Tag Archives: predator

Episode 3: A Quiet Place

We dive into the quiet B O I S from 2018’s A Quiet Place. Dave think lions are from Antarctica, Adam gets too damn excited by Alligator gar and Sam’s stepson ruins the episode.

Movie History/Movie Any Good – 6:28
Quiet Physiology – 17:16
Quiet Ecology – 44:40
A Quiet BOI vs. Dwight Schrute – 1:09:46

Listen to the full episode below. For a more detailed breakdown, head over to Cinematica Animalia.

The Asian Ladybeetle

The Asian Ladybeetle, which has now established itself in Norway and will likely be a permanent fixture in our ecosystem

The Asian Ladybeetle, which has now established itself in Norway and will likely be a permanent fixture in our ecosystem (Image Credit: Scott Bauer, CC0)

Reasons for deliberately introducing novel species vary, from their aesthetic appeal to a boost they may provide the economy with. Using them for biological control is another, and it has led to some of the world’s most infamous biological invasions. Today we look at the Asian Ladybeetle, which Norwegian farmers were keen on importing into the country to use to control pest species that were damaging local crops.

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The American Mink

The American Mink is pretty much a Norwegian mainstay these days. So what sort of impact have they had?

The American Mink is pretty much a Norwegian mainstay these days. So what sort of impact have they had? (Image Credit: Ryzhkov Sergey, CC BY-SA 4.0)

Fur farming isn’t a topic we’ve had much cause to touch on so far in this series. But today, we look at a species that was introduced specifically for that purpose, whose presence in Europe is disliked by ecologists and animal rights activists alike.

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Finding the Key to Reef Shark Conservation

Reef accessibility impairs the protection of sharks (2018) Juhel et al., Journal of Applied Ecology 55

Species such as this Carribean reef shark have higher extinction risks than most fish. But how effective are our management efforts?

Species such as this Carribean reef shark have higher extinction risks than most fish. But how effective are our management efforts? (Image Credit: Wikipedia Commons)

The Crux

The importance of sharks goes well beyond what Jaws did to Hollywood, or one week in the USA each July. In any reef ecosystem, sharks perform a key functional role, exerting top-down pressure, stabilising food webs, and improving general ecosystem functioning. They’re also ‘charismatic’ species, meaning they’re easier to raise funding for, and bring money in through tourism. Yet pressure from fishing suggests that reef shark populations may be under threat, and with high body sizes and long lifespans, their populations are more sensitive than most to overfishing, making extinction risks higher.

Yet the lack of data on shark populations means that the effectiveness of the few existing management programs is largely untested. This paper looks at Marine Protected Areas (MPAs), areas in which national or international bodies prevent fishing or even entry, to see whether or not they are an effective conservation method for shark populations.

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Bringing Back the Wolverine

The Swedish government changed tactics at the end of the 20th century, giving incentives to farmers when there were successful wolverine reproductions in their area

The Swedish government changed tactics at the end of the 20th century, giving incentives to farmers when there were successful wolverine reproductions in their area (Image Credit: Vojtěch Zavadil, CC BY-SA 3.0)

Paying for an Endangered Predator Leads to Population Recovery (2015) Persson et al., Conservation Letters, https://doi.org/10.1111/conl.12171

The Crux

Humans have a long history of driving dangerous predators out of their backyard. Wolves and wolverines have been driven out of different parts of Europe at different points in history at the behest of farmers looking to protect their livelihood, and the Tasmanian Tiger was driven to extinction for the same reason. But with the realisation that these predators bring enormous ecosystem benefits, governments have been searching for ways to bring about co-existence between predators and locals.

This study looks at a scheme introduced by a Swedish government in 1996, where reindeer herders had previously been compensated for any wolverine related losses. The new scheme introduced compensation for successful wolverine reproductions in the area. Persson et al. decided to have a look at how it fared.

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The Red King Crab

The Red King Crab has been invading Norwegian waters over the last 50 years

“… a red army of monster crustaceans – marshaled by Soviet-era leaders – is threatening to invade Western Europe …”

– James Owen, National Geographic, 2004

Ominous. That’s the thing, isn’t it. Some invasive species look harmless. You can’t be scared of a baby Canada Goose, can you? Or a nice purple garden flower. Such florescence. You can, however, be scared of a spiny, alien-looking 10 kilo mass of spines and pincers that has been shuffling its way into Norwegian waters over the last half-century.

What are they?

Paralithodes camtschaticus, the Red King Crab, is the most heavily fished crustacean in Russian seas. They fetch a high price at the market, and over 50 million USD was made in exports in Norway alone in 2016. A common trait amongst invasive species, they are a generalist predator, and will eat anything, from small invertebrates to large echinoderms and bivalves. They are among the largest arthropods living, with 8 legs, 2 pincers, a carapace of around 22cm, and an unholy mass of mandibles and spines to go with it. They are also quick movers, and can relocate based on available food quickly. Basically, if I were a sea urchin, were it not for the sea urchin’s general lack of the concept of fear or any other emotion, I’d be terrified.

The current distribution of the crab (top) and the area it will likely spread to in the Barents Sea over the coming years

The current distribution of the crab (top) and the area it will likely spread to in the Barents Sea over the coming years, demarcated by the 0-4 degree zone (bottom) (Image Credit: Christiansen et al., 2015)

How did they get here?

The crab is native to the northern Pacific Ocean, but like the Pink Salmon, they were deliberately stocked into the Murman coast by Russian scientists for commercial fishery. Since the 60s the crab has spread into Norwegian waters, and was well established in Northern Norway by the 90s. Soon after this the population skyrocketed, and the majority of fjords in Northern Norway are now occupied by the crab. Whilst the crabs prefer colder temperatures, increased temperature doesn’t seem to be a barrier for migration, and the fact that there are also reports of human introductions as far south as Bergen should be worrying.

What do they do?

Their role as a large predator of pretty much anything, combined with the fact that they migrate between different depths and are fast movers, mean that they can significantly change the physical structure of the ecosystem that they inhabit very quickly. Their removal of larger bivalves and echinoderms has lead to lower diversity and abundance in Norwegian fjords, particularly among species with low motility, and subsequent changes in the entire community composition of an ecosystem. They can also contribute to a loss in production and nutrient recycling, and subsequent drops in populations of local fish.

Here we see a Red King Crab singing along to YMCA by The Village People

Here we see a Red King Crab singing along to YMCA by The Village People (Image Credit: Creative Commons)

How do we stop them?

This is difficult, and marks the point in this series where we need to actually consider the term ‘invasive’. So far, I’ve considered invasive species as alien species which demonstrate a negative effect for the ecosystems they are novel to, or on the economy of a nation, with no pronounced positive effects in any other aspect. However in many international and national laws, invasive species are those which have a negative impact on human health or economy. And here lies the issue. Whilst the Red King Crab has an undeniably negative effect of local biodiversity, it has a undeniably positive effect on the Norwegian economy.

I’ll return to this topic next week, but for now let’s approach the issue as if we want to stop the incursion. The crabs seem to display high site loyalty, which means that they’re theoretically easy to prevent from spreading further down the Norwegian coast, given correct management. The crabs prefer cold waters so let’s keep that climate change going and drive them out of Norway oh dear God my apologies that’s a terrible idea.

Reducing supply-and-demand lessens the crab’s economic value, so avoiding crab meat is a good step. Yet the Norwegian government’s tactics here are more likely to make a difference. Currently the practice is to maintain a certain capacity in some areas, whilst aiming for fishing to eradication in areas further south to prevent spreading. However there is little incentive for fishermen to eradicate a substantial part of their livelihood, so these regulations may need to be more strictly enforced, or the quota regulated areas restricted further.

For more information on the crab, we invite you to read the following articles.

Giant Crab ‘Red Army’ Invades Norway by James Owen for National Geographic News

Invasive Alien Species Fact Sheet –Paralithodes camtschaticus by the Online Database of the North European and Baltic Network on Invasive Alien Species

Current Status of the Red King Crab and Snow Crab Industries in Norway by Lorentzen et al.

Thermal behaviour and the prospect spread of an invasive benthic top predator by Christiansen et al.