Bad at Goodbyes

Rough Transcript

Intro 00:05

Welcome to Bad at Goodbyes.

On today’s show we consider the European Sturgeon

Species Information 02:05

The European Sturgeon is a critically endangered fish native to Western Europe, specifically the Gironde estuary on the west coast of France in the Gironde Department.

The European Sturgeon is enormous. It has a long torpedo-shaped body, which can reach lengths of over 15 feet, and weigh over 800 lbs.

It is an ancient species, fossil records indicate that sturgeons first appeared during the Late Cretaceous period, roughly 85 million years ago. So dinos, this is the era of T.Rex and Triceratops and Velociraptor.

Many basic attributes of the sturgeon have not changed much in the millenia of their slow evolution, giving us a kind of echo, or like a glimpse of prehistoric life. For example, the European Sturgeon does not have scales like we typically see on most contemporary fish. Instead, it grows five rows of bony plates called scutes that run along its body. The scutes are a protective armor, against scrapping injury and predation.

The European Sturgeon has a pointed, wedge-shaped snout and its mouth is located on the underside of the head. This mouth position is adapted for benthic feeding. Benthic just means the deepest zone of a body of water, like a river, lake or sea; so the European Sturgeon is a bottom-feeder.

Between its mouth and the tip of its snout, it grows four barbels. Barbels are tubular whisker-like sense organs, um, think catfish or carp. Barbels are sense organs with taste buds and highly adapted nerve endings. And so the sturgeon can “taste” the water and detect chemicals, and sense changes in water currents and pressure, helping them locate food, even in the murky dark depths of their habitat. There is muscle tissue in the barbels, allowing the sturgeon to move them and they’ll use their barbels to probe sand or mud, searching for prey.

The European Sturgeon’s tough hide ranges from greenish-brown to almost blackish on its dorsal side, its back. The flanks, or sides, are lighter, with silvery tints and its belly is typically white.

Its skeleton is cartilage, like a shark or ray. 

It has two spiracles, these are respiratory openings located behind each eye. These are like tiny gill slits, serving as a secondary supportive respiratory system. So like when the sturgeon is resting or feeding, its mouth might be closed, unable to draw in water for respiration. The spiracles allow the sturgeon to take in water, to breathe, even when its mouth is obstructed. That water then passes over the gills, where oxygen is extracted and transferred to the blood. 

Spiracles are considered like an ancient feature in fish evolution. The fossil record suggests that they were present in the earliest fish, but are super rare in modern fish species. As fish evolved, more efficient methods of respiration developed, and today, spiracles are just found in sturgeon, sharks, rays, and skates.

In my research, I found that the Sturgeon is sometimes referred to as a ‘living fossil’, so like a species alive today that closely resembles its ancient fossil record, suggesting they have undergone limited evolutionary change over vast time periods.

I also encountered some contemporary pushback on the ‘living fossil’ concept as a whole. Researchers suggest that it is a kind of misnomer that can lead to misunderstanding or faulty assumptions. So for example it might imply that evolution has stalled, or reached a kind of apex, neither of which are true. Evolution, at least prior to extinction, is ever ongoing, James Rosindell, Professor in the Department of Life Sciences at Imperial College London says “evolution cannot simply be ‘switched off’. Organisms will continue to mutate and not all will survive to reproduce, so evolution will occur.” Rosindell, convincingly to my mind, argues that an evolutionary heritage model offers richer understanding than the “living fossils” nomenclature. His suggested framework identifies species by the rarity of their evolutionary features rather than by their resemblance to ancient species. So like not for their lineage but for their special and sometimes singular contribution to our contemporary biodiversity.

There is also a related conservationist argument against the “living fossils” nomenclature. When we use terms like relic species or living fossils we imply that they are like not of our time, our language consigns that species to the past. But the Dawn Redwood, the Platypus, and the European Sturgeon are all contemporary species, they live in our world, in our time, and are vital contributors to their ecosystems. And so the concern is that calling a being a relic or a fossil, may undermine the urgency needed to preserve and protect it. In particular because in most cases the current threat to these species is not natural selection, it’s not evolutionary, it’s human-caused, anthropogenic.

The European Sturgeon is anadromous. This means they are born in freshwater riverbeds, then as young juveniles migrate downstream to coastal saltwaters, where they spend most of their lives, returning to their freshwater birthplace to mate and spawn.

They have adaptations that allow them to regulate the salt concentration in their bodies (a process called osmoregulation) and survive in waters with vastly different salinity levels. 

So adult European Sturgeon, who live near the coast in oceans, seas, and estuaries, estuaries are the brackish transition zone where river freshwater mixes with ocean saltwater. They leave their marine home, swim upstream, sometimes as far as 200-300 miles, to return to the site of their own birth to mate. Generally solitary, during this reproductive journey which takes place roughly every other year for males and every 3-4 years for females, the sturgeon gather in mass.

Mating is external. At the spawning grounds, female sturgeon release their eggs into the water, males release their sperm near the eggs, fertilization occuring outside the body. A single female can release hundreds of thousands of eggs during a spawning season. And the eggs have an adhesive coating that helps them stick to riverbottom muds or gravel, keeping them from being swept away by the current. And then after spawning, the adults go their separate ways, returning downstream to the sea; there is no like parental care of the eggs or young. The eggs gestate for about a week, hatch, and the young are independent from the moment of birth.

The young will spend between 2-6 years, migrating downstream as they slowly adapt to saltwater, sometimes moving back and forth between river and sea until eventually settling into their primary coastal saltwater habitat.

Female European Sturgeon reach sexual maturity between 10-20 years, males between 10-12 years. Their estimated lifespan is 50 years.

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In the dream, I cannot help myself, in the dream, I dream prehistoric. Of the 85 million years, of the 1 and half million generation of sturgeon, the unfathomable heritage, the long twisting story written in their DNA, in the dream, like an eons-long flipbook of swimming and evolving, in the same waters. That is the thing for me, each cycle, every generation to return over and over, ever and ever to their same birthplace to spawn, to renew, to begin again, ambassadors in a forevers-long renegotiation of the old treaty between water and life. In the dream.

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In both their fresh and saltwater habitats, the European Sturgeon feeds on Benthic Invertebrates, so these worms, crustaceans and small mollusks that live on or in the bottom sediments of the riverbed or sea floor.

The European Sturgeon has a protrusible mouth, meaning it can extend its mouth forward to create a kind of tube and they use a vacuum feeding technique, creating suction to draw prey into their mouths along with water and sediment.

They are seasonal opportunistic feeders, meaning their diet varies depending on the season and they will consume a variety of prey depending on what is available. They tend to be more active and feed more intensively at night.

Historically the European Sturgeon was found across the European Continent, in the North Sea, in the Black Sea, in the Danube, in the Rhine, in the Baltic Seas in the English Channel, in the Mediterranean, and across the Western European Atlantic coasts.

Today, the only remaining wild population is restricted to the Gironde estuary fed by the Garonne River on the southwestern coast of France near the city of Bordeaux. The mature sturgeon in the estuary and the nearby coastal atlantic waters, go upstream, up the Garonne River to spawn.

This is wild, the Garonne River runs right through the heart of the city of Bordeaux, so the sturgeon is swimming upstream, navigating bridges, water taxis, houseboats, tourist river cruises, and industrial and commercial waterway use. Past Bordeaux they still have another 80+ plus miles to reach their breeding site, deeper waters with a gravelly riverbed, further south toward the like Toulouse and the Pyrenees.

This whole bioregion is known as the Aquitaine Basin which includes coastal dunes, pine forests, wetlands, and river systems. The Gironde estuary itself is formed where the Garonne and Dordogne rivers meet the Atlantic, the estuary stretches over 45 miles inland.

The landscape of the estuary is marked by mudflats, sandbanks, and salt marshes and further inland the marshes give way to forests, vineyards and farmlands.

The climate in this region is temperate and oceanic, with warm summers and mild winters. Summer high temperatures typically average in the mid-70s °F, winter lows rarely dip below freezing. The annual rainfall is moderate, averaging around 35 inches per year.

The European Sturgeon shares the Garonne estuary with Northern Pintail, Snails, Common Cordgrass, European Otter, Gorse, Allis Shad, Red Deer, Sea Purslane, Grey Heron, Marine Bristle Worms, Mallard, European Eel, Sowbugs, Common Reed, Opossum Shrimp, Sea Lamprey, Maritime Pine, Wild Boar, European Flounder, Aquatic Earthworms, Great Egret, Sea Couch Grass, Mussels, Purple Heron, and many many more.

Population threats

Historically the European Sturgeon’s population was profoundly reduced by a range of anthropogenic, that’s human-caused, activities. So, habit encroachment and habit reduction through direct development of river systems, so like dams, locks, building canals, and bridges, and riverbed gravel dredging (which specifically affects spawning grounds). Commercial and industrial activities as well, so shipping and other waterway traffic and water pollution from industrial dumping and agricultural runoff. 

Today, most of these threats persist, with the additional threat of bycatch. So contemporary industrial fishing does not look like perhaps what we imagine or have seen on like reality tv. This is not a dozen folks on a skiff braving the high seas. These are massive 1000 ton, 400+ ft, industrial trawlers with like 100 crewmembers. They require powerful engines, guzzling diesel fuel and generating greenhouse gasses, and the bottom-trawlers that impact the sturgeon release these massive weighed nets that scrape the seabed over a roughly 300 ft area and ensnare everything in its path, catching hundreds of thousands of fish in a single haul.

Fishing of the European Sturgeon is globally prohibited but nevertheless bycatch occurs when the sturgeon is caught in these nets. And I don’t want to be too grim here, but bycatch means dead, this isn’t like your grandad in a yellow slicker on his dinghy pulling the hook out and tossing ‘em back. This is thousands of fish, out of water, writhing for breathe, caught in a mesh.

And complicating this is that industrial fisheries, concerns about penalties, are generally disincentivized from reporting bycatch so it is hard for conservationists to know how widespread the issue is.

And lastly, human-induced climate change may prove a nearterm threat to the European Sturgeon. Global warming means that Atlantic ocean undersea currents are changing. This will have broad impact on water temp, ocean salinity, sea level and weather patterns. All of which will likely affect the remaining European Sturgeon population

Management, protection and conservation of the European Sturgeon has been ongoing for over 100 years, for example in 1915, baited hook-lines were prohibited in the Eider River in Germany to protect juvenile sturgeon and in 1932 in Poland, fishing of the European Sturgeon was totally prohibited.

And yet, throughout the twentieth c, their population plummeted, leading to the initiation of captive breeding and artificial reproduction programs in France in the 1990s. Unfortunately, the success of these efforts was fairly limited with initial re-releases in the early 2000s resulting in a survival rate of only 3-5%.

These programs continue though and are expanding, with reintroduction of the species in Germany, the Netherlands, the Baltic sea and continued restock and monitoring of the Gironne population in France.

Conservation of the species is also complicated by like human behavior and bureaucracy and social and governmental systems. You’ll recall that it takes about a dozen years for juvenile sturgeon to reach reproductive age and then another half dozen years for the new spawn to return to the sea. So, evaluating the success of any reintroduction effort is like a 15-20 year process. And well, observations of my species seem to suggest we have a short memory and seem disinclined toward longterm planning and for funding things without immediate gratification.

As an example, a 1999 report indicated planned releases in over 10 European nations, and here 25 years later it appears that only three of those programs remain.

The European Sturgeon has been considered critically endangered on the IUCN Red List since 1996 and their population is currently in decline. Counts estimate that less than 50 reproducing adult European Sturgeon remain in the wild.

Citations 30:47

Information for today’s show about the European Sturgeon was compiled from:

“Acipenser sturio Recovery Research Actions in France.” Williot, P., Rochard, E., Rouault, T., Kirschbaum, F. (2009). In: Carmona, R., Domezain, A., García-Gallego, M., Hernando, J.A., Rodríguez, F., Ruiz-Rejón, M. (eds) Biology, Conservation and Sustainable Development of Sturgeons. Fish & Fisheries Series, vol 29. Springer, Dordrecht – https://doi.org/10.1007/978-1-4020-8437-9_15 

“Biological characteristics of European Atlantic sturgeon, Acipenser sturio, as the basis for a restoration program in France.” Williot, P. et al. (1997). In: Birstein, V.J., Waldman, J.R., Bemis, W.E. (eds). Sturgeon Biodiversity and Conservation. Developments in Environmental Biology of Fishes, vol 17. Springer, Dordrecht. – https://doi.org/10.1007/0-306-46854-9_24 

“Biological Observations on the Atlantic Sturgeon (Acipenser sturio)”. Borodin, N. (1925). Transactions of the American Fisheries Society, Vol. 55 No.1, p 184–190 – https://doi.org/10.1577/1548-8659(1925)55[184:BOOTAS]2.0.CO;2 

“Conservation Status and Effectiveness of the National and International Policies for the Protection and Conservation of Sturgeons in the Danube River and Black Sea Basin”. Strat, Daniela, and Iuliana Florentina Gheorghe. 2023. Diversity Vol. 15, no. 4: 568 – https://doi.org/10.3390/d15040568 

“Energy audit and carbon footprint in trawl fisheries.” Sala A, Damalas D, Labanchi L, Martinsohn J, Moro F, Sabatella R, Notti E. Scientific Data. 2022 Jul 20;9(1):428. – https://doi.org/10.1038/s41597-022-01478-0 

“The Evolution of the Spiracular Region From Jawless Fishes to Tetrapods”. Gai Zhikun, Zhu Min, Ahlberg Per E., Donoghue Philip C. J. Frontiers in Ecology and Evolution Vol. 10. 2022 – https://doi.org/10.3389/fevo.2022.887172 

IUCN – https://www.iucnredlist.org/species/230/242530547

“Meristic and morphological features of the Baltic sturgeon (Acipenser sturio L.)”. Debus, L. (1999). Journal of Applied Ichthyology, Vol. 15: 38-45. – https://doi.org/10.1111/j.1439-0426.1999.tb00203.x 

National Oceanic and Atmospheric Administration, Fisheries. Species Directory: European Sturgeon – https://www.fisheries.noaa.gov/species/european-sturgeon/overview 

“Phylogenetic Biodiversity Metrics Should Account for Both Accumulation and Attrition of Evolutionary Heritage”. James Rosindell, Kerry Manson, Rikki Gumbs, William D Pearse, Mike Steel. Systematic Biology, Volume 73, Issue 1, January 2024, Pages 158–182 – https://doi.org/10.1093/sysbio/syad072 

“Phylogeography of the European Sturgeon (Acipenser sturio): A critically endangered species”. Olivier Chassaing, Nathalie Desse-Berset, Catherine Hänni, Sandrine Hughes, Patrick Berrebi. Molecular Phylogenetics and Evolution, Volume 94, Part A, 2016, Pages 346-357 – https://doi.org/10.1016/j.ympev.2015.09.020

“Reasons for the decline of Acipenser sturio L., 1758 in central Europe, and attempts at its restoration”. J. Gessner. Bulletin of the Spanish Institute of Oceanography Vol. 16 no. 1-4. 2000 pp 117-126 – https://core.ac.uk/download/pdf/71764893.pdf

Wikipedia - https://en.wikipedia.org/wiki/European_sea_sturgeon

For more information about the conservation and protection of the Sturgeon please visit the World Sturgeon Conservation Society at https://www.wscs.info 

Music 32:58

Pledge 37:59

I honor the lifeforce of the European Sturgeon. I will commit its name to my record. I am grateful to have shared time on our planet with this being. I lament the ways in which I and my species have harmed and diminished this species.

And so, in the name of the European Sturgeon I pledge to reduce my consumption. And my carbon footprint. And curb my wastefulness. I pledge to acknowledge and attempt to address the costs of my actions and inactions. And I pledge to resist the harm of plant or animal kin or their habitat, by individuals, corporations, and governments.

I pledge my song to the witness and memory of all life, to a broad celebration of biodiversity, and to the total liberation of all beings.