How many fish species are there?

The first global census of life in the sea has logged some 230,000 species, however a ten year study on the subject performed by over 300 scientists warns of mass extinctions.

This ten year study has been the largest, most extensive study to attempt a stab at that age old question “Just how many fish are there in the sea?”

The ten year study, which was published today, is attempting to answer that question. It has analyzed the diversity, distribution and abundance of life in the world’s oceans. This study, dubbed The Census of Marine Life, hopes to give a ballpark estimate of the present marine life, and has estimated that there are more than 230,000 species living in our oceans.

“From coast to the open ocean, from the shallows to the deep, from little things like microbes to large things such as fish and whales,” explained Patricia Miloslavich of Universidad Simón Bolívar, Venezuela and co-senior scientist of the COML.
The study which was carried out also covers animals such as; crabs, plankton, birds, sponges, worms, squids, sharks and slugs.

Moe than 360 scientists from around the world got together and have spent the past ten years surveying 25 different regions, ranging from the Antarctic through the more temperate and tropical seas, to the Arctic, to attempt a head count of the different kinds of plants and animals.

The results of the study show that just about twenty percent of the marine species of the world are crustaceans such as lobsters, krill, barnacles, and crabs. Toss in Molluscs (such as squid and octopus) and fish (which include sharks) and that adds up to half of the number of species which are found in the oceans of the world.

The charismatic species often used in those ecological conservation campaigns – sea lions, turtles, whales and sea birds – make up less than 2% of the species in our world’s oceans.

Which is really interesting when you think about it.. We tend to only take notice of the species right on the surface, without really giving a second thought to those that dwell within the depths..

The surveys also pointed out the major areas of concern for the conservationist groups. “In every region, they’ve got the same story of a major collapse of what were usually very abundant fish stocks or crabs or crustaceans that are now only 5-10% of what they used to be,” explained Mark Costello of the Leigh Marine Laboratory, University of Auckland in New Zealand. “These are largely due to over-harvesting and poor management of those fisheries. That’s probably the biggest and most consistent threat to marine biodiversity around the world.”

The main threats that have been found up till now are; overfishing, degraded habitats, pollution and the arrival of invasive species. However, it was pointed out that more problems are on the horizon including; rising water temperatures, acidification thanks to global warming, and the expansion of areas unable to support life in the ocean.

Hopefully this survey will raise global awareness, and as a race, we can get together and start trying to preserve the abundant life, which is at the depths of our oceans.