Newly investigated fossils show that a type of filter-feeding fishes that aren’t closely related to today’s whales (who, of course, are mammals and not fishes) roamed the oceans during the Mesozoic Era some 170 million years ago. Previously the whales were believed to have been the first large filter feeders, but these new fossils tell a different story. See pictures here

The giant filter feeders, which have been given the name Pachycormiforms, died out at the same time as the dinosaurs. Eventually sharks began filling the vacant ecological niche some 56 million years ago, followed by modern cetaceans such as whales roughly 22 million years later.

The Pachycormiform fossils have been investigated by a team of researchers* led by University of Oxford scientist Matt Friedman, as a part of a study where both old and new fish fossils from England, Japan and the USA have been put under scrutiny. The article has been published in the journal Science.

Some of these fishes were true giants in the world of bony fishes, such as the 6 meter (20 feet) long Bonnerichthys that inhabited a seaway covering what is today the state of Kansas, USA.

“A previously described species, Leedsichthys, from the Jurassic of Europe that belongs to the same lineage that includes Bonnerichthys was even larger, likely reaching up to about 30 feet, which is the most massive bony fish of all time,” said Kenshu Shimada, co-author of the article and professor in the Environmental Science Program at DePaul University.

Bonnerichthys was first believed to have been similar to a swordfish, with numerous fang-like teeth.

“However, our close examination of the specimen showed that such a long snout and fang-like teeth were not present in the fish,” Shimada said. “Rather, with a blunt massive head, the fish had long toothless jawbones and long gill-supporting bones that are characteristic of plankton-feeding fishes.”

http://www.sciencemag.org

*– Matt Friedman, Department of Earth Sciences, University of Oxford, Parks Road, Oxford OX1 3PR, UK.

– Kenshu Shimada, Environmental Science Program and Department of Biological Sciences, DePaul University, 2325 North Clifton Avenue, Chicago, IL 60614, USA, and Sternberg Museum of Natural History, Fort Hays State University, 3000 Sternberg Drive, Hays, KS 67601, USA.

– Larry D. Martin, Natural History Museum and Biodiversity Research Center, University of Kansas, 1345 Jayhawk Boulevard, Lawrence, KS 66045, USA.

– Michael J. Everhart, Sternberg Museum of Natural History, Fort Hays State University, 3000 Sternberg Drive, Hays, KS 67601, USA.

– Jeff Liston,Division of Ecology and Evolutionary Biology, Faculty of Biomedical and Life Sciences, University of Glasgow, University Avenue, Glasgow G12 8QQ, UK.

– Anthony Maltese, Triebold Paleontology and Rocky Mountain Dinosaur Resource Center, 201 South Fairview Street, Woodland Park, CO 80863, USA.

– Michael Triebold, Triebold Paleontology and Rocky Mountain Dinosaur Resource Center, 201 South Fairview Street, Woodland Park, CO 80863, USA.

In this blog we have written a lot about the sensitive issue of bottom trawling, but unlike what many of us think, the bottom trawling debate is not a new 20^th century environmental concern.

One of the earliest known complaints regarding trawling is in fact 400 years older than the U.S. Declaration of Independence and over two centuries older than all the Shakespeare plays; it dates back to the European Middle Ages but raises the same questions as we discuss to today: the effect of trawling on the ecosystem, the consequences of a small mesh size, and industrial fishing for animal feed.

During the reign of Edward III, a petition was presented to the British Parliament in 1376 calling for the prohibition of a “subtlety contrived instrument called the wondyrchoum”. According to the petition, the wondyrchoum was a type of beam trawl, which caused extensive damage to the environment in which it was used.

“Where in creeks and havens of the sea there used to be

plenteous fishing, to the profit of the Kingdom, certain fishermen

for several years past have subtily contrived an instrument

called ‘wondyrechaun’ […] the great and long iron of the

wondyrechaun runs so heavily and hardly over the ground when

fishing that it destroys the flowers of the land below water there,

and also the spat of oysters, mussels and other fish up on which

the great fish are accustomed to be fed and nourished. By which

instrument in many places, the fishermen take such quantity of

small fish that they do not know what to do with them; and that

they feed and fat their pigs with them, to the great damage of the

common of the realm and the destruction of the fisheries, and

they prey for a remedy.”

According to the letter, a wondyrchoum had a 6 m (18 ft) long and 3 m (10 ft) wide net

“[…] of so small a mesh, no manner of fish, however small, entering within it can pass out and is compelled to remain therein and be taken […].”

Another source* describes the wondyrchoun as ” […] three fathom long and ten mens’ feet wide, and that it had a beam ten feet long, at the end of which were two frames formed like a colerake, that a leaded rope weighted with a great many stones was fixed on the lower part of the net between the two frames, and that another rope was fixed with nails on the upper part of the beam, so that the fish entering the space between the beam and the lower net were caught. The net had maskes of the length and breadth of two men’s thumbs.”

The Crown responded to the 14^th century complaint by letting “[…] Commission be made by qualified persons to inquire and certify on the truth of this allegation, and thereon let right be done in the Court of Chancery”.

Eventually, bans were introduced regulating the use of wondyrchoums in the kingdom and in 1583 two fishermen were actually executed for using metal chains on their beam trawls.

British fishermen continued to use trawl nets despite the ban, but trawling didn’t become the ravishingly successful fishing method of today until the advent of steam power and diesel engines in the 19^th and 20^th century.

In 1863, a Royal Commission was established in Great Britain to investigate the accusations against trawling, among other complaints. One of the arguments presented by the defence was a witness who, when asked what food fish eat, replied:

“There is when the ground is stirred up by the trawl. We think the

trawl acts in the same way as a plough on the land. It is just like

the farmers tilling their ground. The more we turn it over the

great supply of food there is, and the greater quantity of fish we

catch.”**

The Royal Commission also noted that when a trawler harvests an area already harvested by another trawler, the second trawler usually catches even more fish than the first. This was interpreted as a sign of the benevolence of trawlers, when in fact the high second yield is caused by how the destruction inflicted on the area by the first trawler results in an abundance of dead and dying organisms which, temporarily, attracts scavenging fish.

The result of the Royal Commission’s investigations was the abandonment of over 50 Acts of Parliament and a switch to virtually unrestricted sea fishing. Today, the 14^th century issue of destructive fishing practises is more acute than ever.

* Davis, F (1958), An account of the fishing gear of England and Wales, 4th Edition, HMSO

** Roberts, C (2007), The Unnatural History of the Sea, Gaia