For many anglers, fish identification comes almost like second nature, and Maine’s fish species are usually easy to tell apart. But, of course, there are a few exceptions.
Lately I’ve seen some debate on social media, with folks trying to ID splake and brook trout. It seems every ice fishing season this debate rears its ugly head, and without a lot of experience, the two species can sometimes be mistaken for one another.
Let’s start with the basics. What is a splake? A splake is a hatchery-produced hybrid created by crossing a male brook trout with a female lake trout.
This hybrid is not produced outside of hatcheries because the two parent species spawn in entirely different habitats. While splake are genetically stable and technically capable of reproducing, successful wild reproduction is extremely rare — if not practically nonexistent — and has never been documented in Maine.
Splake tend to grow faster than either of their parent species and often live longer than brook trout. These qualities make this hybrid trout an effective tool for fish biologists and allow them to create trout fisheries in waters where native coldwater species are unlikely to thrive.
Like most hybrids, splake can be difficult to identify because they display characteristics of both parents. Still, there are a few reliable traits you can look for to identify your catch and, hopefully, put the debate to rest — at least for now.
Step 1: Know which species are present in the water
The first step: You need to know what waterbody you are on, an idea of fish species present and the current regulations. This may seem obvious, but this step is crucial because not knowing what species you may catch, along with not knowing the regulations, could make it easy to misidentify a fish.
Also, if there is only splake being stocked into the lake and no brook trout or vice versa, then it makes for an easy ID. You can check the stocking report to see if brook trout, splake or even both were stocked in that water recently.
Step 2: Look at the tail, spotting and vermiculation
Tail: When you land a fish and find yourself scratching your head over whether it’s a splake or a brook trout, the caudal fin or tail is often the best place to start. Splake typically have a more noticeably forked tail, a trait inherited from their lake trout parent. Brook trout, on the other hand, tend to have squarer, less forked tails. That said, the depth of the fork can vary, so tail shape alone should not be the only factor you rely on.
Spotting: The spotting is usually what throws people off the most. Splake are often mistaken for brook trout rather than lake trout, and that is mostly because of their spots. I’ve heard many anglers say, “It’s a splake because it doesn’t have blue halos,” but that is not always true. In many cases, splake can have blue halos around their reddish spots, though the halos are often much lighter than those on brook trout.
Of course, some brook trout also have light halos, and sometimes only a few. The spotting on splake can vary greatly from fish to fish, but in general it is basically a mix of lake trout and brook trout spots.
Vermiculation: Vermiculation is the term for the wavy, wormlike pattern along the back of a brook trout or splake near the dorsal fin. Brook trout have a clearly defined vermiculation, while splake may show some, but it is often less distinct and more spot-like.
Other common traits of splake include spots on the gill plate, a slightly elongated head and a “rust” colored stomach.
Like I mentioned before, without some experience, identifying a splake from a brook trout can be tricky at first, but hopefully these few indicators will help. And if you ever have the chance to view both species side by side, these differences become even more obvious.
Remember, in waters that have both splake and brook trout, the regulations are the same for both species. Legally, if you follow the brook trout regulation, you can’t break the law on a misidentification. If you ever are unsure of your catch, the best practice is always to release the fish.
If you have any questions about regulations please refer to the Maine inland fishing laws, and if you have any questions about a fish ID or any other fisheries-related questions, feel free to contact your local regional fisheries biologist.
This was originally published in the MDIFW blog on Feb. 9, 2022.
