So Opinionated: Invasion of the Jellyfish

It seems that people either love fish or consider it repugnant, but either way, one cannot ignore its important relevance to our diet. Speaking on a global scale, millions of people depend on our oceans for their livelihoods, so that restaurant menus are able to offer it's customers a delectable array of seafood.

Here's an eye opener, according to -Overfishing.org :

25% of the entire world's fish stocks are either over exploited or depleted;

52% of fish stocks are fully exploited;

20% are moderately exploited;

17% are over exploited;

7% are depleted;

1% is recovering from depletion.

Another 52% is fully exploited, these are in imminent danger of over exploitation (maximum sustainable production level) and collapse. Thus a total of almost 80% of the world's fisheries are fully - to over-exploited, depleted, or in a state of collapse.

Worldwide about 90% of the stocks of large predatory fish stocks are already gone

In the real world all this comes down to two serious problems.

We are losing species as well as entire ecosystems. As a result the overall ecological unity of our oceans are under stress and at risk of collapse.

We are in risk of losing a valuable food source many depend upon for social, economical or dietary reasons.

For people who dislike eating fish, this probably reads more like 'a solvable problem' as opposed to a 'looming ocean ecology collapse.'

Here is one such discovery about our oceans:

In 1992 the once thriving cod fishing industry (in Canada) came to a sudden and full stop when at the start of the fishing season no cod appeared.

This meant that 40,000 people lost their jobs with an ocean ecosystem in a 'complete state of decay.'

This was caused by decades of massive over fishing and the cod have never returned to the region in 15 years.

The shrimp and and crab fisheries off the coasts of Nova Scotia and Newfoundland are now reporting poor fishing results and are the immediate result of over fishing cod and haddock.

Scientists agree that at current exploitation rates many important fish stocks will be removed from the system within 25 years. [...] The big fish, the bill fish, the groupers, the big things will be gone. It is happening now. If things go unchecked, we'll have a sea full of little horrible things that nobody wants to eat. We might end up with a marine junkyard dominated by plankton.”

Mmmmm appetizing.

Unless these trends are reversed, restaurant favorites such as plaice, hake, haddock and cod will disappear on restaurant menus, to be replaced by exotic alternatives such as jellyfish.

In the west, people for the most part are intolerant of any seafood that comes under the umbrella of an exotic label, whereas China and Japan have been eating such menu items for hundreds of years.

This is not science fiction and it's happening now. Wait till you find out what we might be forced to eat because of a global ignorance that has defied/defies prior warnings concerning over -fishing.

Boris Worm of Dalhousie University in Halifax, Nova Scotia, Canada and the Census of Marine Life project says:

"We are entering a time of great uncertainty," [...] "If we continue as we have been, in 50 years there may not be much left to take from the ocean."

The census findings were published in 'Science' back in 2006 and even then, the news was gloomy for our oceans. The foretelling by scientists is that unless a solution is found, all current and commercial fish and seafood species will collapse by 2050.

To make up their shortfalls, fishing boats have changed their methods (out of necessity - not altruism) to fish for smaller, more currently available fish, such as plankton eating fish - sardines and anchovies.

This is not a solution but a race towards the creation of a yet another potential catastrophe! We can't just keep fishing down the food chain as the larger species disappear from our oceans!

Fish such as hake (and other large predatory fish) help to maintain the lower forms in the food chain. Tom Anderson, a marine ecologist at the National Oceanography Centre in Southampton, UK tells us:

"If you remove small fish there is every possibility that other species in the food chain, like jellyfish, will have a good time of it,"

Nets filled with smaller fish deprive the larger fish of their diets and will increase the demise of rapidly disappearing predatory or larger fish from our oceans.

This is already happening in one of the world's most productive fisheries, the Benguela current off the coast of Namibia in southern Africa.

When Christopher Lynam of the University of St Andrews in the UK and his colleagues surveyed the area in 2003, they found that the ecosystem, which once supported large populations of sardines and anchovies, had been taken over by two species of jellyfish.

The study estimated the biomass of jellyfish in the region at 12.2 million tonnes, more than three times that of mackerel, hake, sardine and anchovies combined.

Jellyfish thrive on food that is not consumed by smaller fish - explaining the current situation in Namibia. A profound ecosystem shift has occurred which does not benefit fishing or what had been the local fish in the area.

Since this 'shift' large jellyfish such as Scyphozoa and Hydrozoa have become prominent, whereas the location had been devoid of jellyfish before.

The Gulf of Mexico, the Mediterranean, Alaska, the sea of Japan, and the Black Sea have all reported enormous blooms of phytoplankton from coastal run-off, which in turn has contributed now to the epic proportion of giant jellyfish (Nemopilema nomurai) which grow up to more than 2 metres in diameter.

Forget my fear of sharks - giant jellyfish? That does sound like science fiction! "The Attack of the Giant Jellyfish!"

In 2003 alone this jellyfish cost the Japanese fishing industry over $100 million, "clogging and bursting nets, causing high mortality of the catch due to venom, increasing the risk of capsizing trawlers and giving fishermen painful stings", says Masato Kawahara, a marine ecologist at Hiroshima University in Japan.

According to George Jackson of the University of Tasmania in Australia, another rapidly increasing species in our oceans are squid, which thrive in all oceans. Their predators have been over-fished, increasing the jellyfish feeding grounds in all directions.

Squid are naturally hunted by larger fish such as tuna, marlin and swordfish, so if the larger fish disappear, the jellyfish will be legion. He calls them "the weeds of the sea."

Closer to home: My father in law, a (sometimes) angler, has lamented many a time that as a child, he remembers when the Columbia River was literally filled with salmon. He describes it as; "you could almost walk across the backs of the salmon to the other side.

It's only taken 60 or so years for it to decline to almost none.

There is so much more to read on this topic so I'll list some recommended reading for readers, rather than continue here.

However, I warn you, further reading, is bordering on frightening.

Recommended Reading:

New Scientist - Tech
Jellyfish Mucous Perfect for Cosmetics
Credit not available.

New Scientist - Tech
Two Recipes for the Seafood of the Future
by Ben Crystall and Hugh Fearnley-Whittingstall

New Scientist - Environment
Fish Numbers Outpace Human Population
by Debora MacKenzie

Sources:

Science Direct
Jellyfish overtake fish in a heavily fished ecosystem
Contributers: Christopher P. Lynam, Mark J. Gibbons, Bjørn E. Axelsen, Conrad A.J. Sparks, Janet Coetzee, Benjamin G. Heywood and Andrew S. Brierley.

Overfishing.org
Overfishing - A Global Disaster
No credit given.

New Scientist - Environment
Jellyfish Sushi: Seafood's Slimy Future
by Caroline Williams

Image Sources:

New Scientist
Jellyfish Sushi: Seafood's Slimy Future
Gordon T. Taylor - Stony Brook University / NOAA

New Scientist
Nomura's Jellyfish
KENPEI - Wikimedia Commons

New Scientist
Going, Going, Gone
Caroline Williams

New Scientist
Jellyfish Sushi: Seafood's Slimy Future