Climate change

If we cast our vision back to the period between 1960 and 1980 we find that the UN’s Food and Agricultural Organization’s (FAO) Fisheries Resources Division, headed by Drs. Sydney Holt and John Gulland, was engrossed in introducing, teaching and promoting population dynamics models as the main tool for stock assessment arpund the world.

One the one hand there were major management flops. On the other, growing criticism came from fishermen and scientists who refused to be bewitched by easily-computerised equations. The noise of unease coming from the U.S. National Academy of Sciences, the Royal Society, the International Council for the Exploration of the Sea and the Scottish Royal Society, also helped to start forcing fisheries and scientific establishments to start revising the methodology.

Systems Ecology

The FAO also started dismantling the already petrified paradigm by publishing reports that dealt with statistical flaws in that methodology and with correlations of massive fish stock fluctuations with climatic shifts and cycles.

A few months ago and not a day too soon, FAO published FAO Fisheries Technical Paper (452), entitled: Future climate change and regional fisheries: a collaborative analysis, (FAO, Rome, 2003), written by Dr. Gary D. Sharp. It’s a contribution to the growing understanding of the innumerable factors which act on the Earth in general and the oceans in particular and they way they interact within their respective ecosystems. This knowledge is now evolving into a new scientific discipline: ‘Systems Ecology’.

Dr Sharp maintains that climatic shifts and the dynamics of ocean systems have affected humanity through their effect on fisheries. Repeated periods of glaciation and deglaciation over millennia and much shorter, decade-long to century-long, climate changes have pushed animal and human populations back and forth more often than most people recognise.

Faulty time machine

The last two centuries or so were relatively mild. They followed the ‘little ice age’, which not only impacted on Greenland’s Vikings and irrigated the fields of the Inca Empire, but also influenced the whole Hanseatic commercial system by causing the collapse of the Baltic herring fishery. Unfortunately, our ability to forecast future climate changes is limited, because we have few really long time-series that cover more than one or two complete fishery rise-and-fall cycles. Our observation systems are so young, our time series so short and our measurements so local that many data (despite more recent satellite coverage) have only been available, at best, since the 1950s.

Since they have also been misused to describe long-term trends, all they can reflect are short-term convulsions and distortions on the back of the former. As growing numbers of studies show, oceans undergo parallel shifts, with dramatic changes in species abundance, composition and distribution and consequently also in fish stocks.

However, there are sufficient scientific examples and documentation to show that fisheries’ dynamics involve much more than just fish and fishing. Oceans, and hence their fisheries, are affected by larger scale dynamic processes and forces. In fact, catches provide unique ecological climate indicators. According to Dr Sharp, the influence of the earth-atmosphere-ocean-climate system on fish populations, although well recognised, is still poorly understood and accounted for in regional stock assessments.

What Sharp is trying to do in his own elegant style is: “… to refocus our objectives within our Solar-System and our own Earth’s Grand Fugue in which humans hold so many instruments, but…alas, not the Time-Keeper’s baton”.

Nature controls man

In short, with all due respect given to our sinful role in affecting the environment, we can only cause contortions, however nasty, in the major fluctuations that are caused by incomparably stronger global, solar and cosmic forces.

The view, advocated by the Inter-governmental Panel on Climate Change is that our polluting activities are producing a major global change. Some might even see this as an almost megalomaniac message. It is all the more to be queried when one sees scientists applying their favourite models to current climate, to predict global change, when they are unable to provide an even approximately reliable picture of the present. So how can these models be safely used for forecasting?

The one thing that can be certain is that the Earth’s climate will continue to change and fish will continue to respond as they have in the past in terms of distribution and abundance. The fisheries most sensitive to climate change are also amongst the most affected by (non-fishing) human intervention. These include the effect of dams, diminished access to up- or down-river migrations, the filling in of wetlands and other issues of human population growth and habitat manipulation and pollution. Of significant importance are expanded agricultural water use and urbanisation.

Dr Sharp provides a wealth of scientific references in support of the need for the System-Ecology approach to help us understand the dependence of fisheries and their management on global climatic-oceanic forces. His bibliography is 10 pages long. But he leaves the reader to identify the “global warming buffs” and those “digital modelers” who who’ve been trying to assess stocks and run management schemes in isolation from all the non-fishing factors that so overwhelmingly influence fisheries.

Not that Sharp is disregarding man’s role in modifying and damaging ecosystems by erasing habitats and depleting Earth’s resources, fisheries included. In the author’s words: “…Ocean ecosystems begin on the highest mountains. Waterways and all downstream and coastal water quality are very much at the heart of the dilemma. High latitude dynamics and related ecological processes have been somewhat under-emphasised, since most humans are averse to such extreme environments. If…our impacts in these regions become greater, it is clear that there will be dire consequences for those ecosystems…the species involved are truly specialised and quite responsive to minor changes. They and all (other) species need options even more than the most highly adaptable predators on Earth – humans do”.

On the other hand, he says “It can be assumed that despite human activities, the solar system will continue to reflect the long harmonic interactions that have evolved over ages, long before life evolved…long after the present amicable conditions have shifted from today’s supportive environments, toward ever more harsh ones — with inevitable consequences”. A gloomy outlook, but the FAO and the author should be praised for bringing a long-neglected perspective back into global climate change and fisheries management.