WORLD FISHING, March, 1996,

BEN-YAMI'S COLUMN:

DR. BEVERTON AND THE FISHERIES SCIENCE

I participated in the Athens world fishery congress and was privileged to hear Beverton's swan-song lecture. I was greatly impressed and reviewed it in WF.

MB-Y

Dr.Ray H.Beverton passed away half an year ago at the age of 72. Dr. Beverton has been one of the best known and most important fisheries scientists on the second half of this century. In 1945 he started his career at the Lowestoft Fisheries Laboratory. In 1957 he published together with Dr. Sidney Holt their famous work "On the dynamics of exploited fish populations" which soon became one of the main pillars of wisdom of the fishery science. The gist of their work was a method of fish population dynamics analysis, known also as yield-per-recruit analysis. Like the other "classical" fish population dynamics models, those that preceded them and those developed later, their model offered an apparently rational decision making option in fishery management, without involving concrete information as to the reasons for stock fluctuations other than fishing. Dr. Beverton's later studies kept him for many years out of fisheries, but he rejoined the fishery science in the early 1980s.

The last time I met Dr.Beverton was on the 1992 World Fishery Congress in Athens. He was invited there to give one of the plenary session overview lectures. Recently, I received the first of several books that the Congress generated*), the others, almost 4 years since the Congress, are still in print. Dr.Beverton's lecture (pp.25-54), entitled "The state of fisheries science", is in my opinion the most important of the 19 lectures which form the book, and the least I can do is to devote to it this month's whole column. I'll come back to the rest of the book in one of the future issues.

In dr. Beverton's opinion, it was well into the 1980s before fisheries science began to appreciate the limitation of all the variants of the mathematical models of fishery dynamics, including the routinelly applied vpa (virtual population analysis) method, and their tendency to produce "dubious though superficially plausible results". vpa - said dr. Beverton - should rather stand as an acronym for "very provisional assessment". in his wiew, the ever improving acoustic methods for fish abundance estimation in combination with test fishing represent a promising way ahead for stock assessment.

The early life history (elh) of fishes is crucial to the recruitment. it's been now well proven that "elh dynamics are intervowen with basic productivity, physical oceanography and even atmospheric dynamics". hence, said dr. beverton, "the broad correlation between year-class strength and physical oceanic conditions over wide areas". and: "with the exception of the dramatic fishery collapses of the 1960s and 1970s, natural factors have had a greater influence on the long-term abundance of many fish species than fishing, but the mechanisms are still largely unknown. they should be given greater prominence in future fisheries research".

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* the proportion of the total amounts of fish consumed *

* that is eaten by other fish, sea mammals, and birds *

* is as great or greater than it is by man. this is *

* true even in the heavily fished north sea. - *

* - dr. r.h.j. beverton, 1992 *

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Not that excess fishing is not to be blamed. According to Dr. Beverton's retrospective study of 62 years of the North Sea haddock fishery, the rate of the fishing has been for many years twice of what it should have been to produce the highest sustainable yield that could have been obtained from that fishery. Only slight increase in the fishing effort rate would have made the haddock population extinct. Fortunately, the haddock stock shows a remarkable resilience.

Notwithstandingly, anticipating the effect of climate change, particularly the global warming, on the world's fisheries, for better or for worse, is a formidable challenge to fisheries science both the related biology and oceanography. The increasing emphasis on climate and fisheries can only be tackled by both disciplines in close partnership, said Dr. Beverton. In fishery management like in other domains, fashions come and go, often following rather political decisions than objective scientific reasoning. The MSY (maximum sustainable yield) concept, nowadays largely out of favour, was mistakenly interpreted "as an actual annual yield from a particular stock or stocks and the goal of practical management". But the love affair with the MSY brought about the reliance on catch quotas (TACs) for management.

Dr. Beverton concluded his lecture with a recommendation to revert to management by direct control of fishing effort however that is achieved. It will be simpler and less frenzied, with year-to-tear fine tuning of regulations not necessary, except for the very short-lived species, and enable longer term strategy for sustainable exploitation than quotas.

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* Regulation by catch limits is fundamentally flawed, *

* except the simplest of single species fisheries. On *

* the other hand, a fishing rate regime is compatible *

* with sustainable harvesting and the preservation of *

* biodiversity. - dr. r.h.j. beverton, 1992 *

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Another of his recommendations was to use the computer technology to look into the existing historical fish stock data which are "among the longest and most reliable of records of trends in abundance of natural populations of any species", confront them with management steps undertaken in the past and thus analyse and evaluate the assessment and management methodologies employed. "Hindcasting" he called it.

There's no doubt in my mind that during his long career in science Dr. Beverton has made quite a bit of way towards the ecological, holistic approach which assumes that there is much more to fishery dynamics than the parameters employed by the conventional models. And to put it in Dr. Beverton's own words: "If (research aimed at gaining a better understanding of the biological basis of fish production in relation to the ecosystem generally) implies a return to a more biologically orientated and longer-term strategy for the fisheries science of the future, it will in my opinion be good for the science, for its practitioners and for its customers". This lecture might have well been Dr. Beverton's swan song. It was music to my ears.

Albert Einstein, the great physicist and father of the theory of relativity, wouldn't accept till the end of his life the validity of the theory of quantum mechanics that didn't fit his concept of the logic of the universe. "God does not play with dice" - said Einstein. Could it be that Dr.Beverton would come to the conclusion that may be He does?

*) The State of the World's Fisheries Resources. Proceedings of the

World Fisheries Congress (Athens, 1992), Plenary Sessions.

C.W.Voigtlander (Ed.). (Oxford & IBH Publishing Co.Pvt.Ltd., 66

Janpath, N.Delhi 110 001, INDIA). 1994. 204 p.

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Menakhem Ben-Yami

Fisheries Development & Management Adviser

2 Dekel St., Kiryat Tiv'on 36056, ISRAEL

Ph&Fx# +9724-983-5928; e-mail <benyami@shani.net>

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