Michael McCarthy: This couldn't have happened at a worse time or a worse place

Analysis

The Gulf oil spill could not have occurred at a worse time or a worse place, environmentally, a United States expert on the region said last night.

The gigantic slick is likely to hit marine and coastal wildlife at the height of the breeding season, said Aaron Viles, the campaign director of the New Orleans-based Gulf Restoration Network.

"We are very concerned, especially if you look at it in terms of sensitive and threatened species," Mr Viles told The Independent. "BP's oil drilling disaster couldn't have happened at a worse spot at a worse time of the year."

Among the deep-water species for which there is great anxiety are sperm whales, because the Gulf of Mexico population have their primary feeding grounds in the "Mississippi canyon" – a deep water trench 40 miles off the coast of Louisiana which is five miles wide and 75 miles long.

This is where the Deepwater Horizon oil platform, which exploded and sank a week ago beginning the colossal oil spill, was located. There are thought to be only about 1,600 sperm whales in the Gulf, in a population which is classed as endangered.

There is also great concern for the western Atlantic population of the bluefin tuna, which is the world's most sought-after fish because of the Japanese demand for it for use in sushi and sashimi.

Just as the eastern Atlantic population of Thunnus thynnus breeds only in the Mediterranean, where its population is thought to be on the brink of collapse from overfishing, so the western Atlantic population breeds only in the Gulf of Mexico – and it is spawning at the moment.

"The primary season is right now," Mr Viles said. "This is a horrible time."

Besides marine mammals and fish, marine reptiles are also threatened: three of the world's seven species of marine turtle breed in the Gulf, the green, the loggerhead, and the Kemp's Ridley, the latter being the rarest of all, officially classed as critically endangered and nesting only on Gulf of Mexico beaches, mainly in Mexico itself, but also on the shore of Texas. (Nearly all of the Kemp's Ridley turtles in the world nest on a single beach, Rancho Nuevo in the Mexican state of Tamaulipas).

But the concern for deep-water marine life is, if anything, exceeded by fears for what the oil slick will do if its hits the shoreline along the four Gulf Coast states of Louisiana, Mississippi, Alabama and Florida.

At the moment it looks like the black tide will, if not prevented, come ashore at the Birdfoot Delta, the estuary where the Mississippi river enters the sea.

But there are fears that it may affect the coastline all the way east to Florida. "This is an oil slick the size of Jamaica," Mr Viles said. "We have never seen an oil spill of this magnitude, and it is likely to be the worst ecological disaster ever to hit the northern Gulf coast."

Birds that nest on the shores and in the marshes of the coastline are likely to be hit by the oil, such as the brown pelican, whose population crashed in the 1970s because of pesticides, and which only came off the US endangered species list late last year.

Another species in the firing line is the least tern, a charming bird closely related to the little terns of Britain and Europe.

In a further dangerous twist, also at risk are the migratory birds which are currently pouring into North America from the neotropics of Central and South America where they have spent the winter: millions of them cross the Gulf from Mexico's Yucatan peninsula and the first place they make landfall is the Gulf coast itself.

The oil slick also presents, of course, a substantial commercial threat to wildlife – especially to the oyster and shrimp fisheries which, along the North-Central Gulf coast alone, are thought to be worth $3bn a year. "The fishermen are likely to have their worst year ever," Mr Viles said.

Gulf wildlife endangered

Brown pelican (Pelecanus occidentalis)

The smallest of the eight species of pelican, the brown pelican nests in colonies, often on small islands, along the coastlines from Washington and Virginia in the north to the mouth of the Amazon in the south. In the 1970s, the birds suffered a severe population decline because of the use of pesticides.

Sperm whale (Physeter macrocephalus)

The largest of the toothed whales, the creature on which Moby Dick, "the great white whale" in Herman Melville's story, was based. The sperm whale lives on squid, for which it can dive as deep as 10,000 feet. It can be 70 feet long and weigh as much as 50 tons.

Western Atlantic bluefin tuna (Thunnus thynnus)

The bluefin is one of the world's most sought-after fish, prized for its flesh, especially in Japan, where it is a prime ingredient of sushi and sashimi. The Eastern Atlantic bluefin spawns in the Mediterranean, where overfishing has nearly driven it to extinction; the Western Atlantic form spawns only in the Gulf.

Green turtle (Chelonia mydas)

Green turtles are mostly herbivorous. Their meat and eggs are considered delicacies in many countries, so hunting has devastated green turtle populations around the world. There is an important population in the Gulf.