Endpoint of overfishing is now in sight: Firth of Clyde

Diagram showinig a dredge behind a diesel-powered ship. (Credit: Greenpeace)

Seems like any time I read about ecology studies lately, its tales of waste and wanton destruction. And a recent paper in PLoS-One about “Ecological Meltdown in the Firth of Clyde, Scotland” was no different. Sigh. May as well have titled this post “Why we need Hands-Off conservation approaches.”

The paper describes commercial fishing in the Firth of Clyde, a small near-shore marine ecosystem nearly due west of Glasgow on the western coast of Scotland, from the 1800s to modern day. The researchers use the Firth of Clyde’s history as a mini-model to  assert that the collapse of fisheries there, and poor policies regulating bottom-trawling, provide a snapshot of what is happening globally to the world’s oceans.

Species that were once caught in the Firth of Clyde in the 1800s, like herring, cod, haddock and turbot are now extirpated. Today, fishers target invertebrate bottom-dwellers like Norway lobster, nephrops and and scallops – all of which are caught using trawls and dredges dragged along the seabed. (Honestly, to me this reads like a tale of biblical waste. Not only are species locally extinct, but now people are tearing up the seafloor too.) The researchers say that these destructive and invasive fishing practices are causing a restructuring of marine communities in the area and that commercially-sought after fish have declined in both abundance and diversity. “The endpoint of overfishing,” they caution, “is now in sight.” (Italics are mine.)

Anatomy of a tuna’s internal compass

Southern bluefin tuna. (Image from http://www.thewe.cc)

NOTE: This post was originally published in August of 2009, it was one of the first few research papers that I wrote about on this site; it’s been receiving a spike in hits due to the recent announcement of a proposed ban on bluefin tuna fishing. This post does not talk about the conservation issues, but I wanted to revisit the fact that this species offers us a chance to learn more about wide-ranging marine species ability to circumnavigate unbelievable distances, and the fact that we still have many lessons to learn about the diversity of life on earth from rare and imperiled wildlife.

I was very intrigued by a research brief that recently ran in New Scientist magazine on the cause for daily deep-diving behavior in southern bluefin tuna. According to the un-bylined brief, these top-predator fish descend deeply like clock-work, penetrating the depths at almost exactly 30 minutes before sunrise and again 30 minutes after sunset. Apparently scientists differ over the reasons behind this behavior. Some say that the tuna make rapid descents to keep track of their prey. Others suggest diving rids the fish of pesky parasites. But a recent study interprets their behavior more complexly. A researcher from the University of Tasmania in Australia is lead author to a paper published in Behavioral Ecology and Sociobiology that concludes the tuna dive regularly to calibrate and fine-tune their internal compasses at the precise time of day when they can get the clearest reading possible.

Deep sea paradox: little food, tons of life

I reported and wrote this post for Science in the Triangle, where it appeared first.

When Craig McClain was a young boy he dreamt of piloting the NASA space shuttle into unknown corners of the Milky Way. As an adult, he explores a different unknown — one that lies in an opposite direction from the space shuttle’s launch trajectory: the deep sea.

McClain is a marine biologist with the National Evolutionary Synthesis Center (NESCent) in Durham, N.C. where he is associate director of science. He spends his days mulling over ecological and evolutionary conundrums of the deep, like why the nearly food-barren deep sea floor is riddled with pockets of biodiversity rivaling that of coral reefs and terrestrial rain forests.

Anatomy of a tuna’s internal compass

Southern blue-fin tuna. (Image from http://www.thewe.cc)

I was very intrigued by a research brief that recently ran in New Scientist magazine on the cause for  daily deep-diving behavior in southern blue-fin tuna. According to the un-bylined brief, these top-predator fish descend deeply like clock-work, penetrating the depths at almost exactly 30 minutes before sunrise and again 30 minutes after sunset.  Apparently scientists differ over the reasons behind this behavior. Some say that the tuna make rapid descents to keep track of their prey.  Others suggest diving rids the fish of pesky parasites. But a recent study interprets their behavior more complexly. A researcher from the University of Tasmania in Australia is lead author to a paper published in Behavioral Ecology and Sociobiology that concludes the tuna dive regularly to calibrate and fine-tune their internal compasses at the precise time of day when they can get the clearest reading possible.

Florida’s imperiled smalltooth sawfish

Smalltooth sawfish

Last October, I wrote a  story about conservation work on the  smalltooth sawfish on  Florida’s Atlantic Coast, and a new “encounters database” set up to track sightings of the elusive elasmobranch. My story started out like this:

About 100 million years ago, smalltooth sawfish emerged in the planet’s oceans, teeth splayed perpendicular from a long bill projecting from where their forehead should have been. Not much has changed in their evolutionary blueprint, though the continents have swung into new positions and different currents pump through the seas…(full story)

Interestingly, the local newspaper just caught up to the story! I’m not positive of the impetus for their timing, but I’m glad they gave it some real estate.