Predators - They're Hunting Your Fish

PREDATORS
We frequently say that a pond is more than a hole in the ground with water in it; it is a mini ecosystem. Unfortunately, that means there is a food chain, and your fish - no matter how pretty or how expensive – are firmly in the “prey” link of that chain. Every part of the country will have different predators, so it’s a good idea to contact your state fish & wildlife department or a local pond group to find out what critters may be visiting your pond. Almost all of us, though, will encounter herons and raccoons…

Herons
The Great Blue Heron is a majestic bird, often standing more than 4’ tall, with a wingspan as wide as 6’. Shy, solitary and territorial, the heron is an incredibly patient – and thorough – hunter of fish and frogs. Once a heron has successfully dined at your pond, they will likely stay until a) they clean you out of fish, or b) you outsmart them. Herons typically land in the yard and walk to the pond, searching out a shallow area with easy access to prey. When spooked, they tend to rise straight up for a few feet and then angle off and away. Decorative fence panels, shrubs and smaller trees around the pond can help block their entrance and escape routes, while thick, grassy plants along the edge can deny them access to the shallows.


There are a number of products such as decoys and motion-activated “water guns” that are meant to scare herons away from your pond, and you may have some success with them – for a while. Initially spooked away, a determined heron will stake out your pond and eventually figure out that the decoy isn’t a threat (we’ve seen pics of a heron dining in the middle of a decoy-guarded pond). As for the water gun, we watched an experienced heron walk up to our own pond, get hit with water from two different directions, shake like a dog, and continue to his favorite hunting spot!

We’ve been told of  people having success with several wires fanned out across the pond, about 8’ off the ground and extending out about 10’ beyond the perimeter of the pond. In one case, right after the wires were installed the resident heron landed on a neighbor’s roof, surveyed the wires, and flew away, never to be seen again. Apparently having the flight path partially blocked was a good deterrent. While I don’t want to say it’s foolproof, we’ve had good luck with a double strand of electric fence suspended out over our pond. (Yes, you want to make sure it is securely attached at the pond edge and well grounded.)

Raccoons
These cute little buggers are also terrific destroyers of backyard ponds. They love to wade around in the shallows, overturning rocks and uprooting plants in their quest for tadpoles, frogs, snails, and fish. If you discover parts and pieces of a fish near your pond, raccoons are the likely culprit. As with herons, raccoons hunt in the shallows, so make your pond as deep as possible with steep sides. Plant shelves should be at least 12” deep. Thick plants along the edge and in the shallows may also deter them, along with an electric fence. If your pond is relatively small, you can construct a protective cover out of rigid, metal grid-style fencing to place over the pond at night. (Raccoons are strong enough to tear netting apart.) Motion-activated lights pointed squarely at the pond may help too, as raccoons are nocturnal creatures and don’t like bright lights.

Oh, There’s More!
While herons are the biggest eaters in the “flying threats” category, kingfishers, owls and even eagles may swoop in to grab a quick bite. The tree cover that can protect against larger birds may give kingfishers a nice perch to hunt from, so you might want to check with a birding organization in your area to see how much of a threat they are. We’ve seen suggestions of placing tethered, artificial fish in the pond on the theory that the swooping birds will latch on, not be able to carry the meal away, get frustrated, and leave. Or, that artificial koi could be a “fish here!” beacon that draws them in – not sure on that one!

If you have a creek or a storm drain nearby, you may be surprised to find a beaver or otter in your pond. While beavers won’t eat your fish, they can wreak havoc on your expensive and carefully selected trees. Otters, on the other hand, are a nightmare, and can wipe out a pond full of fish in no time. In either case, call an experienced trapper right away to relocate these visitors! Bullfrogs are another hazard, as they will eat small fish and can ram the larger fish, causing internal damage that may be fatal. Bullfrogs will eat every other frog, toad, mouse, vole, snake, bird, etc. that they can get in their mouth, so if you see a bullfrog it might be a good idea to remove it.

Your best bets for protecting your fish are to have a water depth greater than 3’, create barriers to entry, and provide hiding places in the pond for the fish. These can be large sections of PVC pipe, or a tunnel made from a large, flat rock raised off the pond bottom (make sure it is secure and there are no sharp edges). Plants such as water lilies, hyacinth and water lettuce are also good cover, and provide shade on hot days. Electric fences should be used with caution – think about small children and/or pets – but can also be very effective.