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October 20, 2014
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Wild vs. Stocked Trout: There’s a difference

This big white tanker is one of the Pennsylvania Fish & Boat Commission’s “Great White Fleet”of dozens of fish stocking tanker trucks. This year the commission will stock nearly four million hatchery fish around the Commonwealth.
Photo courtesy PA Fish & Boat Commission

By Bart Larmouth

The Upper Delaware River has become synonymous with the phrase “wild trout,” a term that may seem unimportant to the general public, but is of vital consequence to trout fishermen. Not only is a river filled with only wild trout in the northeastern United States a rarity; it is a major draw as well. But what is it that makes such a fishery superior to another? What is the allure of these wild fish?

The first thing to understand is what makes a wild trout wild. Simply put, it is a fish that started life as an egg in a stream, hatched and grew without any outside interference from man. There is an alternative to this path—that of the stocked fish. Stocked trout are those raised in fish hatcheries then released or “stocked” into rivers, streams, lakes and ponds.

The majority of streams and rivers in the Northeast warm dramatically in the summer and can only offer a viable habitat for trout for a short period of time, and therefore cannot sustain a wild population. Thanks to robust stocking programs instituted by state fisheries over a century ago, these typically barren bodies of water can (albeit briefly) yield fishing opportunities not normally present.

Contrary to this, wild fish populations are found in those rare rivers that remain cold throughout the year. Because of this, they live their entire lives in the same waters with the same chemistry and topography. They come to know the currents, rocks, pools and riffles in which they were born, allowing them to fully adapt and become one with their environment. Wild fish also have a stronger, more diverse genetic stock that allows them to adapt to local changes in the environment, whereas the stocked fish tend to have a very homogenous genetic makeup, which does not allow for the kind of adaptability required to thrive. Wild trout are typically healthier as well, and are much more beautiful in appearance when compared with stocked fish.

Wild fish will have much more vibrant colorations, as well as larger, fully-formed fins and tails. Stocked fish will take on more color the longer they remain in the wild, but typically they will never reach the bright pigment levels seen in native fish, which have been adapting since birth to the specific hues present in their environment.

Visual differentiation between the two is quite simple at times, with stocked fish being very pale, and exhibiting fins with injuries or deformities brought on as a result of constantly colliding with the walls and floors of their cement home.