Continuing with the beer-themed mini-series, but stepping outside of the trout-sphere, this week I’m going behind the name of Hardywood Park’s Great Return. It’s not only a fish-themed beer, but a beer that supports fisheries conservation!
Those residing outside of the Old Dominion may not be familiar with the label, but Hardywood is a craft brewery rooted in Richmond, Virginia. Owned by two childhood friends, the brewery opened in 2011 and takes pride in brewing with local ingredients and renewable resources. Nestled in the historic German brewing district, Hardywood is the destination for anything from lively block parties to quiet afternoons in the garden.
IPAs are my flavor of choice, so ordering my first Great Return was a no-brainer when it was first released in 2013. I didn’t pay much attention to the name, and it was probably several months before I saw the label and realized it featured an American sturgeon. The Great Return is referencing one of the biggest comeback stories in fisheries, and that’s a cause I can drink to!
So, what’s so great about an American sturgeon return? American sturgeon is a large species of fish reaching nearly 10 feet in the length and weighing up to 300 pounds. They are also one of the oldest living species and it is believed they were swimming around at the same time dinosaurs were roaming the earth.
Despite surviving the same mass extinction that wiped out the T-Rex, Atlantic sturgeon was listed under the Endangered Species Act in 2012. There are two specific aspects of the species’ ecology that make it particularly vulnerable. First, it takes up to 20 years for a female sturgeon to be able to reproduce. In that 20 years a lot of things can happen, that kill the fish before it is able to reproduce. Most notably, a lot of sturgeon mortality could historically be traced to angler harvest. The first rapid decline in sturgeon populations was believed to occur during colonial times and into the 20th century when sturgeon caviar (eggs) were considered a delicacy and the species was overharvested. In fact, Atlantic sturgeon is believed to have largely prevented massive starvation of early settlers because the fish was large, plentiful, and easy to catch. Today Atlantic sturgeon harvest is illegal; however, adults are still at risk of fatal injury when accidentally caught and from being struck by boat propellers.
The other difficultly with Atlantic sturgeon conservation is that they require a wide range of habitats to complete their life cycle. They are a bit like salmon- when not spawning they live in saltwater in the Chesapeake Bay and Atlantic Ocean, but when ready to reproduce they swim into freshwater rivers. Historically, these rivers would have been a safer spot to spawn because there are fewer things to eat the eggs and water currents are not as strong as in the open ocean allowing eggs are more comfortable place to develop. However, in modern times, dams block access to much of the spawning habitat and water quality is so poor that eggs and juveniles can suffocate in sediment-laden water.
The above paints the picture of Atlantic sturgeon populations in the James River which flows from the mountains of Virginia, through Richmond, and into the Chesapeake Bay. Historically the James River was home to one of the largest populations of Atlantic sturgeon. Today, it is estimated that only 300 adults occupy the James River every year, and they are all spawning in the same location. This spawning location is unfortunately placed in a section of the river with heavy boat traffic and is regularly dredged to make the river deeper and navigable by large commercial ships. Dredging not only displaces adult sturgeon, but suspends sediment into the water column making the water quality too poor to support Atlantic sturgeon.
It would appear that this story ends with having to choose between using the river to support sturgeon, or using the river for commercial hauling (Richmond has a deep history of maritime transportation dating back to the early 1600s that is still alive and well today). However, thanks to valiant efforts by The James River Association and research by university, state, and federal biologists, there are early indications that it may be possible to have both the ecologic and economic uses of the river. Detailed maps of spawning grounds have pinpointed critical areas in the river to protect, and more research on spawning behavior has identified spawning windows in fall and spring when sturgeon reproduce and water quality is of highest importance. Further, through the use of radio telemetry, biologists now have a better understanding of where sturgeon go within the river and the Chesapeake Bay. Together, this information has been used to form an adaptive management plan that minimize risks to sturgeon during critical life stages and protects a larger range of habitats used by the species.
It’s still early to tell how these management adaptations have effected long-term sturgeon population health, but the observation of more and larger sturgeon entering the James River to spawn has biologists excited about the future. Improved ecosystem management in the James River is a cause that Hardywood continues to support, and they contribute $10 per barrel of Great Return to the James River Association to not only support sturgeon recovery but James River ecosystem restoration.
So, your next drink may very well be saving the Atlantic sturgeon. Bottoms up!
There are two laws in fish biology. Your waders will leak, and there will be beer in the cooler.
These rules are common knowledge among anglers and biologists, but also brewers who have enticed many weary fish enthusiast with beers donning a fish-centric name. Some of these beers require no stretch of the imagination- Sculpin IPA (Ballast Point), Striped Bass Pale Ale (Devil’s Backbone), and Wall IPA (Northwoods)- which are all well-known fish species.
But some brewers go a step further, intentionally or not, and are able to sell a little fish ecology on every bottle. While my field work continues to crawl along, I felt inspired by the summer heat to introduce a mini-series that goes behind the names of a few beers that may be sitting in your cooler.
Up first is Bell’s Two Hearted Ale. This is a certain eye-catcher for any trout enthusiast as the label features an elegant brook trout surfacing through a stream. But, what does a brook trout have to do with two hearts? Bell’s likely named the beer after the Ernest Hemingway short story ‘Big Two-Hearted River’ which makes mention of trout fishing on the river in Michigan.
But, I like to think the title has another meaning, one Bell’s likely never saw coming. That is, trout actually have two hearts. The first functions as the normal blood-pumping machine and, in most fish, sits right behind the throat. This four-chambered heart pumps deoxygenated blood to the gills where it fills small capillaries. In the capillaries, carbon dioxide is dumped out of the blood and oxygen is absorbed from the water through a processed called diffusion (which basically just means oxygen molecules move from high concentrations in water to low concentrations in blood). From there, blood circulates up towards the top of the fish, and then heads through the body and towards the tail.
Once in the tail, blood is largely deoxygenated and sitting in many small capillaries where the pressure isn’t high enough to efficiently pump it back to the heart. So, evolution fixed that problem and gave many fish a second heart, the caudal heart. The caudal heart is located near the last few vertebrae in the fish’s backbone, in a region called the caudal peduncle. The caudal heart collects blood from all the small capillaries in the tail and forces it into the higher-pressure caudal vein where it can more efficiently flow back to the heart.
The caudal heart is small (about ½ an inch in trout), two chambers, and is powered by a combination of skeletal muscles and movement of the tail during swimming. Muscle contractions force blood from one chamber of the caudal heart into the other. This second chamber then empties blood into the caudal vein where travels back to the heart. With the first chamber now empty, there is room for many capillaries to each deliver a small amount of blood to the caudal heart and the process starts over again.
Interesting, the caudal heart is believed to only be active when fish are swimming, suggesting it is reserved for times when fish are active and in need of more oxygen. So, the caudal heart is kind of like an oxygen mask dropping down when I crank the treadmill up a little higher. Also, not all fish have caudal hearts, and some fish (like eels and hagfish, which both have snake-like bodies) have somewhat different anatomical structures in their caudal hearts. But, the purpose and function of the caudal heart remains the same.
So, next time you’re at a bar order a Two Hearted Ale and think about the caudal heart. Or, maybe go trout fishing and think about the ale. Whichever your fancy.
How High Can a Trout Jump?
I’m not even going to try to hide it. Very little got accomplished this week in the field. We had a lot of struggles early with equipment malfunctions, and no sooner than we started making progress it started raining. That’s field work, and we’ll try again next week.
When I started this blog I intended it to be both a source of updates for my studies, but also a place where interesting research by other trout ecologists could be made more accessible. While I tackle a few big-picture questions in the Previous Research tab, hundreds of research articles are published every day. Unfortunately, these articles are often hard to access without a university affiliation, and sometimes even harder to understand without a dictionary and a lot of patience. The knowledge used to manage our natural resources shouldn’t be held captive in the hands of a select few. Science has to do better.
The unexpected lull in field work left me a little time to catch-up on the growing stack of articles I’ve saved over the past few months. So, there’s no better time to start realizing the next phase of this website and discuss some interesting research by my fellow ecologists. In this inaugural research blog I discuss a paper that addresses the question:
How High Can a Trout Jump?
First off, why do we care? In addition to the increasingly large number of man-made barriers to trout movement (e.g., bridges), mountain streams have many waterfalls of various shapes and sizes. Knowing whether a fish can swim upstream of a barrier has significant implications for management. If a barrier is passable, then the population is said to be “connected,” which is important because connected populations are more resistant to extirpation (a concept I explain more detail here). However, if a barrier is not passable, a population will become separated into two subpopulations, each with a higher risk of collapsing and being extirpated when there is a disturbance.
One way to determine whether a population is connected is to measure genetic relatedness within and among populations. Now, bear with me. I know a lot of people hear “genetics” and tune out thinking the words to follow are going to be impossibly complicated and uninteresting (I once, and sometimes still do, fall into that category). But, the concept is quite easy, and it’s fascinating that we can do this study in fish. When we check for genetic relatedness, we are interested to see how similar the genetic composition is of fish within and among populations. If the genetics are similar, then we know the population is connected.
Put another way, checking for genetic connectivity is basically the equivalent of determining how genetically related everyone is at a family reunion (within-population) and then comparing that family to families across the United States (among-population). You would expect that within-population genetic relatedness would be high because you’re measuring parents, siblings, and cousins that share similar genes. You would also expect that families that live near one another would be genetically different, but still somewhat similar because individuals can easily cross over (marry) into other families. However, we wouldn’t expect a family from Pennsylvania to be too closely related to one from California because not too many people move that far away.
The question is, how many states away do we start seeing families becoming distinctly different? To bring this back to trout, how tall does a barrier have to be before trout can no longer swim past it and there are two genetically distinct populations?
This is the question that Anne Timm and her colleagues addressed in a recent paper published a few months ago in Environmental Biology of Fishes. They measured genetic relatedness of populations upstream and downstream of waterfalls ranging in height from 5-200 feet. They found that 13-foot barriers were large enough to significantly reduce genetic relatedness between two populations, but population separated by smaller barriers still had some degree of connection. This means that brook trout are at least sometimes capable of moving upstream of barriers that are less than 13-feet tall. That’s a really tall jump!
That statement is qualified by “sometimes” because movement is highly dependent on stream flow, availability of pool habitat near the falls for resting, and slope of the fall. So, in reality, 13-feet is an extreme maximum, and it’s unlikely that trout are regularly swimming upstream of barriers that tall. In fact, other biologists have found maximum jumping height to be less than 5 feet for brook trout, which is probably a more realistic height for trout to regularly jump.
More connected populations also have more genetic diversity, meaning that there are more genes in the entire gene pool. Thinking back to humans, a more connected population might have genes for all the possible colors of hair, but disconnected populations might lose the genes for red hair. As predicted, Timm and others also found that genetic diversity of upstream populations decreases when falls exceed 13 feet tall. This is problematic because more genetically diverse populations are usually more likely to survive environmental change, so this suggests that populations upstream of large falls may be more prone to extirpation.
What can we do with this information? Of course we aren’t going to remove waterfalls or artificially connect population near falls. But, it does give a quick threshold for identifying impassable barriers, which could help locate disconnected populations that may be at a higher risk of extirpation. Once identified, populations can receive special consideration for receiving additional habitat protection or possibly stocking to supplement genetic diversity. But, stocking has its own problems, a topic we’ll have to save for another time.
I have few field horror stories this week-probably because I was only out for one day. After sampling, we like to give fish a few days to calm down before tracking so that we aren’t documenting any movements that are from handling stress. My office to-do list has also been growing since May with deadlines now becoming more eminent and I think some no longer believe my “I’m in the field” excuse for not answering emails. So, I spent the majority of the week clearing my desk and staring at the data we’ve gotten so far.
We did go out once this week to track all fish locations. And, it was arguably the most interesting week for movement. As we started tracking one stream, we quickly noticed that a pool that normally contains five fish was down to one. It was irritating at first because we assumed they were lost to predation or post-handling stress mortality. But, as we walked upstream we started hearing the receiver “chirping” at odd locations indicating the location of a fish. They’re finally moving!
In total, several fish from one stream moved over half a mile with one fish approaching the one mile mark. A mile! That fish just moved >8000x it’s body length in a week.
What trigged the movements? It’s hard to tell because right now I don’t have a lot of movement data. But, a leading suspect is an increase in stream flow. A few days before we tracked there were several storms that dropped about four inches of rain. By the time we got out, stream flows had already gone back down to their near-drought conditions, but I think for a few days in there they increased just enough to trigger take off.
I’m always curious why fish decide to start moving after, in this case, two months of hunkering down. But, I’m probably more interested in why they decide to stop moving. Sometimes they stop in really bad habitat, and so maybe they just get tired or there is a resource (like food) there that I don’t immediately see. But, in this case, a more interesting first impression is that some fish seemingly made the decision to pass through some really great pools, swim up small falls, traverse through very shallow runs and find the exact same pool some other migrants chose to stop in. Did they know that habitat was there? Were they following each other? And, why is that pool better than all the others?
If fish could talk my job would be so much easier.
All of them. In every single crevice and in every single hole. And just when you think there isn’t one more rock to overturn, nor one more fish left to shock, you throw the probe in as one last Hail Mary. The crew silently pleads “just please be in there.” The shocker lowers their thumb overtop the switch. You take a deep breath. Electricity flows through the lifeless water. Nothing is left.
A collective sigh is let out, and if you were any less tired you would have moved on long ago. But you continue shocking, continue pleading. Then, suddenly, you hear the unmistakable sound of a tail flipping, and you see a white stomach come to the surface. You hold your breath one last time and wait….it has a silver wire hanging from the side. It’s a tag! We got it!
Now just 99 left to go.
Aside from the trip down south, that play-by-play was the entirety of the last week and a half as we tried to recapture all of tagged fish to take tissue samples. In theory this seemed like a fairly easy idea. We had the receiver to locate the tags, we had electricity to pull them out of the water- now go out and get ‘em!
Never did I imagine they would burrow themselves under so many layers of rocks. Nor did I think it would take, on average, 45 minutes of electrofishing a 4-ft-long pool before we could pull out a single tag. But, that’s what it took, and it wouldn’t have been possible without a lot of help and persistence (thanks to Steve, Linda, Tyler, Megan, Savannah, and Dylan!). In addition, there were several tags we finally got to recover that we suspected have been dropped for a long time, but didn’t have the time or muscle to flip large boulders and look for them.
All in all, it was a pretty successful recapture event. We managed to take tissue samples from a total of 101 fish, of which about half were tagged fish. The other 50% of tagged fish are either burrowed very deep under a rock or in a large pool, or are completely missing from the study. The tags that are completely missing are likely the victims of predation and, while we try to relocate as many of those as we can, we are also focusing our attention to places a trout might go (i.e., we have steered away from tracking on large hillslopes….likely not a living trout). But, even those fish will provide us with data. They were living in the streams for most of the study and so we do have movement histories, and we may also be able to estimate natural mortality during unusually hot and dry conditions.
Looking back, we completed this sampling at about the best timing we could have asked for. This past weekend the skies opened and Loyalsock finally received over 3 inches of rain. I suspect the fish were reenacting the infamous scene of Andy from Shawshank Redemption, because they were struggling. Hopefully this filled some dry pools and lowered stream temperatures a little, and we’ll go out tomorrow to see if the rains triggered any movement.
Now all attention turns to watching the forecast and waiting for temperatures to decrease a few degrees. Our next set of tags arrived yesterday, and I’ve blocked off early September for the next round of surgeries. But, we’ll have to wait until temperatures decrease a few degrees to make sure the fish survive. Until then, office work, tracking, and resting up for the next round.