Why Are They So Big?

By Chance Prestie, BSc, MSc / Plummer’s Arctic Lure

A question that has come up more than a few times in the past has been “Why do Great Bear Lake and the Tree River produce such big fish?” A quick glance at the IGFA hall of fame shows that this is no boast either, with all tackle world record Lake Trout and Arctic Char coming from Great Bear Lake and the Tree River, respectively.

So what makes a lake (or river) capable of consistently producing such large fish? First off, in order to grow to large sizes, fish need food, and lots of it. From a Limnological perspective, Great Bear Lake is actually one of the least productive lakes in the world, with extremely low biological productivity per square kilometer. However, it is the eighth largest lake in the world, with a surface area of over 31 000 km2 (12 000 square miles) and a maximum depth of 446 m (1463 feet). Due to its sheer size, Great Bear Lake has a huge productive capacity for fish even though it has a low biological productivity per square kilometer.

The Tree River on the other hand is a polar opposite. The river itself flows for 160 km (100 miles) before emptying into Port Epworth on the Coronation Gulf of the Arctic Ocean, but only the lower 10.5 km (6.5 miles) are accessible to Arctic Char and far less than half of that length has any spawning habitat. The short length of accessible river and minimal spawning habitat make for a competitive environment for the Tree River Char. The largest and strongest char generally utilize the best spawning habitat, which in turn leads to the best chance of survival for their offspring. Combine this with the productive nature of the Coronation Gulf of the Arctic Ocean and you end up with the trophy char present throughout the Tree River.

Equally important to growing really large fish is genetics. Great Bear Lake has arguably some of, if not the best lake trout genetics in the world, proven through the record sizes of the fish caught in this system. It also has one of the most diverse lake trout populations in the world, with multiple different morphologically different strains of lake trout present throughout the lake such as the smaller “Butterfly Redfins” and the large piscivirous (fish eating) “Silver” or “Greys” which can reach sizes of over 50 lbs. Overall, there is a lot of genetic diversity in the system which allows for some fish with the right genetics to grow to such large sizes. The Tree River also has some unique genetic adaptions compared to other northern rivers. Tree River Char are genetically different from other Arctic Char populations in the area and show a much higher degree of past genetic introgression (hybridization) with Dolly Varden Char. This is what leads to the unique look of the Tree River Char (and likely to their larger size) compared to other Arctic Char populations.

The last major thing fish need to get big is time. Growing seasons in the north are much shorter than in the south, but to counter this, fish have longer lifespans in the north. “Butterfly Redfin” Lake Trout in Great Bear Lake are known to live as long as 65 years, the “Silvers” or “Greys” are known to live past 50, and Tree River Char can live for 30 years or longer (for more information, see the 2017 Arctic Lure newsletter). This is compared to a lifespan of 20 to 30 years for lake trout in the more southern part of their range, which slowly increases with distance north. Even with the long lifespans, proper fish handling and catch and release are necessary for growing such large fish as the fish need to survive for decades in order to reach their potential. A guest I had the pleasure of guiding, put it perfectly in perspective when talking about trophy Lake Trout when he said “Even when there’s a lot of them, there’s not that many of them!” And it is exactly that reason why we need to give each fish the best chance of survival during catch and release fishing by handling them properly. The long natural lifespans, very low fishing pressure and proper catch and release practises and fish handling result in lots of time for fish to grow and potentially reach trophy sizes.

In the world of Lake Trout and Arctic Char, there are no places in the world where the above factors combine to provide a better shot at growing truly record sized trophy fish than Great Bear Lake and the Tree River, respectively. Combine the productivity, genetics, and long lifespans of fish in each system with the extremely low fishing pressure and the proper catch and release and fish handling performed by Plummer’s Arctic Lodges Guides and you get the trophy fisheries these systems offer for world record sized fish.

Plummer’s Arctic Lodges are where dreams come true. To book a trip of a lifetime visit https://www.plummerslodges.com/