A new global report reveals a stark reality: populations of migratory freshwater fish species, including salmon, trout, eel and sturgeon, ar
Excerpt from this story from Mongabay:
A new global study reveals an average 81% decline in migratory freshwater fish populations between 1970 and 2020.
Habitat loss, degradation and overfishing are the main threats to migratory fish, which are crucial for food security, livelihoods and ecosystems worldwide.
While 65% of species have declined, 31% have shown increases, suggesting that conservation efforts and management strategies can have positive impacts.
The report calls for stronger monitoring efforts, protection of free-flowing rivers, and meeting global biodiversity goals to address this crisis.
The report analyzed data from 1,864 populations of 284 migratory freshwater fish species across the globe. Contributing to the report were researchers from the World Fish Migration Foundation, the Zoological Society of London (ZSL), the International Union for Conservation of Nature (IUCN), The Nature Conservancy (TNC), Wetlands International and WWF.
The researchers found that fish populations had declined significantly more in some regions than in others. For example, Latin America and the Caribbean experienced the most severe decrease at 91%, while Europe saw a 75% decline. North America showed a 35% decrease, and Asia-Oceania reported a 28% decline. Data for Africa were limited, making it difficult to determine conclusive trends for that continent.
Please tell me about fish taxi and what's a culvert
Absolutely! Allow me to set the scene:
Two salmon are swimming upstream when they smack directly into a huge concrete wall. One turns to the other and says, "Dam."
...that one definitely works better out loud, with a nice flat delivery. But it's a good starting point. Unlucky salmon are doomed to deliver the punchline to this terrible dad joke. Really lucky salmon are blessed with wild rivers with no dams at all. Medium lucky salmon have to ride the salmon cannon, navigate a fish ladder, or catch the fish taxi to get upstream. These are all fish passage solutions put in place to make up for those most intimidating barriers to migration: dams.
A quick note: I'm going to continue to focus on salmon in the Pacific Northwest, because that's what I'm familiar with. Different locations with different species of fish may have other concerns or solutions related to fish passage. But it's a big deal here because salmon have to migrate upstream to lay their eggs and continue their life cycle and everyone wants there to keep being iconic and delicious salmon around.
With that out of the way, and seeing as this post is already getting long, buckle up for the fish taxi details with a side of culverts under the cut! I promise a video and a meme to liven things up before we wrap.
Fish ladders are old news. Boring. And, frankly, expensive and challenging to design well and impossible to implement at all above a certain size.
Enter the fish taxi. The idea is as simple as it is ridiculous. Just round up your fish on the downstream side, put them in a truck with a big water tank, and drive them upstream of the dam for release. Easy peasy!
In practice there's a little more to it. Puget Sound Energy operates two dams on the Baker River. Their fish trap below the lower dam is pretty fancy, and even includes an "aquatic elevator" to raise fish up into the sorting facility. There's a whole series of gates and chutes and moveable walls that direct fish into the right holding tanks before finally being loaded into the trucks.
Not to boost corporate talking points about their mitigation strategies, but it is objectively a pretty successful site and this video shows the process well:
An extra cool thing about the Baker River fish taxi is that it also runs juveniles downstream. That may sound obvious but it's a huge improvement over old strategies like "hopefully some of them survive tumbling down the spillway or through the turbines." Ok, most dams have some form of bypass around the turbines, and the spillway is often the safer-than-it-looks intended route, but it still seems rough being a small fry. Getting rounded up in the floating collector and taking a taxi ride downstream starts to sound pretty good, all things considered.
Whew! That's the story of the fish taxi!
I'm going to try to keep culverts short (for now) because they're much less sexy. Normal people almost never think about culverts, but they cross them every day. Culverts are the pipes that carry water under roads. Although they aren't just pipes, they can be box or arch shaped structures and made of a variety of materials...but I digress! Basically any time a road crosses water that doesn't rate a bridge, there's a culvert. Some are just to drain runoff. Many driveways have a small culvert for the roadside ditch. But some are larger and allow entire streams to pass under the road. If they're sized appropriately, set at the right height to prevent a water surface drop, and not sloped too steeply, culverts can be completely passable and fish friendly! Alas, they often are not. Dams may be the largest structures that act as fish passage barriers, but culverts are by far the most numerous.
Washington Department of Fish and Wildlife inventories fish passage barriers to salmon and steelhead and estimates some 18,000-20,000 statewide. This is almost certainly on the low end. I mean, just imagine how MANY roads there are, and how MUCH water there is in Washington, a famously wet place. They intersect a lot. If you want to get a sense of the scale, there's a public facing, interactive map of WDFW-identified barriers here. Most of the points are culverts. Only the green points are fully fish passable. There are probably lots more points that haven't been surveyed at all yet. So yeah
[ID: "X, X Everywhere" Meme of Woody and Buzz from Toy Story reading "Culverts. Culverts everywhere." End ID]
Anyone who made it to the end has my gratitude and is welcome to use the very unofficial title of "Junior Fish Passage Nerd" any time they want. And if you made it here and are still interested in hearing about culverts or fish passage more generally...well, you know where to find me!
Here’s one for you DM’s that want a nice environmental world event, that lead to many unique scenarios.
Once a year, for over a two week period, the avian fish makes it’s migration form local rivers, to a secluded lake up on the top of a mountain, in order to mate. During this time it’s open session on the flying fish.
During this time, their will increased activity from flying predators (harpies, hippogriffs, hawks, ect) & increased activity in creatures who can either manipulate air or shot projectiles into the air. The players can also receive quest to make sure the fish’s path doesn't go through important areas & or just protect a majority of the fish from threats
Celebrate World Fish Migration Day: Understanding the Journeys of Our Aquatic Friends
World Fish Migration Day: Celebrating the Incredible Journeys of Migratory Fish
Today, on World Fish Migration Day, we celebrate the remarkable and often arduous journeys undertaken by fish around the globe. These migrations are vital for the health of our aquatic ecosystems and the survival of countless species. Understanding these movements is the first step towards ensuring their protection and the preservation of the delicate balance of life beneath the waves.
What is World Fish Migration Day?
World Fish Migration Day is a global event dedicated to raising awareness about the importance of migratory fish and the challenges they face. It’s a day to highlight the critical need for open rivers and healthy aquatic environments that allow these species to complete their life cycles. From the vast oceans to the smallest streams, fish undertake incredible migrations for feeding, breeding, and seeking suitable habitats.
Why are Fish Migrations Important?
Fish migrations are fundamental to the functioning of aquatic ecosystems. They play a crucial role in:
Nutrient Cycling: Migratory fish transport nutrients between different aquatic environments, enriching ecosystems and supporting food webs.
Population Dynamics: These journeys are essential for reproduction, ensuring the continuation of species.
Biodiversity: The existence of migratory species contributes significantly to the overall biodiversity of our planet’s waters.
Ecosystem Health: The presence and success of migratory fish are indicators of a healthy and functioning aquatic environment.
Challenges Facing Migratory Fish
Unfortunately, many migratory fish species are under threat. Human activities have created numerous obstacles that disrupt their natural life cycles. Some of the most significant challenges include:
Habitat Fragmentation: Dams, weirs, and other man-made structures block fish passage, preventing them from reaching crucial spawning or feeding grounds.
Pollution: Contaminated waterways harm fish directly and degrade the quality of their habitats.
Overfishing: Unsustainable fishing practices can deplete fish populations, making it harder for them to maintain viable numbers.
Climate Change: Altered water temperatures and flow regimes can disrupt migration cues and reduce the availability of suitable habitats.
The Role of Free-Flowing Rivers
Free-flowing rivers are the lifeblood of migratory fish. These waterways provide unimpeded access to all necessary habitats throughout a fish’s life. Protecting and restoring these natural corridors is paramount. Initiatives focused on river conservation and dam removal are crucial steps in ensuring that fish can continue their ancestral journeys.
How You Can Help
Celebrating World Fish Migration Day is more than just acknowledging the event; it’s about taking action. Here are some ways you can contribute to the cause:
Educate Yourself and Others: Learn more about migratory fish and share this knowledge.
Support Conservation Efforts: Donate to or volunteer with organizations dedicated to river conservation and protecting aquatic ecosystems.
Advocate for Policy Change: Support policies that promote free-flowing rivers and responsible water management.
Reduce Your Environmental Footprint: Minimize pollution and water usage in your daily life.
Conclusion
World Fish Migration Day serves as a powerful reminder of the interconnectedness of life on Earth and the vital role that migratory fish play. By understanding the challenges they face and actively participating in conservation efforts, we can help ensure that these incredible journeys continue for generations to come. Let’s work together to save our rivers and protect the biodiversity within them.
