With humans overfishing the oceans, other creatures take over where fish are missing. Today, we follow a common shrimp on his journey through life—and through the journey to become our dinner. This is not a success story.
The fight for the future of humanity seems to be filled with propaganda, misinformation, and contradicting facts. Even well-meaning documentaries such as Seaspiracy seem to add to the problem rather than clarify the state of things. The documentary made the sensational claim that our oceans will be empty by 2048, a figure they cited from a paper that has been corrected by the original publishers, as well as criticized by many scientists and critics.
News of species in decline, species that are at the brink of extinction, or even species where experts think we've passed the point of no return are real, but experts think that such overly sensationalized headlines cause more issues than they solve. It is easy to hear them and conclude there's nothing left to do.
Another issue is that many of these headlines and documentaries are limited to fish, especially fish fit for human consumption. This very limited, but unfortunately popular, way of thinking excludes not just the ocean life humans cannot (or do not) eat, but also the many ways humans exploit mollusks and crustaceans for their food diversity.
Crangon crangon is the dominant shrimp on Europe's Atlantic coast. The tautonymous name, so the doubling of the same name for genus and species, points to a type species, a representative species of the Crangon. Other examples of such type species can be found in any taxon. From less obvious ones such as Delphinus delphis, the common dolphin, to the very impressive Bison bison bison, a subspecies of the American bison, the duplication indicates a type species.
But let's return to our small brown shrimp:
They are fished—or should I say shrimped—in and around the estuaries where they are most populous. Their larvae rely on tidal currents, but all life stages from larva to adult benefit from the higher nutrient levels and lower salinity caused by river runoff in the estuaries.
Humans have been fishing these waters for the little edible critters for centuries, but things changed with the industrial revolution and the later greed for cheap, delicious seafood. Many of the estuaries were closed off by dams and other artificial constructions, changing the living situations for, among many others, the common shrimp.
The reduction of shrimp predators, especially by human fishing pressure, gave the shrimp populations a boost in the seventies and eighties, and ever since. Eutrophication, so the unnatural addition of nutrients into bodies of water, due to river-run off from the larger European rivers might have further increased these shrimp numbers, as the *Crangon crangon'*s major food supply, calanoid copepods, benefit from the higher nutrient levels in the water.
A first instinct might be to think that this development is good, but it is yet another ecosystem thrown out of wack by human activity. The shrimp were thriving, because humanity eliminated the predators by overfishing them for their own needs and wants, while polluting the waters with agricultural run-off. This rise in shrimp populations came at a heavy cost to the environment, especially to the millions of tons of fish that ended up on dinner plates.
The major countries to fish for brown shrimp are Germany, the Netherlands, Belgium, France, and the UK, as they are perfectly situated to take advantage of the common shrimp in shallow waters. But these countries are not solely to blame, as their wares get shipped all over the world. Originally, the shrimp were caught in hand-held nets that looked like a fishing net attached to a slingshot. Later horse-drawn trawls were used to catch more shrimp per unit effort.
Fortunately for the common shrimp, their populations seem to have remained remarkably stable for the past few decades—ever since they received a boost from declining predator numbers.
Nonetheless, our neverending hunger for shrimp—3 million tons of shrimp consumed in the US alone per year—has left even the Crangon crangon in decline.
Even modern shrimping is done with versions of trawling which have long been shown to negatively impact the climate and the local ecosystems by disturbing the sediment and the related infauna and epifauna, so the organisms that live in the sediment and on the sediment. Nowadays, we are still lacking an adequate alternative to shrimp trawling that can be scaled to industrial needs. Recent years have been mostly wasted on improving trawling gear instead of replacing it with more sustainable methods.
Imagine you are one of the millions of C. crangon larvae that hatch every breeding season. You hatch from your egg, which has sunk to the sediment after breeding and developed there in the high-salinity waters of the ocean. Fully hatched, you are now a Nauplius larva and will undergo five stages, each a little larger than the previous one, each a little more developed. You float alongside the plankton, with very limited swimming abilities. With each stage, your swimming abilities increase, and you become a little more independent of the current.
After the five nauplius stages, you develop into the first stage of a protozoea. Through those three stages, your mouth parts form and your abdomen develops until you reach the mysid stage with early developmental stages of legs and antenna. You are almost a real shrimp now. But while you're now in the mysis stage, you don't want to be confused with the mysis shrimp, small little imposters in the aquarium trade that are called mysis shrimp but aren't actually shrimp.
Finally, you enter the postlarval stage with developed walking and swimming legs that make you look like a miniature version of a grown shrimp. In your second postlarval stage, you'll get drawn to the lower-salinity waters of the estuaries, so you ride the tides to get to the nutrient-rich waters there. You are very efficient about this, riding the flood into the estuary, while settling onto the bottom during ebb tides.
And then, finally, you are a juvenile, rapidly growing, and only distinguishable from the adults because of your shorter rostrum—that horn-like thing on your head—and the lack of reproductive maturity.
The subadult stage, your last stage before you are considered an adult, is essentially your teenage years when your reproductive organs start to develop into full functionality. It's also when you leave the nutrient-rich waters of the estuaries to return to the sea, where you hope to find a suitable mate. As an adult, you live a few miles away from shore, and might migrate hundreds of miles along the coast in search for a suitable mate and breeding spot.
Or at least, that would be your life if you don't get eaten by the predators humans haven't managed to fish out of the ocean yet, or caught in one of the trawling nets of shrimpers.
Shrimpers have decades of experience in finding the right spot to catch you on your way out of the estuary or during your long migrations.
If you end up in the shrimper's nets, you won't survive for long.
To keep shrimp fresh, shrimp are typically boiled in seawater and preservatives on the boat, turning them pink or orange. This color can also be observed in the ocean or aquarium when shrimp die of natural causes, and is no reason for concern as of itself. Some wares get sold right when the boat lands at the port, others get sorted by size and exported to countries with cheap labor forces for peeling.
This labor used to be done in the fishermen's homes in the catching countries, but this has been prohibited by the EU for hygienic reasons, so now this step of production is outsourced to cheap-labor countries such as Morocco and Belarus.
Peeling machines were introduced in the 80ies, but the efficiency is much smaller than with hand peeling, leaving even less of the desired meat after peeling.
After peeling, no matter if locally or abroad, the shrimp then return to the markets and restaurants as fresh local seafood, often blazing over the fact that the shrimp took detours of hundreds or even thousands of miles to get peeled.
While humanity's hunger for fish will likely keep shrimp populations stable for potentially decades, the popularity of shrimp meat is bound to rise, and along with it, the catch numbers.
The fact that C. crangon seems to benefit from our overexploitation of the oceans, does not make this a success story. Removing predators from their ecosystems changes the equilibrium, frequently favoring smaller or less specialized organisms. Sea jellies (aka "Jelly fish") take over the water columns of ecosystems where there used to be gigantic tuna fish in unfathomable numbers. And shrimp take over the sediment, benefiting from the ecosystem out of balance.
But even if we focus only on C. crangon and ignore how they came to be so populous, the methods of shrimping with trawls, as well as the practice of shipping them across the globe, both for peeling and consumption, leave deep marks on our planet.
Maybe it is time to return to more sustainable methods of fishing, maybe using the hand-held nets popular now only with children, and reducing our consumption of animal products in general.
- H. Charlier, R., 2012. Crangon crangon, endangered or merely on a via dolorosa? Annals Series on Biology Sciences, 1(1), pp.31-58.
- Boddeke, R. 1996. Changes in the brown shrimp (Crangon crangon L.) population off the Dutch coast in relation to fisheries and phosphate discharge. ICES Journal of Marine Science, 53: 995–1002.