An Arctic Fishery in Summit County?

Why do Biologists love introducing species to try and fix a problem? Are we ever going to learn our lesson? Look at the Cane Toad in Africa, the Mongoose in the Caribbean, and the Nile Perch, all of these were introduced by people into a new ecosystem and every one of them decimated the native species. So why are Biologists trying to get non-native species to become established in a Colorado Lake? Apparently, it is their proposed solution to reducing the over abundant population of Opossum Shrimp (Mysis diluviana) that was introduced in the 1970’s. So can two wrongs make a right?


The Problem

Above- an Opossum Shrimp. Photo credit Peter Bryant 2013

The Opossum Shrimp was originally introduced into Lake Dillon as a means to increase the size and population of the fish in lake. What was not taken into account was the differences in diel vertical migrations (DVM), which is the daily migratory patterns that aquatic species take (The American Naturalist).The trout and salmon in the lake were on diurnal migratory patterns, where they would rise to the surface during the day and feed on plankton and other food sources then, as night approached, they would go deeper into the lake. The Opossum Shrimp had the opposite migratory patterns, being nocturnal, they would spend the days deep in the lake, and as night came on they would migrate to the top and feed. Thus, the two populations had very little to no interaction.

“Mysis can virtually eliminate large zooplankton that support growth of trout and salmon in reservoirs”-Devin Olsen

But how much damage could a little shrimp do? They are tiny, right? Well, being small has its advantages.Sticky 1  As is common in Biology, when a species is introduced into an ecosystem without any predators, its population quickly booms and surpasses the carrying capacity of the ecosystem followed by a crash of the ecosystem; in other words, the shrimp’s population increased so rapidly that it reached a point where there was not enough food to support the ecosystem. This was a real problem for the fish in the lake, which became small in size and numbers. Typically when we talk about an introduced species wreaking havoc on an ecosystem it is because they are a predator and its prey, the native species, are naïve  (in the sense that they do not know to fear the predator). In this case we almost see a naïve predator being undone by an introduced prey.


Above- An Arctic Char, caught by Devin Olsen. Devin Olsen is a Master’s student at CSU who studied the Arctic Char population and other aspects of the Lake Dillon fishery. Photo Credit Devin Olsen (via Denver Post)

Why the Arctic Char?

Sport fishing is a year-round event in these mountain towns bringing in a lot of revenue, both for the locals and the state. Thus, having a beautiful lake just off of I-70 void of game fish is a real detriment. So why introduce the Arctic Char? Well, there are several reasons Sticky 2that make it the ideal candidate. Primarily, it is a known predator of the Opossum shrimp in their native home range, making it perfect for reducing the shrimp population, in theory.

Besides it being a natural predator for the shrimp, it has the potential to shift Lake Dillon from a desolate nightmare to a fisherman’s and ecologist’s dream. By introducing the Char, they brought in a species of fish that is a rarity in the lower 48 states, only occurring
in a few other continental states (Maine and New Hampshire)(FishBase). Colorado is one of two western states that currently has the Char (see the distribution map below). Aside from being a rare species (locally), it is also an incredible sport fish, it’s vibrant breeding colors and hard fighting when hooked make it a fun fish to reel in.


Above- Distribution of the Arctic Char in the USA. Tan area (Alaska) is the natural homerange. The larger spots imply larger populations. Photo credit USGS mapping.

Moving Forward

Sadly, since the introduction of the Arctic Char in 1990 there has only been a small impact on the shrimp population (CSU). This is to be expected though, as the shrimp population had a 20 year head start and is very well established. It has not been until recently that the Char was noted to be sustaining its population naturally, versus yearly stocking; which is a good sign for the Char and a very good sign for the Lake’s health as a whole.

If the Char can become well established in the lake, Lake Dillon will be the only public fishery in the lower 48 states where the Arctic Char can be caught, quickly making it a destination for sport fishers. It has been estimated that if Lake Dillon is successful in becoming a “Boutique Fishery” (a fishery specializing in a certain species), it can potentially bring in $1.3 billion annually for Colorado (Denver Post). This coupled with the potential of bringing the lake back into a healthy equilibrium makes the introduction and continual studying of the Arctic Char and Lake Dillon as a whole extremely important. By continuing to establish the fishery we are supporting a community of people and saving an aquatic community before it completely crashes.



BPA-Free: Only an Assurance


BPA-free is the new label to look for on water bottles, everybody checks for it but do they really understand what they are checking for? Bisphenol A (BPA) is a known endocrine disrupter that is believed to be contributing to the increasing rates of premature birth, reproductive cancer, prostate cancer, and other detrimental human health issues. So where is BPA? It is everywhere. It is in most plastics, receipt paper, and the inner lining of canned foods. It is in us.

Kim Krisberg, a freelance public health writer, recently published an article on the accepted lesser of two evils, BPS. Bisphenol S (BPS) is the common replacement for BPA, but is it actually better? It appeared that there was a solution to the BPA uproar far faster than one would expect and once people were given a “better” alternative they turned a blind eye to what they were putting into their bodies and where else they may encounter BPA.

” BPA is so ubiquitous that federal public health officials estimate that nearly all of us have detectable levels in our bodies”


BPS was selected for the replacement of BPA because it is believed to have lower estrogenic activity, which is how it effects the endocrine system. Instead, BPS stimulates the production of thyroid hormones which can be hazardous for fetal brain development. BPS is known to speed up embryonic development and adversely effect the reproductive systems in animals.

Recently, Nancy Wayne (a reproductive endocrinologist and professor of physiology at the University of California-Los Angeles David Geffen School of Medicine) co-authored a study in the journal Endocrinology, where they studied the effects of BPA and BPS on embryonic zebrafish (Danio rerio). Their studied, which unlike others, compared BPA and BPS side by side, thus showing that the effects were highly similar between the two.

“BPS is not necessarily safer — we just swapped one endocrine-disrupting chemical for another.” – Nancy Wayne

It is important for we as a society to realize the level of exposure that we have implemented in our daily routine. Crumpling up that receipt in your hand and carrying it out with your groceries is a prime example of unneeded exposure according to a study published by JAMA which found that people who routinely handle receipt paper have elevated levels of endocrine disrupting agents in their system. Your hands, frequently are exposed to lotions and hand sanitizers, this can lead to more absorption of these endocrine disrupting agents according to a new study published by Plos OneSo what can we do? We can’t get rid of every piece of plastic, it is unrealistic to think we can. We can make choices that limit unneeded exposure to endocrine disrupting agents, decline a receipt, only use glass and stainless steal container for food storage, pick foods and drinks that come in glass instead of plastic. If we, the consumers, make a hard enough push for less plastic products we may shift the producers to use materials that are safer for human use.

Here is a great video by Democracy Now! that looks at BPA and its replacements.