lot closer to the equator like PNG, Kenya, and Zimbabwe, and a massive hatchery and trout farm beside the hydro lakes in the Kingdom of Lesotho, with a 20,000 tonne salmon farm on the drawing board. It’s amazing really; wherever you can find cool freshwater and a stray Englishman, you’ll find trout stocking.

What is fish stocking and why do we do it?

Stocking fish involves either raising fish in a hatchery for release (hatchery stocking), or their capture in one body of water and their release into another (translocation stocking).

Common goals for fish stocking are to create a fishery where there isn’t one, or to supplement an existing population of a popular fish. Sometimes, it’s as part of an endangered species recovery plan to increase numbers, or to reintroduce a species that has become locally extinct.

The long and challenging process to artificially stock Macquarie perch has been as much about conservation as angling.

Stocking success

If you want to get the best bang-for-your-buck, what should you be thinking about? What species? Stocking big or small? Few or many? Native or exotic? What about habitat like temperature and shelter… and which hatchery has the best fish? I get asked all these questions.

Purely from a fisher’s perspective, we want stocking to create better recreational fishing. We know fish can be produced in their millions and released at almost any point after they’ve hatched.

The size at which we release fish is a really hot topic. A key part of the success of every stocking is dependent on getting the release size right, as well as the stocking timing, environment, and process. One popular strategy is to release millions of fry with the full expectation most will die but a few will survive and thrive as almost-wild fish; or at the other extreme, to release a much smaller number of larger fish that are ready-to-catch, but often considered to be tame, naïve, and unable to ‘make a go of it’ in the wild. And almost every variation between these two extremes. There is no magic bullet – all options have their pros and cons. Stocking large fish into a barren, weedless, foodless, water body is no more likely to get a good result than stocking small fish into a redfin lake.

Effective stocking requires many things, but stocking in the right conditions with good fish, is a handy start.

Then there are the stockings programmed months in advance to align with a Ministerial visit which turns out to be a baking hot day at the chosen release spot: the local concrete boat ramp. This accommodates the Minister’s brogues and the local media, but also (unwittingly) the hungry gulls, cormorants, and pelicans – not forgetting the subsurface predators.

A good friend of mine recalls selling a government department a large consignment of fry which he saw released from boats into the middle of a lake in 70 metres of water. No weed, no food, no hope. Never to be seen again.

But, hopefully that’s all in the past now and our fishery managers are a bit more cautious and less wasteful with their stocking strategies.

Redfin and other predators

Releasing small fish into water where there are plenty of predatory fish will rarely be successful. In Australia, I’m particularly talking about trout stocking in redfin-infested waters, but the same can be applied to other species. There is some excellent science on this. If you stock a redfin-infested lake with small fry or fingerling trout and then net your redfin over the next couple of weeks, you will find nearly all the trout are in the redfin’s stomach contents. The only way to create a successful trout fishery in a redfin lake is to stock larger trout (probably 200mm or more) and hopefully, ultimately turn the tables on the redfin. Adult trout love baby redfin and can grow really big eating them.

Big enough to survive redfin.

I get asked a lot about where trout will survive. I talk a lot about water temperature – they really hate anything north of 23C for prolonged periods. On the plus side of the ledger, good weed-beds in the shallow margins are great for food and shelter; and of course scaring off predators helps, assuming that’s practical and achievable.

Which brings me to a New Scientist magazine headline, ‘Hatchery fish get survival training’ which caught my eye. The article reported on some Scottish research. The researchers estimated that worldwide, five billion salmon(id) hatchery fish are stocked each year, so improving survival would be a good investment. They showed that if you can put naïve hatchery fish with experienced fish, the former can learn to mimic the latter’s response to predators and other dangers. If you can then expose them to those dangers – for example by putting the predators behind a screen – they will learn to avoid them. But it’s not just sight that can trigger a flight response. The scent of poo from a consumed fish can be pretty effective as well. All very Pavlovian and common sense when you think about it.

A bag of prime yearling brownies makes their way from the Ballarat Acclimatisation Society to a new home in the Central Highlands lakes. Thankfully too big for redfin, they will nevertheless be vulnerable to other predators until they adapt to survival in the wild.

I have to say, in all the advice I’ve given about stocking strategy, survival training of stockies has never featured! But what I do say to anyone wanting to spend their hard earned $500 on a few rainbows for their farm dams, is try to catch and remove as many adult redfin as possible, and try to stock the trout at over 200mm in size. Stock in the evening, spread them around the dam, and release them near cover like weed. Early spring is the best time, and check water temperature – especially the difference between the truck water and the dam water. Mix some of the destination water with the shipment water to let them acclimatise, and be gentle. Then, be back at dawn the next few days with a big stick. Cormorants check out dams every day to decide where to go to work. If you’re pointing a big stick at them, they’re pretty smart and will move on. Once cormorants find their water for the day, they’ll stay there. Don’t let it be your dam; at least not until your fish have acclimatised and found their fins.

The bottom line is, we waste a lot of time, money and effort by releasing fish into poor habitat, or by feeding predators – mainly other fish, cormorants and pelicans. So if there are things we can do to reduce that, we should. Starting with, never stock your baby trout at the boat ramp, in the middle of a hot summer’s day!

More on stocking size

I’ve written before about different fisheries management and stocking strategies. In Bristol’s water supply lakes in the UK, they grow out 2lb plus fish for release and some of these grow on in the lakes to be caught as 5lb-plus fish. In Tasmania’s Penstock Lagoon, the Inland Fisheries Service release wild adult fish relocated from Great Lake, as well as hatchery fingerlings and yearlings.

Chew Valley Reservoir stocks comparatively big trout (1kg or so) and it works – for them.

In the Snowy Mountains, Lake Eucumbene and Lake Jindabyne have been stocked with fingerlings for the past 20 years. A new project has recently been announced with the benefit of community funds from the Snowy 2.0 pumped hydro scheme, which could see larger rainbow trout being grown on prior to release. Most Snowy Mountains lake anglers have noticed a serious decline in rainbow trout numbers and there are fewer visiting anglers as a result. Among other things, stocking larger rainbows might boost the fishery enough to bring some of these anglers back – particularly the younger generation of trout fishers. (Rainbows of any background are statistically much easier to catch than browns.)

Finally, I should share this headline from New York State to ponder: “This spring, the state Department of Environmental Conservation is scheduled to stock 2.33 million catchable-size brook, brown and rainbow trout in 311 lakes and ponds and roughly 2,845 miles of streams. In addition, DEC will stock nearly 1.5 million yearling lake trout, steelhead, landlocked salmon, splake (hybrid lake trout/brook trout), and Coho salmon”. Now that’s a serious stocking program!

Next time, I’ll talk more about what we want from stocking – and what we actually get.