Feature articles

When fish adapt to fishing
Building a scientific consensus about the evolutionary consequences of commercial fishing

Commercial fishing is a major industry that has been hard-hit by falling catches in many regions of the world. As a result, fisheries bodies have welcomed research into ways of maximizing sustainable catches. But one area of research, long neglected by international organizations, suggests that commercial fishing on the present scale is causing dramatic evolutionary changes in fish species. This research, developed and extended by IIASA scientists, has recently been recognized by the International Council for the Exploration of the Sea (ICES), the organization that coordinates and promotes marine research in the North Atlantic.

Further recognition came with the publication of an article in the Policy Forum section of the prestigious American magazine Science (23 November 2007). Under the title “Managing evolving fish stocks,” 17 authors from 11 different institutions—with IIASA serving as coordinator of the underlying network—describe how current fishing practices appear to alter the genetic make-up of exploited stocks with unexpected consequences for economic yields, as well as for the ecological stability and recovery potential of exploited fish stocks.

According to one author, Ulf Dieckmann, Leader of IIASA’s Evolution and Ecology Program, the research that started at the Institute in 1999 followed pioneering work carried out a decade earlier that had raised pertinent questions about the evolutionary consequences of fishing without, however, engaging a broad basis of scientists or practitioners.

“Monitoring the size of fish catches was something that national agencies had been undertaking for many years, but their chief role was to support their country’s fishing economy,” says Dieckmann. “Observation and analysis of the collected catch data revealed that over several decades, not only were overall fish populations in decline, but also the body size at which fish started to reproduce dropped. For example, a typical cod caught off the Norwegian coast that used to take up to 10 years to mature was now maturing at the age of only six years.”

“As a result, these fish are smaller and thus produce far fewer eggs at their first reproduction. This is just as expected from evolutionary theory: fish that postpone reproduction for too long are caught before they can contribute to the next generation, which is thus made up of fish that are genetically predisposed to mature earlier.”
Those early observations pointing to the evolutionary impact of fishing had been published in the late 1980s by Richard Law of York University and Adriaan Rijnsdorp of the Netherlands Institute for Fisheries Research. This was a radical hypothesis for fisheries science because discernible evolution was then still thought of as requiring centuries or even millennia. There were also competing explanations of the observed maturation trends. As a result of these varying opinions, coupled with some institutional inertia, by the late 1990s the pioneering work had been put aside or was treated in a cursory way by national fishery bodies and by scientists working in the field. The question of what was really happening in the oceans stayed open.

It was then that IIASA came into the picture. The Institute supports several bridge-building initiatives, visitor programs, and schemes inviting scientists to broaden the research base at IIASA by developing new ideas. In 1997, a recently-graduated Finnish ecologist, Mikko Heino, joined one of these: IIASA’s Young Scientists Summer Program.
Heino picked up on the neglected work of Law and Rijnsdorp and, when he won a scholarship to return to IIASA the following year, he applied himself to developing it further in the form of a paper on the management of evolving fish stocks. This coincided with a sabbatical visit by Richard Law to IIASA. There, Law met up with a former student of his, Ulf Dieckmann, and, after various discussions, the three scientists set out to initiate IIASA’s research on the evolutionary implications of fishing.

“Specifically,” says Dieckmann, “two innovations were needed. First, new statistical techniques had to be devised to analyze existing data for signals of fisheries-induced evolution, taking other hypotheses into account. Second, new simulation models had to be developed that could do better justice to the real-world complexities of stock dynamics.”
Dieckmann believes these developments could not have come together so readily anywhere other than at IIASA: “At the national level, governmental fisheries bodies have little capacity for developing new methodology and might interact little with the academic world. Fortunately, IIASA has this willingness to take on such a challenge, scrutinize it from the perspective of applied systems analysis, develop the necessary methodological tools, and then cooperate with its wide constituency on practical applications.”

The early results of the IIASA work were described in 2002 in two publications. In an article entitled “Measuring probabilistic reaction norms for age and size and maturation,” Heino and Dieckmann, together with their colleague Olav Rune Godø from Norway, laid the groundwork for a new statistical approach to detecting trends in the maturation schedules of exploited stocks. Another article entitled “Fisheries-induced changes in age and size at maturation and understanding the potential for selection-induced stock collapse,” by IIASA’s Bruno Ernande, Dieckmann, and Heino, introduced a modeling framework for understanding and predicting fisheries-induced evolution of maturation schedules.

The latter article was published in a 2002 conference proceedings by ICES, and in 2006 ICES instigated a new Expert Group on Fisheries-induced Adaptive Change, jointly chaired by Heino, Dieckmann, and Rijnsdorp. Such endorsement by one of the foremost international agencies for fisheries research would have been inconceivable only a decade before, believes Dieckmann. Or, as he puts it more succinctly: “Gradually, research on fisheries-induced evolution could no longer be disparaged and dismissed as the work of just a bunch of cranks with an outlandish theory.”
Research in the field has now broadened under IIASA’s auspices. It has spawned the European Marie Curie Research Training Network FishACE (Fisheries-induced adaptive change in exploited stocks), which involves 11 research teams from eight countries. It has also attracted the involvement of the European Union in the form of the European research network FinE (Fisheries-induced evolution), which is designed to contribute to the sustainable management of Europe’s fisheries and brings together 18 research teams from 15 countries.

This element of IIASA’s profile, serving as a bridge between national and international, commercial and academic quarters, deserves further mention. Based on its broad international constituency and political impartiality, IIASA is well-positioned to offer impartial advice that is not affected by national interests.

Ulf Dieckmann’s view of this is diplomatic: “One certainly hears of incidents within national fisheries research agencies, where certain results are not welcome if they contradict government positions. But these things are rarely documented. The other and perhaps even more important problem is that innovative research work may simply never get done at all, since national research priorities are occasionally myopic, national research agencies are typically overburdened with routine tasks, and the temptation to play it safe is not uncommon.”

From his experience with the project Mikko Heino agrees, adding: “I would say it helps to enter a field with a fresh mind. National institutions have a tendency to become stagnant, so somebody coming in from the outside has a better chance with an innovative approach.”

Until now, research on fisheries-induced evolution has focused on fisheries in the developed world. New member countries of IIASA will benefit from the enormous potential for modernizing and improving their fishing practices, to ensure the sustainability of their catches, and to avoid the many mistakes that developed countries have committed in the past.

Further information

IIASA’s Evolution and Ecology Program
Keith Jinks is a freelance writer based in Vienna.

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Last updated: 20 Jul 2009