If you’ve ever wondered how the eyes of flatfish like flounder and sole ended up on one side of the head, you should take a closer look at a newly published article by Dr Matt Friedman.

Dr Friedman, who recently took up a post at Oxford University, has been investigating this mysterious eye migration using 50-million-year-old fossilized Acanthomorph fishes from Italy and France, and has managed to show that the change was slow and gradual rather than abrupt. Over millions of years, the positions of the flatfish eyes have gradually changed, little by little.

Addressing the Society of Vertebrate Palaeontologists’ (SVP) annual meeting at the University of Bristol today, Dr Friedman said: ”Flatfishes and their profoundly asymmetrical skulls have been enlisted in many arguments against gradual evolutionary change, precisely because it is difficult to imagine how intermediate forms might have been adaptive. My work provides clear evidence of the kinds of intermediates deemed ‘impossible’ by earlier workers and answers this long-standing riddle in vertebrate evolution.”

The most ancient Acanthomorph fishes had asymmetrical skulls, but the eyes were still located on both sides of the head. From these foregoers, intermediate species evolved and one of the eyes gradually moved across the head until both eyes ended up on the same side – millions of years later.

The flatfish group puzzled 19^th century scientists trying to grasp the new Darwinian ideas, because during that epoch, the group’s fossil record was incomplete and it was unclear how the gradual migration of one eye could have come about. Today, a much broader range of fossil fish is available to science and Dr Friedman’s study included over 1,200 fossil specimens belonging to over 600 different species.

Commercial, recreational and party/charter boat fishermen from Maine to North Carolina have all rallied together to deal with an out-of-balance population of predatory spiny dogfish sharks that threatens the recovery of New England groundfish and several others fish stocks living along the U.S. East Coast.

The newly formed Fishermen Organized for Rational Dogfish Management (FORDM) has requested the assistance of Dr. Jane Lubchenco, newly appointed National Oceanic and Atmospheric Administration head, in dealing with the predator.

Spiny dogfish

The disproportionate abundance of dogfish is not a new problem; as early as 1992 Dr. Steven Murawski, now chief scientist of the National Marine Fisheries Service’s, wrote “Given the current high abundance of skates and dogfish, it may not be possible to increase gadoid (cod and haddock) and flounder abundance without ‘extracting’ some of the current standing stock.”

That was over 15 years ago and the situation has not improved. On the contrary, the amount of dogfish now exceeds that of skates, and dogfish comprises over half of all fish taken in the annual trawl surveys carried out by the Northeast Fisheries Science Center.

The spiny dogfish can exceed 150 cm in length and preys on virtually all species of fish smaller than itself. Dogfishes can also create a problem for other species by competing with them for prey fish.

This remarkable abundance of dogfish is most likely the result of countless years of ever increasing over-fishing. Spiny dogfish is not an appreciated food fish and the depletion of other species seems to have favoured it greatly in these waters.