U.S. DEPARTMENT OF COMMERCE 

National Oceanic and Atmospheric Administration 

National Marine Fisheries Service 

The Raymond J. H. Beverton 

Lectures at Woods Hole, 

Massachusetts 

The Raymond J. H. Beverton Lectures 

at Woods Hole, Massachusetts 

The Raymond J. H. Beverton Lectures

at Woods Hole, Massachusetts

Three Lectures on Fisheries Science

Given May 2–3, 1994

Edited by Emory D. Anderson

May 2002


NOAA Technical Memorandum NMFS-F/SPO-54


U.S. DEPARTMENT OF COMMERCE 

Donald L. Evans, Secretary 

National Oceanic and Atmospheric Administration 

Vice Admiral Conrad C. Lautenbacher, Jr., U.S. Navy (Ret.), 

Under Secretary for Oceans and Atmosphere 

National Marine Fisheries Service 

William T. Hogarth, Assistant Administrator for Fisheries 
ANOTAN

L OCEANIC AND ATMOSPHERIC ADMINIS 

U.S. DEPARTMENT OF COMMERCE 

TRA I T NO 

This entire publication may be cited as: 

Anderson, E. D. (Editor). 2002. The Raymond J. H. Beverton lectures at Woods Hole, Massachusetts. Three Lectures 

on Fisheries Science Given May 2–3, 1994. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-F/SPO-54, 161 p. 

Invididual lectures from the publication may be cited as in this example of Lecture 1: 

Beverton, R. J. H. 2002. Man or Nature in Fisheries Dynamics: Who Calls the Tune? In E. D. Anderson (Editor), 

The Raymond J. H. Beverton lectures at Woods Hole, Massachusetts. Three Lectures on Fisheries Science Given 

May 2–3, 1994, p. 9–59. U.S. Dep. Commer., NOAA Tech. Memo. NMFS-F/SPO-54. 

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ISBN 0-9722532-1-1 

(✩) U.S. Government Printing Office, 2002—791-811. 

I
Table of Contents

Preface .............................................................................................................................................. 1

Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? ....................................... 9

Lecture 2: Fish Population Biology and Fisheries Research ........................................................... 61

Lecture 3: Reflections on 100 Years of Fisheries Research............................................................. 107

Appendix: Common and Scientific Names of Species.................................................................... 159

Preface

I

n May 1994, Ray Beverton presented a series of lectures at 

facilities of NOAA’s National 

Marine Fisheries Service (NMFS) 

in Woods Hole, Mass.; Seattle, 

Wash.; Auke Bay and Juneau, 

Alaska; La Jolla, Calif.; Beaufort, 

N.C.; and Silver Spring, Md. This 

tour was initiated and organized 

by Michael Sissenwine, NMFS Senior Scientist at the time, and sponsored by NMFS. 

The NMFS Northeast Fisheries 

Science Center (NEFSC) in Woods 

Hole was the first stop on Ray’s 

itinerary, and it was my honor and 

privilege to welcome and introduce him at the first of his three 

lectures during May 2–3. My wife, 

Geri, and I also had the pleasure of 

hosting Ray and his wife, Kathy, at 

our home during those few days. 

Ray was kept quite busy during 

his 2-day stint in Woods Hole. He 

delivered the first lecture entitled 

“Man or Nature in Fisheries Dynamics: Who Calls the Tune?” the 

morning of May 2 in the Woods 

Hole Oceanographic Institution 

(WHOI) Redfield Auditorium, and 

then spent the afternoon being 

shown around Woods Hole and 

preparing for the next day’s activities. That evening, he and Kathy 

were entertained at a typically 

boisterous and enjoyable party at 

the home of Vaughn and Jody Anthony. On the second day (May 3), 

Ray discussed “Fish Population BiProfessor Raymond J. H. Beverton. 

Kathy Beverton

ology and Fisheries Research” in 

the morning in the Marine Biological Laboratory (MBL) Whitman 

Auditorium, and concluded that 

afternoon with his “Reflections on 

100 Years of Fisheries Research” in 

the NEFSC Aquarium Conference 

Room. 

Ray’s original intent was to 

write up and publish the lectures 

as a package of autobiographical 

reflections on the respective 

themes upon which they were 

based. It was fortuitous, therefore, 

that we had made arrangements to 

videotape the three Woods Hole 

3 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Steven Murawski, NMFS 

Guests at the party in honor of Ray and Kathy 

Beverton held at the home of Vaughn and Jody 

Anthony in East Falmouth, Mass., on May 2, 1994. 

Kneeling (l–r): Marvin Grosslein, Stephen Clark, 

Steven Murawski, and Andrew Rosenberg. 

Standing (l–r): Herbert Graham, Jack Pearce, 

Frank Almeida, William Overholtz, Wendy Gabriel, 

Kevin Friedland, Vaughn Anthony, Ray Beverton, 

Ray Conser, Emory Anderson, and Paul Rago 

(holding his daughter, Grace). Spouses of most 

of the above individuals were present at the 

party, but not included in this photo. 

lectures, ostensibly to accommodate some NEFSC personnel who 

were unable to attend them. As it 

turned out, these were the only 

videotapes made of any of his lectures given during the tour. 

Following his return to Wales, 

Ray asked if it would be possible 

to have the text of the lectures transcribed to provide him with a starting point for the intended manuscripts. However, both of us immediately became involved in other 

projects and, inter alia, he began 

making plans for a return trip to 

North America in 1995, in part to 

present the first Larkin Lecture at 

the University of British Columbia 

in Vancouver, B.C., and also to 

spend some time working with colleagues in Seattle, Wash. Regrettably, Ray was never able to see any 

of these initiatives to fruition, as he 

became ill and eventually passed 

away on July 23, 1995. However, 

his Larkin Lecture, which he was 

unable to deliver orally, was eventually drafted by Tony Pitcher 

(University of British Columbia) 

4 
Preface 

and Terrance Iles (University of 

Wales), from detailed speaking 

notes that Ray had prepared, and 

published in 1998 as the lead paper in the Beverton and Holt Jubilee Special Issue of Reviews in Fish 

Biology and Fisheries1. 

It was not until after his death 

that I decided to undertake the 

project of preparing Ray’s lectures 

for publication. What initially began as a full-time effort on my part 

to transcribe the lectures and 

quickly produce a set of manuscripts gradually grew into a much 

more difficult and painstaking task 

than I had ever imagined. Furthermore, as other duties increasingly 

demanded more and more of my 

time and energy, the project 

evolved largely into a “spare-time” 

endeavor and ultimately took far 

longer than originally intended. 

In contrast to the tedium of 

hours and hours of listening to 

tapes and trying to decipher each 

and every word was the sheer pleasure of listening over and over to 

Ray’s presentations. On each occasion when I was able to devote time 

to working on the transcription, it 

was so enjoyable to again hear his 

voice. Each time I replayed a particular section to try to clarify what 

Ray had said (the audio portion of 

the videotapes was not of high 

1

Beverton, R. 1998. Fish, fact and fantasy: 

a long view. Rev. Fish Biol. Fish. 8:229–249. 

quality), I seemed to pick up an 

additional nuance or meaning. Every effort was made to retain the 

exact words used by Ray so as to 

retain the distinctive “Bevertonian” delivery, while making minimal changes primarily to provide 

a more “reader-friendly” description of figures. The question-andanswer sessions following each lecture, which provided a further opportunity for Ray to elaborate on a 

variety of topics, are included in 

full. 

The main purpose in publishing 

this set of lectures was to record 

and preserve for future reading 

and reference some of the accumulated wisdom, ideas, hypotheses, 

and recollections acquired over a 

distinguished career by one of the 

most influential, respected, and 

beloved fishery scientists of the 

20th century. In addition, this publication constitutes my personal 

tribute and memorial to a unique 

and humble man who endeared 

himself to every person who had 

the good fortune of crossing paths 

with him either professionally or 

otherwise. This was a labor of love 

and served, in part, to convey some 

small measure of thanks and appreciation for the friendship and 

many kindnesses which Ray and 

Kathy bestowed on me and my 

wife over the years. 

Everyone who knew Ray 

counted him as a genuine friend, 

and the loss we all felt at his passing is reflected in the extraordinary 

number of in-depth, heartfelt, and 

well-deserved complimentary 

obituaries published worldwide in 

various scientific journals, newspapers, and trade magazines, the contents of which I will not attempt to 

review or emulate here. In addition, several professional fisheries 

societies honored Ray by bestowing upon him posthumously their 

highest achievement awards. 

These included the Silver Medal of 

the Fisheries Society of the British 

Isles and the Outstanding Achievement Award of the American Institute of Fishery Research Biologists, 

both conferred in 1995 and presented to his widow, Kathy. I personally had the honor of presenting the latter award to Kathy during the Opening Session of the 1995 

Annual Science Conference of the 

International Council for the Exploration of the Sea (ICES) on September 21, 1995 in Aalborg, Denmark. 

Although I first heard of Ray 

Beverton in 1965 when I entered 

graduate school at the University 

of Minnesota, I do not recall actually meeting him until 1987. The 

occasion was the ICES Statutory 

Meeting (now called the Annual 

Science Conference) held in 

Santander, Spain. At the time, I was 

ICES Statistician and Ray was Editor of the ICES Journal du Conseil 

(now called the ICES Journal of 

5 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Kathy Beverton accepting the AIFRB Outstanding Achievement Award for 1995 presented posthumously to her late 

husband, Professor Raymond J. H. Beverton at the 1995 ICES 

Annual Science Conference in Aalborg, Denmark, by Emory 

Anderson, former General Secretary of ICES. 

Marine Science), and he was attend- ting over my sense of genuine awe, 

ing the meeting in that capacity I discovered that Ray was exwith Kathy. My wife, Geri, and I tremely personable and unpretenwere invited by Basil Parrish, then tious. I soon settled into a very 

General Secretary of ICES, and his comfortable friendship with Ray, 

wife, Hilda, to join them for din- and Kathy became (and still is) one 

ner with the Bevertons. After get- of Geri’s dearest friends. After I ICES 

succeeded Basil as General Secretary in April 1989, my interactions 

with Ray, both professionally and 

socially, became more frequent and 

generally revolved around issues 

pertaining to the Journal or ICES 

publications in general. 

A favorite memory of Ray relates to the 1991 ICES Statutory 

Meeting in La Rochelle, France. 

Ray had earlier announced his intention to retire as Editor of the 

Journal effective the end of the year, 

so the Council seized the opportunity to recognize his 8 years of service. Jakob Jakobsson of Iceland, 

who was President of ICES at the 

time, paid tribute to Ray during the 

Opening Session and presented 

him with an oil painting of theR/V 

Ernest Holt, the first research vessel on which Ray had worked during his years at Lowestoft, U.K. Ray 

was completely surprised, dumbfounded, and virtually speechless 

following his receipt of the gift, but 

later asked for and received permission to render a response 5 days 

later at the Closing Session. 

Those of us who were privileged 

to be present that day witnessed 

what, in essence, was one of the 

most eloquent farewell addresses 

ever delivered. His speech touched 

on a multitude of points, as Ray 

was generally prone to do, but they 

all focused on the Journal and included his usual sage advice about 

how to write scientific papers. His 

6 
Preface 

closing remarks, which to me highlighted his farewell, consisted of 

some light-hearted “Advice to Prospective Contributors to the ICES 

Journal of Marine Science,” conveyed as a parody of the final verse 

of Rudyard Kipling’s poem “If.” 

Ray and Kathy had lovingly and 

cleverly crafted the words in their 

hotel room the previous evening. 

A full account of his address and 

the parody are contained, incidentally, in the “ICES Annual Report 

1991.” However, what impressed 

and touched me deeply that day 

and has remained with me ever 

since is that the final verse of the 

original poem by Kipling really 

speaks about Ray and his approach 

to life. In fact, the verse, as follows, 

was read by one of his granddaughters at his funeral service on 

July 31, 1995: 

“If you can talk with crowds 

and keep your virtue, 

Or walk with kings— 

nor lose the common touch, 

If neither foes nor loving friends 

can hurt you, 

If all men count with you, 

but none too much; 

If you can fill 

the unforgiving minute 

With sixty seconds’ worth 

of distance run, 

Yours is the earth 

and everything that’s in it, 

And—which is more— 

you’ll be a Man, 

my son!” 

I am indebted to a number of individuals who assisted in large or 

small measure with this project. 

Most importantly, Kathy Beverton 

granted permission to undertake 

this task and kindly supplied all of 

the notes, slides, original figures or 

drawings, and other materials 

which she could find in Ray’s files 

pertaining to the lectures. Terrance 

Iles, a colleague of Ray’s at the 

University of Wales, assisted Kathy 

in searching Ray’s files for hard-tofind items and answered various 

questions. John Ramster from 

Lowestoft, who had worked 

closely with Ray on the editorial 

team of the ICES Journal of Marine 

Science, was particularly helpful in 

providing the photographs used as 

figures in the third lecture and in 

answering a number of questions. 

Others at Lowestoft who helped or 

advised, particularly in tracking 

down literature citations, were 

David Cushing, Bob Dickson, 

David Garrod, John Pope, and Sarah Turner. Henrik Sparholt and 

Judith Rosenmeier in the ICES Secretariat assisted in locating a literature citation and several figures. 

Tore Jacobsen (Institute of Marine 

Research, Bergen, Norway) and 

Steven Murawski and Mark 

Terceiro (NEFSC, Woods Hole) 

provided special assistance in clarifying information on Figure 31 of 

the first lecture. Murawski, William 

Overholtz, Fred Serchuk, Jackie 

Riley, and Jorge Csirke also helped 

with some literature citations. 

Brenda Figuerido made 8.5 × 11-

inch reproductions from the 35-

mm slides used by Ray in giving 

the lectures that were used in preparing many of the figures in this 

publication. Malcom Silverman 

videotaped the lectures. My wife, 

Geri, assisted in transcribing the 

audio portion of the videotapes 

onto Dictaphone tapes to facilitate 

my efforts to record in writing the 

full text of the lectures and all the 

question-and-answer sessions. 

Last of all, I owe a huge debt of 

gratitude to David Stanton of the 

NMFS Scientific Publications Office (SPO) in Seattle for the monumental task of reproducing, from 

assorted drawings, handmade 

sketches, and graphs, most of the 

figures included in this book, for 

the layout of the book, and for all 

of the interactions with the Government Printing Office. SPO Chief 

Willis Hobart provided editorial 

assistance. The NMFS Office of Science and Technology in Silver 

Spring, Md., provided the funding 

for this publication. 

Emory D. Anderson


Editor


Silver Spring, Md.


May 2002


7 

“Man or Nature 

in Fisheries Dynamics: 

Who Calls the Tune?” 

LECTURE 1 

May 2, 1994 

Redfield Auditorium

Woods Hole Oceanographic Institution

Ladies and Gentlemen. I am 

Emory Anderson, and on 

behalf of the NMFS Northeast Fisheries Science Center, as 

well as the Woods Hole Oceanographic Institution and the Marine 

Biological Laboratory, who have 

graciously provided auditorium 

facilities, it is my pleasure to welcome you to the first of three lectures to be presented today and tomorrow by a very distinguished 

European guest. I might add that 

our guest is starting a nationwide 

lecture tour here today that will 

continue in Seattle, Wash.; Auke 

Bay, Alaska; La Jolla, Calif.; and 

Beaufort, N.C.; and then conclude 

in about 3 weeks in Silver Spring, 

Md., the headquarters of the National Marine Fisheries Service. 

This tour is sponsored by the National Marine Fisheries Service. 

Our guest is one of the world’s 

preeminent fisheries scientists 

whose name is synonymous with 

quantitative fisheries science. He 

was educated at Cambridge University, received his M.A. degree 

with first class honors in zoology 

in 1947, and in that year joined the 

staff of the Fisheries Laboratory in 

Lowestoft as a research officer. 

However, as he told me, he actually started working there briefly 

in 1945 after the war, but then went 

on to Cambridge to finish his degree. Together with colleague 

Sidney Holt, he authored the classic 1957 monograph entitled “On 

the Dynamics of Exploited Fish 

Populations” (Beverton and Holt, 

1957) which, perhaps more than 

any other single contribution, has 

defined and described the theoretical and quantitative basis for fish 

stock management. The results of 

that work are still as relevant today as they were 40 years ago. The 

familiar “Beverton and Holt yieldper-recruit” concept constitutes 

only a small part of that masterpiece. 

Ray remained in Lowestoft for 

18 years, leaving in 1965, having 

served as Deputy Director since 

1959. During those years, he was a 

very energetic proponent of the use 

of quantitative methods for providing a sound scientific basis for the 

management and rational exploitation of fisheries resources. As 

such, he was very active in international fisheries work in the 

North Atlantic under the auspices 

of organizations such as the International Council for the Exploration of the Sea (ICES) and the International Commission for the 

Northwest Atlantic Fisheries 

(ICNAF). 

In 1965, he assumed the post of 

Secretary and Chief Executive of 

the newly formed U.K. Natural 

Environment Research Council 

(NERC) which was the principle 

U.K. funding source for nongovernmental life science and environmental research. The NERC was responsible then and until recently 

for directing the activities of, for example, the British Geological Survey, the British Antarctic Survey, 

and the well known Continuous 

Plankton Recorder survey. 

In the early 1980’s, following 

mandatory retirement from NERC, 

Ray ventured into the academic 

arena and returned to a more direct involvement in fisheries research, first at the University of 

Bristol as a Senior Research Fellow, 

and later at the University of Wales, 

Cardiff, where he became Professor of Fisheries Ecology in 1984. 

From 1987 to 1989 he was Head of 

the School of Pure and Applied Biology and then, again because of 

reaching another mandatory retirement age, he was obliged to retire 

a second time. Since 1990, Ray has 

been Professor Emeritus at the 

University of Wales, but he has 

continued to lecture (giving the 

only fisheries course there), write 

papers, and provide advice to students. To say that he had retired is 

really a misnomer of the first order. 

Since the early 1980’s, Ray has 

held positions of leadership in a 

number of societies, committees, 

and organizations including President of the Fisheries Society of the 

British Isles, Vice President of the 

Freshwater Biological Association, 

Head of the U.K. Delegation to the 

Intergovernmental Oceanographic 

Commission (IOC), and President 

11 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

of the Challenger Society for the 

Advancement of Marine Science, 

just to name a few. I might also 

point out that Ray is a recipient of 

several very prominent awards, including Commander of the British 

Empire in 1968, Fellow of the Institute of Biology in 1973, Fellow 

of the Royal Society in 1975, Honorary Doctorate of Science from the 

University of Wales in 1989, and 

most recently, which some of you 

in this room witnessed in August 

1993, the American Fisheries Society Award of Excellence. 

As author of innumerable scientific papers, Ray established a very 

high standard in the art of describing, in writing, the results of 

scientific inquiry. It was perhaps 

only natural, then, that in 1983 he 

was asked to assume the post of 

Editor of ICES’ premiere publication, the Journal du Conseil (now 

called the ICES Journal of Marine 

Science). In that capacity, and with 

the assistance of his good wife, 

Kathy, he singlehandedly restored 

the quality and reputation of this 

prestigious journal. While serving 

as Editor until the end of 1991, he 

gained the respect of many young 

authors for his willingness to work 

with them to improve their manuscripts to acceptable standards. I 

think it is fair to say that this attribute is not universally shared by 

many journal editors. When I was 

General Secretary of ICES, I had the 

good fortune to interact with Ray 

in his capacity as Editor and to become personally acquainted with 

him. 

As university students and then 

as fish stock assessment scientists, 

many of us have for years been in 

awe of this man and his achievements in fish population dynamics. But in spite of his brilliance, in 

spite of having had such a profound impact on his profession and 

on the discipline of a magnitude 

that few others can claim, and despite being a recipient of so many 

accolades, he is still a very downto-earth, enthusiastic, likeable, 

friendly person, which is why he 

has endeared himself to so many 

of us. 

We are indeed fortunate to have 

such a stalwart with us today and 

to be privileged to hear him speak 

on the topic “Man or Nature in 

Fisheries Dynamics: Who Calls the 

Tune?” Please join me in welcoming Professor Ray Beverton.” 

Ray Beverton 

Emory, Ladies and Gentlemen. 

First of all, thank you, Emory, for 

those very kind remarks. If I sound 

a little hoarse, it’s because I have 

spent all morning saying hello to 

many old friends and making 

some new ones, and I mean some 

very old friends. It’s wonderful to 

see Bob Edwards and Herb Graham in the back row, former Directors, of course, of the NMFS Woods 

Hole Laboratory, and indeed many 

others with whom I have been able 

to resume acquaintances that were 

forged many, many years ago. I 

first came to Woods Hole in 1961 

for the ICNAF Tagging Symposium, and have been helping to 

identify some of the names on a 

group photograph of those participants, and I need some help from 

Bob Edwards and Herb Graham to 

finish that job off before I leave. I’m 

very grateful to have this opportunity of coming back to the United 

States where I’ve been many times 

before. 

It seems a long time ago when I 

first came in 1951 to Beaufort, N.C., 

and this is a wonderful opportunity. I’m most grateful to Michael 

Sissenwine who first conceived of 

the idea of having this tour, and I 

thank the National Marine Fisheries Service for making it possible. I 

think I’d better leave things at that 

Malcolm Silverman, NMFS 

12 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

point to get on with the substance 

of my talk because there is quite a 

lot I want to try and say in a relatively short time. Incidently, I also 

want to thank Brenda Figuerido for 

getting last-minute slides done for 

me which I couldn’t get through in 

time before I left. 

The subject of today’s talk, 

“Man or Nature in Fisheries Dynamics: Who Calls the Tune?” was 

chosen because I felt that this is a 

dilemma, a polarization of approaches, attitudes, and evidence 

that has been with us right from the 

beginning. You’ve only got to turn 

the clock right back to the beginning of ICES at the turn of the century, and there you find the Scandinavian lobby, the Norwegians in 

particular, pressing for studies in 

fluctuations1 because they had 

been used to knowing what it is 

like to have a fishery that was 

highly fluctuating, which I will tell 

you more about in a moment. 

1

This led to the establishment of an ICES 

Committee on Migration of Food Fishes, 

headed by Johan Hjort of Norway. 

Malcolm Silverman, NMFS 

The other committee [the second of the three ICES Committees 

established initially] that was set 

up was, in effect, on the overfishing problem in the North Sea, 

which was perceived quite clearly 

even in those days. This Committee was headed initially by Walter 

Garstang, who founded the Lowestoft Lab in 1902, and later by 

Friedrich Heincke who took it over 

from him. So there were the initial 

steps, but they were running in 

parallel in those days, and it wasn’t 

too difficult to keep the two lines 

of approach separate. Of course, 

the first one led to Johan Hjort’s 

classic paper [on the great fisheries fluctuations of northern Europe] (Hjort, 1914). The Committees reported in 1913 and 1914, 

each with very important monographs, of which Hjort’s is possibly the better known, but Heincke’s 

(1913) was equally important. 

But nowadays, of course, we’ve 

got much more complicated situations. We’ve got both fishing and 

nature’s influence going hand in 

hand, and the problem of how to 

disentangle these, how much of a 

given change or lack of change is 

being due to one or other factor. 

How to unravel their joint action 

or effect is no trivial problem. And 

it pervades all our thinking just as 

much now as it did a hundred 

years ago. And I expect you will 

find, if you talk to your colleagues, 

some of them are much more concerned with the oceanographic 

side of things and others with the 

fisheries side, so you will still get 

tendencies of, well, “Most of it’s 

due to big influences and climate 

and all the rest of it,” while others 

will say, “No, the fisheries has really been the thing that really made 

the profound impact.” 

So I’m going to see if I can just 

lead you gently through a little bit 

of this undergrowth in the hope 

that, at the end of it, we can perhaps get at least some idea of how 

it is possible to unravel, to a certain extent, these complicated interactions. Tomorrow’s lecture will 

be looking down to the individual 

fish and asking how they can respond, in terms of their lifestyle 

and their reproductive strategies, 

to the sort of changes, natural and 

manmade, that are imposed on 

them. 

Let’s get started then. I think it 

might be appropriate, since I am in 

the area of the Pilgrim Fathers, to 

show you a little example where, 

for once, it is possible (because almost certainly the influence of fishing was very trivial in those days) 

to go back to the 1600’s and see an 

alternating act between two species2

, herring and pilchard in the 

U.K.’s West Channel, and it gives 

2

Scientific names of the fishes referred to 

in this book are given in Appendix I. 

13 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

LUXEMBOURG 

SWITZERLAND 

SHETLAND 

ISLANDS 

ORKNEY ISLANDS 

Falmouth

VIa 

VIIb 

VIIj 

IVa 

VIIg 

VIIh VIIe 

VIIIa 

VIId 

VIIa 

IVb 

IVc 

IIIa 

60A W 

11A W 

9A W 

12A W 

5 AW 

55A N 

60A 30 ́ N 

52A N 

51A N 

50A 30 ́ N 

49A 30 ́ N 

48A N 

47A N 

7A W 

57A 30 ́ N 

53A 30 ́ N 

IIIc 

IRELAND 

UNITED 

KINGDOM 

BELGIUM 

FRANCE 

GERMANY 

DENMARK 

200m 

1000m 

2500m 

1000m 

200m 

47A 30 ́ N 

5A W VIIf 

HEBRIDES 

7A E 

8A E 200m 

CELTIC 

SEA 

NORTH 

SEA 

1000m 

Plymouth

NETHERLANDS 

NORWAY 

VIb 

VIIc 

VIIk 15A W 

18A W 54A 30 ́ N 

52A 30 ́ N 

1000m 

Figure 1. Map showing the western approaches to the United Kingdom and 

Ireland, with surrounding water bodies delineated as ICES statistical areas. 

you a little confidence that indeed 

you can see some effects without 

having to worry too much about 

the complexities of extrapolations. 

In Figure 1, Plymouth and Falmouth are in the southwest corner 

of the U.K., so that locates you with 

two names you are very familiar 

with. The oceanography of this 

area is dominated by a front that 

appears between essentially the 

Gulf Stream, with its meanderings 

and sawtooths going up to the 

north, and the more reserved water that eventually finds its way to 

the North Sea. People at Plymouth, 

not so long ago, unearthed the history of this right back to 1660 (Fig. 

2) with a sufficient temperature 

record to follow it. The shaded areas are where the temperature is 

below the long-term norm, and the 

unshaded areas are above. You can 

see, in general, the herring was 

strong, in terms of the fishing activity, when the temperatures were 

below normal, and the pilchards 

took over when the temperature 

was above. There are one or two 

14 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

ACentigrade ACentigrade 

Pilchard only 

in W. Cornwall; 

exports low 

Increased trade 

in herring; 

herring exported 

from Cornwall 

Pilchard fishery 

at Dartmouth 

and in S.E. 

Cornwall 

Little or no pilchard fishery in Devon; 

fluctuating autumn/winter 

fishery in Cornwall 

Pilchard fishery poor 

9 

8 

1660 1680 1700 1720 1740 1760 1780 1800 1820 

10 

9 

Autumn fishery 

for pilchard 

in Cornwall 

Pilchard in 

Bigbury Bay 

Devon 

pilchard 

fishery fails 

Pilchard 

in 

Lyme 

Bay 

No pilchard 

in Lyme Bay 

Herring fishery in Devon 

Failure of Devon 

herring fishery 

Summer pilchard abundant 

off Plymouth 

Pilchard in 

Lyme Bay 

Poor winter 

pilchard fishery 

in S.E. Cornwall 

Summer 

pilchard 

leave 

S. Devon 

Winter 

fishery for 

pilchard 

Herring 

fishery in 

E. Devon 

1820 1840 1860 1880	 1900 1920 1940 1960 1980 

Year 

Figure 2. Long-term fluctuations in her-


ring and pilchard landings in Devon and


10 10 Cornwall vs. air temperature (from


Southward et al., 1988). Upper plot: Fish­


ery data for 1650–1820 compared with


mean air temperatures for central Eng­


land (Manley, 1974). The temperatures


are shown as 5-year running means


9 

8 

10 

9 

(black line) and as smoothed curves 

drawn through 11-year running means 

(gray line). The horizontal line is the 

mean for the whole period. Lower plot: 

Fishery data and scientific evidence 

compared with mean air temperatures 

for central England, 1820–1984, as for 

the upper plot. The temperature series 

has been extended to 1984 as suggested 

in Lamb (1977). 

I need to turn now to a little 

study which I did on this theme in 

1990 when our Fisheries Society of 

the British Isles held a Symposium 

on the Biology and Conservation 

of Rare Fish (Beverton, 1990). I was 

asked by David LeCren, who organized the Symposium, to try to 

answer the question, “What impact 

has fishing had on the major small 

pelagic fisheries worldwide?” remembering, of course, that for 

those who were close to the events 

of the late 1960’s and the early 

1970’s (or indeed earlier still in 

3

S2 = S1 + (A + G) – (C + M) where S1 is the 

weight of the stock at the beginning of the 

year and S2 at the end, A is the sum in 

weight of the number reaching the minimum size of the catchable stock during the 

year, G is the annual increment in weight 

by growth, C is the annual decrement in 

weight of catch, and M is the annual decrement in weight due to natural mortality. 

cases when the evidence is missing, but by and large this alternation between herring and pilchard fits pretty closely to the 

temperature regime. You may ask, 

“Well, temperature, yes, but what 

is the mechanism?” Actually, David Cushing and people at Plymouth have done a lot, in what he 

calls the Russell cycle3, trying to 

unravel the mechanism. It did get 

quite complicated and I don’t need 

to take you into that for the moment. 

15 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

S tock

P eak C ollapsed

S equel

Y ear A dult

n os. 109 Y ear A dult

n os. 1 09 

F raction

o f peak

N orwegian springs pawning herring

1 957 4 0 1 972 0 .16 1 /250 L imited recovery after 10 years;

d ependent on 1983 year class x 

I celandic springs pawning herring

1 957 3 1 972 0 .001 1 /3000 N o sign since 1982

I celandic summers pawning herring

1 961 1 1 972 0 .03 1 /30 S trong recovery to highest recorded

l evel

S outhern North Sea

h erring

1 949 2 .5 1 976 0 .01 1 /300 M oderately strong recovery to aboutt 

1 /4 off p eak x x

G eorges Bank herring 1 967 5 1 976 p robably

< 0.01

p robably

< 1/500

V irtually disappeared 1977–84;

n ow recovering fairly strongly

C alifornia sardine 1 949 3 1 965

( 1975)

0 .015

( 0.01)

1 /250

( 1/750)

2 0 years with no fishery, but larva pres ent; fairly strong recovery since 1985x x

S outh African pilchard 1 960 4 .5 1 982 0 .06 1 /70 S low recovery since 1982

P eruvian anchoveta 1 962 5 00 1 973

1 980–82

2 5

2 5

1 /20

1 /20

1 972 and 1982 were El Niñ o years;

r apid recovery, but not back to peakx x

B arents Sea capelin 1 981 3 5 1 986 0 .3 1 /100 N o fishing since 1986, but stocks

r ecovering rapidly

P acific mackerel 1 933 1 1 968 0 .003 1 /300 N o records between 1968 and 1975;

t hen rapid recovery to 1/2 peak sizex 

Figure 3. Collapses of various marine pelagic fisheries. 

California), the memory of some of 

those very dramatic collapses is 

only too fresh. So I thought, “Well, 

that’s an interesting one; we’ll have 

a look and see what can be done.” 

Somewhat to my surprise, what 

didn’t seem too promising at the 

time turned into a very systematic 

study. I got out a list of the ten best 

documented examples (Fig. 3) of 

what I could call pretty serious fishery collapses, right down to 1/20 

or less of their peak abundance. 

The first five are herring, and the 

first three of those are the AtlantoScandian (which I shall go into 

more detail in a moment), southern North Sea, and Georges Bank. 

Then come some related species 

(not herring): the California sardine, South African pilchard, Peruvian anchoveta (of course, that’s 

the El Niño story), Barents Sea 

capelin, and Pacific mackerel. 

These species all had boom 

years around about 1950 and 1960, 

and then collapsed at the end of the 

1960’s or early 1970’s. Some went 

right down to a very small fraction 

of their peak abundance. The final 

story, which we can pick up later, 

16 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

NMFS 

is that in all but one case, they hung 

on, as it were. They persisted, often at very low levels, and eventually, to some degree or other (in one 

or two cases very substantially), 

notably right on your doorstep 

here on Georges Bank, they have 

come back with a bang. But one, 

the Icelandic spring-spawning herring, didn’t, and we’ll have a look 

at that in a moment. 

Atlantic herring, Clupea harengus. 

Now, we have to know how to 

examine the data when we have 

enough to be able to disentangle 

the effects. Because just looking at 

the ups and downs, or even at good 

abundance estimates rather than 

catches and some kind of environmental signal that you hope is going to be the relevant one, is not a 

terribly rewarding experience, except in the very simple case like I 

showed you in Figure 2. Indeed, 

there have been many false alarms 

in pursuing that inevitably natural 

question. Where else can you have 

all the data that you need to see 

whether the ups and downs are 

correlated? But here, in most cases, 

in this top ten, we have much more 

information than that. 

17 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

S/R decreasing A 

R/S decreasing 

B 

R R 

S S 

R

R 

S 

R/S 

Time 

S 

C 

E 

R 

S S 

Time 

R/S R/S 

S S 

Time Time 

R 

S 

D 

R/S 

S 

F 

Let me just remind you of the 

way you need to analyze the situation when you have these estimates of stock and recruitment as 

in Figure 4. If you have stock size 

on the bottom and recruitment up 

the side (Fig. 4A), and if you have 

a situation in which the survival to 

recruitment from the stock is given 

by the curve there, and any of the 

straight lines is the other way 

around, that is the stock produced 

throughout the subsequent lifetime 

giving you recruitment, and where 

those two lines cross is the stable 

point. If they don’t cross, then the 

population is either in the process 

of declining or expanding. 

If fishing pressure increases 

(Figs. 4A, C, E), then the steepness 

of those lines increases because the 

amount of stock which a given recruitment can produce becomes 

less and less. If it gets to the point 

at which it doesn’t intercept that 

curve anymore, then the population is heading for its graveyard. 

How long it takes to get there will 

depend, of course, upon fluctuations and various things, but sooner or later, it is technically in an unstable state. 

Figure 4.Theory of collapse as described 

by stock-recruitment relationships, with 

A, C, and E illustrating the effects of increasing fishing pressure and B, D, and 

F representing the effects of environmental impacts. 

18 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

NMFS 

The symptoms, therefore, indicate (if that’s what’s happened to 

a stock) that this is a fishing generated event, and then the stock will 

fall as this goes across that way. It 

will initially stay up pretty well, 

depending on how flat-topped the 

curve is, but eventually it will start 

to plummet quite radically (Fig. 

4C). A particularly valuable index 

is, in effect, the reproductive rate 

(recruitment rate per parent or R/S) 

which increases steadily throughout (Fig. 4E), because on that shape 

of curve, the recruitment rate (the 

proportion of the recruitment over 

stock), the survival rate is improving all the way as the stock falls. 

So in time, the recruitment rate 

goes up as the stock falls. 

The British herring fleet departing at daybreak. 

Now, the other way around is 

when it’s an environmentally mediated event (Fig. 4B, D, F), especially if it’s an event that is affecting the early life history, and most 

are. It’s a bit of a simplification to 

take that as the only way it can happen, but it’s the general way. Then, 

fishing pressure stays the same, but 

the survival curve would gradually decrease and you’d get fewer 

recruits from a given stock. And so 

there will be a series of stable 

points (Fig. 4B), falling possibly, if 

the survival rate’s going faster than 

that, you might even come down 

the right side. The effect of that is 

that the stock still declines as before, but the recruitment falls also 

initially and at roughly the same 

rate (Fig. 4D). Whereas, in particular, the recruitment success rate, instead of going up all the time, actually is either staying constant or 

even possibly declining slightly as 

the population attempts to stabilize 

itself on the way down (Fig. 4F). 

I’m sorry about that little bit of 

an explanation, but I think we need 

that in order to examine, therefore, 

these top ten stocks in terms of 

what happened, the time sequence 

of stock abundance and recruitment success rate as time went by. 

19 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Loge R/S Loge R/S Loge R/S 

Figure 5. Plots of spawning stock biomass (SSB) and 

the natural logs of recruitment/stock (R/S) for stocks 

of Atlanto-Scandian herring: Norwegian springspawning herring (A), Icelandic spring-spawning herring (B), and Icelandic summer-spawning herring (C). 

In each part of Figure 5, the stock 

size is the heavy gray curve and 

years are along the bottom, starting back in 1945 right up to the 

1990’s as near as I can get it. The 

heavy gray curve is the stock size, 

and the black dots are the recruitment rate [R/S] calculated year by 

year. The shaded area is where the 

fishing pressure has exceeded the 

capacity of the recruitment rate at 

that moment to replenish itself. In 

other words, the recruitment rate 

would have to go up to the top of 

the shaded areas to be able to compensate, over the lifetime of those 

recruits, for the depletion, caused 

by fishing, of the spawning stock. 

It’s a little bit of a problem because 

recruitment rate happens year by 

year and these are the other way 

around. It’s a long-term projection, 

but it’s an unavoidable problem 

with this kind of data, and it’s the 

simplest way of indicating whether 

the reproductive rate, the recruitment success rate, is able to keep 

up with or compensate for the 

depletion. 

Now, in the case of the Norwegian spring-spawning herring (Fig. 

5A), the answer was that as the 

population fell, especially when it 

got down to the extreme low level 

in the early 1970’s [A], the recruitment rate went up quite markedly. 

Fishing was stopped in about 1973, 

but then as the population recovered a bit, it [recruitment rate] came 

down very substantially, much 

1945 1950 1955 1960 1965 1970 1975 1980 1985 

4 

3 

2 

1 

0 

–1 

Norwegian 

spring-spawning 

herring 

SSB (1

0–9 kg) 

A 

5 

6 

7 

8 

–2 

4 

3 

2 

1 

0 

5 

6 

7 

8 

9 

10 

B 

4 

3 

2 

1 

0 

–1 

5 

–2 

–3 

–4 

1945 1950 1955 1960 1965 1970 1975 1980 1985 

4 

3 

2 

1 

0 

5 

6 

7 

8 

9 Icelandic 

spring-spawning 

herring 

A 

4 

3 

2 

1 

0 

–1 

–2 

1945 1950 1955 1960 1965 1970 1975 1980 1985 

Icelandic 

summer-spawning 

herring 

A 

4 

3 

2 

1 

0 

5 

6 

SSB 

R/S 

R/S 

SSB 

SSB 

R/S 

SSB (1

0–8 kg) SSB (1

0–8 kg) 

(R/S)0 

(R/S)0 

(R/S)0 

A 

B 

C 

Year 

20

Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

Allen Shimada, NMFS 

more than you would have expected it to, and except for one blip 

[B], which is the 1983 year class, it 

stayed rather disappointingly 

down. As a result, the recovery of 

the Norwegian springs has been 

very slow. 

The Icelandic spring-spawning 

herring is a real boom-bust story 

(Fig. 5B). It came from very small 

beginnings and then faded away, 

A catch of herring. 

but as it was going down, the recruitment rate did not increase as 

it did for the Norwegian springs; 

it too went on down. So the deficit, 

the condition caused by fishing, 

was enormous. The stock didn’t 

even make any attempt to replace 

the depletion that was going on. 

Finally, in Figure 5C, is the Icelandic summer-spawning herring 

which first went up, then came 

down, and then has come back up 

again. The recruitment rate [R/S] 

went down, following quite closely 

the rise, and then went steeply up 

as the population dropped. Then 

as the population came up again, 

the R/S declined, which stabilized 

out at the point which enabled the 

stock to sustain itself at that higher 

level. 

21 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Southern North Sea herring 

A B 

SSB R/S 

(R/S)0 

Now, the next two figures are on A 4 5 

this same topic, which I won’t have 3 4 

time to go into detail, but I’ll just 2 3 

run through very quickly just to 1 2 

show you that the same kind of 0 1 

patterns can be found in the vari- –1 0 

ous others. That’s the southern 1945 1950 1955 1960 1965 1970 1975 1980 1985 

North Sea herring (Fig. 6A) where 1.5 

it went down and stayed down 3 

over a long period. The reproduc2

Georges Bank herring 

SSB 

R/S 

(R/S)0 

B 

1 tive rate did increase, especially in 1 the end, and they were able to 

bounce back fairly well. Georges 0 0.5 

Bank herring (Fig. 6B) was very –1 

much like the Icelandic springs in –2 

1945 1950 1955 1960 1965 1970 1975 1980 1985 

0 

the sense that, over the period, its 

R/S ratio did not respond to the declining stock. California sardines 

4 

3 

8 

7 

(Fig. 6C) were dipping about for 2 

6 

5 

some 10–20 years and finally gave 

California sardine 

A 

? 

SSB 

R/S 

(R/S)0 

C 

4 

up the ghost, as it were, and their	 1 3 

0 2 

reproductive rate fell off quite dra- 1 

0 matically toward the end, and that 1945 1950 1955 1960 1965 1970 1975 1980 1985 

meant a complete collapse of the 

stock. Finally, the South African pilSouth African pilchard 

SSB 

R/S 

(R/S)0 

D 

16 

chard (Fig. 6D) did respond quite 14 

well to the initial decline, but then 6 12 

has not responded beyond that 5 10 

point. 4 8 

3 6 

2 4 

1 2 

0 0 

1945 1950 1955 1960 1965 1970 1975 1980 1985 

Year 

Figure 6. Plots of spawning stock biomass 

(SSB) and the natural logs of recruitment/stock 

(R/S) for stocks of southern North Sea herring 

(A), Georges Bank herring (B), California sardine (C), and South African pilchard (D). 

Loge R/S Loge R/S Loge R/S Loge R/S 

SSB (1

0–8 kg) SSB (1

0–9 kg) SSB (1

0–8 kg) SSB (1

0–8 kg) 

22 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

Finally, just to finish the top ten, 

the Peruvian anchovy (Fig. 7A), 

which of course had this very massive El Niño effect in the early 

1970’s, responded up to a point, but 

not very dramatically so. So, it 

didn’t recover as well as it might 

have done because fishing had to 

be pretty drastically stopped. 

Barents Sea capelin (Fig. 7B) was 

going up and down all over the 

place, but that’s a story we’ll have 

to come to in a moment. Finally, 

with Pacific mackerel (Fig. 7C), 

again, we see a recruitment rate 

that was rather erratic, sometimes 

tracking the declining stock and 

sometimes not, although at the end 

it went up quite steeply. By this 

time, the depletion caused by fishing was too much for it to cope 

with, and it too disappeared for 

quite some time. 

Figure 7. Plots of spawning stock biomass (SSB) 

and the natural logs of recruitment/stock (R/S) 

for stocks of Peruvian anchovy (A), Barents Sea 

capelin (B), and Pacific mackerel (C). 

7 

6 

5 

4 

3 

2 

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 

10 

20 

Peruvian 30

anchovetta 

7 

6 

5 

4 

3 

8 

9 

1945 1950 1955 1960 1965 1970 1975 1980 1985 1990 

Barents Sea 

capelin 1.5 

2.0 

1.0 

0.5 

0 

A 

1 

0 

–1 

–2 

–3 

2 

3 

–4 

3 

2 

1 

0 

Pacific 

mackerel 

1935 1940 1945 1950 1955 1960 1965 1970 1975 1980

0 

SSB (1

0–9 kg) SSB (1

0–9 kg) SSB (1

0–8 kg) 

R/S 

R/S 

R/S 

SSB 

SSB 

SSB 

(R/S)0 

(R/S)0 

(R/S)0 

A 

B 

C 

Year 

Loge R/S Loge R/S Loge R/S 

23

The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

So much for that story. Now we 

have to look in a little more detail 

and concentrate on the three 

Atlanto-Scandian herrings: the 

Norwegian and the two Icelandics. 

75A�

Icelandic spring 

and summer 

spawners 

Spawning 

area 

(Icelandic) 

Polar 

front 

Norwegian 

spring 

spawners 

Wintering 

area 

Spawning 

area 

(Norwegian) 

Feeding area 

Feeding 

area 

Between them, they really cover 

the full range of what’s happened: 

one disappearing completely, another recovering very strongly, and 

the third dithering about for a long 

time before it reappeared. Indeed, 

70A� I’d just remind you that we’re talking about the area between Norway and Iceland (Fig. 8), the feeding area up against the polar front, 

a migration back for the Norweg65A� ians to spawn, and then starting, 

when they’re mature, that cycle 

again. The Icelandic springs and 

summers spawn off the southern 

part of the island and feed and mix 60A up with the top ones to feed in the 

summer. So that’s the general geography. 

20A 10A 0A 10A 20A 30A 

Figure 8. Distribution of stocks within the Atlanto-Scandian 

herring group. Redrawn from Dragesund et al. (1980), and 

with additional detail provided by Ray Beverton. 

An early scientific illustration of 

a herring, showing fine detail. 

24 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

Now, here’s a diagram (Fig. 9) 

which I shall show two or three of 

for the next few minutes, with 

apologies for the current part that 

it is attempting to distinguish. Here 

is the difficulty with this: you have 

to look at several variables going 

at once, or otherwise you can’t really see the interplay, what’s happening. The catch is the black line, 

the stock size (gray line) the same 

as you’ve seen before (in Fig. 5), 

and then the dotted line is the fishing mortality rate [F]. You see that 

in each case there was a dramatic 

increase in the fishing mortality 

rate up to levels which imply a removal rate of around 75–85% per 

year. And then, of course, a complete zero because the fisheries 

were all through—they stopped for 

several years. Then gradually the 

fishing rate was allowed, in the 

case of the Norwegian spring 

spawners (Fig. 9A), to catch up 

very little; there was no fishing until the early 1980’s. On the 1983 year 

class, some fishing was allowed. 

The Icelandic springs disappeared 

altogether (Fig. 9B). The Icelandic 

summers (Fig. 9C) came up, and 

the fishing rate was maintained 

around about 0.1, and that indeed 

has been a very good example, as 

you will see in just a moment of 

how things are happening. 

Catch (1

0–4 t) Catch (1

0–5 t) Catch (1

0–4 t) 

10 

18 

SSB 2.0 

1.5 

1.0 

0.5 

Catch 

F Norwegian 

spring 

spawners 

A 

F 

9 

16 8 

14 7 

12 6 

10 5 

8 4 

6 3 

4 2 

2 1 

0 0 

1950 1960 1970 1980 1990 

25 

9 

20 

8 

7 

15 6 

5 

10 

SSB 

Catch 

F 

1.5 

2.0 

1.0 

0.5 

Icelandic 

spring 

spawners 

B 

F 

4 

3 

5 2 

1 

0 0 

1950 1960 1970 1980 1990 

6 

10	

SSB 

Catch 

F 

1.0 

1.5 

0.5 

Icelandic 

summer 

spawners 

C 

F 

5 

4 

3 

5 

2 

1 

0 0 

1950 1960 1970 1980 1990 

Year 

Figure 9. First-order diagnostics of the AtlantoScandian herring stocks: catch, spawning stock 

biomass (SSB), and fishing mortality rate (F ) for 

Norwegian spring spawners (A), Icelandic spring 

spawners (B), and Icelandic summer spawners (C). 

SSB (1

0–6 t) SSB (1

0–5 t) SSB (1

0–5 t) 

25 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

10 

5 

0 

0 5 10 

SSB (10–6 kg) 

49 

67 

65 

F = 1.2 

(1967) F = 0.9 

(1964) 

F = 0.15 

(1960) 

F = 0.05 

(1947–57) 

F = 0 

66 

64 

48 

63 

47 

62 

50 

51 

52 

53 61 

54 60 

55 

58 

59 

57 

56 

Figure 10. Stock-recruitment relationship for 

Recruits at age 1 (1

0–6) 

Icelandic spring-spawning herring. 

But now, in terms of the stock 

and recruitment diagram for the 

Icelandic springs (Fig. 10), first of 

all, it disappears. They went up 

with the dots (�) (upper arrowed 

curve)—this is the actual data corresponding to those theoretical pictures I showed you (in Figure 4)— 

and came down with the circles (�) 

(lower arrowed curve). You see 

they came down on that right hand 

side; they didn’t come down the 

left loop. That meant the R/S ratio 

was declining instead of responding positively to the depletion. And 

the replacement rate starting off 

somewhere like that for an unexploited fishery, which meant that 

it could stabilize out here probably, 

under no fishing, ended up by 1967 

at F = 1.2. There was no question 

of it’s being anywhere near a stable 

situation. It was miles away from 

any possible attempt for the population by then to cross over, as it 

were, on that replacement rate. 

Now, at the opposite extreme 

(Fig. 11), the Icelandic summers 

came down on the circles (� ). 

Again on the [lower arrowed 

curve], notice the two or three very 

poor year classes in the middle of 

the late 1960’s. The fishing pressure 

was building up, the replacement 

line is seeking an all-time high (F 

= 1.0, 1966), but then fishing was 

stopped, so it dramatically came 

right back to the line at F = 0.05 

(1974). In the meantime, the good 

response of the recruitment rate 

26 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

meant that the recovery went up 

on the upper arrowed curve, the 

dots (�). So now, I think this was 

certainly one of the best, if not one 

of the few, cases where you see a 

complete cycle of growth, collapse, 

and recovery. And they are now 

around about here [top graph, 

right side of thick black arrowed 

curve] on the curve which enables 

you, on that curve, to really put in 

a real yield calculation with that 

stock-recruitment relationship in it. 

And it predicts an F max of about 0.3, 

and they are just about at that point 

now [in 1994]. So, it’s, to a very 

large degree, the fact that they got 

that fishery under control after 

such a dramatic collapse, due to the 

Director of the Marine Research Institute in Iceland, Jakob Jakobsson, 

who himself is a son of a fisherman. 

In fact, he fished on the east coast 

before he went to Glasgow to get 

his degree. He personally has 

monitored the recovery of this 

stock and persuaded the industry 

that they really couldn’t expect to 

return to anything like the fishing 

pressure that occurred before the 

collapse. I think it is one of the success stories, and I hope that they 

will be able to keep the fish population up at that point. Of course, 

if there is another series of very bad 

year classes, this will put some real 

pressure on the system. But, at the 

moment, they are working very, 

very effectively, as close as they 

need get, to the maximum sustainable position. 

Yield (1

0–4 t) 

Recruits at age 1 (1

0–8) 

15 

10 

5 

0 

0 100 200 300 400 500 

SSB (10–3 t) 

SSB at MSY 

Collapse 

Recovery = 

71 

74 

70 72 

73 51 

48 

49 

69 68 

66 

67 

52 

53 

75 

54 

76 

77 

65 

47 

64 

56 

78 

81 

80 

55 

57 

79 

58 

82 

63 

84 62 

59 

60 

86 

85 

61 

83 

89 

87 

88 

F = 1.0 (1966) F = 0.7 964) 

F = 0.3 

(1961 & 1994) 

F = 0.15 

(1947–60) 

F = 0.5 (1974) 

F = 0 

Stock and recruitment 

50 

= 

(1

10 

5 

0 

0 0.5 1.0 1.5 0 500 1000 1500 

F SSB (10–3 t) 

MSY = 10 Z 10–4 t 

at F max = 0.3 SSB at MSY = 35 Z 10–4 t

= 30% of SSB max 

10 

5 

0 

F max 

Fext = 1.7 

Figure 11. Stock-recruitment relationship for Icelandic summer-spawning herring and corresponding maximum sustainable yield (MSY) plots. 

27 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Now, in terms of the Norwegian ment. That’s another of those di- plot), and there is the attempt to resprings, they are taking a long time agnostics that [shows that] fishing covery along the bottom with the 

to get back up; just to remind you, has had a very profound effect. You 1973 year class. And it wasn’t until 

these springs are much more fluc- can’t always get this sort of good the 1983 year class that enabled the 

tuating than the other ones. They age composition data, but when stock to begin to pick up and then 

are the ones in Figure 12 with the you can, it adds to the whole inter- it’s the last two, 1990 and 1991, exheavy periods of landings from pretation. tremely good year classes, and that 

1810 to 1870, a very bad period, stock is back on the map again with 

and then they came back with a There is the stock-recruitment a replacement line somewhere 

bang with the 1904 year class diagram (Fig. 14) with the replace- around 0.2 or 0.3. 

which put it right up and was fol- ment lines going first shallow and 

lowed by a bigger one. Eventually then up to the top and back again. 

in the immediate post-war period, The circles show the decline, conit was at its height with a stock size 

of 10–12 million metric tons (t) and 

a very low fishing rate during this 

period. I’m working on some of 

their old data now with Ole Johan 

Østvedt, and it appears that F 

couldn’t have been much more 

than about 0.1 during that period. 

But, then came again some bad 

year classes and the whole position 

changed dramatically. 

I’ve got a better stock-recruitment figure in a moment. What I 

really want to show in Figure 13 is 

the age composition in 1965–70 

compared to that in 1950–60. This 

[1950–60] is the period when there 

were many old fish, right up to 22– 

23 years old, with an average age 

way up in the early teens. By 1965– 

70, all of these old fish were gone 

and we were left simply depending on rapidly declining recruitnected with a very difficult-todraw curve because of the two very 

good year classes (1950 and 1959), 

but if you put it somewhere like 

that, you can see that when they 

are down here (lower left corner of 

left plot)—the 1962, 1965, and particularly the 1965, 1967, 1968, 1969 

are very poor indeed—the median 

sort of line, and when it came back 

from 1973, it was very weak indeed. You can’t see it from there, 

so I expanded the square (right 

Figure 12. Landings (millions of hectoliters) of winter herring from western 

Norway. Redrawn from and data through 

1960 taken from Devold (1963).

13 

12 

11 

10 

9 

8 

7 

6 

5 

4 

3 

2 

1 

Landings in millions of hectoliters 

1760 1770 1780 1790 1800 1810 1820 1830 1840 1850 1860 1870 1880 1890 1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 

28 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

3 

Recruits at age 0.5 (1

0–10) Population numbers (1

0–9) 

1950–1960 

1965– 

1970 

Figure 13. Age composition of the stock 

2 of Norwegian spring-spawning herring 

in the periods 1950–60 and 1965–70. 

1 

0 

0 5 10 15 20 25 30 

Age in years 

30 

83 

73 90 

91 

85 

88 

89 

50 

59 

60 

53 

54 

55 56 57 

58 

52 51 

62 65 

61 66 64 

? 

68 69 67 

F = 1.4 (1970) 

F = 1.0 (1967) 

F = 0.37 

(1965) 

max for 

stability 

F = 0.2 

1964) 

F = 0.1 

(1950–60) 

F = 0.02 

(1975) 

F = 0 

10 

25 

20 

5 

15 

10 

F = 1.4 

73 

91 

90 

89 

88 

83 

86 87 

F = 1.0 

F = 0.37 

F = 0.1 

F = 0.02

F = 0 

67 

68 69 

70 

71 

72 

74 

75 

76 

77 78 

79 

8081

8285 

F = 0.2 

84 

5 0 

0 1 2 

0 

0 2 4 6 8 10 SSB (10–9 kg) 

SSB (10–9 kg) 

Figure 14. Stock-recruitment relationship for Norwegian spring-spawning herring. 

The right plot is an enlargement of the block in the lower left corner of the left plot. 

Recruits at age 0.5 (1

0–10) 

29 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Catchability coefficient Catchability coefficient 

8 

0.03	

Norwegian spring-spawning herring 

b = .0 ~ 

A 

–1

7 

6 

5 

0.02 

4 

3 

0.01 

2 

1 

0 0 

0 10 20 30 40 0 5 10 15 

Stock size (no. Z 10–10

) Anchoveta biomass (B) (10–6 t) 

Peruvian anchovetta; seine 

b = 0.97 

q = 0.352 x B–0.97 

B 

0.10 

Georges Bank haddock; trawl 

r 

2

 = 0.67 

C 

b = 0.38 

4 

0.09 

0.08 3 

0.07 

0.06 

2 

0.05 

0.01 

1 0.03 

0.02 

0.01 0 

0 10 20 30 40 50 60 70 80 0 500 1000 1500 2000 2500 

Cape hake; 

trawl = 1.0 

= 10.0 

D 

b = 0.72 VPA 

λ

λ

Relative haddock abundance Exploitable biomass (10–3 t) 

Figure 15. Plots of catchability coefficient (q) vs. stock size for 

Norwegian spring-spawning herring (A) (Ulltang, 1980), Peruvian 

anchoveta (B) (Csirke, 1989), Georges Bank haddock (C) (Crecco 

and Overholtz, 1990), and Cape hake (D) (Gordoa and Hightower, 

1991). Plots were redrawn from figures in these references. Catchability coefficient Catchability coefficient (1

0–6) (month x GRT) 

30 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

© Instituto del Mar del Peru 

Now, you may ask why the fishing mortality rate went up so dramatically and catastrophically and 

the catch dropped so fast compared with all those we’ve looked 

at, and the answer was that it 

wasn’t entirely due to an increase 

in fishing effort. The number of 

boats, of course, and the gear had 

indeed increased up to about 1960, 

but that wasn’t anywhere near 

enough. What happened was that 

the catchability—that is, the ability to catch a given proportion of 

the stock—went up as the stock 

shrank. Don’t forget, this was a 

spawning fishery. They were accumulating quite close to the coast, 

there wasn’t a long searching time, 

they had advanced acoustics, and 

had a very good acoustic survey 

The Peruvian anchoveta, 

Engraulis ringens. 

group in the lab [Institute of Marine Research, Bergen] helping to 

catch them, to locate the shoals. 

And so, it was nearly as easy to 

catch 10 shoals out of 11 as it was 

to catch 10 shoals out of 100. And 

that created a massive mortality 

rate which is manifest by the fact 

that the relationship between this 

catchability coefficient and the 

stock size is almost hyperbolic (Fig. 

15). 

It’s interesting that there are 

similar kinds of relationships (Fig. 

15). I’m very glad to see that this 

lab [Woods Hole], amongst others, 

has been looking into this problem 

in other fisheries. There is a tendency for this to happen in some 

others: silver hake, Georges Bank 

haddock, which has been down in 

the last few years, but the escalation doesn’t happen until the stock 

size is a much smaller percentage 

of the unexploited than it was in 

the Norwegian herring. So that’s 

why it [decline in stock abundance 

due to fishing] got out of control; 

it wasn’t just that fishing went 

along increasing in terms of number of vessels. This is what made it 

so difficult; it was happening so 

very quickly, so suddenly, it was 

just impossible to convince the administrators and the fishermen, 

and even I think the scientists were 

only finally sure that they were on 

an edge of a precipice. And it is the 

catchability problem that did it. 

31 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

LR 

DT 

REF 

Unstable 

Stable 

A 

–1.0 –0.5 0 

Catchability coefficient 

5.0 

Unstable 

Stable 

LRD-D 

DT 

REF 

B 

5.0 

4.0 4.0 

3.0 

X increase in effort 

3.0 

X X 

2.0 2.0 

1.0 1.0 

–1.0 –0.5 0 –1.0 –0.5 0 +0.1 

X increase in effort 

Unstable 

Stable 

12 

13 

9 

6 

1 

11 

10 

8 

7 

5 

4 

3 

2 

C 

X 

Catchability coefficient 

Figure 16. Stock-recruitment stability envelopes for 

Norwegian spring-spawning herring, where X, which is 

F/(F+M)

b , is plotted against catchability for three different 

assumptions about M (instantaneous natural mortality). 

F = instantaneous fishing mortality. A: stochastic mode: 

effect of lognormal recruitment (LR) on reference stability 

envelope; discrete time (DT) model with zero random 

recruitment equivalent to reference envelope of steady 

state model (REF). B: stochastic mode: combined effect 

of lognormal recruitment and density-dependence of 

growth and maturity parameters (LRD-D). C: continuation 

of reference envelope (discrete time model) to positive 

values of the catchability coefficient. 

Catchability coefficient 

32 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

© Leo J. Shaw, The Seattle Aquarium 

I have actually done a little bit 

of modeling with this population 

with a very weak curvature on the 

stock-recruitment curve (Fig. 16). 

Anyway, in any case, even without 

any bad year classes, this catchability business means that an increase in effort from the 1950–60 

period could only accept about a 

two-fold increase in effort before it 

became unstable, even with a low 

catchability. With a high catchability coefficient, which is what it 

was, it meant that even a small increase in effort would have set the 

Herring circling in a ball. 

population on a course which 

eventually would have rendered it 

unstable. I can give it more elbow 

room by putting in density dependence, of which we’ve got good 

data, and change the maturity, but 

still, when you’re up in this range 

of catchability, it meant that a very 

small proportional increase in effort would put you, sooner or later, into an unstable position. 

Now, let’s now turn our attention to the fact that in all those 

cases, I picked up the point that, in 

the 1960’s, there were some very 

poor year classes. They, of course, 

made things much more difficult 

because just that alone would have 

decreased the population size even 

without a catchability problem. 

With a catchability problem, it 

meant that the natural decrease in 

population size caused the catchability to go up. So if they’d done 

nothing at all except just fish as 

usual, they would have been catching a much higher proportion of 

the stock for that reason alone. 

33 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Figure 17. Temperature (left) and salinity (right) of the 50–200 m layer in 

sections A, B, and C, and temperature in 50–200 m in the Kola section (K), 

35.2 

35.1 

35.0 

34.9 

34.8 

B 

C 

70 71 72 73 74 75 76 77 78 79 80 81 82 83 70 71 72 73 74 75 76 77 78 79 80 81 82 83

6 

5 

4 

3 

2 

1 

0 

Temperature (AC) 

A 

B 

K 

C 

Salinity ( A

AA 

A 

Year Year 

)

August–September, 1970–83. 

Now, let’s return to the question 

of what happened in the 1960’s. 

Well, the answer was that the 

1960’s, at least in this part of the 

North Atlantic, proved to be a very 

difficult time for fish stocks. The 

evidence was rather poor, in fact, 

in the 1960’s; it was nonexistent 

until quite recently. But, there was 

a very strong signal coming through 

in the late 1970’s with temperature 

and salinity and the polar meridian, which is up off northern Norway, showing very distinct dips 

(Fig. 17), and that’s what started it. 

What they came up with (Fig. 18) 

is that this wasn’t just in the late 

1970’s, but this was an event that 

could be traced back to the mid 

1960’s. It was called by Bob Dickson, Günter Dietrich and others at 

Kiel, Germany, and Arthur Lee— 

and there was an ICES Mini-Symposium in the middle 1980’s on it 

—the “Mid-Seventies Anomaly.” 

That was a funny name, but it 

means there were some unusual 

temperature and salinity events at 

particular parts of the Norwegian 

Sea in the North Atlantic. They 

were able to trace it as a large mass 

of Arctic water overflowing from 

the Arctic basin, very cold, much 

colder than normal. It’s possible, 

with a certain amount of guesswork, to trace it down on the East 

Greenland side, where it got entrained with the Irminger Current. 

It circled around off the east coasts 

of Labrador and Newfoundland 

and then got tangled up in the early 

1970s in the main Gulf Stream and 

went up much more to the east this 

time. It looped into the northern 

North Sea, caused a marked drop 

in salinity there, and upset the 

whole Atlantic salmon migration 

in those 2–3 years, and finally 

ended up off Norway again, this 

time much more to the east in the 

late 1970’s and 1980’s. 

So, the extraordinary thing 

about this is that it took so long to 

34 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

70A 

60A 

50A 

40A 

Mid 

1960's 

1969–70 

1971 

–72 

1973–74 

1977 

–78 

1976– 

78 

1980–82 

1978– 

80 

50A 40A 30A 20A 10A 

Figure 18. Projected track of the “Mid-Seventies” temperature/ 

salinity anomaly (black) (after Dietrich et al., 1975) and the Gulf 

Stream (gray). 

be picked up. I suppose the answer 

is, as much as anything, that attempting to do any sort of monitoring off the East Greenland coast 

is extremely difficult. It’s the most 

inhospitable place to work, with ice 

traveling at high speeds. I remember trying to get a section done off 

Cape Farewell, and the innermost 

section was 4 miles off. We really 

much wanted to complete it because we knew we were picking up 

this very crucial current system. 

The captain was on the bridge and 

was watching us like a hawk. He 

wasn’t watching us as much as he 

was watching the ice flows moving down on us. Of course, if we’d 

had one very close, we’d have had 

to cut the wire and lose all the water bottles and give it up. Fortunately, we managed to hang on and 

do it. Trying to do it up off East 

Greenland would have been much 

more difficult, and it would have 

been difficult on the very inhospitable Labrador coast. 

35 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

However, there is little doubt 3 

that that was what was causing it. 2 

In this little diagram I’ve put to- 1 gether (Fig. 19), the anomaly of the normalzed for stock size normalzed for stock size 

Norwegian springspawning herring 

0 

–1 

–2 

–3 

1950 1960 1970 1980 1990 

2 

1 

0 

–1 

–2 

–3 

–4 

1950 1960 1970 1980 1990 

Icelandic 

spring 

spawners 

2 

1 

0 

–1 

–2 

–3 

Icelandic 

summer 

spawners 

1950 1960 1970 1980 1990 

+1 ̊ 

0 

–1 ̊ 

1950 1960 1970 1980 1990 

Year 

A 

B 

D 

recruitment success rate, over the 

long-term average, is taken as a residual in the stock-recruitment 

curve (Fig. 19A), and shown as a 

time sequence with the countermeridian temperatures section, 

also calculated above and below 

the means. So I think you can see 

that without too much difficulty, at 

least for the Icelandic springs (Fig. 

19B) and summers (Fig. 19C), 

which were much more affected by 

the anomaly on its way down, as 

it’s going to the west, fits the lower 

temperatures. Even though that 

section (Fig. 19D) isn’t in the right 

place to catch it, we still see the 

backwash from it. On the way 

back, when it was going to the east 

side, it missed the coastal Icelandic springs altogether, a very weak 

effect on them. They were far too 

far to the west, but it really hit the 

Norwegian spring-spawning herring badly in 1979 and 1980. Of 

course, it was more of a different 

sort, it wasn’t a temperature signal 

Figure 19. Reproductive rate anomalies 

in the Atlanto-Scandian herring stocks 

depicted as ∆loge R/S normalized for 

stock size vs. years (A, B, C) and temperature anomalies at the Kola section 

(33A30’ E) vs. years (D). 

∆loge R/S 

∆loge R/S 

normalzed for stock size anomalies (AC) 

Temperature 

∆loge R/S 

36 

C 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

5th level 

4th level 

3rd level 

2nd level 

1st level 

PRODUCERS 

C O N S U M E R S 

Sea mammals 

Cod 

Pred. 

zoopl. 

Juv. 

gadoids Capelin Herring Redfish Prawns 

Mesozooplankton 

Microzooplankton 

Macrozooplankton 

Phytoplankton 

Detritus 

Figure 20. Main food webs in the Barents Sea ecosystem (after Ajiad et al., 1992). 

here that was doing it, and we’ll 

come to it in just a moment. So, I 

think, although this is rather spotty data, and you have to work your 

way around all the uncertainties, 

the message is fairly clear. There is 

a signal coming through here—a 

message, that is, even despite all 

the differences of the information. 

We now have to answer the 

question, “Why did Norwegian 

herring take all through the 1970’s 

and did not come back up again as 

the springs did, because the MidSeventies Anomaly didn’t affect 

them on its way back until the end 

of the 1970’s.” To do this, we have 

to go beyond the physical story. We 

have to look at the whole of the 

Barents Sea ecosystem (Fig. 20), 

and I only had time to just pick out 

a few headlines to remind you it’s 

what I call an oligospecific system. 

It’s got a small number of very 

strongly interacting species, unlike 

the North Sea or Georges Bank, 

which has more species and complexities, which certainly Steve 

Murawski will know because he’s 

shepherded the Multispecies Working Group through the last 3–4 

years. Life in the Barents Sea is a 

much more straightforward simple 

system, with much stronger interactions on which the main players, 

leaving aside for the moment—but 

it won’t last long—the marine 

mammals, which haven’t been 

brought in yet, but they’ve got to 

before long. The Atlantic cod is the 

main predator, with the capelin 

and the herring. For the moment, 

that’s the main triangle that we can 

look at. They dominate the middle 

and upper trophic levels. This is a 

program which the Norwegians 

and the Russians are doing. There 

37 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Autumn distribution 

of capelin 

Spawning 

Franz Josef 

Land 

Novaya 

Zemlya Distribution of cod 

COD 

COD 

CAPELIN 

Spitsbergen 

NORWAY 

RUSSIA 

of capelin 

migration 

Figure 21. Cod and capelin in the Barents Sea. The winter spawning 

migration of capelin is shown by the arrows (Tjelmeland, 1992). 

have been one or two meetings, but 94] and put in the picture. They’ve 

they haven’t really started publish- kept me up with what’s going on 

ing in the full press yet. I’ve had and given me permission to use 

the privilege of being over in Ber- some of this material in this talk 

gen in the last year or two [1993– and others. 

The interaction, on the other 

hand, between capelin and cod 

(Fig. 21) is variable from year to 

year and greatly complicates the 

question of measuring the predation effect. But broadly speaking, 

the capelin moves into the shores 

to spawn, as it does, of course, in 

Newfoundland. The cod, to varying degrees, are overlapped in distribution. 

Now, I just have to quickly raise 

the capelin story again (Fig. 22). 

The stock crashed in the mid-late 

1980’s, with a fishing mortality rate 

again estimating the same problem. The stock-recruitment curve 

(Fig. 22B) was initially well up, almost throughout this period (1965– 

85). In fact, it was capelin that the 

Norwegian fishing industry went 

onto when their herring collapsed, 

and they were managing it very 

well. There were debates going on 

between the Norwegian scientists, 

administrators, and the fishing industry on or about this sort of position until, first in the 1983 year class 

and then dramatically in 1984, the 

bottom fell out of the whole thing 

(Fig. 22A). There were very poor 

year classes in 1985 and 1986. It’s 

only been in the last year or two 

that it’s come back up again. 

38 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

4 2.0 

? 

C F 

C 

F 

A 

SSB 

Recruits at age 1 (1

0–11) Catch + SSB (1

0–6 t) 

3 1.5 

2 1.0 F 

1 0.5 

0 0 

1965 1970 1975 1980 1985 1990 

Figure 22. Catch (C), spawning stock 

Year biomass (SSB), fishing mortality rate 

(F ), and recruitment in Barents Sea 

capelin. 

12 

10 

8 

6 

4 

2 

0 

0 1 2 3 4 

B 

Cod + 

herring 

low 

Cod + 

herring 

high? 

72 

73 

74 

75 

76 

77 

78 

79 

80 

81 

82 

83 

87 86 85 84 

88 

89 

90 

91 

SSB (10–6 t) 

39 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

10 

5 

0 

77 78 79 80 81 82 83 84 85 86 87 88 89 90 

Year 

Figure 23. Larval index of abundance, spawning stock 

biomass, and stock biomass at age 2 of Barents Sea 

capelin (redrawn from Fossum, 1992) compared with 

cod and herring year-class strength (R) in numbers. 

So, I think now I can show you I’ve just shown you—and that corthe missing jigsaw piece for this responds to the herring and cod 

(Fig. 23); that is, there are the cape- year classes, of which the 1983 year 

lin year classes dramatically fall- class (I’ve already mentioned the 

ing, as measured in the year as 1- herring made a good one), so it was 

group—so it’s a year less than what for cod. They know from feeding 

12 

14 

10 

8 

6 

4 

2 

0 

1.0 

0.8 

0.6 

0.4 

0.2 

0 

Larval index 

1981 1982 1983 

1984 1985 

1986 1987 1988 

1989 

1990 

1991 

SSB (1

0–6 t) 

Year-class 

Strength 

Cod: R3 (10–8) 

Herring: R3 (10–9) 

2.0 

3.0 

4.0 

5.0 

6.0 

? 

? 

1.0 

Stock 

biomass 

(age 2) 

(10–6 t) 

experiments, stomach content 

analysis, that it (capelin) was 

essentially very heavily preyed 

upon by the 1- and 2-group cod, 

and, to a lesser extent, by herring. 

The herring story is not so clear, 

and the cod is very much stronger, 

and it was this that has caused that 

particular situation. 

Now, the answer so far then is 

that the cod and herring year 

classes really hit the capelin hard, 

but have we explained why the 

herring didn’t recover until 1983 

and why they did then? Well, my 

theory, which my Norwegian colleagues are treating with some reserve at the moment, quite understandably, is that what’s happened is that if the herring get really low, which they did in the late 

1960’s and early 1970’s, the capelin in effect take over. They are very 

similar in their ecological status, 

and it does look very much as if 

once the herring got below the 

threshold, caused primarily by 

fishing, but by a mixture of fishing 

and the very poor year classes due 

to the Mid-Seventies Anomaly, the 

capelin held them down and they 

couldn’t get back into the system 

until 1983. And then once that happened, it’s just the whole situation 

back again, to more like it was 

when the herring were more abundant. It is, I think, one example as 

near as I can get to a really good 

example—there may be several 

others, but there aren’t many— 

40 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

1.5 

1.0 

0.5 

0 

–1.5 

–1.0 

–1.5 

1.5 

1.0 

0.5 

0 

–1.5 

–1.0 

–1.5 

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 

1983 

0.15 

0.10 

0.05 

0 

–0.05 

–0.10 

–0.15 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 

1983 

0.15 

0.10 

0.05 

0 

–0.05 

–0.10 

–0.15 

Section A 

temperature 

Section B 

temperature 

Section A 

salinity 

Section B 

salinity 

Salinity ( AA A/ Salinity ( AA A/ ∆

∆ ) ) 

77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 

Year Year 

Figure 24. Changes in temperature and salinity conditions 

at sections A and B off northern Norway, 1977–91. 

what ecologists would call alterna- ture and salinity off northern Nor- temperature alone, not because sative stable states. It does look as if, way (Fig. 24) of a kind that hadn’t linity at those ranges is itself necuntil the very good 1983 year class, been seen for some while. Now, essarily harmful, but it could be 

the herring would have gone on here is the favorable signal [i.e. in more indicative of water condibumping along the bottom, as it 1983]. I don’t know of a mech- tions than temperature alone. But 

was all through the 1970s. As for anism, and I don’t think anybody whatever it was, that was the phythe question of what caused that does, but I have a feeling, and I sical situation that was associated 

good year class, the best clue is that shall mention it again in the last with the timing with those two 

in 1983 there was a very consider- part of my talk, that the salinity sig- good year classes in both species. 

able upward blip in both tempera- nal is a better diagnostic than the 

∆Temperature (AC) 

∆Temperatue (AC) 

41 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Distribution 

Spawning 

60A 

70A 

100A 60A 20A 0A 

80A 70A 

50A 

40A 40A 

50A 

60A 

20A 

40A 

60A 

60A 40A 20A 0A 

Figure 25. Distribution of the cod stocks in the North Atlantic 

(redrawn from ICES, 1991). Area of distribution depicted by 

shading; spawning areas depicted by darkened spots. 

Now, I’m going to move over in 

the last part of my talk to cod, because cod and herring are very 

different animals. I used to tell 

David Cushing when he first started work on herring at Lowestoft, 

“David, you must remember that 

herring isn’t really a fish at all, it’s 

an animal unique to itself, and 

you’ll have to learn all about the 

biology of this animal; it’s nothing 

like plaice or cod or haddock.” And 

indeed, the more I see of the comparative population biology of cod 

and herring, to take these two main 

species, the more I see examples, 

and I can show you some tomorrow, where they clearly do live 

quite differently. Even although 

they appear to be living in the same 

cold environment, I have to remind 

42 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

57A 

60A 

63A 

66A 

69A 

80A 76A 72A 68A 64A 60A 56A 52A 48A 44A 40A 36A 32A 28A 24A 20A 16A 12A 

72A 

69A 

63A 

60A 

57A 

60A 56A 52A 48A 44A 40AW 36A 32A 28A

66A 

Subarctic water 

West Greenland Current 

100 0 500 km 

Greenland 

Iceland 

Polar Current (cold) 

Irminger Current (warm) 

Spawning grounds 

of West Greenland cod 

Spawning grounds 

of Icelandic cod 

Figure 26. Surface currents (redrawn from Hansen and Hermann, 

1953) and cod spawning grounds in Greenland waters. 

you that we are talking about a 

whole series of cod populations 

scattered over the northern fringe 

(Fig. 25), a fascinating distribution 

because it gives you a double-degree temperature gradient each 

side of the Atlantic, with some very 

fringe physical conditions, around 

Greenland, in the middle. I expect 

you know the Greenland story 

pretty well (Fig. 26). There is the 

current system, the warm [Irminger Current], the cold [Polar Current] coming around West Greenland. The spawning area, when 

there are fish to spawn, is off the 

West Greenland side. The story is 

one of these where there’s no question of disentangling the effects 

here, not the start of it anyway or 

indeed the finish of it. There are 

43 
- - - - - - - - -

The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Recruits at age 3 (1

0–6) Catch (1

0–3 t) 

500 

400 

300 

200 

100 

0 

1910 1930 1950 1970 1990 

Catch 

A 

1910 1930 1950 1970 1990 

600 

500 

? 

? 

? 

Recruitment 

and 

temperature 

C 

5 

400 4 

300 3 

200 2 

100 1 

0 

1910 1930 1950 1970 1990 

Year 

Figure 27. Annual catch of West Greenland cod (A), + or – 

atmospheric pressure over Greenland (B), and recruitment 

(vertical bars) of West Greenland cod and surface water 

temperature (dots) at West Greenland (C). 

Temperatue (AC) 

catches (Fig. 27A), and that’s a fair 

measure of abundance too, starting 

with nothing, just a few catches in 

the 1920’s until the peak of half a 

million tons a year in the 1960’s and 

then down to nothing again or very 

small levels in recent years. The 

temperature picture (Fig. 27C) was 

down around about 1A C or less, 

which was obviously too cold for 

any of the migrants, because they 

are migrants from Iceland which 

stay and spawn; they go to West 

Greenland and spend some time 

and go back to Iceland to spawn. 

To comment on this at West Greenland, they say they couldn’t do this 

when the temperature was like 

that. When the temperature got up 

above 2–3A C, they could and did. 

They stopped here, but then went 

up and stayed up consistently all 

through the 1960’s, and that led to 

sustained population spawning for 

a period of some 30 years. 

So, that’s a very clear-cut signal 

and it’s now possible to see the circumstances which led to that, and 

this, I think, is one of the more dramatic developments in understanding the relationship between 

atmospherics in the Northern 

Hemisphere, comparable to the influence that the Southern Oscillation has on the El Niño in the 

southern part of the Pacific. 

Pressure over Greenland ( pos neg) 

+ - - - - - + ++ - - ++ + ++ -

+ - B 

44 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

This is the North Atlantic (Fig. 

28), and what Bob Dickson and 

others particularly—there are very 

recent publications—have been 

able to show is that, when there is 

a general high pressure system in 

this [southern] part of the North 

Atlantic and a low pressure over 

Greenland (Fig. 28A), you’re getting, of course, that kind of anti-cyclonic winds, and that is associated 

with an increase in the year classes 

in the period which saw expansion. 

And then, particularly in the 1960’s 

and 1970’s, the whole thing changed 

over (Fig. 28B). This [over Greenland] became a high pressure center and that led to northeasterly 

winds, and it was those, so they 

surmised—and I think with good 

reason—that led to the generation 

or origin of the Mid-Seventies 

Anomaly. In fact, it was cold water 

being sucked out of the Arctic basin. I can remember, incidentally, 

talking about the barrenness. Jakob 

Figure 28. North Atlantic wind fields, 

1910–90 (A and B) (from Buch, 1990 and 

Dickson and Brander, 1993). A shows 

70

60

A

50

A

A

40

30

A

A

20A 

70A 

60A 

50A 

40A 

30A 

20A 

80A 

60A 

40A 

20A 

0A 

20A 

40A 

70

60

A

50

A

40

A

30

A

A

20A 

70A 

60A 

50A 

40A 

30A 

20A 

80A 

60A 

40A 

20A 

0A 

20A 

40A 

A 

B 

+4 

0 

+ 

+ 

– 

– 

winters of negative pressure over 

Greenland, 1910–30 and 1970–80. B 

shows winters of positive pressure over 

Greenland, 1935–45 and 1960–70. C 

shows Kushnir’s (1994) index of cyclonicity, 1906–80. Positive values correspond to a cyclonic center in the central 

North Atlantic, positive pressure over 

Greenland, and strong northerlies from 

the Arctic. Negative values depict 

opposite conditions. Redrawn from 

figures in the above references. 

Sea level 

pressure (mb) 

U index 

4 

2

B 

A 

B 

A 

C 

0 

–2 

–4 

1900 1920 1940 1960 1980 

Year 

45 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

NE Arctic cod 

W Greenland cod 

P R2 

<0.01 

<0.001 

7 

67 

8 

7 

6 

5 

4 

3 

2 

0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 

Temperature (AC) 

Figure 29. Year-class strength vs. temperature on the spawning grounds for Northeast Arctic and West Greenland cod. 

–6

) Loge recruits at age 3 (10 

Jakobsson recalls how he was off 

northern Iceland at this time in the 

middle 1960’s and he said that the 

sea was just crystal clear, very cold, 

and actually devoid of any obvious 

life. I can remember trawling—we 

had some time on our hands and it 

was very good weather—in the late 

1950’s. We trawled right around 

the top of Spitsbergen doing a bit 

of fishing as we went. We got broken up a lot, lots of rocks up there, 

but we hardly caught a thing. The 

net would come up after 3 hours 

with virtually nothing in it. It was 

clear, very clear, very cold, and 

very fresh. So, that sort of Arctic 

water—I don’t know if it’s true of 

the Arctic basin generally, but that 

could possibly have been Arctic 

water coming down—was clearly 

very inhospitable to anything from 

primary production onwards. I 

think that is rather a very convin46 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

cing demonstration over a period 

of half a century when you have 

waxing and waning of the weather 

systems as being the prime cause 

of what’s happened to the Greenland cod 

In fact, so strong is the signal between recruitment and temperature that, without any attempt to 

adjust for stock size or anything, 

you get a very strong correlation 

between recruitment against temperature in Greenland (Fig. 29). 

Compare this with the Northeast 

Arctic cod; a much more limited 

range of temperature, they spawn 

in Lofoten, which is never exposed 

to these extreme conditions, it fluctuates somewhat, as you can see, 

between 1.5 and 4A C, but that’s still 

not as intolerable as it would be 

down at 0.5A C or so, which happened at Greenland in the early 

part of the century. So, there is a 

weak signal here, but other things 

obviously have a big influence on 

what actually happens in terms of 

recruitment. 

I did mention that the returning 

slug of cold water caused problems, not only for the Norwegian 

herring in the late 1970’s, but also 

for the cod (Fig. 30). So, the Northeast Arctic cod was nevertheless 

very much affected at that end at 

that time. It wasn’t affected early 

on because the whole slug of cold 

water moved much more to the 

west. 

∆loge R/S 

∆loge R/S 

3 

2 

1 

0 

–1 

–2 

–3 

2 

1 

0 

–1 

–2 

–3 

–4 

1950 1960 1970 1980 

1950 1960 1970 1980 

Norwegian spring-spawning herring 

NE Arctic cod B 

A 

Year 

Figure 30. Reproductive rate anomalies in the 

Norwegian spring-spawning herring (A) and 

Northeast Arctic cod (B) stocks depicted as 

∆loge R/S normalized for stock size vs. years. 

47 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

–9) Catch and SSB (1

0–6

) Recruits at age 3 (10 

3 

SSB 

F 

A 

C 

1.5 

2.5 

2 1.0 

1.5 F 

1 0.5 

0.5 

0 0 

1950 1960 1970 1980 1990 

Year 

2 

1 

0 

0 0.5 1.0 1.5 

F = 0 

F0.1 = 0.14 

F max = 0.25 

Fmed = 0.46 

F = 0.33 

F = 0.58 

50 

51 

52 

53 

54 

55 

56 

57 58 

59 

60 

61 

62 

63 

64 

65 

66 

67 

68 

69 

70 

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71 

73 72 

74 

75 

76 

77 

79 78 80 

81 

82 

83 

84 85 

86 

88 

89 

90 

B 

87 

SSB (10–6 t) 

Figure 31. Catch (C), spawning stock biomass (SSB), fishing mortality rate (F ), 

and recruitment in Northeast Arctic cod. 

Just to see what the picture looks 

like for cod, there is the general 

story (Fig. 31), nothing like the dramatic collapse that we see in the 

pelagics, but a steady attrition on 

its stock size over a long period, except at the very end when two very 

good year classes would come in 

(Fig. 31A). The fishing mortality 

rate was gradually increasing up to 

a pretty high level, nearly 1, which 

is nothing like the extremes of the 

Norwegian spring-spawning herring fishery, but it’s still pretty high. 

In terms of a stock-recruitment diagram (Fig. 31B), we haven’t got, of 

course, the collapse and recovery 

in the same sort of way. The nearest you can get to it is the upper 

arrowed line, with the replacement 

lines, unexploited at one point, 

steepening, as they did, right up to 

another point, leaving still a possibility of a stable sustainable situation, a very poor one in terms of 

stock size and yield, but nevertheless sustainable when recruitment 

was between 0.4 and 0.5 x 109

 and 

SSB was between 0.2 and 0.4 x 106 

t. But you see again there were 

some very poor year classes, and 

these have helped pull the thing 

down. 

The other important cod fishery, 

the Icelandic (Fig. 32), has a rather 

similar story: slow decline, a bit 

steeper, the stock size is a bit more 

erratic, and a gradual climb in fishing mortality nearly the same 

amount. There is a more strongly 

48 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

compensated stock-recruitment 

curve, in the sense that it’s pretty 

well horizontal over a wide range, 

and where it goes down [near origin], I don’t know, and I hope we 

don’t find out because that’s not 

where the fishery should be at all— 

it should be up at a higher level. 

You might say, “If they got the herring up, why haven’t they got the 

cod?” The answer is that it’s probably one of these problems we face 

here. At least the collapsed herring 

did, at least, jolt the whole industry out of its old frame of mind to 

realize that life just couldn’t go on 

as it did before. The cod fishery 

hasn’t suffered such a collapse, and 

the problem is to get the fishing 

pressure permanently down. Even 

for a country that’s got it all to itself, its own shelf and its own stock, 

like Iceland, it’s not easy to do it. 

Even with a director [Jakob Jakobsson] who’s got a great reputation 

in Iceland in getting the herring 

straight, he’s having a tougher job 

getting the cod straightened out. 

But he knows what’s got to be 

done, and I’m pretty sure that 

they’ll get it right over the next few 

years. They are, at the moment, 

somewhere on the replacement 

line, with a stable point which is 

safe, in that sense, but it’s not 

where it should be, in terms of 

whether or not they’re getting the 

maximum sustainable yield out of 

it. 

–3 t) Catch and SSB (10 

1500 

C 

SSB F 

0.5 

1000 1.0 

F 

500 0.5 

0 0 

1955 1965 1975 1985 

Year 

5 

4 

3 

2 

1 

0 

0 500 1000 1500 

F = 0.6 

(1970–85) 

F = 0.3 

(1950–65) 

F = 0 

52 

53 

54 

55 

56 

57 

58 

59 

60 

61 

62 

63 

64 

65 

66 

67 

68 

69 

70 

71 

72 

73 

74 

75 

76 

77 

78 

79 

80 

81 82

83 

84 

85 

86 

87 

88 

89 90

91 

SSB (10–3 t) 

Figure 32. Catch (C), spawning stock 

biomass (SSB), fishing mortality rate 

(F ), and recruitment in Icelandic cod. 

–6

) Recruits at age 3 (10 

49 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Now, it would be, I think, inappropriate to finish my lecture without some mention of the northern 

cod, much closer at hand on the 

western side. May I say straight 

away that I don’t think it’s very 

wise for an outside person to try 

and tell the professionals on the 

spot what their answer is or what 

their job should be, in the sense of 

sorting this out. It’s problem 

enough, a desperate problem, with 

having an industry virtually crippled like this. But it did seem to me 

that if I am going to try to give you 

this kind of scan around what’s 

happened to some of these fish 

stocks, in terms of the interplay between fishing and natural causes, 

it would be inappropriate not to 

mention this one because it’s, in 

some ways, the most unexpected 

and the most dramatic of all. At 

least the herring stocks that we’ve 

looked at, many of them, those that 

we know a long history of, there’s 

been a history of instability. So it’s 

not all that surprising if we’re in 

the middle of one now. But I think 

your northern cod have never had 

anything near that degree of erratic 

behavior in the past, at least not 

that I’m aware of. The Grand Banks 

fisheries have been going more or 

less off and on with some fluctuations, but they’ve going for many 

hundreds of years. 

Now, this seemed to me to be a 

critical diagram (Fig. 33). This is in 

Rivard and Maguire (1993) from 

Yield (t) 

900,000 

800,000 

700,000 

600,000 

500,000 

400,000 

300,000 

200,000 

100,000 

0 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 

1962 

1990 

1976 

Equilibrium yield 

in the early 1970's 

Equilibrium yield 

in the late 1980's 

F 

Figure 33. Productivity of the northern cod stock (NAFO Div. 2J3KL). 

The productivity of the early 1970’s is compared with that of the late 

1980’s.The productivity curves correspond to the yield per recruit (using 

the growth characteristics for these periods and assuming knife-edge 

selection at age 5) multiplied by the average recruitment for the year 

classes contributing to these periods (redrawn from Rivard and 

Maguire, 1993). 

the Canadian workshop on Risk 

Evaluation and Biological Reference Points for Fisheries Management which was held a few 

years ago. They plotted the actual 

yield against fishing mortality rate 

in the 2J3KL and 3NO stocks, the 

Labrador and northern banks 

stocks. They regard this as a quasi 

stable point there [about 450,000 t], 

and another one here [about 

200,000 t], but the yield’s half that, 

50 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

and yet the fishing mortality rate 

appeared to be the same in both 

cases. Now, if that’s to happen, either one or the other wasn’t a stable 

point at all (it was on the way 

down), or else there was a dramatic 

drop in recruitment, or both. 

Let’s just see whether we can see 

that, in terms of a stock-recruitment diagram (Fig. 34A). The data 

I’m using are read off a graph; I 

couldn’t get hold of the original 

CAFSAC4 report. I didn’t ask for 

the information to be changed. 

Anyway, here’s the stock-recruitment story. This is the earlier period when yield was higher, and this 

is the later period. I notice first of 

all there’s no doubt there is a cluster of bad recruitment in the early 

1970’s. If you plot the recruitment 

rate against time (Fig. 34B), there 

is the drop in the early 1970’s. It recovered quite a bit, but hasn’t kept 

up, and the recruitment rates there 

[last two on right side] are rather 

worrying. I think that’s probably 

the Mid-Seventies Anomaly at its 

southern-most point. In a paper at 

the Reykjavik Cod and Climate 

Symposium last summer, Taggart 

et al. (1994) did detect a signal in 

salinity, although not in temperature. I think that’s probably what 

it was. However, at the moment, if 

we look at it in terms of how to interpret this, I think probably the an4

Canadian Atlantic Fisheries Scientific Advisory Committee. 

∆loge R/S Recruits Z 10–8 

1965–75 

and 

1980–90 

? 

F = 0.5 

67 

66 

68 

69 

70 

71 

72 

73 

74 

75 

76 

77 

78 

79 

80 

81 

82 

83 

84 

85 

86 

88 

87 

89 

90 

A 

10 

5 

0 

0 5 10 15 

SSB (10–5 t) 

1.0 

0 

–1.0 

B 

1965 1970 1975 1980 1985 1990 

Year 

Figure 34. Stock-recruitment plot for cod in NAFO 

Div. 2J3KL (A), and reproductive rate anomalies 

(B) depicted as ∆loge R/S vs. years. 

51 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

swer is it wasn’t in equilibrium, it 

wasn’t a stable point here. If you 

had a safe fishing rate then, you 

must have more or less the same 

replacement line, subject to growth 

rates and things not being all that 

dissimilar. If it’s stable down here 

[lower left side of Fig. 34A], which 

is where it might just be or where 

it was in the 1980’s, it could not be 

up there [on the F = 0.5 replacement line], and I think the reason 

for this is that it’s a very shallow 

curve. This is a very weakly compensated stock on the northern end 

of its limits, which is what we 

would expect. Alec MacCall’s ideas 

on dynamic geography of fish 

stocks would suggest exactly that. 

Stocks at the fringe of their distribution have a very weak density 

dependence, but are very much influenced by the environment, a 

harsh environment. And we can 

probably see, rather like the Norwegian herring story, a very potentially unstable population doesn’t 

take a lot of fishing to drive it 

down. Fishing at that level is almost certainly too much for it, but 

that isn’t, of course, the real answer. 

I think the real answer to the immediate problems must lie in this 

very massive downward push of 

cold water. It’s almost like a cold 

slug coming down (the Mid-Seventies Anomaly) the Labrador 

coast and pushing everything in its 

path. 

There are still some unexplained 

events. Why the fish have gone into 

deeper water may be to get away 

from the temperature. Whether the 

capelin is partly responsible, I 

think it’ll be a little while yet before we really know the answer. 

But it is one of the most disturbing 

of all the events I’ve seen and heard 

in my time because it really seems 

to be unexpected. But it’s so widespread and so dramatic, and fishing may have weakened the stock, 

in the sense that it was, the northern one in particular, a very poorly 

compensated one, but it wasn’t an 

escalation problem like as the herring had been, I’m sure. 

So, let’s see if I can sum up now, 

for I’ve been talking longer than I 

should have anyway. I think the 

picture that I get from all this is 

how complex the environment is 

in time and space. It is only when 

things really become very sharply 

defined, as in the extremes of marginal habitats or in extremely escalating fishing pressures, that we 

really become convinced of what’s 

happened without having to weigh 

one thing up too carefully with another. 

In terms of the small pelagics 

that we were looking at—the top 

ten—there was only one that really 

disappeared and never came back. 

That was the Icelandic springs, but 

two or three others that were 

clearly on the way down—and 

what fishing did was to hasten 

them on their way and push them 

over the edge—would have gone 

anyway in time. Then there would 

be the intermediate case where 

they would have been in a pretty 

poor state, but they were driven 

down by fishing in such a way that 

when there was some adverse environmental condition, you were in 

a pretty poor state to deal with it. 

There’s no doubt fishing pushed 

down the Norwegians particularly, 

and southern North Sea herring as 

well, and several of the others, into 

a state much lower—much, much 

lower—than they would have been 

in just on their own, and indeed 

this happened in the case of the 

Norwegian one—it upset the whole 

balance of the ecosystem in the process. Finally, for those for which the 

Icelandic summer spawners is a 

good example, where they are 

pretty resilient and fishing did 

push them down quite a bit, no 

doubt about it, they probably 

would have just done a little blip 

and ridden out one or two bad year 

classes quite easily, but having 

been pushed down, they at least 

came back up again quite quickly. 

So, can we make any sort of 

check list of [situations] when fishing is a real threat, in the light of 

this review (Fig. 35). I still think 

that the most important single 

thing, as far as the fishing side, is 

when catchability escalates out of 

control, and especially when a de52 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

Fishing poses a threat to sustainable harvesting and, potentially, to the viability of the 

resource, when: 

1. Catchability escalates out of control, especially when accentuated by a declining stock 

whose reproductive potential has been weakened by adverse environmental conditions. 

2. Long-term fishing capacity is maintained or increased by political/economic incentives 

remote from, ignorant of, or indifferent to the long-term productivity of the resource. 

3. The species is caught incidentally, but is more vulnerable than the target species. 

4. Capture is by interception on a migration route to a spawning ground, making it 

possible to harvest the whole spawning stock with no immediate economic penalty. 

5. These threats are compounded if the species is: 

a) long-lived, 

b) has a low per capita reproductive rate, 

c) has a weakly compensated parent-progeny relationship, 

d) is easily accessible and cheap to catch, and 

e) has a high market value. 

In these circumstances, clear objectives, good science, strong political will, firm control, 

and a cooperative fishing community are more than usually necessary for sustainable 

harvesting and good resource husbandry. 

clining stock’s reproductive potential has been weakened by adverse 

environmental conditions, which 

was true for some of the herring examples. That’s a very serious situation. Another one is when the 

long-term fishing capacity is maintained or increased by political and 

economic incentives remote from, 

ignorant of, or indifferent to the 

Figure 35. Summary points. 

long-term productivity of the resource. Now that’s a rather pompous sort of statement, but what 

I’m trying to say is that this is 

where management in general, or 

industry or whatever, just doesn’t 

see what is happening, and maybe 

until there is rapid escalation of 

fishing, it’s hard to expect that they 

could. There are many other cases 

where they could see it, and you 

have some on your doorstep and I 

don’t need to remind you of them. 

When a species is caught incidentally, of course, but is more vulnerable than the target species, that 

creates a problem we haven’t 

talked about, but it is obviously a 

problem. There are some examples, 

53 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

possibly one of the rays, the common skate in the Irish Sea, that 

seems to have disappeared, probably because it was caught not as a 

target species, but was taken very 

easily while fishing for other species. This is a general category, and 

it is not just on marine species either. Another is when you’re intercepting fish on the migration route, 

more especially in rivers, and you 

can take the whole run totally without any immediate economic penalty for so doing. You just wake up 

to the fact the next day there aren’t 

any fish left. That is an extreme 

case, but there are some other examples in the marine fisheries 

where it gets quite close to that sort 

of thing. 

Problems in all those situations 

can be compounded: the species is 

long-lived, it has a low per-capita 

reproductive rate anyway. In other 

words, it has a low fecundity rate 

and a low birth rate, so it’s not able 

to ride out these troubles. It has a 

weakly compensated parent-progeny relationship, such as some of 

those I’ve shown you. Of course, it 

is easily accessible, cheap to catch, 

and has a high market value, which 

adds to the problem. Under these 

circumstances, fair objectives, good 

science, strong political will, and 

firm control by a cooperative fishing community are more than usually necessary for sustainable harvesting and good husbandry. Usually one will say, “Yes, that’s what 

we’re doing; we’re very familiar 

with that situation.” 

Well, I started to ask the question right at the beginning: “Who 

calls the tune?” Perhaps if I just 

simply finish by saying that it 

seems to me nature decides what 

the melody should be and produces the score, and man has to 

decide how he going to play it. It 

might be a very complex score, and 

it might be that an orchestra is 

needed to play. Therefore, it depends very much on whether the 

conductor can read the score in the 

first place, and whether his musicians can play their instruments 

decently. I’m afraid the record 

shows that most of the time man 

makes a right old hash of playing 

most of the scores that nature produces. The only possible excuse is 

that nature will produce a new 

score at the last minute. The concert will be halfway through, and 

along will come the second half of 

the concerto which will require a 

new score that nature’s just produced. But we haven’t seen that 

one before, so we’ve got to be good 

at sight reading and we’ve got to 

have a good memory, and we’re 

not good at either of those things. 

Thank you very much. 

Emory Anderson 

Ray has talked for a little over 

an hour, but I’m sure he’d be willing to answer a few questions at 

least. Do any of you have particular comments? I see a few hands 

going up. 

Andy Rosenberg 

I wonder if maybe you have a 

unique perspective because you 

watched the development of a lot 

of these fisheries, both as they were 

going up and when they came 

down again. Some of us, I guess, 

only saw them coming down. Do 

you think it’s possible, given those 

pictures of stock and recruitment 

that you have, to have been able to 

diagnose what was going on at the 

time? In other words, to use your 

musical analogy, instead of knowing or having rehearsed the score 

in advance, could you have predicted what was going to happen? 

Ray Beverton 

I don’t think, at the time (the 

1950’s), that we had the experience, 

the know-how, or the evidence to 

really pick up anything like the 

pulse. So I don’t really think there 

was much that could have been 

done at the time. But another aspect of your question is whether 

we could again pick it up, armed 

with what we now know. I think 

this is a very important question. 

One thing that could be done, and 

I’ve thought about trying to do it, 

but I haven’t got around to it yet, 

and it may be something which 

needs more advanced computing 

than I can do now, is to actually try 

to hindcast backwards. 

54 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

Supposing we really were on 

that and we didn’t have those two 

year classes or supposing we had 

stopped fishing when the stock, 

such as the Norwegian herring, 

had fallen to, say, 4 million t, could 

they have held it at that point, 

could it have sustained itself with 

no fishing then, not waiting until 

they had no fish and then stop fishing? That means you’ve got to be 

able to predict, given the recruitment rate at that moment from 

your expected curve and the actual 

thing, whether you could safely assume that’s what would have happened if you’d had a bigger stock. 

The trouble with the herring is you 

would have a great problem, if I’m 

right, because of the threshold beyond which capelin takes over. But 

you could hindcast the Icelandic 

one, the summer spawners, I think. 

Reversibility enables a hindcasting 

to be done. 

Say, had you stopped at such 

and such a point, this is what 

would have happened. And I think 

this sort of approach—I’ll call it sophisticated hindcasting—is something we really ought to develop. I 

think it’s maybe possible, especially with computer interaction. 

Fishermen are prepared to listen 

and are able to respond, and you 

can say to them, “Look, here’s what 

actually happened, remember? 

Now, this is the story of what we’ve 

done. Now try and press this button and see what would happen if 

you had done that.” In Australia, 

they actually did something like 

this for one of their little inshore 

fisheries. I believe it’s something 

we should do. How you put it 

across is another thing. Only those 

who know their fishermen and 

know how to talk to them should 

say how to do it, but it seems to 

me we have an opportunity here, 

with data as good as that, for some 

of us to hindcast and say, had we 

been able to hold the fishing back, 

keep the fishing mortality down, 

we could predict with some reasonable precision what would happen. I don’t think we’d really start 

doing it very systematically, but I 

think it would be very valuable to 

do. I don’t know if that is what you 

had in mind, Andy, but it’s certainly what your question triggered off in my mind. 

Andy Rosenberg 

Yes, I think it is what I had in 

mind. Even if you took on some of 

these stock-recruitment plots and 

blocked out the information so you 

just looked at the first 10 years to 

see what you would come to, and 

then 20 years, and so on. If you 

could actually come to a conclusion, that would reasonably suggest what would happen next. 

Now, that’s difficult to do because, 

of course, you have only one history to pick. 

Ray Beverton 

I think in some of our stock-recruitment data—and they look 

awful on the diagram—there really 

is a lot more information. There is 

an enormous amount of information in them, and if it is possible to 

manipulate them in such a way, 

you could draw out a signal from 

a mass which, at first sight, seems 

to be impossible. 

George Kelly 

If a bumper year class of any of 

the major species in the North Atlantic were to come, is anyone prepared to manage them scientifically or otherwise? 

Ray Beverton 

Well, I gave you the example of 

the summer-spawning herring 

which the Icelanders are doing, 

exactly on that basis. 

George Kelly 

Is it the Norwegians who were 

responsible? 

Ray Beverton 

No, this is the Icelanders. It was 

not an ICES fishery because once 

Iceland had extended her 200-mile 

limit, this put both their herring 

and their cod entirely under their 

own jurisdiction. So it never came 

to either NEAFC5 or the EC6 because it was outside the jurisdiction of both. And indeed, it wasn’t 

until about 3 or 4 years ago that the 

5

North-East Atlantic Fisheries Commission. 6

European Commission. 

55 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

story has really been produced at 

ICES scientifically. I think I can take 

a very modest credit for persuading Jakob: “Now come on Jakob, 

you’ve got a wonderful story here, 

you must put this into the ICES 

bowl.” He did it; he and Gunnar 

Stefánsson, his very good statistician, have done this very effectively. So, they’re doing it, but the 

Norwegians are doing it with the 

Russians now. The Russians, of 

course, are very much affected by 

the recent upheaval in Russia. 

That’s what’s led to the withdrawal 

of much of the Russian fishing 

pressure and enabled the fishing 

mortality rate to dramatically drop 

up in the north, on the Arctic cod 

in particular. That one I’m hoping 

they will be managing in accordance with this joint RussianNorwegian multispecies exercise 

they’re getting now. They’ve got to 

make a decision as to how much 

more cod they want. If they really 

bring the cod anywhere near to its 

maximum, they’re not going to 

have anything like the capelin fishery they’ve got. And the herring is, 

at the moment, the joker in the 

pack. They haven’t really got that 

put into the system, but they’ve got 

a decision to make about how to 

balance between these three major 

species. 

George Kelly 

Did you say you were optimistic for the future of the fisheries in 

the north? 

Ray Beverton 

For that one I am, as long as the 

Russians can keep up with it, as it 

were, and put into practice what 

their scientists are saying. Their 

scientists are pretty involved in 

this, but it’s a question of whether 

they can deliver the goods. But I 

think there is a good chance for 

that, and I think we’ll see the Iceland cod coming under a better 

management before long. As to the 

rest of it, that’s a different matter, 

at least on our side of the Atlantic 

it’s a very different problem and 

something I might talk about tomorrow, but that’s another story. 

George Kelly 

You mentioned the California 

sardine only in passing, but I didn’t 

get whether you were attributing 

[the problems to] man’s operation 

or the environment. 

Ray Beverton 

Both were to blame, I’m pretty 

sure. You have an upwelling that 

was causing periodic upheavals, 

and every time there was a bit of a 

drop in the stock size, up would go 

the catchability. So the effort was 

suddenly taking a lot more [fish] 

than it should have been. And then 

there was another bit of a relaxation [in effort]. It dribbled around 

in a half-baked state between sort 

of going off and finally it did tip 

over and went down, with, of 

course, the sardine coming back up 

again, I mean in that case the Pacific sardine. That’s happened in 

historical times, so we’ve seen the 

alternation between sardine and 

northern anchovy, I mean in this 

case, and so also in the Peruvian 

story. There’s some very complicated, knock-on effects once either 

man or nature starts really to upset the system to this extent. 

Steve Murawski 

In the last few years, the concept 

of sustainability has entered into a 

lot of our natural resource management, at least in theory if not in 

practice. I wonder, given the interplay between environment and 

fishing mortality, if sustainability 

as a concept in fisheries is really an 

unattainable goal? 

Ray Beverton 

I very firmly believe that it is a 

perfectly attainable goal, provided 

we can really get the fishing pressure down to where we often said 

it should be, which is down well 

below F max. Then you are to a point 

at which none of the stock-recruitment arrays I’ve seen, the replacement line, would be anywhere near 

a nonsustainable situation. So I 

think any stock that cannot sustain 

a doubling of its natural mortality 

rate would be in difficulty anyway, 

because that could easily happen 

for natural reasons. I’m trying to 

put some evidence together on this 

one. I don’t think there will be time 

tomorrow, but I think I can begin 

to show that you’ve got, histori56 
Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

cally, some pretty sustainable situations provided you can get that 

fishing mortality right down. It’s 

not a new thing; if you like, it’s 

Gulland’s F0.1 (Gulland and Boerema, 1973). I would not put it in 

terms of economics. I’d just say, for 

goodness sake, get that fishing 

pressure down to something around 

about the natural mortality rate or 

not much more. You may say that’s 

not proof that it’s sustainable, but 

you have then to rely upon all the 

background evidence that you’ve 

got about what’s made things unsustainable and make sure you’re 

not in that situation. You could, at 

least in the negative sense, say that 

we’ll avoid all those situations that 

in the past made it unsustainable. 

Not a particularly convincing answer, but you asked me a very profound question which I think is a 

vitally important one which we’ve 

got to face in terms of the Rio Convention7 and all those sorts of 

things—sustainability and biodiversity. But a fishing pressure of 

an amount that is not more than, 

at the most, twice the natural mortality rate and preferably less, is 

below Fmax usually, and that means 

only a biomass of about half the 

unexploited biomass or at most 

one-third of it. 

7

United Nations Conference on Environment and Development (UNCED) held in 

Rio de Janeiro, Brazil, in June 1972. 

Steve Murawski 

I think it’s safe to say we can find 

fishing mortality rates that are so 

low that would guard against almost any sort of fluctuation in the 

environment. On the other hand, 

that may be the price of a tremendous foregone yield in times when, 

in fact, there are good year classes 

to harvest. 

Ray Beverton 

If you approach it in terms of 

keeping a harvesting rate at a very 

modest level, you will then have 

to accept that, if you’ve got some 

good year classes, you will get better yields, but the harvesting rate 

will still be the same. Now, that’s 

not what the industry likes; they 

want stability. I think the industry’s 

pressure for stability has been one 

of the real difficulties that has 

caused us to try to manage stability by fiddling about with the harvesting rate. John Shepherd tried 

at an ICES Dialogue Meeting (ICES, 

1990) to convince our industry that 

you can’t have both good husbandry and try and stabilize it all 

by fiddling about with the harvesting rate. Fishermen know in the 

past that their resources have fluctuations; they expect good years 

and bad years. Fishermen don’t really expect the scientists to suddenly produce everything full, 

calm, and unruffled and going on 

evenly from year to year; they 

know it’s going to vary. I think 

we’ve got ourselves hooked on trying to satisfy an economic demand 

for stability—which is a genuine 

one, I accept that—by trying to manipulate the harvesting rate. That’s 

a recipe for trouble. If we keep the 

harvesting rate there or thereabouts, then you have to accept 

that the stock will go up and down. 

It’s only when there’s a succession 

of very, very unfortunate year-class 

events that you really have to look 

at even that harvesting rate and 

say, “I’m sorry, we’re now down to 

such a low level that we’ve got to 

stop even that.” Now that makes 

life a lot nicer if you can get that 

across. Don’t forget, this would be 

the stock left which would be very 

productive on the average. The 

problem would be to hold it like 

that because it would attract 

people who would look at this and 

say, “Look at these profits!” You 

have to have a system—you are 

getting me into my management 

theories now—you have to have a 

way of feeding off the excess profits. In the ideal world—and maybe 

this is too socialistic an answer— 

you’d put these profits away for a 

rainy day, and they would be released when, on scientific evidence, it was shown that, yes, 

things are now falling below the acceptable profit margin. So you can 

now release some of the pie. But 

basically, that’s how you try and 

stabilize the situation. You don’t try 

and stabilize by maneuvering the 

harvesting rate all the time, because it causes all kind of trouble. 

57 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

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Murmansk, Aug. 1991. Inst. of Mar. 

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pelagic fish and the threat of fishing; 

are they endangered? J. Fish Biol. 37 

(Suppl. A):5–16. 

—————, and S. J. Holt. 1957. On the 

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Buch, E. 1990. A monograph on the 

physical environment of Greenland 

waters. Meddelser om Grønland, 405 p. 

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D. Pauly, P. Muck, and I. Tsukayama 

(Editors), The Peruvian upwelling ecosystem: dynamics and interactions, p. 

207–219. ICLARM Conf. Proc. 18, 438 p. 

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Effects of a changing windfield on cod 

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G. Siedler. 1975. General oceanography, 2nd ed. John Wiley, N.Y., 626 p. 

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Barents Sea capelin (Mallotus villosus) 

from a larval point of view. ICES J. Mar. 

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Gordoa, A., and J. E. Hightower. 1991. 

Changes in catchability in a bottomtrawl fishery for Cape hake (Merluccius 

capensis). Can. J. Fish. Aquat. Sci. 

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Fisken og havet ved Grønland. Skrifter 

fra Danmarks Fiskeri- og Havundersøgelser, 15. 

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plaice. General report. I. The plaice 

fishery and protective regulations. 

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fisheries of northern Europe, viewed 

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ICES. 1991. Report of the Study Group 

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389–405. 

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Fish. Aquat. Sci. 120. 

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Maddock. 1988. Fluctuations in the 

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Lecture 1: Man or Nature in Fisheries Dynamics: Who Calls the Tune? 

Tjelmeland, S. 1992. A stochastic model 

for the Barents Sea capelin stock with 

predation from an exogenous cod 

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177:489–504. 

59 

“Fish Population Biology 

and Fisheries Research” 

LECTURE 2 

May 3, 1994 

Whitman Auditorium

Marine Biological Laboratory

My name is Vaughn Anthony. I’m from the 

NMFS Northeast Fisheries Science Center, and I want to 

welcome you to the second lecture 

by Professor Ray Beverton. I assume everyone attended the lecture yesterday and heard the fine 

introduction by Emory Anderson. 

There will be another informal lecture this afternoon from 3:15 to 5:00 

in the NMFS Woods Hole Laboratory’s Aquarium Conference 

Room. 

Just to repeat a little bit of introduction so you’ll know who our 

speaker is. Ray worked at Lowestoft, in the U.K., from 1947 to 1965 

and was there, with Sidney Holt, 

when they put together the material for this very fine book, “On the 

dynamics of exploited fish populations” (Beverton and Holt, 1957). 

From 1965 to 1980, he was Secretary and Chief Executive of the 

newly formed U.K. Natural Environment Research Council (NERC). 

He was there for 15 years. During 

1981–82, he was a Senior Research 

Fellow at the University of Bristol, 

and from 1982 to 1986, he was a 

professor at the University of Wales 

at Cardiff. During 1986–87, he was 

head of the department, and in 

1987–89, following restructuring, 

he was head of the School of Pure 

and Applied Biology at the University of Wales at Cardiff. In 1990, he 

became Emeritus Professor at the 

University. 

Emory went through a lot of the 

things that Ray has done over the 

years, and I won’t repeat them. He 

was, of course, editor of the Journal du Conseil for about 10 years. 

Some of you probably met him in 

that capacity. He worked very hard 

and did a very fine job of putting 

some good documents together. 

He spent a long time digging and 

searching for the right material and 

pushing people to produce information from lots of places that normally would not have come forward without his urging. 

For those of us who have been 

involved with ICES, ICNAF, and 

NEAFC over the years, we have 

known Ray for a long time and 

known how helpful and useful he 

has been, with his knowledge and 

inspiration and ideas, just facing all 

these functions that he has served 

over the years. He has been leading committees or certainly on the 

committees helping everybody understand the population dynamics. 

He has received a number of awards, 

the latest one being the Award of 

Excellence from the American Fisheries Society last year. 

I think the thing that he will be 

most remembered for is his 1957 

book. Mine is a little ragged; I 

bought it in 1960 at the University 

of Washington and paid $16 for it, 

by the way. When I went to the 

University of Washington for my 

degree, I was told by Karl Lagler 

at Michigan and Harry Everhart at 

Maine not to go there for a PhD 

because it would take forever to get 

through. So when I went there, I 

approached the Dean of the College, Richard Van Cleve, to try to 

impress him and said, “There are 

people here now that have been 

here 10 years and don’t have a degree. How long will it take to normally get a degree at the University of Washington?” Van Cleve 

reached behind him and took his 

latest edition of Beverton and Holt 

(1957) off the shelf and handed it 

to me. I hadn’t seen it at that time— 

this was 1960. He asked me to go 

through it, and I sat there and 

thumbed through pages 1–100, 

100–200, 300–400, 400–500, going 

through these things, and he said, 

“Look, when you understand everything that’s between those two 

covers, you’ll deserve to get your 

PhD from the University of Washington.” I said, “Thank you very 

much,” but, I fooled him. I got my 

degree, and I never ever understood everything between those 

two covers, and I never will. 

You can see all the notes I have 

on this thing; I still go back to it; 

it’s a bible; it’s very useful. It’s 

amazing what’s in this. Constantly, 

right today in ICES and many of 

the working groups, when people 

talk up new ideas, they say, “Oh, 

it’s in the back of Beverton’s book, 

we just haven’t gotten there yet.” 

When you go through the table of 

63 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

contents, go to the last 100 pages— 

everybody reads up to about page 

370 where you look at the yield isopleths of plaice and so forth—but 

after that you’ve got the economics material, the regulation options, 

eumetric curves, the technical 

interaction work that people like 

Benoit Mesnil are doing in France 

and Steve Murawski is doing a 

little bit here, biological interactions, multiple species, multiple 

fisheries management, and so 

forth. The book is amazing; the 

only problem is we just haven’t got 

to it yet. 

Now, I’ll move on so we can get 

to what we really want to get to 

today. He’s going to tell us a little 

bit about some of the biology that’s 

in here [his book], like food consumption and diffusion rates. 

There’s chaos theory in here for 

anybody who’s interested, and it 

was 40 years ago that he put this 

together. Just looking at the slope 

of the recruitment curve, the egg 

production curve, you can see 

things explode—a typical cobweb 

model. People are taking those 

ideas today and calling it chaos. 

Ray did this 40 years ago. 

I’m very pleased to introduce 

Ray Beverton for his second lecture: “Fish Population Biology and 

Fisheries Research.” 

Ray Beverton 

Thank you, Vaughn, for those 

introductory remarks. It’s hard to 

follow that; I’m not quite sure how 

best to start. I had my ideas thought 

out and that sort of sneaked me. 

I’m sorry about that. 

Seriously though, thank you for 

coming, those of you who came 

yesterday, for sticking it out for two 

consecutive sessions. As for the 

newcomers, I hope I’ll have a little 

something to tell you about fishes, 

the way they do things—mainly 

food for thought. 

Actually, much of what I’m going to talk about today has probably arisen after that period [pre1980s]. Indeed, it’s very interesting, 

I think, to look back and realize that 

fisheries biology has always been 

and always will have to be very 

closely linked with fundamental 

marine biology, both in terms of the 

ecological and the individual 

physiology and behavior of the 

fishes and the other animals they 

interact with. Right back in the 19th 

century, some of the first exploratory work was undertaken on the 

sex of fish species, alongside the 

deep-sea exploration. It’s interesting that in the last decade or so, 

fisheries laboratories proper have 

probably been more heavily 

pressed with day-to-day problems. 

It’s an applied science, and, of 

course, they’ve got to produce the 

answers that are needed for good 

management of natural fish resources. The advent of attempting 

to manage through TAC’s [total allowable catch] and other matters 

has put a very heavy burden on the 

use of ship time and the use of 

people. I rather feel yet, at the same 

time, that the importance of the understanding of the fundamental biology has not decreased, but has 

gotten more important. 

As we look ahead to the issues 

raised by the Rio Convention1

—the 

long-term effects of sustainability 

and biodiversity—it becomes all 

the more important that fisheries 

biology should be closely linked 

with, both contributing to and receiving from, the more fundamental aspects of fish biology and fish 

ecology which have increased 

enormously over the last two or 

three decades. In fact, if I had been 

talking to you 40 years ago, I would 

have had only about three, four, or 

five journals I needed to keep in 

1

United Nations Conference on Environment and Development (UNCED) held in 

Rio de Janeiro, Brazil, in June 1992. 

Malcolm Silverman, NMFS 

64 
Lecture 2: Fish Population Biology and Fisheries Research 

LIFE HISTORY STRATEGY 

1.	 BROAD CONCEPT—Rationalizing natural history in terms 

of staying alive long enough to breed successfully for the 

next generation, i.e., satisfies the Euler-Lotka equation for 

stability: 

λ

where	 Σe−rtl

t

mt = 1 

t = 0 

r = intrinsic rate of increase 

l

t = probability of survival to age t 

m = production of female offspring at age t 

2. DEMOGRAPHIC INTERPRETATION 

L.C. Cole (1954)


G.C. Williams (1957)


A. Comfort (1955–65)


Reproductive Strategy Population Ecology


Spawning Pearl


Eggs Hatch MacArthur


Larvae Metamorphosis Southward


Juveniles Maturation Fenchel


Adults May


Growth r/K hypothesis


Mortality Foraging theory


Maturation Energetics


Fecundity Predator/prey


Longevity


Figure 1. The broad concept and demographic 

interpretation of the life history strategy of fish. 

touch with everything, and perhaps two or three dozen people 

around the world, the Bill Rickers 

and so forth, of that type. Now it’s 

almost impossible for any one person to keep up with the relevant 

information that is standing about 

on fish stocks and fish biology. It’s 

spread over a whole host of journals, not just in the fisheries world, 

but outside. So, I must apologize, 

in a way, that I can only give you 

possibly a rather narrow look at 

fish. 

However, the theme I’m thinking of for today is what has come 

to be called life history strategy. 

Now that, to me, is almost another 

way of saying simply how best to 

get through the problems of living, 

reproducing, and producing the 

next generation. It embraces almost 

every aspect of ecology and biology. I think we have to narrow that 

down somewhat. 

Let me just start then to put us 

in the picture, as it were, of the 

overall context of that which I’ve 

been exploring aspects (Fig. 1). Rationalizing natural history in terms 

of saying, “I’ve got enough to 

breed success over the next generation.” If you want to put it in mathematical terms, it would satisfy the 

Euler-Lotka equation of stability, 

which is another way of saying that 

each adult has got to produce 

enough eggs to carry off against 

losses and mortality, at least to replace themselves by one individual 

in the next generation. If that’s the 

case, then you have essentially a 

stable situation. 

The demographic interpretation 

of that formal mathematical equation owes a lot to L. C. Cole and 

his classic paper in 1954, which is 

very interesting because it was 

written as a rebuttal to very severe 

criticisms by William Allee, the 

great American field ecologist who 

said that theoretical ecology was 

useless. Having been stung by that 

criticism, Cole wrote what was to 

become the classic in setting down 

the framework for producing a the65 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Cod eggs, hatchling, and larva. 

© C. Kuehn, http://www.larvalbase.org (all three photographs) 

oretical interpretation that would 

guide us into the complexities of 

the real world. 

I have to mention also George 

Williams (1957), who really developed the theory of senescence and 

longevity, and Alex Comfort (e.g. 

Comfort, 1965) in London, who 

was also working on the whole 

question of the relationship between the sexes, longevity, and the 

whole of that aspect of fishes. So, 

in a sense, I’ve sent those three up 

because they do enable us to subdivide people into two branches, 

of which I’m going to deal essentially with reproductive strategy. 

There is the reproductive strategy of how the individual fish, in 

this case, and its cohorts with it, go 

through their life cycle—spawning 

to eggs and larvae, through to juveniles and adults. The parameters 

that we need to be able to measure—to understand how this is 

happening—are essentially those 

of growth, mortality, maturation, 

fecundity, and longevity. Think of 

that in parallel with the population 

level—the philogeny level—concepts like the r/K hypothesis, the 

foraging theory nowadays, energetics, predator-prey interactions 

pioneered not just in the previous 

works, but, of course, very much 

in the fundamental world. It started with Raymond Cole back in the 

1930s, Alan J. Southward, Raymond Pearl, Tom Fenchel, and 

Robert M. May, I’m just mentioning a few names, with very different countries involved. I am going 

to concentrate on reproductive 

strategy and, in particular, on this 

crucial transition between juvenile 

and adult—the attainment of maturation—because surrounding 

that depends so much of the effectiveness of the life history of the 

others. 

66 
Lecture 2: Fish Population Biology and Fisheries Research 

Before we get into too much detail, I expect you’ve seen the material in Figure 2 before. It’s from a 

paper by Gross, Coleman, and 

McDowall in 1988 which I find to 

be one of the more encouraging 

pieces of evidence to suggest that 

there really is a rationale between 

the way animals do things. They 

showed that the number of anadromous, compared with catadromous, species varies systematically 

with latitude. The anadromous 

ones, that is, the ones that are born 

and spawn in the freshwater and 

go down to the sea to grow up, are 

much more abundant in the high 

latitudes, and vice versa. They 

showed that this was because the 

productivity in freshwater is very 

limited and poor in the northern 

high latitudes. So, to grow up effectively and fast, they have to go 

down to the sea. Whereas, conversely, in the tropics, freshwater 

is more productive, and the sea is 

less so. The general question of 

how you should arrange your 

whole reproductive life in accordance with where you live does 

make sense. 

Figure 2. Diadromy and productivity. A: 

Number of anadromous and catadromous species by latitude. B: Primary 

productivity of sea and freshwater by 

latitude. C: Percentage anadromy vs. 

ocean/freshwater productivity. Figures 

redrawn from Gross et al. (1988). 

Anadromous fish species (%) Number of fish species 

50 

40 

30 

20 

10 

0 

Catadromy 

Anadromy 

A 

0–5 10–15 20–25 30–35 40–45 50–55 60–65 70–75 

(Equatorial) (Polar) 

Latitude (5A intervals) 

1000 

800 

600 

400 

200 

0 

2 

3 

10 

1 1 

5 

8 26 

15 

26 

16

8 7 6 

Freshwater 

Ocean B 

0–5 10–15 20–25 30–35 40–45 50–55 60–65 70–75 

(Equatorial) (Polar) 

Latitude (5A intervals) 

100 

80 

60 

40 

20 

0


–1.2 –0.8 –0.4 0 0.4 0.8 1.2


12.5 

7.5 

2.5 22.5 

27.5 

32.5 

37.5 

42.5 

52.5 47.5 

57.5 

62.5 

72.5 

67.5 

Freshwater>ocean Freshwater<ocean 

C 

Log (ocean/freshwater) productivity 

Primary productivity 

(carbon, g/m2/year 

67 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

If we now take the whole question of maturation and the factors 

governing it, the size and age at 

which this happens, we arrive at 

the adult phase of life history. Concern about it and measurements 

about it go right back to the turn of 

the 20th century. In reading some 

of the early fisheries atlases, it’s fascinating to see how much concerned they were that this property 

was already becoming a critical factor. 

Figure 3 is an extract, a combination, two diagrams, from George 

Atkinson (1908), who was the fisheries inspector at Lowestoft. He 

was called the naturalist inspector 

because he was, in fact, a qualified 

biologist as well. He was very 

much stimulated by work that 

Figure 3. A quote from Atkinson (1908) 

regarding the effect of fishing on the 

length at maturity of plaice (Pleuronectes platessa L.), and length compositions (mm) of mature (black lines) and 

immature (gray lines) female plaice 

sampled in 1907 from the Barents Sea 

(A) (2,125 fish) and North Sea (B) (895 

fish), with m = 50% maturity. The reference to Kyle is Kyle (1903). 

25 27 29 31 33 35 37 39 41 43 45 47 49 51 53 55 57 59 61 63 65 67 69 71 73 

360 

350 

340 

330 

320 

310 

300 

290 

280 

270 

260 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 19 21 

130 

120 

110 

100 

90 

80 

70 

60 

50 

40 

30 

20 

10 

0 

140 

23 

Year (1919–73) 

“Kyle (Journ. M. B. A., Vol. vi, p. 496) suggests that one effect 

of fishing a plaice population is to reduce the average size at 

first maturity. The Barents Sea will afford the opportunity of 

testing this; meanwhile, if we were to accept the suggestion 

that such a reduction has taken place to the extent of, say 5 

cm in home waters, the deterioration of the stock would be 

still more evident, and even a greater proportion of North Sea 

plaice than my curves tend to show would be prevented from 

attaining maturity.” 

m 

m 

A 

B 

A 

68 
Lecture 2: Fish Population Biology and Fisheries Research 

Harry Kyle was doing at Plymouth. Kyle, incidentally, at the beginning of ICES, was the first assessment secretary, of which Emory 

is one of the more recent examples. 

So ICES was already concerned 

with this sort of thing, and people 

like Kyle were writing about it at 

the turn of the century. 

Anyway, Atkinson (1908) went 

off to the Barents Sea, where there 

is another population of plaice 

which, at that time, was wholly 

untouched, and measured the onset of maturation as a function of 

size—length more importantly. He 

showed that, in the Barents Sea, the 

proportion of mature fish showed 

that there were vastly more mature 

fish compared with the immature 

fish. The 50% point was there. In 

the North Sea, similar work had 

been going on, and in this case, the 

size of the two was very similar, but 

the proportion of mature fish compared to immatures was much less. 

They correctly drew the conclusion, even then, that this must have 

been due to the selective removal 

of the mature fish in the North Sea 

compared to the untouched resource in the Arctic. I think that is 

one of the more telling observations which, in fact, is now provMalcolm Silverman, NMFS 

ing to be very critical in trying to 

establish the really long-term effects of fishing in the North Sea. 

The contributions to this study 

of maturation have been rather 

patchy over the years. There was 

much concern in the early days, 

taken up particularly in the period 

between the two wars, by the Scandinavians, because they were pioneering on fisheries where the fisheries themselves were based on the 

spawning aggregations. So, to 

them, even the basic demography 

of the stock they were working on 

depended on the onset of maturation. That meant they really had to 

take it seriously. 

69 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

So, we have Paul Hansen’s work (upper part of 

Fig. 4), published in 1954 

but done in the 1920’s and 

1930’s, on the cod at West 

Greenland. Those at yesterday’s lecture will recall 

that as one of the classic 

stories of growth, as the 

commissions2 formed up, 

where he was comparing 

the length, growth, and 

maturation of the year 

classes. What impresses 

early on is that the early 

year classes were maturing up there at an average 

age of about 10. By the 

time we get into the 

1940’s, the average age 

had gone back to 6 or 7. 

He saw very clearly the 

implication of that in 

terms of the life history of 

the animal. A similar sort 

of work was going on in 

Iceland by Jón Jónsson 

(1954) (lower part of Fig. 

4), where he was finding 

that the percentage of recruit or first-time spawn2

The International Commission 

for the Northwest Atlantic Fisheries (ICNAF) was established 

in 1951. The Permanent Commission was established in 1953 

for the Northeast Atlantic fisheries and 10 years later changed 

its name to the North-East Atlantic Fisheries Commission 

(NEAFC). 

Figure 4. 

Upper part: Growth rate and 

maturation of West Greenland 

cod, 1924–52 (redrawn from 

Hansen, 1954). 

Lower part: Growth and maturation of Icelandic cod, 1932–50 

(redrawn from Jónsson, 1954). 

100 

90 

80 

70 

60 

50 

90 

80 

70 

60 

50 

90 

80 

70 

60 

50 

North 

Greenland 

1924–29 year class 

1934–42 year class 

Sukkertoppen 

District 

1924–26 year class 

1932–42 year class 

Nanortalik 

1931–32 year class 

1932–42 year class 1924 

- 26 

- 29 

- 31 

- 32 

- 34 

- 35 

- 36 

- 42 

5 10 15 

Age (years) 

Length (cm) 

% recruit spawners, 

ages 10–12 years 

Year class (1922–40) 

Mean length (cm), 

ages 10–12 

% recruit 

spawners 

Mean length 

1917 

- 22 

- 24 

- 32 

- 34 

- 36 

- 42 

60 

50 

40 

30 

20 

10 

50 

40 

30 

20 

10 

10 

5 10 15 

1934–42 

year class 

1917–24 

year class 

1934–42 

year class 

1922–32 

year class 

Southern 

districts 

Northern 

districts 

% mature 

Age (years) 

50 

40 

30 

20 

10 

0 

22 25 30 35 40 

100 

95 

90 

85 

70 
Lecture 2: Fish Population Biology and Fisheries Research 

ers coming into the spawning fish- Percentage of recruit-spawners in age groups 7–14 years 

100 ery changed inversely with the av- 90 erage length. In other words, there 

80 

appeared to be a connection be- 70 

tween age and length already 60 

beginning to be established. 50 

40 

In Norway, similarly, Gunnar 30 

Rollefsen, a man whom I found to 20 

be a very stimulating person to 10 

work with, led some of the early 0 

working parties which pre-dated 

the now, very well established 

ICES working groups. I had the 

privilege of being associated with 

one of the very first ones in the 

early 1950’s. He was the chairman 

of it and Director of Fisheries RePercentage 

search in Norway at Bergen, and 

was a cod specialist. He had observed, during the pre-war period, 

when the emphasis in the Institute 

was on herring, the technique of 

distinguishing, from the otoliths of 

the fish, or, in the case of herring 

in the North Sea, the scales, the 

change in the spacing of the rings 

which measured the onset of maturity. I’ll come to that later on. 

There are some examples of the 

changes in the age at which fish 

were arriving into the spawning 

fishery. Hence (Fig. 5) he was able 

to calculate the percentage of firsttime spawners and use this as a 

technique for predicting next 

year’s, and the year after’s, size 

composition of the spawning stock. 

Now, after the war we see, and 

I myself feel a little responsible or 

32 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 

95 

94 

93 

92 

91 

90 

89 

88 

87 

86 

85 

84 

83 

Length (cm) 

7 

8 

9 

10 

11 

12 

13 

8 

9 

10 

11 

12 

13 

14 

7 

8 

9 

10 

11 

12 

13 

Skrei. Lofoten 

Year (1932–53) 

Mean lengths of age groups 8–13 years 

33 

32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 

Year (1932–53) 

Figure 5. Growth and maturation in 

Northeast Arctic cod, 1932–53 (redrawn from Rollefsen, 1954). 

ashamed in a way that I didn’t spot 

at that time, how important this 

was going to be. We rather neglected the maturation work, and 

it wasn’t just in the U.K., but it was 

quite widespread. Even the Norwegians didn’t follow it up in a 

way they now wished they had. So, 

for quite a long time, fisheries science didn’t contribute much to this 

subject after the Second World War. 

But it was going ahead in other 

71 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

NMFS 

fields, and it was not really until 

the 1970’s that the fundamental 

fish biologists and ecologists generally picked up the whole question of maturation, stimulated by 

Cole’s 1954 paper, in particular. 

People like Steve Stearns and Derrick Broadford at Montreal in the 

1970’s and 1980’s began to really 

point to the importance of this sort 

of thing. But towards the end of the 

1950’s, after Sidney Holt and I had 

done our book (Beverton and Holt, 

1957), we were looking at this, not 

from a point of view of life history 

Cod, Gadus morhua. 

strategies, as we would now call it, 

but to find a way of trying to measure natural mortality rates, which 

has always been very difficult and 

for which there are very limited 

data. It seemed to us that there 

ought to be a link between the natural life expectancy of a species 

and its growth potential. There’s no 

point in dying long before you’ve 

reached the limit of your growth 

span, and there’s no point in reproducing vastly too early when you 

can leave it until later, or too late 

to make the best of what life span 

and growth you have. So, we used 

this as a device to try to arrive at a 

shorthand way of getting more 

sense into the very limited demographic data we had then. That led 

to our dimensionless approach, 

ratios of natural mortality to speed 

of completion of the growth curve, 

which was not picked up at the 

time at all by the academic world. 

In fact, it wasn’t until Larry Charnov, a few years ago, from Utah realized that it was this, and he’s 

taken it much further since then 

(Charnov, 1993). 

72 
Lecture 2: Fish Population Biology and Fisheries Research 

I should mention, before I go on 

to this particular work which is a 

sequel to that, that the one person 

in the fish world who really did, in 

the post-war period, put the whole 

question of this on the map was 

Gunnar Alm, the Swedish fish biologist. He was concerned also, 

from an applied (not a life history) 

standpoint, with utilizing the very 

many lakes and rivers in Sweden 

to best advantage to grow up his 

trout. He wanted to make sure that 

he knew how to adjust the stocking levels, given the different maturation rates and growth rates. He 

really laid the groundwork for our 

modern understanding of the 

interactions between growth and 

maturation, at least in the trout 

species (Alm, 1959) and more 

widely. 

In 1992, our Fisheries Society of 

the British Isles had a Symposium 

on Fish Life History Strategies. I 

was asked whether I could look 

again at the whole question of the 

relationship between length at age 

and maturity which Sidney and I 

had done at the end of the 1950’s, 

and I had done a bit on in the early 

1960’s. It is sometimes a rather 

questionable exercise to go back to 

something you did a long time ago 

when you know there is a lot more 

data that has come on since to see 

whether it still holds up, and I did 

so with some trepidation. Somewhat to my surprise and relief, it 

did hold up and indeed, if anything, it’s enabled it to be seen 

more clearly. It was work published a couple of years ago now 

(Beverton, 1992). 

I just need to remind you of 

these definitions (Fig. 6): length 

and age at first maturity (L m, T m), 

length at infinity (L∞) from the von 

Bertalanffy growth curve which is 

a very fundamental way of representing the growth of fishes, and 

its other parameter, K, the rate of 

curvature or how fast it gets up 

towards its asymptote, which you 

will appreciate is a very vital part 

of the tradeoff between growth and 

maturity. A characteristic maximum age is often all you have in 

some limited data. The natural 

mortality rate would be ideal, but 

it’s a very difficult thing to measure. Sometimes we need an adult 

life span—that’s the difference between the age at which they mature and the age at which they find 

the average characteristic maximum size at age. We have the following ratios from those which are 

these dimensionless ratios which 

Charnov (1993) has taken so much 

further than we did: length at maturity over L∞, which is the proportion of the potential growth span 

of the species before maturation, 

and M/K, the ratio of these two vital rates, the rate of dying off, the 

rate of growing, and one or two 

variations on those. 

Patterns of 

reproductive 

parameters 

Symbols and definitions 

Lm = Length at 50% maturity 

L∞ =	 Asymptotic length (von 

Bertalanffy growth 

curve) 

K = Rate of curvature of 

the von Bertalanffy 

growth curve 

Tm = Age at 50% maturity 

T = Characteristic maxi­ max 

mum age 

Tad = Adult life span 

M =	 Instantaneous coefficient of natural 

mortality 

Ratios (dimensionless) 

Lm/L∞ = Proportion of potential 

growth span completed before maturation 

M/K = Ratio of the two vital 

rate coefficients: 

mortality and growth 

M/Tmax = v 

M = v/Tmax 

M/K = v/KTmax 

Figure 6. Symbols and definitions associated with patterns of reproductive parameters. 

73 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Let’s just run through the evidence on the relationship between 

these essential parameters: length 

and age at maturation and maximum values, in four groups. There 

are a lot more other data available, but I want to concentrate on 

within-major-taxon-group comparisons, so Clupeiformes is one 

(Fig. 7). In Figure 7A is the length 

at maturity against L∞, and in Figure 7B is age at first maturity against 

maximum age. In Figures 7C and 

7D are the same relationships for 

Atlantic cod, Gadiformes—very 

tight relationships, in the case of 

herring; rather less so in the case 

of cod. That difference between cod 

and herring is one of many differences which I keep coming across 

as we can now do comparative 

population biology between these 

two species from a very, very rich 

data base in both cases. 

Figure 7. Lm vs. L∞ and Tm vs. Tmax 

in Clupeiformes and Gadiformes 

(redrawn from Beverton, 1992). 

40 

30 

20 

10 

0 

0 0 20 30 40 

L m cm 

T 

max (years) 

T m (years) 

25 

20 

15 

10 

5 

0 

0 5 0

150 

100 

50 

0 

50 

L m (cm) 

T 

max (years) 

25 

30 

20 

15 

10 

5 

0 

T m (years) 

5 0 

C. harengus harengus L. 

North Atlantic 

C. harengus harengus L. 

Baltic Sea 

C. pallasii Valenciennes 

North Pacific 

C. pallasii Valenciennes 

White Sea 

Sprattus sprattus L. 

North Sea and Bay of Biscay 

Sardinops caerulea Girard 

California 

Sardinia pilchardus Walbaum 

East Channel 

Sardinella aurita Valenciennes 

Southwest Atlantic 

Engraulis encrasicholus L. 

North Sea and Biscay 

Engraulis ringens Jenyns 

Southeast Pacific 

Cetengraulis mysticetus Günther 

Tropical Pacific 

Gadus morhua L. 

North Atlantic 

Gadus morhua L. 

Labrador 

Gadus morhua L. 

White Sea 

Gadus morhua L. 

Faroes 

Gadus morhua L. 

Irish Sea 

Gadus morhua L. 

Norwegian fjords 

Gadus macrocephalus Tilerius 

Northeast Pacific 

Gadus ogak Richardson 

Hudson Bay and North Atlantic 

Boreogadus saida Lepechin 

Barents and Beaufort Seas 

Trisopterus minutus L. 

West Scotland 

Trisopterus esmarki Nilson 

North Sea 

Clupeiformes 

Gadiformes 

A 

C 

0 0 

1

1

1

B 

D 

L∞ (cm) 

L∞ (cm) 

74

Lecture 2: Fish Population Biology and Fisheries Research 

Pleuronectiformes 

250 

200 

A 

40 

150 30 

100 20 

50 10 

0 0 

0 50 100 0 5 10 15 

B Solid = male, open = female, where both 

are shown 

Pleuronectes platessa L. 

North Sea 

Hippoglossus platesoides Fabricius 

Northwest Atlantic 

Reinhardtius hippoglossoides (Walbaum) 

Norwegian Sea 

Hippoglossus hippoglossus L. 

North Atlantic 

Hippoglossus stenolepis Schmidt 

North Pacific 

Limanda ferruginea Storer 

Northwest Atlantic 

Glyptocephalus cynoglossus L. 

Northwest Atlantic 

Solea vulgaris Quensel 

North Sea 

Eopsetta jordani Lockington 

Northeast Pacific 

Lm (cm) Tm (years) 

Sebastes spp. 

60 

4 

1 

2 

2 

4 3 

3 

5 5 1 

6 

7 

7 

6 

C 100 

50 80 

40 60 

30 

40 

20 

20 

10 

0 

11 2 

2 

4 5 4 

3 3 

77 6 6 

Pacific species 

Atlantic 

species 

D 5 

Solid = male, open = female, where both are shown 

S. emphaeus Starks; Puget Sound 

(a small cave-dwelling species) 

S. serranoides Eigenmann & Eigenmann; California 

S. fasciatus Storer; Gulf of Maine 

S. mentella Travin; Northwest Atlantic 

S. mentella Travin; Barents Sea 

1 S. alutus Gilbert; Northwest Pacific 

2 S. brevispinnis Been; Northwest Pacific 

3 S. flavidus Ayres; Northwest Pacific 

4 S. pinniger Gill; Northwest Pacific 

5 S. reedi Westrheim &Tsuyuki; Northwest Pacific 

6 S. zacentrus Gilbert; Northwest Pacific 

7 S. proriger Jordan & Gilbert; Northwest Pacific 

0 10 20 

0 

0 10 20 30 40 50 Tm (years) 

Lm (cm) 

Figure 8. Lm vs. L∞ and Tm vs. Tmax in Pleuronectiformes and Sebastes spp. (redrawn from Beverton, 1992). 

It is sufficient for this purpose coming up quite significantly. And, side. That length business is just 

just to show you there is a quite interestingly, a group that couldn’t because of the ease of labeling, but 

strong proportionality between be done before because there was it’s also, as we’ll see in a minute, 

these two pairs of parameters: nothing known about them, which because length is a more conservalength at age of maturity compared was Sebastes (Fig. 8C and 8D), very tive parameter than age. 

to maximum values. In Figure 8A long lived, but still conformed to 

and 8B is the flatfish, with the dif- giving the same, quite tight rela- How are we going to interpret 

ferences between the two sexes tionship, especially on the length what these very strong relationL∞ (cm) 

L∞ (cm) 

T

max (years) 

T

max (years) 

75 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

ships mean? I think this is where I 

need to just scurry through the 

very complicated and fascinating 

subject which goes into behavior 

very strongly as well as demography. That is, even if we stay with a 

strategy, as defined originally by 

Maynard Smith (1982), the theoretical ecologist at the University 

of Sussex. He wrote it this way (Fig. 

9): “...a phenotype such that, if almost all individuals have that 

phenotype, no alternative phenotype can invade the population.” 

That means, take over, in terms of 

reproductive capacity, to become 

the dominant source of reproductive material. In my terms, as applied to reproductive demographic 

strategy, I like to think of it as a 

combination of reproductive parameters, such as those we’ve just 

been looking at, that satisfy the 

evolutionary stable strategy (ESS). 

But indeed, no other combination 

within the scope of that phenotype 

could produce a greater life-time 

reproductive output. That’s my 

definition. So, we are really very 

much closer to the evolutionary 

considerations. That relates to what 

I was saying right at the beginning 

about the importance of the very 

long-term effects of fishing, because here we are on a time scale 

long enough to be thinking in 

terms of at least aiding in the evolutionary change. 

There is a nice little exercise that 

Derrick Roff at Montreal did. He 

showed (Roff, 1984) that there is a 

simple equation (Fig. 9) which enables you to predict the age and 

size at which a group of fish would 

reach their maximum biomass. He 

showed that is the requirement for 

evolutionary stable strategy, although he didn’t call it that, but 

that is, in fact, what it was. He derived that equation by differentiating the number at weight as a 

function of age. In fact, it’s the same 

equation that Sidney Holt (1958) 

developed, for different reasons, as 

a means of showing at what size 

to start catching a year class in order to get the maximum yield out 

of it if you fish hard enough. In a 

sense, it’s this curve (Fig. 9), where 

numbers are coming down and 

weight is going up; the product of 

the two is the biomass, and it’s 

roughly where the two cross that 

is the size. It means, therefore, that 

if you can know the M/K ratio, you 

can predict the F max or Fopt, whatever you want to call it, which optimizes or conforms to the evolutionary stable strategy. That shows 

that these parameters, mortality 

and growth, are so balanced that it 

is the best arrangement they can 

have to maximize their life-time 

productivity. Roff calculated the 

expected value of this (he called it 

Lopt, in terms of knowing what M 

and K were for various species), 

and it showed me you get a very 

close fit between the predicted 

length at first maturity against the 

observed one in a number of species. That’s what he did in Figure 9 

(lower graphs). 

Malcolm Silverman, NMFS 

76 
Lecture 2: Fish Population Biology and Fisheries Research 

Roff (1984) showed that the same equation also gives 

maximum life-time biomass per recruit and defined L max as Lopt. 

Definition (Maynard Smith): 

“...a phenotype such that, if almost all individuals have that phenotype, 

no alternative phenotype can invade the population.” 

As applied to reproductive (demographic) strategy (?): 

“...a combination of reproductive parameters satisfies ESS if no other 

combination within the scope of that phenotype could produce a 

greater life-time reproductive output.” 

Holt (1958): 

for maximum biomass: 

Age 

Numbers 

Biomass Weight 

16 

14 

12 

10 

8 

6 

4 

2 

0 

0 10 12 14 16 

Predicted age 

at maturity (years) 

Observed age 

at maturity (years) 

r = 0.78 

n = 31 

P < 0.001 

80 

100 

60 

40 

20 

0 

0 0 40 60 0 100 

r = 0.93 

n = 31 

P < 0.001 

Predicted length 

at maturity (cm) 

Observed length 

at maturity (cm) 

Evolutionary Stable Strategy (ESS) 

Maynard Smith (1982) Number and weight 

d(Nt •Wt)/dt = 0 

L max = L∞[1/(1+M/3k)] 

2 4 6 8 

2 8

Figure 9. Definition and supporting examples for the 

evolutionary stable strategy 

(Maynard Smith, 1982). 

77 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

I have never been able to quite 

find out exactly how Roff got all 

this data together because, in fact, 

there’s an M/K problem here as 

well as another, and it seems to be 

important to put the two together 

if we’re going to get a proper comprehensive statement. So what I 

did in Figure 10 was to plot the ratio of L m over L∞, up the left-hand 

side, against the product of K and 

maximum age. Maximum age and 

natural mortality are inversely reMalcolm Silverman, NMFS 

lated, as they are a first approximation. I actually used M/K, which 

gives a nice asymptotic theoretical 

curve. That’s the predicted range 

you should have to compare with 

how the data actually distribute 

themselves, using observed length 

at maturity compared to the predicted one. It’s only roughly, but 

bringing in the other parameters as 

well, it’s just a length problem. In 

fact, for the four groups, they did 

distribute themselves quite significantly (Figure 10D). Something 

clearly isn’t right and proper in 

here [plot for Sebastes]. Either the 

data or the parameters are wrongly 

estimated or the fish is not able to 

leave as strong as it should before 

it matures. But leaving that point 

aside, there is no doubt that there 

are some general envelopes which 

spread themselves out in that sort 

of direction. There is a clear distinction between the Sebastes and 

the Clupeoids, whereas Pleuronectiformes and Gadiformes are indistinguishable. 

All that I’ve been talking about 

is what you’d call statics of the 

story. These are established patterns, probably built up over evolutionary time, certainly over long 

periods. We take a snapshot of 

them, and then this is the pattern 

that emerges. But, that’s only part 

of the story because the next question is: What’s going to happen in 

time if a population is pressed, for 

some reason or other? That could 

be overfishing. Is it going to respond with its maturation at size 

and age, as those patterns that I’ve 

just shown you would predict? In 

other words, are the dynamics of 

maturation predictable from the 

statics of maturation? 

Figure 10 (opposite page). Evolutionary 

stable strategy combination of growth, 

maturation, and longevity parameters 

and resulting plots for Clupeiformes, 

Gadiformes, Pleuronectiformes, and 

Sebastes spp. (redrawn from Beverton, 

1992) using the following maximum lifetime biomass equation: LESS/L∞ = 1/ 

(1+M/3K). See Figure 7 for keys to symbols for A and B, and Figure 8 for keys 

to symbols for C and D. 

78 
Lecture 2: Fish Population Biology and Fisheries Research 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 1 

KT max 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 1 

L m/L∞

KT max 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 1 

L m/L∞

KT max 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 12345678 

KT max 

9 10 11 12 13 14 15 

E M 

1 1 

2 2 

2 

3 3

4 

5 

5 

6 

7 

7 S 

0.9 

0.8 

0.7 

0.6 

0.5 

0.4 

0.3 

0.2 

0.1 

0 2 3 4 10 11 12 

L m/L∞

KT max 

Pleuronectiformes 

Gadiformes 

Clupeiformes 

Sebastes spp. 

Sebastes spp. 

Clupeiformes Gadiformes Pleuronectiformes

B C 

D 

E 

2 3 4 5 6 7 8 2 3 4 5 6 7 

2 3 4 5 6 

1 5 6 7 8 9 

A 

Lm/L∞

Lm/L∞

79

The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Well, the answer is they are not. 

You may be not surprised to hear 

they are not. This is where we’re 

breaking into, at the least the data 

is not all that new, but I think putting it together like this is perhaps 

a little step further than certainly 

I’ve been able to get so far. Those 

of you who were with me yesterday will remember the story of the 

collapse of the Norwegian springspawning herring, a very dramatic 

event in the 1960’s. The solid line 

in Figure 11, SSB, is coming whistling down, and it’s taken a long, 

long time before finally, in the last 

2–3 years with a few good year 

classes, it has come back up again. 

During that time [1960’s and early 

1970’s], the measurements of age 

and length at maturity were not 

taken. This is where the Norwegians are kicking themselves for 

not getting this filled in. Not many 

others at the time realized the importance of it. There’s no doubt 

that L∞ was up right about 30 cm 

and age somewhere getting on to 

6 years old—average age of maturity for the whole population. You 

30 6 

5 

T m 

L m 

SSB 

A 

10 

20 4 

3 

5 

10 2 

1 

0	 0 

1950 1960 1970 1980 1990 

Year class 

Lm (1950–60) 

Lm (1974) 

35 

30 

25 

20 

15 

10 

5 

T m(1974) T m(1950–60) 

1974 year class 

1950–60 year class 

B 

40 

0 5 10 15 

Age (years) 

Figure 11. Spawning stock biomass (SSB) and length and 

age at maturity (A), and length vs. age for the 1950–60 

and 1974 year classes (B) of Norwegian spring-spawning 

herring. Data from Østvedt (1964), Dragesund et al. (1980), 

Toresen (1986, 1990), and ICES (1994). 

Lm (cm) 

m (years) 

SSB (1

0–6 t) 

Length (cm) T 

80 
Lecture 2: Fish Population Biology and Fisheries Research 

can pick it up certainly by the mid1970’s; it was coming in—it was 

way down to 31/2 years—but the 

length was hardly any different. In 

the meantime, it’s been coming 

back up. It’s not back up as far as it 

was, but then neither has the biomass built back up as far as it was. 

Nevertheless, there is quite a bit of 

reversibility in this. 

Another point, of course, of importance that we need to know is 

reversibility. How far do these sort 

of changes, in fact, reverse. There’s 

some preliminary evidence for it in 

Figure 11. In fact, what was happening in the 1950’s and 1960’s and 

the 1974 year class, which was one 

of those growing up from a very 

reduced base, perhaps 1

/200 of the 

population size compared to earlier, is that it’s growing up on a 

much, much steeper growth curve, 

and the shift in length at maturity 

was almost horizontal. 

Figure 12 shows the Icelandic 

herring, which also collapsed and 

recovered much more strongly 

than the Norwegian. Again, the age 

at maturity is pitching right down 

(late 1960’s–early 1970’s), coming 

back up again to pretty well where 

it was, length at maturity calm and 

unruffled and hardly taking any 

notice of all these things going on, 

staying pretty well constant around 

about 25 cm while the population 

was busy coming back up again. 

Lm (cm) 

35 

30 

4 

3 

2 

1 

0 

T 

m (years) 

9 

5 

3 

2 

1 

T m 

N 

L m 

2600 

2200 

30 25 

1800 

1400 

20 

1000 20 

600 

10 

200 

0 15 

0 

60 62 64 66 68 70 72 74 76 78 80 82 84 

Year 

Figure 12. Changes in age (Tm) (heavy gray 

line) and length (Lm) (dotted gray line) at maturity of Icelandic herring compared with 

changes in mean length for 1, 2, 3, 5, and 9 

ringed herring (thin solid lines) and total stock 

size in numbers (N ) (dashed line) from 1960 

to 1983. Data from Jakobsson and Halldórsson 

(1984). 

Mean length (cm) 

Stock size (numbers Z 10–6) 81 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

So, I’ll try and see if I can put 

together some of this evidence 

from several other species which 

we have covered, starting with age 

and measuring the change in average age at maturity against the 

degree of stock depletion on the log 

scale (Fig. 13). Catch for each species, roughly represented by the 

heavy gray lines, is coming down. 

On the x-axis you can see half stock 

size and quarter stock size, and the 

various plots show what was happening to age at maturity. The 

heavy gray lines are very much 

odd fits which, nevertheless, are 

showing a pretty broad resemblance to catch, with one exception. 

The Nova Scotia cod data I had discarded first. It was data, I think, 

from Beacham’s (1983) study which 

had been savagely criticized, and I 

thought I’d probably better not use 

it. But then after a bit, I began to 

think maybe it’s not quite so funny 

as it seems when you compare that 

with these other species which are 

T

m (years) Loge 

2.5 

11 

10 

9 

8 

2.0 

7 

6 

5 

1.5 

4 

3 

1.0 

2 

0.5 

(1.1) 

(1.0) 

(0.9) 

(0.8) 

0

H. platessoides (North Atlantic) 

H. hippoglossus (Norway) 

M. aeglefinus (Northeast Arctic) 

G. morhua (Northeast Arctic and 

Nova Scotia) 

61–64 

60 

60 

69–72 

1950 

1984 

82 

82 61–64 

62–66 69–72 

82–85 

50–60 

1973 

80–89 1955? 

? 

62 

71–74 

1970 1980 

60 

1989 

84 

64 

Cod 

(Northeast 

Arctic) 

Cod 

(Nova 

Scotia) 

1 

0.5 0 –0.5 –1.0 –1.5 –2.0 –2.5 –5.0 

1/2 1/4 1/10 1/20 

Loge relative stock depletion 

Figure 13. Change in average age at maturity 

(Tm) for nine different fish stocks vs. the degree of stock depletion. 

T

m (years) 

C. harengus (Norwegian 

spring spawning) 

C. harengus (Icelandic) 

S. scombrus (North Sea) 

S. solea (North Sea) 

82 
Lecture 2: Fish Population Biology and Fisheries Research 

56 similar, except for the possibility of 

54 the later trend in the Arctic cod. 

52 There wasn’t much happening 

during the early period for the Arc50 tic cod. But, we’ll see in a moment. 

33 

32 I’ve put [Nova Scotia cod] in 

31 

S. scombrus (North Sea) much more recently because may30 be it wasn’t quite so unreliable as 

it was made out to be. On the other 

32 hand, the length changes (Fig. 14), 

31 as you might expect from what I’ve 

30 just been saying, were almost 

29 undetectable, except again for cod. 

G. aeglefinus (Northeast Arctic) 

G. morhua (Nova Scotia) 

C. harengus (Norway) 

Mean length at maturity (

Lm) (cm) 

28 

29 

28 

27 

26 

29 

28 

27 

26 

25 

C. harengus (Iceland) 

That was really unexpected and, 

again, that’s really what made me 

wonder whether I should proceed 

with that figure. So, I’ve included 

it because I want to show you some 

more sharply defined evidence 

that was coming from this story. 

There’s a general picture of the 

very robust, very conservative 

S. solea (North Sea)	 change in length, but a much 

sharper change in age at maturity 

in response to whatever reason, but 

mainly by fishing in these cases. 

0.5 0 –0.5 –1.0 –1.5 –2.0 –2.5 –3.0 

1/2 1/4 1/10 

1/20 

Loge relative stock depletion 

Figure 14. Change in mean length at maturity (Lm) for six different fish stocks vs. the 

degree of stock depletion. 

83 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

In fact, to summarize it, Figure 

15 shows the percentage fall in T m 

and L m for a given halving of the 

stock biomass. They [stocks] all 

went sliding down the growth 

curve; the length is going off and 

staying up horizontally, even 

though the age is dropping, and it’s 

not coming down the growth curve 

like you would think if it had been 

in the same state. Nova Scotia cod 

had a very large change, not only 

in the age, which is remarkable, but 

in length as well. 

Just to make that point just now, 

in Figure 16 are the growth curves 

that you’ll get if you had that relationship between L m and L∞. Right 

across the range of different species, the top two [Fig. 16A] are the 

Norwegian and Icelandic growth 

curves. That’s the maturation 

curve on the left that they should 

be coming down if they were rightevolutionary-established on the basis of that static pattern. They 

didn’t come down that way at all. 

They came up one side, keeping up 

almost the same length at maturity. 

Looked at in more detail [Fig. 16B], 

you can see how both the two herrings, as their age at maturity fell, 

didn’t come down the interpopulation maturity envelope established by evolution. So here’s a 

S tock

F all in Tm 

( %)

F all in Lm 

( %)

E xpected fall in Lm ( %) if

o n average growth curve

N orwegian spring-spawning herring 1 1 1 7 –10

I celandic summer-spawning herring 7 0 .5 4 

N orth Sea mackerel 1 9 1 1 0–15

N orth Sea sole 9 0 5 

N ortheast Arctic haddock 1 4 4 7 –10

N ova Scotia cod 5 9 3 2 4 3

Figure 15. Percentage fall in Tm and 

Lm per halving of stock biomass. 

dynamic which is really not conforming at all to the established 

evolutionary structure. 

Now, the trouble is, to analyze 

this further presents considerable 

difficulties because really what 

we’re looking for is a tradeoff between growth, maturation, longevity, and all the rest of it. But if you 

are only seeing the average change 

in the total average of the population, attempting to try to measure the natural mortality before 

the population began to be depleted and then after is a nearly impossible task. It’s so dominated, 

due to fishing as it was in those 

days, by a very high fishing mortality. So the natural mortality, 

which is a brutal thing to estimate 

in the best of times, is pretty well 

impossible to try to do in these circumstances. 

The real question of just how 

much did a decrease in average age 

actually shorten the lifespan, if it 

did at all, which is what it did in 

those established static patterns, is 

a pretty critical thing to know because otherwise we may be very 

wrong in applying our same ideas 

of natural mortality rate to the 

population which has had its average age at maturity coming 

down the chart. There was, however, a thought that we had that 

might open up this question, and 

that is going back to the Norwegian 

herring and cod. I mentioned 

briefly in passing a few minutes 

ago that Norwegians started in the 

early 1930’s to measure both the 

84 
Lecture 2: Fish Population Biology and Fisheries Research 

Length (cm) Length (cm) 

40 

35 

30 

25 

20 

15 

10 

5 

0 

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 

Age (years) 

Immature 

Mature 

L∞ = 37.5 

Icelandic 

Norwegian

36 

30 

25 

L∞ = 20 

35 

Interpopulation 

maturity envelope 

A 

32 

31 

30 

29 

28 

27 

26 

25 

24 

23 

22 

21 

20 

Interpopulation 

maturity envelope 

Icelandic 

Norwegian 

B 

1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 

Age (years) 

age at which the fish matured as 

well as its maximum age in the 

fishery, and they had been using 

that for a short-term stock measure 

for both herring and cod, but they 

dropped that after the Second 

World War and didn’t use it. Well 

they did at first, but after the crash 

of herring anyway, they didn’t really use the cod very much after 

that. So I said to Ole Johan Østvedt 

(who had used it very much in the 

1950’s), and Arvid Hylen at Bergen, 

Figure 16. Growth curves for varying values of L∞ ranging from 20 to 37.5 cm and 

showing the interpopulation maturity 

envelope (A), with an expanded portion 

(B) contrasting the theoretical curves 

with observed values of length at age 

for Icelandic and Norwegian herring. 

85 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

“Why don’t we go back to the old 400


data set and work it up in a differ­


ent way?” Ask the question, “Can 300


we see which fish mature from a


different year class at age 6, 7, 8, 9,
 200 10?” In the case of cod (Beverton 

et al., 1994), this (Fig. 17A) is the 

distribution of the age at which 100 

they matured. The cod is the shaded area and herring is the un- 100


shaded area. You can see that the 3 4 5 6 7 8 9 10 11 12 13


1925–30 year classes A 

Cohort maturation age (years) 

8 

6 

4 

2 

0 

–2 

0 5 10 15 20 

1933 year class MC-9 

MC-10 

MC-8 

MC-7 

MC-12 

MC-13 

B 

Age (years) 

Figure 17. A: Frequency distribution (per mille) 

of maturation cohorts (MC) of Northeast Arctic cod (1925–30 year classes; shaded area) and 

Norwegian spring-spawning herring (1933–37 

year classes; unshaded area) at maturation. 

B: Loge CPUE vs. age of the maturation cohorts of the 1933 year class of Northeast Arctic cod. 

Frequency % 

CPUE Loge 

86 

14 
Lecture 2: Fish Population Biology and Fisheries Research 

range of the maturation in herring 

was between 3 and 9, and in cod it 

was from 6 to 14. Why have we 

worked them up on a cohort, maturation cohort? That is to say, “Well, 

let’s look at the fish that matured 

one year at 7 years old of the year 

class and see how many of those 

are left as 8 year olds the following 

year.” In other words, follow 

through an age composition based 

on a maturation cohort and ask 

then the question, “Can we see a 

difference in survival rate and 

growth rate between cohorts maturing from the same year class, but 

maturing at different ages?” There 

are, in fact, the age compositions 

of the 1933 year class of cod (Fig. 

17B), the 7 year olds (they didn’t 

have enough 6’s to measure), the 

8’s, the 9’s, 10’s, right on up to age 

14. There isn’t a lot of difference in 

those spokes. There were more 

differences in some of the other 

year classes, but that’s the sort of 

thing I mean—splitting the year 

class up into its maturation cohorts. Of course, you dilute the 

data if you subdivide it again and 

again, and it gets much more difficult to make sure that you are really seeing something. You’ve got 

to sort the scenarios out rather carefully. But still, it was giving coherent results on the cod. 

Malcolm Silverman, NMFS 

87 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Loge CPUE Loge CPUE Loge CPUE 

7 

6 

5 

4 

3 

2 

1 

0 

–1 

–2 

4 

3 

2 

1 

0 

–1 

–2 

7 

6 

5 

4 

3 

2 

1 

0 

–1 

1944 year class 

All cohorts 

A 

0 5 10 15 20 25 

Age (years) 

0 10 15 5 10 15 20 

Age (years) Age (years) 

1947 year class 

MC-3 

1943 year class 

MC-4 

1938 year class 

MC-8 

1937 year class 

MC-9 

B C 

D E 

5 

0 5 10 15 5 10 15 20 

Age (years) Age (years) 

Figure 18. LogeCPUE vs. age of various maturation cohorts (MC) of several year classes 

of Norwegian spring-spawning herring. 

In the case of the herring (Beverton et al., 1993), it leads you right 

back to the days before fishing in 

the 1940’s and early 1950’s. We 

knew fishing pressure was really 

very small; F was measured 

around about 0.1 at that time overall. That’s the cohort, the year class 

1944 (Fig. 18A), as an example year 

class, all maturation cohorts together. Notice the very marked 

curve suggesting that the mortality rate with these increases with 

age. In fact, if you split it out into 

its cohorts, the cohort 3 (Fig. 18B) 

is quite steep actually and more or 

less straight. There is the cohort 9 

(Fig. 18C), much, much shallower, 

even despite the accuracy of the 

data, no doubt a much shallower 

one. For 4 (Fig. 18D) and 8 (Fig. 

18E), I’ve put those so you can see 

the gap between those slopes narrowing as you get to 4 and 8. You 

can see it even more in terms of the 

5’s (Fig. 19A) and 6’s (Fig. 19C–F), 

with a new phenomenon coming 

in that gives it a pretty straight line 

to a certain point and then a very 

dramatic fall-off, but being the 

same for the moment on the 

straight line part. But by the time 

you get to the 6’s, you’re into a 

slope depicted between a very 

steep one with the young ones and 

a shallower one with the late ones. 

The reasons for the drop-off after 

age 16 for maturation cohort 6 of 

the 1937 year class (Fig. 19F) are 

partly because of the aging factor 

there, but we are still not absolutely 

88 
Lecture 2: Fish Population Biology and Fisheries Research 

sure we’ve sorted out as much as 

the data would allow. An estimate 

is highly obtuse, but there is no 

doubt that some of this is very real. 

It’s, in fact, senescence, which has 

been detected, of course, in other 

species. But I hadn’t realized until 

we looked at this how marked it 

was in the herring, and it’s only 

possible to see it when you go back, 

such as we did here, to years where 

the level of fishing pressure was 

very small. The lifespan quite 

sharply finished at about age 23 or 

24, irrespective of which cohort 

you’re talking about. There is a 

marked change in overall circumstances since this is mainly due as 

much to natural mortality. It means 

no doubt, in the case of herring, as 

far as we can see from this way of 

analyzing data, that the early 

maturers certainly had a much 

higher total mortality rate and 

probably, therefore, a higher natural mortality rate than did the late 

maturers. So here is evidence that 

if you mature young, you have a 

short life and a merry one, and if 

you leave it to later, you’ll have a 

much calmer, unruffled, but not 

very exciting life. 

Loge CPUE Loge CPUE Loge CPUE 

5


4


3


2


1


0 

–1 

–2 

1941 year class 

MC-5 

A 

5 10 15 20


Age (years) 

6


5


4


3


2


1


0 

–1


5 10 15 20


1938 year class 

MC-6 

C 

Age (years) 

5 6 

4 5 

3 4 

2 3 

1 2 

0 1 

–1 0 

–2 –1 

–3 –2 

7 10 15 20 

1939 year class 

MC-6 

E 

Age (years) 

1938 year class 

MC-7 

B 

5 10 15 20


Age (years)


1940 year class 

MC-6 

D 

5 10 15 20


Age (years)


1937 year class 

MC-6 

F 

7 10 15 20


Age (years)


Figure 19. LogeCPUE vs. age of various maturation cohorts (MC) of several year classes 

of Norwegian spring-spawning herring. 

89

The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Now, we can also measure the 

growth parameters of each of these 

cohorts separately. So we’ve asked 

the question, “If you mature early, 

do you have a bigger K or longer 

L∞?” The answer is in the cod (Fig. 

20A), except in the first two ages, 

the youngest. The 6’s and 7’s are 

not much different, they are rather 

below, but after that they’re pretty 

flat. In other words, it didn’t affect 

K or L∞, nor incidentally in the cod 

could we detect any real difference 

in slope of the survival curves. In 

other words, from about full maturity rate onwards, there seemed 

to be no difference in the natural 

mortality rate. That fit in with the 

fact that the growth parameters 

didn’t change either. Whereas in 

herring (Fig. 20B), L∞ stayed pretty 

flat, but the K, the parameter which 

should be much more closely related to natural mortality, came 

down quite sharply. In fact, our estimate of natural mortality from 

the age composition is even 

steeper—it may be too steep. We’re 

having to check whether that could 

possibly be a little shallower than 

that. It’s steeper than the drop in K 

in herring. There’s no doubt for 

both those that the change is different than in cod. 

K and M 

K and M 

150 

0.2 

100 

0.1 

0 

Cod 

K 

M 

L∞

A

50 6 7 8 9 10 11 12 13 14 

Cohort maturation age (years) 

0.5 

L∞

K 

M 

Herring B 

45 

0.4 

40 

0.3 

35 

0.2 

30 

0.1 

0 25 

2 3 4 5 6 7 8 9 

Cohort maturation age (years) 

Figure 20. Plots of K, M, and L∞ vs. cohort 

maturation age for Northeast Arctic cod (A) 

and Norwegian spring-spawning herring (B). 

L∞ (cm) 

L∞ (cm) 

90 
Lecture 2: Fish Population Biology and Fisheries Research 

With that pattern of parameters, 40 

you’re not surprised with the 

growth of the cohorts, as a growth 

curve—in Figure 21 for herring 35 

where we’re plotting length 

against age for the 3, 4, 5, 6, 7, 8, 

and 9-year-old maturers. You see 30 

that with the age at first maturity, 

shown by the line of the maturity 

25 envelope, that it isn’t running 

along the growth curve at all. It’s 

running off horizontally to it. Not 20 actually is the horizontalness a 

short-term response that is shown, 

it was still much more horizontal 

15 than it could have just been follow­


ing up a growth curve. It came up


in the previous run that the differ- 10


ence in K meant that there was a


very, very big difference in prema­


ture growth going on to cause fish 5


to arrive at not much difference in


length at maturity at ages 3–9.


There is, incidentally, the 1974 year 0


class compared with it. In other 0 5 10 15 20


words, it was the whole of the year Age (years)


class in 1974, which matured when


it was about 3 years old, growing


Mature 

1974 year class 

1978 year class 

Maturation envelope 

Cohort maturation age 

Immature 

MC-7 

MC-3 

3 5 6 7 8 9 4 

faster than even the fastest growFigure 21. Growth of maturation cohorts (MC) ing 3-year-old maturers of the of the 1934–40, 1974, and 1978 year classes 

1940’s and 1950’s population. of Norwegian spring-spawning herring. 

Length (cm) 

91 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Length (cm) 

150 

125 

100 

75 

50 

25 

0 

0 5 10 15 20 25 30 35 

Year classes 

1924–29 

Length (cm) 

Age (years) 

MC-6 

MC-10 

MC-7 

MC-11 

MC-8 

MC-12 

MC-9 

MC-13 

6 

140 

120 

100 

80 

60 

40 

20 

0 10 15 20 25 

0 

7 

8 

9 

10 

11 

12 

13 

14 

Maturation 

130 

140 

120 

110 

100 

90 

L∞ (cm) 

13 

9 

7 

6 

11 

12 

8 

10 

14 

5 

Age (years) 

Figure 22. Growth of maturation cohorts (MC) 

of the 1924–29 year classes of Northeast Arctic cod including (insert) the actual data points. 

Now, when we looked at cod 

(Fig. 22), thinking we would find a 

similar thing, it was quite different. 

In this case, the growth curves were 

almost indistinguishable, and they 

only started moving apart because 

of, really, differences in L∞ for the 

6’s and 7’s. Other than that, they 

were all bunched together and the 

maturation envelope—these are 

the observed maturations—just 

simply fell almost, not quite exactly, but nearly, on the growth 

curves. That’s the actual data on 

eight year classes on which this 

theoretical curve was drawn with 

the 6-year-olds doing that. It’s what 

that is, if you take K and L∞ and 

draw a curve through it. In other 

words, in the cod, the latent maturity is sliding up and down the 

overall growth curve, unlike the 

herring, where it isn’t. And that’s 

what made me realize that maybe 

those data from the Norwegian 

paper weren’t necessarily as funny 

as they were thought to be. You 

would expect to see a change in the 

length at maturity much more pronounced in cod than in the other 

species because of this [maturation 

for each maturation cohort fitting 

to the overall growth curve]. Before 

I finish, I’ll just try and comment 

briefly on why that should be and 

what the implications of that are. 

But I’ll leave you just on that 

point, for the moment, with that 

difference and the fact that when 

92 
Lecture 2: Fish Population Biology and Fisheries Research 

you superimpose those ages and 150


lengths at maturity on the static


pattern I’ve showed you, in the


case of the cod (Fig. 23A), the


straight line comes from the whole


of the Gadiformes that I showed in


Figure 7. That’s superimposing L∞ 100


and L m for the different cohorts. In


the first two or three, they’re on the


line, and after that they drop off to


9 

11 13 

6 

7 

8 10 

12 

14 

Maturation 

cohorts age 

6–14 years 

Cod 

A 

50 

3 4

7 

9 

568 

Maturation 

cohorts age 

3–9 years 

Herring 

B 

0 

0 50 100 150 

L m (cm) 

50 

40 

30 

20 

10 

0 

0 10 20 30 40 50 

Lm (cm) 

Figure 23. Lm vs. L∞ for maturation cohorts age 6–14 

years for Northeast Arctic cod (A) and 3–9 years for 

Norwegian spring-spawning herring (B) contrasted 

with the static pattern (straight line) for each species. 

the right. In the herring (Fig. 23 B), 

it’s also bunched up and it’s very 

much less steep than the overall, 

between-species, three population 

comparisons. So not only do we 

have a dynamic response which is 

very different from the static, but 

we have also, within one and the 

same population and within one 

and the same year class, a distance 

which is not conforming between 

the ages of the maturation cohorts, 

and which is not conforming to the 

overall pattern. 

Now, can we, however, use this 

evidence to ask the question, 

“What is it that is sustaining that 

range of maturation and size and 

age in those two populations?” 

Could we have asked the question, 

“Is this an evolutionary stable arrangement? Why don’t those awful cod start maturing at age 6 or 

leave it until 14? Why do all the 

herring start maturing at age 3 or 

why don’t they all leave it to 9?” 

They’re capable of doing so. The 

potential to do so is there in the 

year class. 

L∞ (cm) 

L∞ (cm) 

93 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

LIFETIME BIOMASS PER RECRUIT AT MATURITY 

3 

SSB = RmqL3 • 1/M Σ Un(1−Lm/L∞) 

∞ n = 0 1 + (nK)/M 

If fished with fishing mortality rate F: 

3 

SSB = RmqL3 • 1/M Σ Un(1−Lm/L∞) 

∞ n = 0 1 + F/M + (nK)/M 

This is an equilibrium statement. If Tm changes, then so may Lm/L∞, K, 

and possibly M. Furthermore, an extra multiplier is needed to adjust 

change in number of fish reaching maturity: 

if Tm2 >/Tm1 ; e−M1

 (Tm2 −Tm1) 

if Tm2 >/Tm1 ; e−M2

 (Tm1 −Tm2) 

Figure 24. Equations for lifetime 

biomass per recruit at maturity. 

Well, to answer this question we 

can do a simple calculation (Fig. 

24). We can ask, “What is the lifetime biomass?” It would be nice to 

be able to do a weekly age production, but I don’t have maturity data 

for each of these cohorts. There is 

overall maturation data for the herring, but nobody has ever done it 

on a maturation cohort yet. It 

would be easy enough to do, but it 

hasn’t been done. But we can do it 

in terms of biomass and ask the 

question, “Is the lifetime biomass 

produced by each of these cohorts 

reaching its maximum point?” 

Does that give us a clue, because if 

it’s conforming to the evolutionarily stable principle, it should be 

reaching its maximum point. The 

maximum lifetime production is 

best on the interquartile range. I’ve 

just put up Figure 24 to remind you 

that it is rather fascinating that the 

simple biomass equation is, in fact, 

the product of or involves these 

crucial ratios, M/K, and it is what 

makes that an interesting situation 

too. So, the whole spawning biomass per recruit derived in that 

equation can be written in purely 

dimensionless terms. 

But, bringing these same ratios 

together, when you use that calculation for cod and herring, the dotted line in Figure 25 is the lifetime 

biomass per recruit arriving at 

maturity and, of course, of the fish 

arriving at maturity, which has to 

take any account of mortality 

losses in weight while immature. 

Then the later you mature, the better the biomass. However, if you 

ask the question for cod (Fig. 25A), 

you arrive at 6 years old, and you 

now have a choice: either mature 

at age 6 or wait until some later age 

to mature. If you wait until some 

later age, you’ll have to suffer a 

mortality rate in the process. So, although you’ll get a better lifetime 

biomass per numbers of eggs 

spawned if you survive to that age, 

you may not survive. If you put 

that into the equation using the 

rather limited range of mortality 

that we have, because we don’t really know what the overall level is, 

0.1 or 0.15 or 0.2, there are three 

curves shown. But in each case, 

though, there is an intermediate 

maximum, much stronger with 

curves (a) and (b) than with curve 

(c) which has a rather high natural 

94 
Lecture 2: Fish Population Biology and Fisheries Research 

mortality rate. For 0.15, it’s more 5


intermediate than the other one;


then you get a maximum around 4


about 9 years, which for cod is


around about the middle of the distribution of the maturation. 

In the case of the herring (Fig. 

25B), the answer to the question at 

what age you make a decision, it’s 

got to be asked before you reach 3 

years old. By the time you reach 3 

years old, you’ve committed yourself to a totally different growth 

curve than your brothers and sisters. So you have to ask the question right back at a much earlier 

age. The evidence is from Devold’s 

(1963) work on herring because 

that’s where it all starts from. 

That’s basically what I’ve done, a 

biomass curve, individuals eventually reaching maturity, very marked increase, no question of that being conformed to any kind of stable 

strategy. But if you put the immature mortality rate into this, this is 

very steep. You can actually get 

answers according to how steep it 

is. So you get a maturation moment 

around about 6 years, which is the 

middle or a little bit shifted to the 

left if it’s higher still. And I think 

that gives me some confidence that 

we are beginning to be able to answer the question. Yes, there’s good 

reason to the tradeoffs in growth 

and mortality, why these distributions should peak when they 

do at the age they do. 

Relative SSB per recruit 

Relative SSB per recruit 

(a) adult M = 0.10 

(b) adult M = 0.15 

(c) adult M = 0.20 

Cod 

SSB/R m 

SSB/R6 

(a) 

(b) 

(c) 

(a) 

(b) 

(c) 

A 

3 

2 

1 

0 

6 7 8 9 10 11 12 13 14 

Cohort maturation age (years) 

5 

4 

3 

2 

1 

0 

3 4 5 6 7 8 9 

(a) Immature M = 0.55 – 0.0005L

2 

(b) Immature M = 1.10 – 0.0011L

2 

Herring 

SSB/R m 

SSB/R0.5 

(a) 

(b) 

B 

Cohort maturation age (years) 

Figure 25. Relative spawning stock biomass 

(SSB) per recruit vs. cohort maturation age 

for Northeast Arctic cod (A) and for Norwegian spring-spawning herring (B). 

95 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Lm/L∞ and 

Lopt/L∞

110 

100 

90 

80 

70 

60 

6 7 8 9 10 11 12 13 14 15 16 

M = 0.1 

M = 0.15 

M = 0.2 

L m 

A 

Maturation cohort age (years) 

1.0 

0.9 

0.8 

0.7 

0.6 

0.5 

0.5 1.0 1.5 2.0 

M = 0.2 

M = 0.15 

M = 0.1 

Lopt/L∞

B 

K/M 

Figure 26. Lm at each maturation cohort (age in 

years) (A) and Lm/L∞ vs. K/M (B) at three levels of 

natural mortality (M) for Northeast Arctic cod. 

L and 

Lopt (cm) m 

In fact, in the cod—I haven’t 

done this for herring yet—we can 

actually go back to that plot of L m/ 

L∞ against maturation age (Fig. 

26A). For the different natural 

mortalities, 0.15 conforms most 

closely with the observed curve. 

Similarly, plotting those ratios 

against K/M (Fig. 26B), it’s again M 

= 0.15 that fits the observed curve 

much, much closer. So, it rather 

suggests there may indeed be a 

way here of distinguishing which 

level of natural mortality is the 

most realistic one. In that case, it 

would be 0.15. 

Well, that really stands out as a 

method of estimating mortality. I 

think we’ll have to leave it until 

more work is done to be sure about 

it. It’s a rather intriguing possibility. 

Now, just to finish up with a few 

concluding remarks to try and 

bring this back to the more general 

biological scene. I mentioned in the 

herring that there was evidence of 

this cohort distinction. It began to 

be noticeable much earlier in life 

that we saw them come to maturation. Figure 27 is from Lambert’s 

(1984) work on Nova Scotian herring, and it shows growth curves 

of cohorts from that coming 

through and staying distinct and 

producing length compositions in 

which you can see modes—in 

other words, from the very early 

stages of life history, the embryonic 

96 
97

Lecture 2: Fish Population Biology and Fisheries Research

form of the maturation cohorts and the cohorts’

growth curves. They’re

not as much maturation

curves as they are growth

curves. The successive

weekly larval productions

coming up that early are

distinctive curves, and

that’s the reason the survivors are becoming stronger. But, where you see this

most clearly is in Atlantic

salmon where the whole

question of whether they’re

going to smolt or not is dependent on what their

growth rate is doing in the

early stage.

Figure 27. Larval cohort succession in herring in St. Marys

Bay (redrawn from Lambert,

1984), with length frequency

histograms of larval herring

(A) and growth curves of larval herring cohorts (B). In B,

points are mean lengths of

component populations, �

derived from analsis, and �

plotted by eye.

30

0

30

0

20

0

10

0

10

0

10

0

15

0

10

0

10

0

10

0

5

0

30

0

20

0

20

0

10

0

10

0

20

0

10

0

10

0

30

0

30

0

20

0

10

0

15

0

20

0

10

0

10

0

10

0

5

0

5 0 15 20 25 30 5 0 5 0 5 0 5 0 5 5 0 15 20 25 0 5 0 5 0 5

Sept. 7, 1960 n = 27,520 Oct. 13, 1961 n = 739

Nov. 10, 1961 n = 238

Dec. 2, 1961 n = 114

Feb. 23, 1962 n = 19

Apr. 11, 1962 n = 1184

May 3, 1962 n = 991

Sept. 6, 1962 n = 20

Sept. 14, 1962 n = 254

Oct. 3, 1962 n = 432

Nov. 6, 1962 n = 401

Feb. 14, 1963 n = 9

Apr. 6, 1963 n = 66

May 7, 1963 n = 976

June 1, 1963 n = 16

Dec. 5, 1962 n = 158

Oct. 4, 1960 n = 1,447

Nov. 2, 1960 n = 302

Dec. 1, 1960 n = 87

Jan. 16, 1961 n = 15

Mar. 29, 1961 n = 40

Apr. 21, 1961 n = 844

May 10, 1961 n = 5,674

May 22, 1961 n = 2,609

June 22, 1961 n = 131

July 27, 1961 n = 275

Aug. 31, 1961 n = 127

Sep. 29, 1961 n = 4,304

Feb. 1961 n = 23

Length (mm)

Length (mm)

Year and month

60

50

40

30

20

0

S N

1960 1961 1962

D F M A M J A S O N D J F A M

A

B

Frequency (%)

Length (mm)

1 3 4 4 5 5 6 6 7 7 1 3 3 4 4 5 5

O J J M
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

40 

20 9 June 

30 

27 June 

10 

30 

10 

25 July 

30 

Figure 28 shows early hatching 

salmon larvae just in a single mode, 

then beginning to develop within 

a couple of weeks into two modes, 

more still during the summer, and 

before long there is the group of 

smolts that go down the river 

(shaded area) and the group that 

stays behind (unshaded area). 

Some of those become precocious 

males—John Thorpe3 doesn’t like 

calling them precocious males— 

but they actually stay back and mature within a year or two at this 

size. Hence, it drives the tradeoff 

Frequency (%) 

22 August between staying as a precocious 

10 male or having to deal with the 

problem of dominant males com30 

9 September 

ing back from the sea, of course, 

risking lots of mortality on the way, 

10 but then having the females, as it 

were, under his own control and 

30 

29 September 

able to ensure that the larger proportion of the fertilization came 

10 

from him, whereas the little ones 

have to sneak in and do the best 

they can. The tradeoff between the 

30 efficiency of the fertilization and 

the more terrifying choice between 

10 staying in the river, where you’d 

4 6 8 10 do rather well in that case, or goLength (cm) ing down to sea, almost balances. 

In other words, the evolutionary 

stable strategy. 

8 November 

Figure 28. Salmonid developmental variation. Length-frequency distributions showing 

the progressive segregation of non-smolting 

(unshaded) and potential smolting (shaded) 

individuals of a population of age 0 Atlantic 

salmon (redrawn from Thorpe, 1989). 3John E. Thorpe, Freshwater Fisheries 

Laboratory, Pitlochry, Perthshire, Scotland, 

U.K. 

98 
Lecture 2: Fish Population Biology and Fisheries Research 

Length at metamorphosis (mm) 

Figure 29. Relationship between age and length at: (A) metamorphosis in various flatfishes (redrawn from Chambers and Leggett, 1992) 

(see Fig. 30A for key to symbols) and (B) maturation in AtlantoScandian herring and in walleye (Beverton, 1987; Toresen, 1986; 

50 

40 

30 

20 

10 

0 

0 

8 

12 

4 

0 

0 30 60 90

A B 

Length at maturation (mm)

Age at metamorphosis (days) Age at maturation (years) 

Atlanto-Scandian herring 

Walleye 

1 2 3 4 5 6 7 8 9 

Jakobsson et al., 1993). 

Now, finally, there is one other 

landmark, just to put us right back 

into the life story, of course, not just 

maturation, but metamorphosis, 

where again we find the very remarkable same patterns of age and 

length. Figure 29 is work done particularly by the Montreal group of 

Bill Leggett4 and Chris Chambers5

. 

4

William C. Leggett, Principal and Vice 

Chancellor, Queens University, Kingston, 

Ontario, Canada, and formerly at McGill 

University, Montreal, Quebec, Canada. 

In Figure 29A, it shows age at metamorphosis in days and length in 

millimeters for flatfish, and they 

are almost straight out. In other 

words, the age didn’t vary a lot and 

length hardly changes. In Figure 

29B are the data, part of which I’ve 

used to understand herring and 

also, for walleye, which I did a year 

5

Robert Chris Chambers, NMFS Northeast 

Fisheries Science Center, James J. Howard 

Marine Science Laboratory, Sandy Hook, 

Highlands, New Jersey, and formerly at 

McGill University, Montreal, Quebec, 

Canada. 

or two before, which is doing just 

the same thing. Age is moving 

along with the length hardly 

changing. So, we now have the second major benchmark in life, the 

metamorphosis benchmark, but 

conforming to the same general 

pattern. 

99 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

25 

90 

20 

60 

A. rostratus 

P. olivaceus 

P. stellatus 

P. americanus 

R. tapirina 

S. solea 

A 

15 

10 

30 

5 

B 

T m 

T max 

Tm 

* 

0 0 

0 5 10 15 20 0 1 2 3 4 5 6 

Temperature (AC) Temperature (GDD Z 10–3) 

Figure 30. Effect of temperature on: (A) age at in this case), and GDD (mean growing degreemetamorphosis in various flatfishes (redrawn days) is an index of ambient temperture derived 

from Chambers and Leggett, 1992) and (B) age by Colby and Nepszy (1981) as the sum of the 

at maturation and longevity in walleye (redrawn products of days ✕ degrees >5oC, this being the 

from Beverton, 1987). In B, Tm * is the lowest minimum temperature in the growing season 

physiologically possible age at maturity (2 years which allows growth to take place. 

Age (days) 

Age (years) 

In view of the importance of 

temperature and the concern about 

temperature changes in the ocean 

that we talked about yesterday, or 

indeed long-term climatic changes, 

you can see how each of these two 

benchmarks is influenced by temperature. Figure 30A shows the relationship between age at metamorphosis and temperature from 

Bill Leggett’s data (Chambers and 

Leggett, 1992), markedly coming 

down and flattening out. Figure 

30B is the age at maturation and 

maximum age or longevity against 

temperature in the walleye from 

my own earlier paper (Beverton, 

1987). You’ll see the remarkable 

similarity and the general shape of 

those two, and the very considerable effect that these temperature 

differences had on all three: the age 

at metamorphosis, the age at maturation, and the maximum age. 

I hope that, by ending on that 

note, it might put all this story— 

you don’t have to worry about 

what the individual is doing—back 

into the overall framework of understanding how a population will 

try to respond to changes imposed 

on it by man or by nature. Thank 

you very much. 

100 
Lecture 2: Fish Population Biology and Fisheries Research 

Vaughn Anthony 

I forgot to tell you we’ll have an 

examination now on all this. I’m 

sure Ray will take some questions 

if you have some. 

Andy Rosenberg 

My question is about the point 

you made about using the life history strategy for estimating natural mortality. The only one I know 

who has tried that, and successfully, is Ram Myers, although I don’t 

think very many people have used 

that method, probably because it’s 

so difficult to do the computations. 

Now that was just a comment. The 

question is, at one point you mentioned the issue of reversibility, and 

for the cod and herring cases which 

you went through in detail, it 

wasn’t clear to me whether you 

would suppose they would be 

equally reversible as changes in 

fishing pressure or abundance occurred. For herring, you probably 

have some evidence that they are 

reversible, but for cod, I don’t 

know if we have that same evidence. 

Ray Beverton 

I don’t think we have yet seen a 

cod population start to come back 

up again. I hope the Barents Sea 

cod is now doing so. I mean, it certainly is doing so. Maybe within 3– 

4 years, we may begin to see them 

following up the same as herring. 

Andy Rosenberg 

But even if they are doing different things, one holding the size 

at maturation relatively constant 

(Fig. 21), the other one moving up 

and down the growth curve (Fig. 

22), would you expect them to be 

essentially reversible? 

Ray Beverton 

I’m not sure that I could say they 

wouldn’t be. I’m not sure that it immediately makes me think one is 

reversible and the other is not. 

That’s a point I must admit I really 

haven’t thought that far through. 

There is such a difference between 

the patterns in the two cases. It certainly isn’t just a question of 

whether one or both is equally responsive to the first. The fascinating thing, of course, is what is it 

that causes a cod to start to turn at 

age 6, compared with others at age 

14? For the herring and the salmon, 

the answer is yes. Actually, to take 

it much further back in salmon, 

John Thorpe at Pitlochery and Neil 

Metcalfe of Glasgow have shown 

(Metcalfe and Thorpe, 1992) that it 

is a distribution of basic metabolic 

activity right back to the emerging 

larvae that sets off a whole series 

of better feeding, higher feeding 

rates, earlier feeding, using up yolk 

sacs and getting feeding quickly, 

establish parentry, and become 

more aggressive. The whole thing 

snowballs once they start. This is 

detectable within a few weeks of 

emergence. We’re a long way from 

explaining why the size composition of salmon is diverse. It could 

also be, although I don’t accept it, 

it could be exactly the explanation 

for herring. But what about cod? 

They’re not doing that. They appear to all be growing up the same 

sort of curve, with some variation, 

but all basically, on maturation, the 

same. And yet, one bunch starts at 

age 6 and another won’t mature 

until they’re age 14. That is a complete mystery to me. I must admit 

I’ve only really realized this in the 

past year or so that there is such a 

difference between species, one of 

which is certainly explainable on 

the classic salmon story, when perhaps Clupeiformes are not that far 

removed from the Salmonidae. We 

wish we knew where the Gadoids 

are somewhere, but that is only a 

passing comment and does not explain anything. But it opens up 

some very interesting possibilities; 

the reverse question is surely one 

of them. Are they going to be 

equally responsive in reverse? I 

don’t know, but we may find out 

in a short time after cod can get 

back up again. Thanks for the question. 

Vaughn Anthony 

Some of this is related to where 

these fish are caught and where the 

salmon run. Georges Bank herring 

for years, for example, never had 

poor recruitment until age 6 or 7, 

although full maturity was around 

age 4. I think some of them didn’t 

101 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

go there to spawn, and the sampling was from the spawning 

grounds in some cases, in some 

cases not from the spawning 

grounds. It makes all the difference 

in the world for the maturity rates. 

Hal Caswell 

If I understood correctly, in describing the ESS calculations [evolutionary stable strategy], using as 

your criteria the expected lifetime 

of the population, one of the properties of lifetime expected reproductive level is insensitive to timing of the reproduction event in the 

life history. It’s those timing differences that quantities of life, intrinsic rates from the Lotka equation 

or growth rates. Has anyone looked 

to see whether the ESS calculations 

are changed in these cases like using those measures that are sensitive to timing as well as the density average output? The questions 

involve ages and sizes at maturation. It seems like timing effects 

might have a role to play here. 

Ray Beverton 

To the extent that the calculation 

is done on the change in the average compilation of maturation age, 

in a sense once you’ve got directly 

to it, once you specify the K, then 

you specify the age at which it’s 

beginning to happen. So there is an 

age component to that link or the 

link between maximum reproductive lifetime amount. But, I think 

you can’t say beyond that value 

because you can’t tell what’s happening within it. But on this maturation cohort analysis, that is indeed casting a setting for some experiment. What is the difference in 

maximum lifetime biomass production? To some extent, isn’t that 

your question? 

Hal Caswell 

I don’t think so. I’m asking a different question. Suppose you have 

two different strategies, one of 

which begins reproducing at 3 

years, the other at 6 years, and they 

both produce the same lifetime reproductive output. Which one is 

the better strategy? According to 

the use of lifetime reproductive 

output as the criteria, they are 

equal, but according to calculation 

output, for example (r from Lotka’s 

equation), they would not be the 

same. Probably the one which began producing earlier would have 

the advantage just because of the 

timing, not because of a change in 

the amount of the production. 

Ray Beverton 

I think there must be a link between what I have been showing 

you happening within one year 

class and in fact in one population 

that would get back the rate of increase. I haven’t bothered with that 

at all. It’s totally different timing, 

and with what I have associated, 

really different within the measure, 

different components. What is 

within that limited framework? 

What is the best thing to do? What 

if the relationship between that 

were fed back into this population? 

That has to be a second-stage question. That brings us back to the 

stock-recruitment story of mine. 

Bringing in this sort of thing means 

we have to perhaps ask this, we 

need a population model which is 

based on maturation cohorts taken 

separately. Operating the rules 

along the line that I’ve been showing and then putting them together 

each year, now they are all spawning. Now that will develop the next 

year class which will then split itself up and maybe, in that way, we 

can build together the question you 

were asking. This brings us back to 

a natural rate of increase alongside 

the within-life pattern. It’s very 

unclear what to do with this mess. 

We’re beginning to develop population models to do this, just beginning to sketch them out. They’re 

complicated, but that’s how to do 

it. 

Ione von Herbig 

I understand populations are 

limited by the number of spawning females. Do you know of any 

work or have you noticed any 

change in sex ratios as a result of 

fishing pressure over time? I think 

this might be appropriate to look 

at. 

Ray Beverton 

Yes, there are changes in the sex 

ratio, but not systematically, not in 

102 
Lecture 2: Fish Population Biology and Fisheries Research 

the same way in all species. In the 

herring, the sexual dimorphism 

difference is generally very slight. 

There is, of course, the mature fishing phase, but everything else 

about them, we don’t really know. 

Maybe Vaughn can comment on 

this, but there is very little difference in this. There is more in 

cod, but not all that much, but it is 

possible—I expect we have the 

data, we’ve subdivided it again in 

half—to do it in two sections. But 

when you get to the flatfish, that’s 

very strong. Indeed, remember 

those two sets of data showing a 

difference between sexes? Because 

the natural mortality of males is 

significantly greater, and lifespan 

less, the effect of fishing on them is 

different. In addition, the behavior 

of males, especially at spawning 

time, makes them more vulnerable 

to capture, significantly more so. 

They are very active; females are 

quiescent on the seabed. Fishing at 

that time captures markedly more 

males than females. So the answer 

is yes. The real question is whether 

the greater fishing on males than 

females is a factor in influencing 

the reproductive capacity of the 

population. I don’t think you were 

really asking that, but my impression is that it’s unlikely that there’s 

such a shortage of males in most 

species to really put that at risk. I 

can only say that in a rather hunchy 

sort of way without really figuring 

it out carefully. But I think in most 

of the species, certainly in the ones 

we’ve looked at, I don’t think the 

shortage of males due to differential fishing is enough to put 

at risk their reproductive potential. 

Vaughn Anthony 

We can see this in Atlantic 

salmon where if you have poor 

food supply in winter—December, 

January, and February—they will 

mature as grilse and come home 

after one sea-winter, and those 

grilse are males. But females won’t 

fall for that, and they’ll stay out a 

little bit longer. As a result, the twosea-winter population will be 

heavy in females and, of course, the 

one-sea-winters in males. That’s 

dramatic when you see that. 

Ione von Herbig 

I have seen a lot of variation in 

cod on the Scotian Shelf. We catch 

an awful lot of males which are 

running ripe and very, very 

small—27 cm. Along with the large 

amount of males we caught, only 

two or three are females. Most of 

them are behind males in maturation, and there are noticeably much 

fewer females than males, almost 

like an aggregation for spawning. 

I was wondering if fishing pressure 

had affected them? 

Ray Beverton 

Certainly, in the case of the response of whales and their response to males and females, but 

in age and size it’s more marked 

in males than in females. 

Vaughn Anthony 

Spiny dogfish will school by sex 

and size, and you will get a differential mortality rate fishing on the 

larger females. You will get a disproportionate result of the population of males. More males will be 

left behind because of the disproportionate fishing mortality rate, so 

you can get an effect from fishing 

directly caused by this. 

We have to terminate this. I am 

really pleased with the subjects 

talked about yesterday (stock-recruitment) and today (growth and 

maturation). You couldn’t have 

picked two better subjects for our 

needs. I’m very happy about that. 

Thank you very much. 

103 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

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Alm, G. 1959. Connection between 

maturity, size and age in fishes. Rep. 

Inst. Freshw. Res., Drottningholm, 

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Atkinson, G. T. 1908. Notes on a fishing voyage to the Barents Sea in August, 1907. J. Mar. Biol. Assoc. N.S. 

8(2):71–99. 

Beacham, T. D. 1983. Variability in 

median size and age at sexual maturity of Atlantic cod, Gadus morhua, on 

the Scotian Shelf in the northwest Atlantic Ocean. Fish. Bull. 81:303–321. 

Beverton, R. J. H. 1987. Longevity in 

fish: some ecological and evolutionary 

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K. H. Thompson (Editors), Evolution 

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approach, p. 161–186. Plenum Press, 

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————, A. Hylen, and O. J. Østvedt. 

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Chambers, R. C., and W. C. Leggett. 

1992. Possible causes and consequences of variation in age and size at 

metamorphosis in flatfishes (Pleuronectiformes): an analysis at the individual, population, and species levels. 

Proc. First Int. Symp. Flatfish Ecol. Pt. 

2, Neth. J. Sea Res. 29(1–3):7–24. 

Charnov, E. L. 1993. Life history invariants: some explorations of symmetry 

in evolutionary ecology. Oxford Univ. 

Press, Oxford, 167 p. 

Colby, P. J., and S. J. Nepszy. 1981. 

Variation among stocks of walleye 

(Stizostedion vitreum vitreum): management implications. Can. J. Fish. Aquat. 

Sci. 38:1814–1831. 

Cole, L. C. 1954. Some features of random population cycles. J. Wildl. Manage. 18:2–24. 

Comfort, A. 1965. The biology of senescence. Routledge and Paul, London, 

257 p. 

Devold, F. 1963. The life history of the 

Atlanto-Scandian herring. Rapp. R.-v. 

Réun. Cons. Perm. Int. Explor. Mer 

154:98–108. 

Dragesund, O., J. Hamre, and Ø. 

Ulltang. 1980. Biology and population 

dynamics of the Norwegian spring 

spawning herring. Rapp. P.-v. Réun. 

Cons. Perm. Int. Explor. Mer 177:43– 

71. 

Gross, M. R., R. M. Coleman, and R. M. 

McDowall. 1988. Aquatic productivity 

and the evolution of diadromous fish 

migration. Science 239:1291–1293. 

Hansen, P. M. 1954. The stock of cod in 

Greenland waters during the years 

1924–52. Rapp. P.-v. Réun. Cons. Perm. 

Int. Explor. Mer 136:65–71. 

Holt, S. J. 1958. The evaluation of fisheries resources by the dynamic analysis of stocks, and notes on the time factors involved. ICNAF Spec. Publ. 1:77– 

95. 

ICES. 1994. Report of the AtlantoScandian Herring and Capelin Working Group, October 1993. ICES C.M. 

1994/Assess:6. 

Jakobsson, J., and Ó. Halldórsson. 1984. 

Changes in the biological parameters 

in the Icelandic summer spawning herring. ICES C.M. 1984/H:43, 36 p. 

————, A. Guomundsdóttir o , and G.

Stefánsson. 1993. Stock-related changes 

in biological parameters of the Icelandic summer-spawning herring. Fish. 

Oceanogr. 2(3/4):260–277. 

Jónsson, J. 1954. On the Icelandic stock 

of cod during the years 1928–1953. 

Rapp. P.-v. Réun. Cons. Perm. Int. 

Explor. Mer 136:51–57. 

Kyle, H. M. 1903. Fishing nets, with 

special reference to the otter trawl. J. 

Mar. Biol. Assoc. N.S. 6(4):562–586. 

Lambert, T. C. 1984. Larval cohort succession in herring (Clupea harengus) 

and capelin (Mallotus villosus). Can. J. 

Fish. Aquat. Sci. 41:1552–1564. 

Maynard Smith, J. 1982. Evolution and 

the theory of games. Cambridge Univ. 

Press, Cambridge, 224 p. 

104 
Lecture 2: Fish Population Biology and Fisheries Research 

Metcalfe, N. B., and J. E. Thorpe. 1992. 

Early predictors of life-history events: 

the link between first feeding date, 

dominance and seaward migration in 

Atlantic salmon, Salmo salar L. J. Fish. 

Biol. 41(Suppl. B):93–99. 

Østvedt, O. J. 1964. Growth and maturation of the Norwegian herring. ICES 

C.M. 1964, No. 141, 9 p. 

Roff, D. A. 1984. The evolution of lifehistory parameters in teleosts. Can. J. 

Fish. Aquat. Sci. 41:984–1000. 

Rollefsen, G. 1954. Observations on the 

cod and cod fisheries of Lofoten. Rapp. 

P.-v. Réun. Cons. Perm. Int. Explor. Mer 

136:40–47. 

Thorpe, J. E. 1989. Developmental 

variation in salmonid populations. In 

C. E. Hollingworth and A. R. Margetts 

(Editors), Fish population biology. The 

Fisheries Society of the British Isles 

Symposium, p. 295–303. J. Fish. Biol. 

35 (Suppl. A), 363 p. 

Toresen, R. 1986. Length and age at 

maturity of Norwegian spring-spawning herring for the year-classes 1959– 

61 and 1973–78. ICES C.M. 1986/H:42, 

8 p. 

————. 1990. Long-term changes in 

growth of Norwegian spring-spawning 

herring. J. Cons. Int. Explor. Mer 47:48– 

56. 

Williams, G. C. 1957. Pleiotropy, natural selection and the evolution of senescence. Evolution 11:398–411. 

105 

“Reflections on 100 Years

of Fisheries Research”

LECTURE 3 

May 3, 1994 

Aquarium Conference Room 

Northeast Fisheries Science Center 

Before I [Steve Murawski] 

introduce the specific topic 

that Ray Beverton is going 

to speak on and tell you what the 

house rules are, I would like, if you 

will oblige me, to make a few personal reflections on Ray Beverton’s 

career and mine. I certainly wouldn’t 

put them on the same level, but certainly he has had an influence, as 

Vaughn Anthony said earlier, on 

the careers of all of us who work 

in the field of population dynamics. I first met Ray in the mid 

1980’s—I find it difficult to call him 

Ray—Professor Beverton. 

Ray Beverton 

Please do. 

Steve Murawski 

That certainly illustrates the 

type of person he is. I first met him 

at an ICES meeting in Copenhagen 

where I had just given a scintillating paper, I’m sure, having to do 

with something. I can’t even remember what it was. This guy in 

the back got up and was really agitated, really excited about something I had said, really enthusiastic. The last thing he said was “And 

I’d like to get a manuscript for the 

Journal.” I went to the moderator 

after the session and said, “Who 

was that guy?” He replied, “That 

was Ray Beverton.” I just about 

died right there, certainly died and 

went to heaven. 

In terms of familiarity with Ray, 

it goes back farther than that. As 

most of us who got an education 

in population dynamics, we had a 

personal relationship with him before we ever met him, in terms of 

the books and papers that he has 

published. Unlike Vaughn’s experience with Richard Van Cleve, who 

certainly had a reputation, mine 

was a little less stilted. The first 

interaction I had with my major 

professor talking about Ray’s work 

is analogous to that shown in Figure 1. It was this miracle part in the 

middle the professor couldn’t understand, but he said, “It’s in there 

somewhere.” 

Actually it came home to roost 

after I had completed my PhD 

work where I thought I had sort of 

reinvented the world in terms of 

technological interactions research. 

© Sidney Harris 

Figure 1. Cartoon drawing, copyright by and 

courtesy of Sidney Harris (Harris, 1992). 

109 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

I got my thesis published and a 

couple of papers out, and then I 

started flipping through the last 

chapter of Ray’s book (Beverton 

and Holt, 1957) where he had all 

the economics worked out, the 

number of shillings per pound, and 

all the good stuff that I thought I 

had invented and certainly had to 

take back in subsequent papers. I 

am sure that most of our training, 

either formal or informal, has similar interactions with “Ray the publisher,” and a few of us have been 

lucky enough to know “Ray the 

man.” 

In terms of today’s talk, the formal title is: “Reflections on 100 

Years of Fisheries Research.” I am 

not sure if that represents your personal history or represents the history of population dynamics or research in general. I guess we’ll find 

out about that. The house rules are 

going to be these: the first part of 

his talk is going to be basically his 

personal reflections, and in the 

second part we are going to open 

it up so we can have perhaps a discussion rather than a talk on where 

we think the next 100 years worth 

of fisheries research are going. 

Hopefully we can get some dialogue and interaction with Ray in 

terms of where he might think we 

are going and where we might 

think we are going. With that, I 

would like to reintroduce Ray 

Beverton. 

Malcolm Silverman, NMFS 

Ray Beverton 

Thanks Steve. A very fine introduction. Thank you very much. I 

am going to venture to be a little 

reminiscent on this occasion. I hope 

that won’t bore you too much, because sometimes it does get dull to 

hear people talking about themselves long ago. It’s easy enough 

to get into a somewhat sort of jaundiced and nostalgic sort of frame 

of mind. Anyway, I think perhaps 

there might be a few interesting 

specifics of one sort or another. 

You are quite right. I didn’t really try to go back to 1894, I have 

to admit, but I did meet a few of 

the old sages from the pre-Second 

World War days, in fact pre-First 

World War days, so I can offer 

something of a bridge with some 

people who, to you, would just be 

names way back in the past. 

The way I’ll do it is to just run 

through the period from roughly 

the middle of the 1890’s, which is 

where I think fisheries science, in 

an accepted sense, came together. 

There had been, of course, important developments before that 

through hatchery work in this 

country as well as in Europe and 

through the big expeditions, the 

Challenger expedition, John Murray, 

and people like that. As we shall 

see, there had already been beginnings of worries, in the North Sea 

in particular, about the effects of 

fishing, which was spreading very 

rapidly, from the middle of the last 

century, all into the North Sea. In 

terms of serious, organized, recognizable fisheries science, as we see 

it today, it is probably about 100 

years ago, of which I came into it 

on the second part of that time. 

110 
Lecture 3: Reflections on 100 Years of Fisheries Research 

It divides itself quite conveniently and rather quadratically, in 

a way, into the periods governed 

by the two World Wars. If we start 

with the first of those periods, as I 

just mentioned, several different 

countries had already begun to realize that they needed to get a better scientific base to work on. In the 

U.K., we were very much concerned in those days—I say “we”— 

”they” were very much concerned 

in those days with the effects of 

fishing. E. W. H. Holt (no relation 

to Sidney, but after whom the postwar research ship Ernest Holt was 

named) was commissioned by the 

Marine Biological Association 

(MBA)—in those days there was no 

fisheries lab until 1902—to sample 

the fish on the fish market, on a 

pontoon at Grimsby, and to establish whether or not the worries of 

the fishing industry, reporting to 

several Royal commissions during 

the latter part of that period about 

the decline in fish stocks, were 

genuine or not. 

The Scottish people were, in fact, 

in action even sooner, people like 

Thomas Wemyss Fulton. I mentioned Harry Kyle this morning; he 

became the first assessment secretary when ICES started in 1902. In 

Denmark, of course, the great 

Christian G. Johannes Petersen, 

who developed the Petersen tag for 

flatfish, was concerned with transplantation into and out of the 

Limfjord as an enhancement program. So enhancement was very 

much one of the driving forces in 

the early days of fisheries science. 

In Germany, which in those days 

was a very strong trawling country and had very similar interests 

to the U.K., there was Friedrich 

Heincke, who was the turn-of-thecentury Director of the Helgoland 

Biological Station. 

Even before the turn of the century, Johannes Reibisch at Kiel, actually had been, I think, the very 

first to really work out the fact that 

you could age plaice from the 

otolith. That was critical, although 

it wasn’t taken up very seriously 

for several years. It was well into 

the 1903–04 period that William 

Wallace at Lowestoft, in particular, 

took it further, but Reibisch was the 

pioneer. Of course, in the Scandinavian countries, the Norwegians 

had been in action even before this, 

with Johan Hjort, G. O. Sars, and 

people like that very much concerned with the fluctuation of their 

big cod and herring fisheries, and 

with a strong physical oceanographic backup through people 

like Martin Knudsen [from Denmark] and indeed Fridtjof Nansen 

the explorer, who was very active 

in those days. It was the realization 

that all these things ought to be 

coming together in some way, instead of just being done on a national basis, that led to the setting 

up of ICES in 1902. 

I’ll come to that in just a moment, but I think it might be useful if, while I’m staying with the 

Lowestoft part of it, I tell you just 

how things did start in those days. 

As I said, it was the MBA of Plymouth which was commissioned 

to do this survey work by a special 

Treasury grant, because there was 

no other base, no other organization to do it. This was where it started, but by the turn of 1900, it was 

realized that there had to be a more 

established base. 

My very dear friend and colleague, Arthur Lee, who died last 

Christmas [1993] and was Director 

in the 1970’s at Lowestoft, a contemporary of mine in the post-war 

years with whom I spent many 

long months up in the Arctic 

Ocean, fortunately finished and 

published a wonderful history of 

the Lowestoft Lab right back to 

even its precursor days (Lee, 1992). 

There is some fascinating material 

in that, and those who are students 

of history will find it interesting. I 

expect Tim Smith has made sure 

he’s got quite a lot of that built into 

those aspects of his book (Smith, 

1994), which I’m very much looking forward to seeing. I am, in no 

sense, trying to cover that sort of 

ground in a way that he will be 

doing. These are just the odd snippet or two of things. 

111 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, U.K. 

Figure 2. The staff at Lowestoft in 1907. Front row (l–r): W. Wallace, W. 

Garstang, J. O. Borley. Middle row: L. H. James, A. E. Hefford, Rosa M. Lee, 

R. A.Todd, G.T. Atkinson, Dykes. Back row: Potter, Arrowsmith, Walton, Ansell. 

The first recognized picture very considerable figure, the most First World War. That’s William 

we’ve got of the Lowestoft staff is leading fisheries scientist in those Wallace [front row, left] who pioin 1907 (Fig. 2) That’s the then-Di- days in the U.K. With him is J. O. neered the work on plaice and 

rector, Walter Garstang [front row, Borley [front row, right], who be- whose work Adriaan Rijnsdorp 

middle]. Walter Garstang was a came the Deputy Director after the and I are using to try and recover 

112 
Lecture 3: Reflections on 100 Years of Fisheries Research 

Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, U.K. 

Figure 3. Deck of the RV Huxley and the crew with a catch of, primarily, flatfish. 

the early history of it. That’s Rosa 

Lee [middle row, middle position] 

of “Lee’s phenomenon” fame— 

back-calculation of growth rates. 

That’s George Atkinson [middle 

row, second from right] as a young 

man who went off to the Arctic, as 

I told you this morning, to work on 

Barents Sea plaice. He was fisheries inspector at Lowestoft until the 

outbreak of the Second World War 

when the Lab closed and everybody went off to the war. He was 

asked to stay on, and he did after 

the war, and I remember him for a 

number of years. He was retired by 

then, but he lived next door to the 

Lab and was always in and out the 

whole time. He was a wonderful 

man, one of the people who nearly 

knew how to get on with everyone, 

whomever they were. George was 

respected, his advice sought, and 

his knowledge was enormous. The 

others are lesser-known people, 

but those are the four whose names 

survive in terms of folklore as well 

as in publications, Garstang in particular. 

The first ship we had was called 

the Huxley (Fig. 3). It did its first 

station in November 1902 southwest of Dogger, and there are logbooks recorded and surviving from 

that. That’s a rather dim picture of 

113 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, U.K. 

Figure 4. Lowestoft Laboratory at The Marina, 1906–10. 

the deck, typical sort of trawler as The Lab (Fig. 4) was near the horse and cart taking nets unit was, of course. There’s the catch, yacht basin at Lowestoft. That was doubtedly to the trawl dock not far 

a considerable catch of flatfish, I a building now, of course, long away. Figure 5 shows the Lab they 

think, for those days. moved out. The picture shows a went to after the First World War 

114 
Lecture 3: Reflections on 100 Years of Fisheries Research 

Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, U.K. 

Figure 5. The Blenheim and Apsley Houses on the sea 

front housed the Lowestoft Laboratory during 1920–55. 

in which, indeed, I worked at in the Lowestoft, a very imposing build- got to sea and saw the symmetry 

first few years when we were at ing, seen especially along with its of it, you couldn’t appreciate that 

Lowestoft, in fact, until 1955. On whole terrace along here, built to it was really a lot more than it 

the front, on the esplanade at be seen from the sea, and until you might look in that picture. 

115 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, U.K. 

Figure 6. Participants (l–r) at the “Fish Population” course given at 

Lowestoft February 20–March 7, 1957: George Bolster, Robert Clarke, Ole 

Johann Østvedt, Alec Gibson, Luit Boerema, Aage Jonsgaard, Torolf 

Lindström, Albert Percier, Don Hancock, Rodney Jones, Richard Vibert, 

Rui Monteiro, Dick Laws, Sidney Holt, Dietrich Sahrhage, Manuel 

Larrañeta, Jón Jónsson, Arvid Hylen, Erling Bratberg, Vincent Hodder, 

Olav Aasen, John Gulland, Olav Dragesund, Ronald Keir, Knud Peter 

Andersen, Gotthilf Hempel, Basil Parrish, Ray Beverton, and Dick Baird. 

116 
Lecture 3: Reflections on 100 Years of Fisheries Research 

Figure 6 contains a group of 

people that you probably know 

some of the names of. In the 1950’s, 

after I had come to Beaufort, N.C., 

and done the 1951 course, it was 

decided, it was really ICES helping 

to encourage this, that we should 

run one or two residential population courses at Lowestoft lasting a 

couple of weeks. This was the second one. There are a lot of people 

here who subsequently became 

well known. There was John 

Gulland, Basil Parrish, Gotthilf 

Hempel, K. P. “Jydefar” Andersen, 

there’s me in the corner, Sidney 

Holt, and so forth. Those courses 

that we ran, two of them, Basil and 

Rodney Jones from Aberdeen and 

Sidney came over to help us do it. 

It provided a linkage, a knowledge 

of one another, of methods, as well 

as people, and stood us in enormously good stead in the later 

years when the ICES working 

groups had to really be put together and function. The contacts 

that we’ve made like this proved 

to be enormously important. 

Lastly, and there’s a certain 

poignancy in giving you a history 

of this, because Figure 7 is the 

Lowestoft Lab as it is now. We 

moved to the Grand Hotel, as it 

was called, in 1955, which is that 

part of the building [in the center]. 

I was there for 10 years until 1965. 

We didn’t have any of the building [right side] at the time. It was 

built much later to house radioFigure 7. The Fisheries Laboratory, Lowestoft, in 1982. 

Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, U.K. 

biology, which was previously 

down on the docks. A lot of the 

buildings along this [far left] end 

and behind, that you can’t see, 

have been added since then for experimental facilities. This is a 

lovely position on the sea front, 

with the beach and bathing huts 

and so forth, because I think there 

are changes afoot now of which we 

have never seen the light for the 

whole of the times. It is very likely 

that Lowestoft and Aberdeen are 

going to be put under single management. This is only hearsay at the 

moment; I haven’t really heard it 

very positively, but Emory knows 

a bit about it. It looks as if it will, 

not surprisingly, with the Lowestoft fishing industry now one-fifth 

the size of the Scottish. 

117 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

118

Lecture 3: Reflections on 100 Years of Fisheries Research 

Once the distant-water fishing 

was gone in the 1970’s, with the 

extension of 200-mile limits, that 

changed totally the relative balance 

of the commercial interest in fishing in England compared to Scotland. Prior to that, it was 2 or 3 to 1 

the other way. Since then, the 

Lowestoft and Grimsby fishing has 

itself subsided. Lowestoft made, I 

think, a complete hash of picking 

up threads again. In the meantime, 

the Dutch went steaming ahead 

with their beam trawls, advanced 

beam trawl technology, and left 

Lowestoft far behind. That withered even further, and as a result 

the imbalance is so strong that the 

cries, which have been heard all 

through the century for some form 

of amalgamation between the two 

labs, Aberdeen and Lowestoft, 

have now become, I think, turned 

into reality of some form. I don’t 

think that means the Lab will disappear. It just means that the position will be probably, as you like, 

like a substation to Aberdeen. It’s 

not surprising that sort of thing 

will happen because the new factor that’s come into it is Brussels 

and the European Community 

(E.C.). There is a considerable possibility, and some logic behind it, 

Figure 8 (opposite page).Text of a letter 

exchanged between two officials of H.M. 

Treasury in December 1909 regarding 

fisheries research in the United Kingdom. (Provided by John Ramster, former 

oceanographer at the Lowestoft Laboratory.) 

CWT/year 

1,000 

800 

600 

400 

200 

0 

1860 1870 1880 1890 

Haddock 

Plaice 

Year 

Figure 9. CPUE (hundredweight/year) of haddock and plaice recorded by four Grimsby 

sailing trawlers, 1867–90 (redrawn from 

Garstang, 1900) (CWT = 100 lb.). 

that Brussels will become the funding source for the assessment work 

for the E.C. fisheries, which includes the North Sea; funded to 

strong countries and then refunded 

back on a contract basis to different groups, rather than different 

countries, to do different things. 

I’d just like to leave this early period with a lovely minute (Fig. 8) 

between two Treasury officials 

which Arthur Lee unearthed and 

John Ramster put in our newsletter a year ago, because it was a 

great argument as to who should 

be paying for this. The MBA would 

be funded directly from the Treasury grant, but the Treasury didn’t 

want to get involved in arguments 

going on even then between Aberdeen and Lowestoft as to who 

should do what. So there is a lovely minute from one Treasury official to another with a stinger at the 

end of it all which you might find 

interesting. I have a facsimile of the 

original in very nice handwriting. 

Right, so let’s leave the history 

of the Lab, as far as the Lab itself is 

concerned. I’ll come now to the 

more scientific work and bring in 

the part of it that I had more to do 

with in the post-war years. Garstang 

had charge of this early investigation into what was happening with 

North Sea plaice fisheries over the 

latter part of the last century (Fig. 

9). The paper he wrote in 1900 was 

119 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

COMMITTEE A 

Migration of Food Fishes 

J. Hjort (Norway) Convener 

D. W. Thompson (Great Britain) 

W. Garstang (Great Britain) 

F. Heincke (Germany) 

N. Knipowitsch (Russia) 

C. G. J. Petersen (Denmark) 

F. Trybom (Sweden) 

O. Nordqvist (Finland) 

COMMITTEE B 

Over-fishing 

W. Garstang (Great Britain) Convener 

T. W. Fulton (Great Britain) 

H. Henking (Germany) 

C. G. J. Petersen (Denmark) 

F. Trybom (Sweden) 

H. C. Redeke (Netherlands) 

COMMITTEE C 

Baltic 

O. Nordqvist (Finland) Convener 

H. Henking (Germany) 

C. G. J. Petersen (Denmark) 

F. Trybom (Sweden) 

Figure 10. The three Committees and 

their members established at the Inaugural Meeting of ICES in Copenhagen, 

July 1902. 

published in the JMBA (Journal of 

the Marine Biological Association), 

because there was no other vehicle 

at that time appropriate. There 

were four particular specified 

named sailing trawlers whose 

catch per unit of effort followed 

right through from 1867 to 1891 

showing the decline in CPUE for 

plaice. As usual, the haddock’s 

[CPUE] was all over the place, but 

even so, they quite rightly weren’t 

prepared to take that as very strong 

evidence, but that was, and I think 

that is possibly, the first tangible 

piece of evidence of a decline in 

catch per unit effort that almost certainly was correctly attributed to 

the effect of fishing. That was in the 

period between 1870 and 1890. 

Not surprisingly, when ICES 

was established and set up their 

three Committees in 1902, one of 

them was called the “Migrations of 

the principal food-fishes of the 

North Sea” (Fig. 10). In fact, Hjort, 

who chaired it, didn’t do anything 

about migrations. He took it in 

terms of fluctuations because that’s 

what they were much more concerned with. So when he reported 

in 1914, the classic Hjort (1914), 

Rapports et Procès-Verbaux, Volume 

20, it wasn’t about migrations at all, 

but about fluctuations of the fisheries. Out of that came his very famous hypothesis of the first critical phase, first feeding, and so 

forth. You notice that Garstang, 

however, was a member of it. 

Garstang chaired one of the other 

ones, the Overfishing Committee, 

and this had, amongst others, C. G. 

J. Petersen on it, and Fulton from 

Aberdeen as well. That became 

much more concerned with plaice 

and took further the work that had 

started, that I just described, that 

Garstang had been concerned 

with. 

Garstang never stayed long 

enough to report. By 1907, they had 

run into lots of difficulties. Only 

England and Germany were providing length compositions, which 

every country had been asked to 

do, and Garstang was getting more 

and more fed-up with trying to 

keep this together. Harry Kyle was 

a great help in the first 2–4 years, 

but he left for ICES headquarters 

in 1906 and that left the whole 

thing rather high and dry. Garstang 

again had difficulties arguing over 

this same sort of problem which 

was going as to who was going to 

fund it from the U.K. He eventually moved to the Chair of Zoology 

at Leeds, and later at Oxford, and 

indeed his daughter married Sir 

Alister Hardy who was a much 

later occupant of the same Chair at 

Oxford, a Chair now held by Roy 

Anderson, who some of you know 

is a great exponent of theoretical 

and practical parasitology, hostparasite interactions. 

120 
Lecture 3: Reflections on 100 Years of Fisheries Research 

One of the little gems of those 

early days, which isn’t widely 

known, and in fact I hadn’t spotted it until, a couple of years ago, 

Emory asked me to do a little piece 

for the ICES newsletter. I had been 

reading the Heincke report, which 

was 1913, on all this plaice story because of the study that I’m doing 

now with Adriaan Rijnsdorp of 

IJmuiden trying to reconstruct 

some of this early dynamics. I was 

struck by the fact that he had spotted, or appeared to have spotted, 

that they could plot the logs of the 

length compositions and get a very 

nearly, on the right-hand side, 

straight line. He had said that 

means that log N is A + B × L, and 

if that’s a general rule—which he 

said he did not believe—then it 

means we have a means of constructing a life table. In fact, it 

wasn’t Heincke, it was Thomas 

Edser, who was the statistician in 

London assigned to the organization of the massive 5 million 

length compositions that came in 

over those first 2–3 years in Lowestoft, 1905–07. He wrote in a paper 

in the Journal of the Royal Statistical 

Society in 1908 which, in fact, had 

that in it, as you will see (Fig. 11) 

on the first page where he says that 

“It appears that, within certain limits, the number of plaice at any 

length is directly related to that 

length by a formula of the type, log Figure 11. Reprinted first page from Edser (1908) from the Joury = A + bx where y is ...” etc., etc. nal of the Royal Statistical Society regarding commercial 

He produced the length com- length samples of plaice from the southern North Sea. 

position and logged the whole of 

121 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Logarithm of the number of plaice 

4 

3 

2 

1 

0 

10 20 30 40 50 60 70 

Length of plaice in centimetres 

Figure 12. Reprinted plot from Edser (1908) of 

the logarithm of numbers vs. length for plaice 

taken from the southern North Sea in 1906. 

5 it (Fig. 12). So there’s a nice little 

piece of population demography 

dating back to 1906. Actually, to be 

fair to Heincke, he did sort of put 

that reference to Edser, and I don’t 

want to be trapped for a moment 

on the very great achievement that 

Heincke had in the whole exercise. 

He took over this exercise from 

Garstang and knocked it into 

shape, got help with the analysis 

of the data, and really produced the 

first assessment working group 

report with a recommendation that 

the size limit should be increased 

from almost nothing—they were 

catching an average size of around 

17–18 cm—up to 21 or 22 cm. That 

sounds pretty modest for today, 

but still it didn’t come into effect, 

because the First World War stopped 

it. It probably wouldn’t have come 

anyway because there was no kind 

of official arrangement for this. It 

was just ICES writing around to 

member governments. The Belgians, amongst others, were already beginning to say “We’re not 

having anything to do with this. 

This will upset and wreck our fishery.” So, in fact, it never came into 

force. 

Moving into the post-FirstWorld 

War period, of course, that starts 

with one of the great contributions 

Fiodor Ilyich Baranov published in 

1918, in Russian of course (Fig. 13). 

We didn’t see it in the Western 

world until the latter part of the 

1930’s. I didn’t see it until 1947, but 

122 
Lecture 3: Reflections on 100 Years of Fisheries Research 

it had been seen. E. S. Russell, who 

was then Director of Lowestoft, 

had picked it up. This particular 

translation was, in fact, published 

by our Foreign Office and copied 

through to the California State 

Fisheries Laboratory by the International Fisheries Commission in 

1943. That’s the equation at the bottom. All you need to know is that 

it is a length-based yield biomass 

equation with a linear growth function (RwL3 q), and indeed it is exactly that with that formulation in 

it. 

In the post-war period, Baranov 

wasn’t known. His paper didn’t 

have any effect at all because it disappeared into the limbo with the 

First World War and the Russian 

Revolution. He was an engineer, 

not a biologist, and was put onto 

other things and rather disappeared, certainly from Western 

view. I have never heard or seen 

him, and I’ve never heard of anyone else who met him, except for 

one or two Russians whom I’ve 

met from time to time. 

During the inter-war period, of 

course, was when the sigmoid 

curve first appeared, and the birth, 

by Raymond Pearl originally in 

this country from the point of view 

of human demography, of the idea 

of the logistic growth (Pearl, 1925). 

It was the Norwegians—Per 

Ottestad—from the point of view 

of whaling (Ottestad, 1933), who 

Figure 13. Reprinted portions of the 

classic paper by Baranov (1918). 

123 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, U.K. 

first realized this could possibly be 

the basis for population and yield 

assessment. Michael Graham, who 

was my Director after the war; here 

he is as a younger man (Fig. 14); 

his main species was cod—that’s in 

the 1930’s, realized that this was a 

potential way of coping with the 

problem of assessment, and he 

rather cleverly used changes in 

abundance during the First World 

War to try to get some estimate of 

the natural rate of increase and 

used it to develop the idea of getting a maximum yield (Fig. 15). In 

fact, it was more luck than anything else, but he didn’t get it far 

wrong back at that time. He didn’t 

put formal mathematics into it, but 

left it essentially in that sort of form 

[as in Fig. 15]. It wasn’t until 1954 

when Benny Schaefer picked it up 

and really did it systematically 

(Schaefer, 1954). Before that, Ottestad was probably the first to do 

that exercise. 

Figure 14. Michael Graham, Director of 

the Lowestoft Laboratory, 1945–58, 

marking a cod aboard ship. 

124 
Lecture 3: Reflections on 100 Years of Fisheries Research 

0 

Relative rate of increase 

20 

Figure 15. Redrawing of Michael Graham’s (1935) use of the simple logistic 

production curve and the effects of the partial cessation of fishing in the 

North Sea during World War I to estimate requirements for maximum yield. 

Maximum stock 

10 

30 

40 

70 

–4 –3 –2 –1 0 

200 

100 

Age in years compared with that of 1913 

(2.7) 

Y max 

War effect

Weight of stock 

0 

Fishing effort 

Pre-1914 stock 

1933 stock 

1919 stock 

Yield 

1 2 3 4 5 

(42) 

Weight of stock 

50 

60 

They weren’t just concerned in 

those days with the question of 

population assessment, and incidentally it wasn’t only, of course, 

Graham. That was the period when 

E. S. “Bill” Russell, whom I met 

briefly after the war because he 

was on the interview committee 

when I first went for a job at 

Lowestoft in 1945, had been Director at Lowestoft. In the inter-war 

period, he developed his Russell 

equation (Russell, 1931), a simple 

statement of what comes in must 

go out if you ever get it balanced, 

which itself has had a profound 

influence, simple though it was. At 

the same time this was going on, 

the other major thrust forward was 

Bill Thompson on the Pacific halibut. Thompson and Bell (1934) 

were doing really arithmetic yield 

equation calculations in arithmetic 

form, essentially basically the same 

sort of thing that is fundamental to 

the whole question of working out 

the whole population age composition. 

125 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Simplified view of brood years, classified. 

1904 

= 

= 

= 

= 

= 

Figure 16. Cod year-class = strengths (redrawn from 

Sund, 1 = 936). 

= 

= 

= 

1917 

= 

= 

= 

1922	

Stock 

1897 

1900 

1910 

1920 

1930 

8 

9 

3 

4 

05 

6 

7 

8 

9 

1 

2 

3 

4 

5 

6 

7 

8 

9 

1 

2 

3 

4 

5 

6 

7 

8 

9 

1 

2 

3 

4 

35 

1 

2 

Area Gr Ic Br Fi Lo Fa Sk Da NS Bl 

N-W A-N L L L L L 

Gr 

Ic 

N-W 

A-N 

L 

Br 

Fi 

Lo 

Fa 

Sk 

Da 

NS 

Bl 

1) 

1) 

1) 

1) 

1) 

= 

= 

= 

= 

= 

1) Based on 2 samples from the West Coast (Lat. 59° and 62° N). 

Areas thus: 

West Greenland 

Iceland 

Barents Sea 

Finnmark coast 

Lofoten 

Faroe 

Skagerrak 

Danish waters 

North Sea 

Middle Baltic 

Symbols 

very rich 

rich 

medium 

lean 

very lean 

Stocks thus: 

Iceland-Greenland 

Arcto-Norwegian 

Local 

126 
Lecture 3: Reflections on 100 Years of Fisheries Research 

Jahrgang 

Island: 

West 

Nord 

Ost 

Süd 

Nördl. Nordsee: 

Moray Firth 

Aberdeen- u. Lunan- B 

Carnoustie- u. St. Andrews- B 

Firth of Forth 

Südl. Nordsee: 

1923 1924 1925 1926 1927 1928 1929 1930 1931 1932 1933 1934 1935 1918 1914 1915 1916 1917 1919 1920 1921 1922

Ostfries. Küste 

Holländ. Küste 

Nordfries. Küste 

Hornsriff-Gebiet 

Limfjord (Nissum) 

Gesamt (Engl. Dampftrawler) 

Übergangsarea: 

Skagerrak 

Dän. K.: 

Dän. K.: 

Schw. K.: 

Schw. K.: 

Nördl. Kattg 

Südl. Kattg 

Beltsee 

Westl. Ostsee 

Ostsee 

{ 

{ 

A 

............................................. 

............................................ 

............................................... 

.............................................. 

................................. 

............... 

... 

............................... 

.................................... 

.......... 

.............................. 

............................................. 

............ 

............................ 

............................ 

......................... 

......................... 

...................... 

... 

But it wasn’t just that sort of 

thing. There were very interesting 

ICES-sponsored symposia. They 

were just the same sort of things 

we have now on, for example, yearclass strength. In the 1936 Rapports, 

they were looking at year-class 

strengths coming through from 

sampling on a number of species. 

In this case (Fig. 16), it was cod 

which Oscar Sund, a Norwegian 

cod expert, put together, and they 

were able to pick out a synchrony 

of good year classes—1904, 1917, 

1922 in the same volume and using the same symbols, so it was obviously an organized exercise. 

Adolph Bückmann, the German 

flatfish expert of that period, did 

the same thing for plaice (Fig. 17A), 

picking out the 1922 and 1928 year 

classes. Here is the haddock (Fig. 

Iceland Faroe Rockall W. Scotland N. Ireland North Sea Skagerrak Kattegat Belt Sea W. Baltic Norway Bear Island Barents Sea 

17B), rather less clear-cut, but still 

evident. This was Robert Clark, 

who was then Director of the Aberdeen Lab, picking out the strong 

Year- B Class 

1916 

1917 

1918 

1919 

1920 

1921 

1922 

1923 

1924 

1925 

1926 

1927 

1928 

1929 

1930 

1931 

1932 

1933 

1934 

1935 

Figure 17. Plaice (A) year-class strengths 

(redrawn from Bückmann, 1936) and 

Comparison of age groups in different regions haddock (B) year-class strengths (re­

= Poor = Intermediate = Abundant drawn from Clark, 1936). 

127 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

1941 

1942 

1943 

1944 

1945 

1946 

1947 

1948 

1949 

1950 

1951 

1952 

1953 

1954 

1955 

1956 

1957 

1958 

1959 

1960 

1961 

1962 

1963 

1964 

1965 

1966 

1967 

1968 

1969 

1970 

1941 

1942 

1943 

1944 

1945 

1946 

1947 

1948 

1949 

1950 

1951 

1952 

1953 

1954 

1955 

1956 

1957 

1958 

1959 

1960 

1961 

1962 

1963 

1964 

1965 

1966 

1967 

1968 

1969 

1970 

Year-class Georges Bank 5Z haddock Browns Bank 4X haddock Browns Bank 4X cod Georges Bank 5Z cod Sable I. Bank 4W haddock 4W and 4Vs cod St. Pierre Bank 3Ps haddock St. Pierre Bank 3Ps cod Grand Bank 3N + 3O haddock Grand Bank 3N + 3O cod Iceland haddock Iceland cod East Greenland cod West Greenland cod Arcto-Norwegian haddock Arcto-Norwegian cod Southern Gulf St. Lawrence 4T cod North Sea haddock Year-class 

? 

? 

? 

? 

? 

? 

? 

? 

? 

? 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ 

+ ? 

? 

Figure 18. Successful year classes of cod and haddock 

in various areas of the North Atlantic (Templeman, 1972). 

128

Lecture 3: Reflections on 100 Years of Fisheries Research 

year classes there. It wasn’t, of 

course, until Wilf Templeman 

(1972) picked this up again in 1972 

in an ICNAF publication (Fig. 18) 

and traced the synchrony again 

across the whole of the North Atlantic cod stocks. I don’t think he 

had realized that sort of approach 

had been done earlier. As far as I 

can tell, he didn’t, but there you 

are, it’s the same parallel thinking 

again. 

I did my first two years at Cambridge in 1940–42 and then—I was 

initially going to be a chemist, and 

did physics, maths, chemistry, and 

things at school, no biology—when 

I got back to Cambridge, I had to 

take a third major subject, and I 

took zoology. You couldn’t take 

mathematics as a science subject in 

those days. You had to do it as an 

extra half subject. I was playing 

football [rugby] for the University 

and needed two afternoons a week 

for training. Those two afternoons 

clashed with the 4 o’clock lecture 

of maths on the half-subject track. 

I stuck with the maths for a little 

while until I got to a point halfway 

through the second term with the 

Oxford-Cambridge match moving 

up two weeks ahead. I played left 

fullback and we had the Oxford 

captain on the right wing against 

us and he was very fast and very 

strong and they said, “You’d better get fit or don’t collapse halfway 

through the game.” So I was beginning to watch my time allocation. 

We got to a lecture by a chap 

named Todd, who actually had 

written a textbook on algebra, and 

he was showing us how to develop 

the method of solving a cubic equation, for which there are two or 

three methods. One is by Newton’s 

method and another by Carlton. 

Well, he started with Newton’s 

method and this covered two 

whole blackboards that size. It got 

pretty complicated when you are 

trying to put together all the various terms. Now, at about 4:55 pm, 

he looked at it and said, “Oh, I’m 

terribly sorry, but I’ve made some 

mistake and have to do it over.” So 

I thought I’d give it one more try. 

So, the next week he got Newton’s 

right after about 10 minutes and 

then he went on to Carlton’s method 

of doing it, and the same thing happened. At about 5 o’clock he said, 

“I’m terribly sorry; we’ll have to 

leave this question. You can look it 

up in your textbook anyway.” That 

wasn’t the best use of my time in 

those days, so I didn’t do maths 

anymore at Cambridge. I had done 

enough to get me by, and by the 

late 1940’s, one or two textbooks 

were appearing on mathematics 

and biology, as there was no such 

thing at first. 

Anyway, to cut a long story 

short, my professor at Cambridge, 

James Gray, said, “Why don’t you 

spend a few months at Lowestoft 

before you come back to do your 

final year? They’ll have to rebuild, 

they have quite a few people, and 

they need some people with some 

reasonably quantitative skills. 

That’s the way it’s going.” So I did, 

and went in the autumn of 1945 

and was immediately taken off to 

sea by Michael Graham in the Arctic on a commercial trawler that 

had just been decommissioned 

from the war from mine sweeping—filthy dirty and smelly, covered in rust and everything. He 

had said, “We have to have an Arctic program after the war and we’ll 

have to have a research vessel if we 

want to find out what’s going on.” 

I went on that trip, but wrote up 

my resignation three times. We 

steamed straight out in a gale in the 

North Sea and I was in the fo’c’sle 

with a smokey coal fire going, and 

there were some good old chaps up 

there. Oh dear, it was a time! However, it was never as bad again, and 

I didn’t submit my resignation. 

When I finished my last year, I 

knew this was what I wanted to do. 

In that first period before I went 

back, in the spring of 1946, Sidney 

Holt came. He had just finished at 

Reading University where Basil 

Parrish 4 years previously had 

graduated. Michael Graham said, 

“I want the two of you to really see 

if you can’t put the whole of this 

fish population stuff on a more 

substantial basis. We’ve had a go 

at it, the sigmoid curve stuff. 

Thompson is doing arithmetic over 

in Seattle, and it really needs a 

129 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Figure 19. Reprint of “Population Studies in Fisheries Biology” by Hulme et al. (1947). 

more systematic approach.” When your own devices. I can’t tell you protect you any longer. You’ll have 

I came back to the Lab in 1947, I how to do it. I’m satisfied you to take a chance after that, but for 

remember him saying to the two know more than I can tell you those 4 years, I will.” We did have 

of us, “Well, I’ll give you 4 years. about it. It’s up to you. If you don’t 4 years together, 1947–51. We were 

We’ll leave you alone for 4 years to succeed at the end of 4 years, I can’t left to our own devices. We had a 

130 
Lecture 3: Reflections on 100 Years of Fisheries Research 

room for ourselves in an adjacent 

house next door to the Lab deliberately to put us away from the rest 

of them, and it was a wonderful 

time. Sidney and I got on wonderfully together. We never had an argument or a cross word or anything. We just simply found we 

had that sort of partnership that 

doesn’t often happen. It was just 

superb. 

Figure 19 shows a little paper by 

a chap named Henry Hulme, who 

was in Operational Research with 

Michael Graham. He was his aide 

and, in fact, died not long ago 

(1991). He was a very considerable 

figure. They were working up the 

theory of convoys and how to place 

and do convoy work in relation to 

the U-boats and so on. Graham 

said to Hulme, “Come down to the 

Lab and talk to my two young 

boys.” And so he did, and out of 

this came a paper we wrote, which 

is really what Baranov put in an 

age-specific form instead of a 

length-specific one and still with a 

linear growth rate, and that was in 

Nature. Some people afterwards 

said, “What was Hulme, Beverton, 

and Holt (1947)?” Well, that’s what 

it was, and it was done while I was 

still at Cambridge. I was sent the 

draft and so on. I hadn’t come back 

to the Lab yet. 

When we did come back, Sidney 

had discovered Bertalanffy (Fig.	 Figure 20. Reprint of the first page of “Problems 

20). This was the summer of 1947. of Organic Growth” by von Bertalanffy (1949).

131 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Centre for Environment, Fisheries, and Aquaculture Science, Lowestoft, U.K. 

Figure 21. Photo of Ray Beverton (left) and Sidney Holt (right) at work on their 

magnum opus in 1949 in the Fisheries Laboratory, Lowestoft. Ray can be seen 

working next to a three-dimensional cardboard model of a yield isopleth diagram, while Sidney can be seen operating a hand-Brunsviga calculating machine. 

He did so because he had two very 

good friends at Reading. One was 

a mathematician, Bill Thomas, who 

taught him, and me, quite a lot of 

maths. The other was a physiologist, Peter Jewel, who actually 

became Professor of Physiology at 

Cambridge, which is a very prestigious Chair, but he himself more 

ran the department while people 

like Alan Hodgkin and other great 

names, Nobel Prize winners, did 

their grant and private work. Peter Jewel picked up Bertalanffy, because Bertalanffy was a human 

physiologist. He had wide talents, 

but that was his special field. He 

introduced this to Sidney, and 

Sidney immediately realized that 

this was what we were looking for. 

When I came back, he said, “Look, 

I think I’ve got the equation. Let’s 

put it into the yield equation.” In 

no time at all, we were able to do 

that, and the algebra comes out 

quite neatly except for a few places. 

But the original von Bertalanffy 

(1938, 1949) formula was, of course, 

unspecified. It didn’t specify what 

those two powers [n and m] were. 

132 
Lecture 3: Reflections on 100 Years of Fisheries Research 

Prof. John G. Shepherd, FRS 

Figure 22. Sidney Holt (left) and Ray Beverton (right) at the April 1–6, 1984, 

Dahlem Workshop in Berlin on Exploitation of Marine Communities. 

It was anabolism and catabolism, 

and we often found the need to go 

back to that formulation of it in 

terms of weight, which is what this 

was, rather than worrying about 

the length version of it. And so did 

other people like Andersen and 

Ursin (1977), when they developed 

the multispecies version of it, and 

Jan Beyer and others, who picked 

up the whole question of lengthbased methods and tried to build 

in and simulate food, growth, and 

so on. They often found it’s much 

better to go back to that basic formulation. Even if you put 2/3 and 

1 as powers in Bertalanffy’s equation, you are still back into a basic 

dw/dt formulation. 

So, it was really getting the 

Bertalanffy off the ground that 

gave us the lead we wanted. And 

then as long as we knew how to 

adjust for density-dependent 

growth, a whole lot of things came 

up. Figure 21 shows Sidney and me 

in 1949 with our yield isopleth— 

that’s in the frontispiece of the reprint (Beverton and Holt, 1993) of 

our 1957 book—in this little room 

of ours in the next-door house 

beavering away at our work. 

Figure 22 is another picture of 

Sidney and me at the 1984 Dahlem 

133 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Workshop1 where we had one of 

the discussion groups; Sidney 

chaired and I was rapporteur. The 

Lowestoft people, when they saw 

that, suggested that I was saying, 

“Come off it, Sidney, you can’t do 

that.” It probably was their comment too. 

By this time, Sidney had achieved a wonderful result. He had 

saved the great whales in the early 

1970’s. He became very much involved with whales, firstly from 

FAO, and then he gradually lost 

interest in FAO and became more 

and more concerned with whales 

and whaling conservation. By setting up very rigorous standards for 

any kind of whaling approval, he 

really took the Japanese, in particular, to the cleaners on this one. They 

couldn’t match this, and it really 

meant that they stopped whaling 

just in time to save the great 

whales. Of course, it’s gone on 

rather more than that since then 

and has become a very much more 

politicized exercise. So, there’s 

Sidney, and now if you ever saw 

him, he’s still got a mass of white 

hair, beard, and he’s got little dots 

1

Workshop held in Berlin April 1–6, 1984 

on Exploitation of Marine Communities 

(May, 1984). Dahlem Workshops were begun in 1974 to promote an interdisciplinary 

exchange of scientific ideas and to stimulate cooperation in research among international scientists. These workshops involve invited experts who engage in concentrated discussion on specific topics. 

up there, and he’s just one mass 

and looks like a real guru! 

I think I’ve gone on for so long 

I’m not going to spend more than 

just a few minutes picking up a few 

of what I think are the highlights 

since then and then I’ll hand over 

to Steve. 

I suppose going into the 1950’s 

and the 1960’s—let me just consult 

my little aide-memoire—we had 

finished really all our work on the 

book by 1951 or 1952. Sidney 

wasn’t happy; he didn’t like seagoing, and he didn’t really like 

Lowestoft very much as a place. 

When Geoff Kesteven came over in 

the early 1950’s headhunting for 

setting up the Fisheries Division of 

FAO, he said to Sidney, “Will you 

come over and start it up with 

me?” And Sidney did. So from then 

onwards, I did the writing of it 

from 1952 to 1954. We kept exchanging letters and every time 

Sidney got back to the U.K., which 

he did quite a few times during the 

year (his parents were still there), 

we would have all-night sessions 

at Lowestoft. We were ever working on new ideas and ways of putting things, and so forth—wonderful times. So by 1954, the manuscript was finished and Michael 

Graham said, “Right, we’ve got to 

get it published at the Stationery 

Office.”2 He took it up there and 

they wouldn’t have anything to do 

with it at all. He said, “All right, if 

you don’t do it, I’m resigning as 

from now.” They didn’t believe 

him, but, of course, he actually was 

serious, and within a day or two, 

they had capitulated. They took 3 

years to publish it. It wasn’t until 

1957 that it finally appeared. They 

actually did very well. There were 

very, very few typos, considering 

the complexity of some of it, which, 

looking back, was a bit over the 

top, but still that’s the way it was. 

Vaughn Anthony 

What was their problem with it? 

Too long? 

Ray Beverton 

Too big! I mean, how many were 

they going to sell? We had great 

difficulty persuading them to print 

1,500 of them, and they thought 

they’d be lucky to get rid of 100. It 

was expensive to do, too. It took 3 

years to do it because it was so 

large and with detailed typesetting. There were no modern methods available then. 

In the meantime, in 1954, out 

came Bill Ricker’s classic on stock 

and recruitment. It was really— 

you mentioned about chaos, yes 

we addressed that—an Oxford 

statistician, Paul Moran, in a paper 

in 1950 on insects (nothing to do 

with fish) that he [Ricker] spotted, 

2

Her Majesty’s Stat. Off., publisher of official U.K. documents. 

134 
Lecture 3: Reflections on 100 Years of Fisheries Research 

who found that if you get a degree 

of feedback, stronger feedback in 

a difference equation from one 

term back to the next, you can get 

some very funny things. He did, in 

fact, a stock-recruitment curve with 

a replacement line on it. I know Bill 

didn’t know it, and we didn’t 

know it, but Bill worked this one 

out. And that classic stock-recruitment paper, when we saw it we 

thought, “Oh, God, this has driven 

the coach and horses through it.” 

With a sigh of relief, however, 

we realized that he hadn’t actually 

tackled it from the way we had at 

all. He had gone for a totally different formulation, and so the two 

approaches still survive as the two 

basic ways of looking at stock and 

recruitment. Incidentally, it’s all a 

question of time lag. In the Beverton and Holt equation, which is 

a dN/dt view on N – μ2N2

, it’s instantaneous. The density at that 

moment determines the mortality 

rate, but in Ricker’s equation, the 

density-dependent part is backdated to the initial numbers, N0. 

Contemporary abundance has no 

effect at all. It’s entirely based on 

the original starting numbers, or 

the adult population, if you turn 

the original numbers back to the 

previous parents. So those are the 

extremes of no time-lagging and 

complete time-lagging. If you are 

interested in thinking in terms of a 

relationship between them, that’s 

one way of looking at it. 

Moving on briefly to the 1960’s, heimo and Dickie (1964) on catchI think that, by then, one of the big ability, and several others—a clasdiscoveries in the 1960’s was VPA3

. sic Rapports. Every now and again, 

Normally regarded as developed the Rapports really hit the right 

by John Gulland (1965) in an ap- moment when everything came 

pendix to an ICES Arctic Fisheries together. There were a number of 

Working Group report, in fact it others where this was done, e.g., 

was discovered before and simul- “Fish Stocks and Recruitment” at 

taneously by Garth Murphy, in- Aarhus in 1970 (Parrish, 1973), 

cidentally from California (Murphy, “The Biological Basis of Pelagic 

1965). I’m sure they had no kind of Fish Stock Management” in Aberknowledge of each other’s efforts, deen in 1978 (Saville, 1980), and 

but it was the idea of back-calcu- “Early Life History of Fish” here in 

lating instead of forward-calculat- Woods Hole in 1979 (Lasker and 

ing that was obviously dawning on Sherman, 1981). 

several people at once over that 

time. I think, of course, the beginnings 

of the dimension of this story, 

The earliest record I’ve found of which we have begun to get init was Rodney Jones (1961), in an volved in, really dropped out once 

appendix again. It’s a very reluc- the discrete time business came on 

tant discovery; it always appeared the street, because you didn’t want 

in an appendix with something to worry about the yield equations 

else. This was an appendix to a or the purely equilibria. Once you 

paper he did in 1961 on calculation do it on a year-to-year basis, you 

of mesh increase. He said, “Look, have your weight-at-age table and 

if you work this backwards, this don’t bother about growth rates 

catch equation business, lo and be- and things as such, but I think perhold, it doesn’t matter what F you haps we are beginning to have to 

start with, it will converge.” He left think a bit more about them now. 

this as an appendix and then 

brought it into a paper at the 1963 However, then, of course, ICNAF 

ICES Symposium on “The Mea- was well on stream. I had some 

surement of Abundance of Fish wonderful times with ICNAF and 

Stocks,” which I think was again its Assessments Subcommittee and 

one of the landmarks because it not with ICES all at the same time. By 

only included Rodney’s paper the late 1960’s and early 1970’s, the 

(Jones, 1964), but it included Palo- collapses that I talked about yesterday began to influence a lot of


the way fisheries science was mov-
 3

Virtual population analysis. ing. The daily [otolith] rings were


135 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

discovered in 1974, and by then the 

computer was coming on stream. 

Now that was somewhat of an animal that we never had anything to 

do with at all. All our calculations had to be done by handBrunsviga4

, so you can imagine 

when we did our density-dependent stock and recruitment and 

growth rate [and] put [it] into our 

haddock thing, which was probably the pinnacle of our modeling 

efforts. It took about 8 months to 

get that done. The only way we 

could solve these four simultaneous equations, growth and everything, was by taking batteries of 

things and plotting until you got 

the answers. 

So, the VPA didn’t come easily. 

It caused quite a lot of “cububble“ 

until people really realized just 

how complicated it was and the 

sort of implications that can happen when you apply it in circumstances which it really isn’t designed for. I still think there is 

maybe a stinger in the tail or two. 

Some of these cases where the fishing mortality rate does decline with 

age, and you don’t know it, and 

there is no way of putting in a 

catchability adjustment, it will give 

you an apparent answer which is 

not necessarily a true one at all. It 

can’t do otherwise, I think, but I 

4

Brand name of a mechanical calculator 

that was operated by punching keys and 

pulling a lever (hence by hand). 

may be wrong. I also think that 

spatial phasing, which we have begun to play with in terms of diffusion work and that sort of thing: 

whether or not the VPA can cope 

with this all right, I’m not so sure. 

But there’s no doubt, it’s a very 

powerful weapon. 

Finally, of course, we come to 

the more recent eras which I think 

it would be presumptive of me to 

talk about because I was out of the 

front line until the early 1980’s and 

only then on the sidelines. So I 

think you are much better and able 

to take it all forward from there 

than I am, not necessarily now, but 

I think I’ll leave it at that. It was 

rather long winded, but I hope 

you’ve found some specifics of interest in this that rang true. Thanks, 

Steve. 

Steve Murawski 

What we had planned to do was 

make this free-form at this point. I 

don’t know if there are maybe a 

few questions for clarification that 

Ray might want to take at this point 

in terms of the first century of fisheries research. Certainly one comes 

to mind for me. You mentioned 

about Hulme’s early work. I had 

heard the story that he actually was 

an artillery operations research 

person and had worked out trajectories for firing shells, and under 

the cover of fire one day he sort of 

whipped out the basic equations 

for yield-per-recruit. 

Ray Beverton 

I wouldn’t be surprised at all. 

He was on ballistics and, with Graham, on convoy strategies. 

Fred Serchuk 

I wonder whether, from the 

early part of your experience, realizing often that we don’t seem to 

learn from our experiences and history repeats itself, and seeing that, 

now you’ve gone back to some historical data, I am concerned, and 

wonder if you are concerned, with 

the deterioration of data bases. 

We’ve come a long way in terms of 

computing and modeling, and 

we’ve got tools to do much more 

in 2 minutes than you could do in 

8 months, and yet we are losing the 

basic ingredients with which to use 

these models. Do you have a viewpoint on that? 

Ray Beverton 

Yes, I’ve watched it rather than suffered from it directly. But, I’m not 

sure this is the only cause. But, undoubtedly one cause for what has 

undoubtedly been the deterioration in some of the data is the fact 

that we try and manage by TAC’s5

. 

That is, in fact, not foolproof. It is 

so easy in some circumstances to 

just completely ignore it and have 

landings that are not recorded. You 

know as well as I do that in the mid 

1980’s the ICES North Sea Flatfish 

Working Group said for 2 years 

5

Total allowable catch. 

136 
Lecture 3: Reflections on 100 Years of Fisheries Research 

that they couldn’t make an assessment because they knew that twothirds of the plaice landings were 

not being reported. That’s twothirds of 120,000 t, and by countries 

that ought, strictly speaking, to 

have known better. In the end, they 

got around it, but even now, looking at the most recent ACFM6 report, on the gadoids (not the flatfishes) they are saying the data 

base is still suspect. There may be 

other reasons, but is that the sort 

of thing you had in mind, because 

that seems to me to be one of the 

most serious causes of the data 

base problem? 

Fred Serchuk 

There are other aspects of it. The 

early history you talked about was 

trying to establish reliable data 

bases which make inferences about 

either the effect of fishing or the life 

history attributes of these renewable resources. I find it ironic that 

nearly universally the data bases 

are deteriorating [under-reporting, 

misreporting, etc.], and it’s contagious. One of my colleagues who 

just came back from a working 

group meeting in the Baltic basically said this North Sea nonsense—the misreporting and all 

sorts of problems—has now infected the Baltic such that, for those 

fisheries for cod, and there is a sizable cod stock there, countries are 

6

ICES Advisory Committee on Fishery 

Management. 

officially reporting 1,000 t and yet 

they are getting landings at Bornholm7

, which is a major cod port 

in the Baltic, of 100,000 t. Fish are 

coming in from the former Soviet 

Union, and there are all kinds of 

ways around quotas. I don’t mean 

to throw up my hands as a pessimist, but one does start to wonder, 

particularly from a management 

point of view. I guess I should ask 

this other question. How does one 

manage fisheries when data are deteriorating, and what disincentives 

should be provided to increase the 

volume of data? Politically, as you 

know, it is often the case where 

fishermen don’t want to provide 

the data because they might be 

impugned because of it. On the 

other hand, if they don’t provide 

the data... 

Ray Beverton 

It’s really very distressing. I 

quite agree. I’ve watched it and 

found it disturbing to see it happening. I think some of the reason 

is, of course, that most of the fisheries that we’re talking about are 

in a heavily overfished state so 

there is a lot of pressure to somehow or other get around or circumvent the regulations if that is what 

is involved. If only we could get to 

a rather happier state where things 

were not under such pressure, I 

think some of these incentives to 

get around, to avoid, to evade 

7

Danish island in the Baltic Sea. 

would disappear. So, in a sense, it’s 

a problem generated by the state 

we’re in. That’s not our problem. I 

think also, I suppose, it’s partly 

because it’s so difficult to get across 

to different fishing communities, 

different nationalities, and different cultures just what it is they 

are doing. The problems that were 

faced 100 years ago trying to convince the more enlightened fishermen here and there are still with 

us very much. It’s not easy; it’s only 

here and there that we can really 

get it across. I think the problem of 

communication of all this, not just 

the fishermen but the administrators, is still [with us] as one of the 

really big headaches. I don’t think 

there is a single formula for this because it must depend so much on 

knowing your fishermen and 

knowing their attitude and what it 

is that would appeal to them in 

terms of trying to convince them 

of what is really going on and what 

we should be doing. 

I have a feeling that we ought 

to try, amongst other things, to develop more sophisticated ways of 

recasting past events and saying, 

“Look, this is what actually happened. You’ll remember the state 

the thing was in 20 years ago. Now 

had you been able to do that, you 

try it yourself and see what will 

happen.” It’s easy for me to say 

that, but it’s another thing to convince the fishermen that what they 

can see coming on the screen 

137 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

would actually be real. I believe 

there is scope for using modern 

interactive visual methods to backtrack and get across to them, 

“Look, life could have been different now had you done this, that, 

or the other. Try it yourself and 

see.” It’s easy for me to say this, but 

I have a feeling it is a thing we 

ought to be thinking about. It’s not 

trivial, that one. It isn’t just a matter of turning everything backwards. 

If you’re not careful with VPA, 

you’re just recapitulating the VPA 

the other way because it’s already 

used to go back to your stock-recruitment. Now, if you do it that 

way, you can only do it when you 

have a fairly good reversibility 

built into the system, such as the 

Icelandic summer-spawning herring, and you’ve got a reasonably 

good stock-recruit curve you can 

work on. You can say, “Look at 

what would have happened if we 

had held the biomass at 2 million t 

by stopping everything then. How 

long would it have taken, knowing what recruitment we did have, 

knowing what the R/S ratio was 

in those subsequent years? You 

have to allow for a bad year class 

or two and see how long it would 

take to come up.” Whether that 

would be convincing at all, I don’t 

know, but I do think there are some 

glimmers of hope. Iceland certainly 

got their herring fishing and their 

herring fishermen well onboard on 

this one. And so I think the Norwegians. The problem they’ve got 

is whether they can carry the Russians with them, not scientifically, 

but in terms of putting it into practice. I think some of the lessons of 

the collapses have been learned 

and will not be repeated, but there 

are many other areas where the 

message has never been experienced quite like that, and it never 

has been driven home to them just 

what happened and why it happened. I think we can try and do 

that. 

Vaughn Anthony 

I want to follow up on this and 

ask a loaded question. One of the 

problems, of course, with the bad 

data is now everybody is moving 

towards surveys, our own independent surveys, to get away from 

dealing with the fishermen and so 

forth. We are getting to the point 

where we’re getting ridiculous 

about some of our surveys. What 

is your opinion about using or developing age/length keys from research surveys and applying them 

to fisheries in general? 

Ray Beverton 

Well, you have to be careful with 

applying age/length keys from 

one situation to another. I wouldn’t 

be too worried if it’s the same time 

and place, but you’ve got to be 

careful if you’re trying to use it 2– 

3 years behind. 

Vaughn Anthony 

Oh yes, it would be the same 

year, but apart from the year, you’d 

be using a different gear. 

Ray Beverton 

I think the answer is that I have 

no personal experience in trying to 

do that, so I don’t think my advice 

is very helpful. 

Vaughn Anthony 

We’re getting to the point where 

we’re doing that more and more, 

and it scares the heck out of me. 

Ray Beverton 

We’ve had to use research 

samples now, but we didn’t use 

any research surveys in my day. 

Maybe we should have done them, 

but we didn’t dream of spending 

research vessel time doing that. But 

you can see now why it would 

have to be done. It’s the only possible way of getting anything out 

of it. Ironically, I think the northern cod story turned itself into 

“Which data do you put your 

money on: research vessel data or 

commercial data?” 

Vaughn Anthony 

I’m not talking about indices of 

abundance, but it’s very expensive 

to go to the docks and sample ages 

and lengths from the fishermen. 

Ray Beverton 

The age/length key is reasonably safe, provided you are careful 

138 
Lecture 3: Reflections on 100 Years of Fisheries Research 

with it. I don’t think you can go a 

long way adrift as long as you are 

doing it on the same year with the 

same dominant, or otherwise, set 

of year classes. If you don’t do that, 

you can get some funny answers, 

but I think there is enough practical experience of applying age/ 

length keys now, and the theory of 

it too. John Hoenig has looked at it 

and all the rest of it. I think it is reasonably safe to do it. Don’t you 

think so, those of you who know 

it, or don’t you agree with me? 

Andy Rosenberg 

We have tremendous attacks by 

fishermen on the survey8, of 

course, just because of the selectivity. Presumably you have attacks on either end, the selectivity 

of the trawl and using different 

gear. 

Ray Beverton 

I would think that was one of 

the lesser problems rather than the 

greater ones actually. 

Vaughn Anthony 

Most of our stocks are overfished, and you get only a couple 

of year classes, so it may not be too 

much of a problem. But, we do 

have selective gear from our research trawls, and we don’t catch 

8

Stratified random bottom trawl survey 

conducted continuously since 1963 by 

NMFS Northeast Fisheries Science Center 

in Woods Hole, Mass. 

too many larger ones. We catch 

more of the smaller ones, that type 

of thing. Even if you had four or 

five ages in your age composition, 

it scares me a little bit. We could be 

off a bit in some species by using 

survey stuff. I’m afraid we’re getting more and more to that point 

because of budget problems. We 

have got to find a cheap, simple 

way of doing an “analytical” assessment. I’m afraid we are getting 

away from sampling the docks too 

much, and just the principle of this 

bothers me a little bit. When you 

get the stocks recovering and have 

six or eight ages per year type of 

thing, and you try to use our survey gear now, we’ve standardized 

it back to 1963, so it doesn’t perform anywhere near the way the 

commercial nets do. 

Ray Beverton 

The Norwegians have, as you 

probably know, done a lot of calibrating of their trawling—their 

catching power. It is a bit worrying when you see how vertical 

stratification of different sizes of 

fish can very dramatically change 

what a trawl is catching. Of course, 

this is learned presumably through 

the sea-going measurements to get 

around this problem of not relying 

wholly on the market. Whether 

that’s a partial answer to it, I don’t 

know. 

Vaughn Anthony 

We’re doing that now, but we’ve 

ended up doing it for the managers 

who want to see where certain 

things are occurring—bycatches 

and so forth for the management 

stuff. It’s now gotten to the point 

where all of our days at sea are 

“brush-fire” management type activities, and it’s nowhere useful at 

all for what we want for our scientific staff to relate to a fishery and 

so forth. I had hoped when we 

started that we would have some 

real good data, but it’s catch-ascatch-can now. People go to sea one 

day, and you don’t know where 

they’ll be going to go. The next day 

they’ll go another direction. It’s a 

shotgun approach on everything 

we do on that program. That is a 

new program that we’ve had just 

for a few years now. 

Steve Murawski 

It’s interesting because people at 

this facility [Woods Hole Laboratory] launched a sea sampling program in 1913 when there were nine 

trawlers at most. The fishery was 

dominated by hook-and-line trawling. The idea back then was to see 

if we should ban trawling altogether. Basically, they prepared 

fishing trials to look at the size and 

species compositions. Unfortunately, we didn’t learn the lessons 

from those early data, but they 

were well documented back then 

and they represent a gold mine for 

comparative work. I know you are 

trying to dredge up the early history on the plaice fishery. 

139 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Robert Edwards 

Ray, I have a question with a 

twist on it. I’m curious about how 

you would react to a statement that 

appeared in Sierra9 magazine about 

three months ago. The president of 

the society, you’ve heard of it, of 

course, was quoted in an article 

(Mardon, 1994), and I was struck 

because one of the comments that 

she made was, “In many cases, 

such as ocean fisheries, we’re still 

waiting for the scientists to help 

guide us as to what real sustainability is.” I’m really curious about 

how you’d react to that. 

Ray Beverton 

I think one answer is that if 

they’d listened 50 years ago, they’d 

had the answer. We’ve been saying 

it for the last 50 years or more, as 

you can tell from some of the things 

we’ve been saying today. It’s rather 

worrying in a way that the finger 

is being pointed at the scientists. If 

we’ve done anything, if we fail, it’s 

because we haven’t gotten it across, 

rather than not having done it. 

Robert Edwards 

Ray, I’m not so sure about that. 

It’s a troubling problem and I think 

one of the examples on how you 

get around this is what Sidney Holt 

did with the whales. You make the 

problem an ethical question, and 

once it becomes ingrained as an 

9

Official organ of The Sierra Club, a conservationist group. 

ethic to manage the fish properly on 

the part of the population, and not 

the fishermen, then you begin to 

make progress. But as long as there 

is no ethical background within any 

particular civilization to manage 

these resources properly, I don’t 

think the scientists will ever win, 

nor do I think the public will win. 

Ray Beverton 

I think maybe this text leads on 

to another point that has struck me, 

looking at the difficulties we’ve 

been wrestling with over the last 

10 or 15 years in the North Sea anyway, and that is because we’ve, unavoidably—our administrators 

and everybody else have not been 

able to accept anything other than 

this—been pushed into a position 

of having to work with absolute 

predictions and measurements of 

total yield, absolute yield. That follows from the principle of maximum sustainable yield, but in fact 

it presents us with real difficulties 

because I really don’t think we’re 

in a position to predict, though 

most people would say so, what 5 

years of yield is going to be, if anything, and yet we seem to be 

caught in a situation in which that 

is what we’re expected to do. Of 

course, in talking with ICES and 

Lowestoft people, as David 

Garrod10 says to me, “The trouble 

10Fisheries scientist at the Lowestoft Laboratory from 1961 to 1995; Director from 

1989 to 1995. 

is, the only currency which, in the 

North Sea situation anyway, we 

can work with between countries 

is catch or landings, accurate or 

otherwise. There is no other common currency which you could do 

anything with.” And yet it isn’t really the catch that we’re trying to 

or ought to get at. The real question is the harvesting rate, to put it 

in modern terminology. That’s 

what Michael Graham was saying 

when he said, “We should stay at 

home and not fish too hard.” His 

principles of “The Great Law of 

Fishing” (Graham, 1943) say that 

unlimited fishing sooner or later 

drives the whole thing down, for 

better or worse, to a more-or-less 

break-even zero profit. It was being said 50 years ago, and it is just 

as true now as it was then. How 

we get out of it is another matter. 

I’m not saying to completely disregard any kind of attempt to manage on a catch basis. All I’m really 

saying is that the ultimate aim 

must be to keep the harvesting rate 

down to a reasonable level. It 

doesn’t matter after that, within a 

certain amount of variation, what 

Malcolm Silverman, NMFS 

140 
Lecture 3: Reflections on 100 Years of Fisheries Research 

is happening; you can get good 

year classes or bad ones. Within 

limits, within the first order, you 

should harvest them all about the 

same, unless you’re trying to rebuild an overfished stock, of course, 

and then you should not fish a 

good year class as well. But if only 

you can get there. The problem is 

where you are aiming at, and the 

second question is how you get 

there. 

The article that Mike Sissenwine 

and Andy Rosenberg wrote for 

Fisheries back in the fall (Sissenwine 

and Rosenberg, 1993) put it extremely well. I think they said absolutely clearly we know where we 

want to get to, but to get there is 

going to cost money because you 

can’t get there with the present 

capitalization of the fishing effort. 

There is no way you can, so you’ve 

got to unravel it, and that’s hard. 

People have gradually got to have 

an opportunity of saying, “Fishing 

isn’t for me. I’ve got to do something else.” There’s going to be a 

lot of difficulty in getting there [recovered fish stock], and then when 

it is there [recovered fish stock], of 

course, it’s going to be very profitable. Whenever you can get to 

that point with half as much effort 

or a third as much effort, or whatever it is, it is going to be a very 

profitable exercise. I’m pretty sure 

before long, if we get anywhere 

near that, people will start saying, 

“Well, what are we going to do 

about these fishermen who are 

making pots of money.” Big business is going to say, “This looks 

good to us. We’re going to start 

putting our money into this.” Before long, you’ve got a different 

kind of problem than catch limits. 

You have effort pressure booming 

again. 

Theoretically, in a way, one answer to that is to charge a rental. 

You have the owner, the landlord, 

because somebody owns the resources. You can’t just ignore it. It’s 

either inside the 200-mile limit, 

which means it’s a national responsibility or, in the case of the North 

Sea, it’s the European Commission. 

The landlord has to set the rental 

based on a fair return against the 

going rate elsewhere. There are 

other ways of using money and 

resources, and anything in excess 

of that is cleaned off and put into a 

reserve fund as a rainy day fund 

for when there will be some bad 

year classes, the release of which 

is dependent upon the green sign 

of the assessment. This sounds like 

a fantasy, but if you look at the full 

situation and they say, “How ever 

are we going to get out of this?” 

what do we try to offer them as the 

eventual goal of 20–25 years off? 

Unless we do offer them something 

that has the attraction in it that it 

really could have if it were done 

like that, we’ll never get them to 

bite the bullet and try to get out of 

the present situation. 

Andy Rosenberg 

I think you’ve said a couple of 

times that it’s really the idea of having an insurance policy for fisheries, which is something that John 

Beddington and John Gulland 

worked with a bit and used in the 

Falklands, I think, to reasonably 

good effect, and Marinelle Basson11, 

of course, and me doing occasional 

dirty work. I think that sort of idea 

works very well when you have an 

all-foreign fishery. It’s more difficult to do when you’re dealing 

with the European Community 

and so forth. 

I wanted to go back to the science issues, as opposed to management issues, a little bit and see 

if you had any thoughts on what I 

think is possibly a major change or 

trend in the way that we are giving scientific advice now; that is, 

including uncertainty estimates. I 

know you have just come from 

Miami a short time ago, and they 

have been doing an awful lot of 

work on Monte Carlo simulation 

and boot strapping, and we have 

done a fair amount here within the 

NEFSC, both in terms of projections 

and in terms of the assessments 

themselves. Ray Conser has done 

a lot of work, and Paul Rago has 

done some work on stochastic projections, and that is really, in my 

11NRC Post-doctoral fellow at NEFSC. Currently on staff of Lowestoft Laboratory, 

U.K. 

141 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

mind, changing the form of the scientific advice. I wonder if you have 

some thoughts on how those uncertainty estimates will be used in 

terms of advice in the future. 

Ray Beverton 

Yes, I have been watching this 

for some time with mixed feelings 

because, while I accept that there 

has to be the degree of reliability 

of a given sort of estimate, of a 

given assessment, or a given parameter value built in and taken 

very seriously, I think when it’s a 

question of transmitting what it is 

you are saying to the operators and 

the fishermen, what the risk is, it’s 

not always as clear-cut as it seems 

it ought to be. First of all, we are 

not making decisions which are 

going to last forever. I mean, if 

you’re doing Monte Carlo simulations, you may get the answer, 

“Well, at the end of 20 or 30 or 40 

or 50 years, there is a 1 in x chance 

that it’s gone.” But, you wouldn’t 

sit back for 20 or 30 or 40 years and 

wait to see if you got the 1 in 50 

chance. You would have to react as 

you go along. I mean, if you like, 

it’s Carl Walters’ (1986) adaptive 

management. You, therefore, have 

to build in, it seems to me, how 

long is it going to be or how far will 

it have gone before you can detect 

that you are wrong, and when you 

have detected that it’s wrong, how 

easy and quick can you reverse engines and get back again. Unless 

you can bring that, and what is the 

penalty for having gone that far 

and the cost of getting back, that 

seems to be the trade-off. Just to put 

down what, in effect, is a statement 

of whether we are right or wrong 

within a certain precision, if you let 

the thing go indefinitely, seems to 

me to be not the sort of work, not 

the sort of risk assessment that the 

real operator at the other end or the 

administrator is really concerned 

with. I’m not saying that it’s all 

daft, that it hasn’t been taken into 

account, but quite a bit of it hasn’t. 

Andy Rosenberg 

I think in some cases that’s a 

very useful point about looking at 

how things adapt through time, 

particularly for a lot of the overexploited stocks. Contemplating 

uncertainty estimates, it seems to 

me to simply say, “No matter how 

you look at this information, it’s 

telling you the same thing. It’s telling you the same direction. So let’s 

not argue about the details very 

much because the direction is clear, 

irrespective of your viewpoint of a 

lot of the data.” I don’t think that 

would really work very successfully in cases such as bluefin tuna 

and so forth where probably the 

most uncertainty analyses have 

been done for any stock, but it 

seems for the over-exploited stocks 

in particular, that’s one of the roles 

of including the uncertainty estimates. Probably the best comment 

I ever heard was in our Council12 

meetings here where I presented 

some of this stuff from the NEFSC 

Stock Assessment Workshops, and 

a fisherman got up and said at the 

end of it, “That was really interesting. It’s the first time I’ve ever 

heard you guys say that you could 

be wrong.” 

Ray Beverton 

Oh yes, I’m sure if it’s [results 

of uncertainty analysis] presented 

right. There comes, of course, a 

point if you say it too “honestly,” 

you’ll so undermine those who are 

looking for any excuse to say you 

are wrong as a reason for doing 

nothing, and you will have failed 

to get home what is probably 99% 

or at least 9 out of 10 times right. 

But, it’s the tenth time you’re 

wrong, and the penalty for being 

wrong, the speed with which you 

can put it right again, and the loss 

of political capital trying to put it 

right again that has to be put into 

the equation. It’s not just a fact that 

there’ll be a 1 in 10 chance. Would 

you accept a 1 in 10 chance? I don’t 

know. That’s the sort of judgment 

that is highly personal. 

Fred Serchuk 

I wanted to tie in the thread that 

you mentioned and the thread that 

Bob Edwards mentioned, because 

the conventional wisdom in fisheries is that managers have never 

12New England Fishery Management 

Council. 

142 
Lecture 3: Reflections on 100 Years of Fisheries Research 

done anything right and no fish 

stocks are being rebuilt, i.e. there 

are no success stories. You can pick 

up any fisheries magazine, and 

they list the litany of problems. Bob 

mentioned an ethics to fishing or 

an ethical approach, in terms of the 

utilization, to the resource. You 

mentioned that the success stories 

that you are most familiar with 

happened after collapses. Either it 

happened after the collapse of the 

North Sea herring or the collapse 

of the Norwegian spring-spawning 

herring or in Iceland. 

We have the same things here. 

Our herring stock collapsed. Subsequent to that, some of the management and the whole structure 

of fisheries changed because they 

witnessed that event. It’s a catastrophe they don’t want to repeat. 

The harvesters, the managers, the 

whole system responds differently. 

Once, for example, a fishery is 

closed, and that’s a draconian action if we close a fishery down, and 

if you have growth or rebuilding 

after that, then you have a positive 

feedback, and they [fishermen] 

don’t want to repeat the situation. 

For example, the insurance policies they come up with are: “Fish 

at a moderate level.” I’ve seen this 

in the North Sea where they have 

stock levels they want to build to. 

We’ve seen this with striped bass 

here when the fishery collapsed 

and we said no fishing—moratorium—so on and so forth. Our herring fishery on Georges Bank collapsed in the 1970’s, and it’s been 

almost 20 years now of no fishing 

there. That stock is now rebuilt. 

Sooner or later, we will fish that 

stock, but we will not fish it anywhere, in my mind, near the previous levels, and I think it’s because of this ethics. It’s not the 

same as the ethics that these animals have feelings, but I think there 

is a thread of commonality of how 

people react after stocks have 

crashed, taking, in most cases, very 

severe action such as closing fisheries, and then they look at things 

differently after that. 

Ray Beverton 

I think you’re right on that, and 

I think it raises the point again because, amongst others, Hilborn has 

written about it (e.g. Hilborn, 1979, 

1985). I would put it in an even 

stronger way. I think the one player in this whole drama who can 

and has the responsibility for making sure that the memory survives, 

and the reasons for past events, is 

the scientist. The administrator 

changes quickly; he might be done 

next year; he couldn’t care less. The 

fishermen, of course, have long 

memories, but they have their own 

memories and we have to help 

them put it down. 

I don’t want to sound patronizing because fishermen are wonderful naturalists in their own 

ways, but they have their own idiosyncratic ways of explaining 

events which are often way off. So 

how do we get them to or shepherd 

them into the right sort of direction 

is our task. Who else could do it if 

the scientist doesn’t do it? Therefore, this comes back to, in my 

mind, part of it being the hindcasting business I was talking 

about. Memory is not just preaching at them saying, “Don’t forget 

what happened 30 years ago.” 

You’ve got to keep rubbing it in, 

driving it home, “This is what it 

might have been had it been different.” That’s all part of it, I think. 

I wonder whether we can just 

have a moment to look at what I 

think is quite an interesting little 

slide or two that relates to the problem of assessing risk and things. 

I’ve always thought, until fairly 

recently, that the North Sea plaice 

was one of the tamest animals you 

could have to not only “cut your 

teeth on,” as I did, but to carry 

through. That and Pacific halibut 

have been about the steadier lot as 

anything, and they have survived 

quite a lot of ups and downs, but 

I’m beginning to wonder whether 

my dear friend the North Sea plaice 

hasn’t turned a bit nasty in its old 

age. 

143 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

A Total North Sea catches (1903–1990)

4500 

4000 

3500 

3000 

2500 

2000 

1500 

1000 

500 

0 

0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 

Year 

Herring and mackerel 2000 (1948–1986) 

C 

Large gadoids 

(1947–1985) 

1500 

1000 

Saithe 500 Whiting Mackerel Haddock 

Herring 0 Cod 

50 60 70 80 50 60 70 80 

Year Year 

Small industrial species Plaice and sole 

D 

(1948–1986) 200 

150 

Sprat 100 

(1948–1985) 

E 

Plaice Norway pout 

Sandeel 50 

0 Sole 

50 60 70 80 50 60 70 80

Year Year 

Figure 23. Total North Sea catches, 1903–90 (A) and 

catches of herring and mackerel (1947–85), large gadoids (1948–86), small industrial species (1948–86), and 

plaice and sole (1948–85) (B–E). Data from ICES (1992a). 

B 

Tonnes (1

0–3) 

Tonnes (1

0–3) 

Just to remind you, the top portion of Figure 23 [Fig. 23A] is the 

long-term recorded landings from 

the North Sea right back to 1903 

when the Bull. Stat.

13 started. This 

is taken out of the report of the 

ICES Study Group on Ecosystem 

Effects of Fishing Activities (ICES, 

1992a), which some of you have 

seen. Apart from the total, which 

is the top portion [Fig. 23A], you 

notice it sort of shot up with really 

the massive fishing of the pelagics 

in the 1960’s and then collapsed, 

settled out to about 21

/2 million t. 

There’s the herring and mackerel 

collapsing and coming back again 

(Fig. 23B). Undoubtedly it was 

genuine, even though it’s in catch; 

no doubt it’s there. Niels Daan, for 

the Reykjavik Symposium, did a 

very nice recasting of the North Sea 

story (Daan et al., 1994), and he’s 

quite sure this gadoid outburst 

(Fig. 23C) was genuine, although 

there have been doubts about it. 

The small industrials (Fig. 23D), of 

course, could be very much a 

development of the fishery on 

them rather than what they really 

were. One of the things we shall 

never know, I don’t think, is 

whether the small industrials—the 

sprats, Norway pout, and sandeels—were abundant pre 1970 or 

whether it was just that they 

13Bulletin Statistique, the ICES publication 

series which contains Member Country 

fisheries catch statistics in the ICES area 

(FAO Area 27). The series was discontinued following publication of Vol. 73 for 1988. 

Tonnes (1

0–3) Tonnes (1

0–3) 

2500 

2000 

1500 

1000 

500 

0 

2000 

1500 

1000 

500 

0 Tonnes (1

0–3) 

144 
Lecture 3: Reflections on 100 Years of Fisheries Research 

200 

100 

0 

10 20 30 40 50 60 70 80 90 

Year 

Figure 24. North Sea plaice 

landings, 1904–1991. 

weren’t fished. There is the plaice 

and sole (Fig. 23E). There is a distinction between them—you can’t 

see them very well — they’re going steadily up the whole time. 

You can probably see them 

when you see the next picture (Fig. 

24), which is plaice landings from 

1904 right on to the present time. 

You can perhaps say, “Well, perhaps we might have been excused 

thinking we were dealing with a 

rather equilibrium situation in the 

pre-war years.” But look what’s 

happened to it since then. It’s now 

up to around 170,000 t, and that’s 

probably been underestimated, but 

those figures have got the best estimates that can be made of the true 

catches. 

Figure 25 is the sort of diagram 

I was showing yesterday in the first Landings (1

0–3 t) 

Catch (1

0–3 t) Catch (1

0–3 t) 

1.0 

55 60 70 75 80 85 90 

500 

400 

300 

200 

100 

0 

65 

200 

150 

100 

50 

0 

0.8 

0.2 

0 

0.6 

0.4 

F 

Year 

SSB 

Catch 

Catch 

F 

F 

North Sea plaice 

0.5 

0.6 

0.7 

55 60 70 75 80 85 90 

100 

130 

140 

80 

60 

40 

20 

0 

65 

35 

30 

20 

10 

0 

0.4 

0.1 

0 

0.3 

0.2 

F 

Year 

SSB 

North Sea sole 

A 

B 

Figure 25. Landings, fishing mortality, and 

spawning stock biomass of North Sea plaice 

(A) and North Sea sole (B), 1957–90. 

SSB × 10–3 SSB × 10–3 

lecture on the plaice and the sole 

with the landings and the fishing 

mortality [for plaice] going steadily 

up and the biomass just dipping a 

bit and coming back up again from 

a peak where it’s the 1963 year class 

in particular which was such a 

good one. It’s much more erratic in 

the sole, but despite a decline in the 

biomass, there is a steady increase 

in the yield and the fishing mortality, which means that the reproductive rate, the recruitment rate, 

must have been going up. 

145 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Recruits at age 1 (1

0–8) Recruits at age 1 (1

0–7) 125 

100 

75 

50 

25 

0 

0 100 200 300 400 500 

Spawning stock biomass (10–3 t) 

F = 0.45 

(1980–92) 

F = 0.35 

(1970–80) 

F = 0.25 

(1950–70) 

F = 0 

? 

North Sea plaice 

86 

88 

87 

83 

79 

81 

91 

90 

80 

58 73 

82 

76 

78 

77 

74 

75 

59 

61 

60 

71 

70 66 

62 

65 

69 

64 68 

67 

89 

72 

63 

85 

84 

A 

6 

5 

4 

3 

2 

1 

0 

0 50 100 150 

F = 0.4 

(1965–75) 

F = 0.15 

(1950–65) 

F = 0.5 

(1975–92) 

F = 0 

? ? 

North Sea sole 

57 

58 

59 

60

61 

62 

63 

64 

65 

66 

67 

68 

69 

74 

75

76 

77 

78 

79 80 

88 89 

90 

91 

92 

81 

82 

83 

84 

85 

87 

70 

71 

72 

73 

B 

Spawning stock biomass (10–3 t) 

If we look at the stock-recruitment diagram (Fig. 26), however, 

we begin to see something which 

is rather or creates a rather worrying situation. That’s the plaice story 

(Fig. 26A), stock and recruitment, 

and you notice the cluster of rather 

low recruitments (right side) compared to the more recent ones. The 

right hand cluster is in the 1960’s, 

(1962–71), and the more recent 

ones, although the stock is lower, 

there is no doubt they are higher. 

Now, if we just look at that as an 

array of data, there’s little doubt 

that the cluster around the bottom 

to the right hand side is lower than 

the one to the left. In the case of sole 

(Fig. 26B), which is also a beginning of [a stock-recruitment relationship], except for these odd big 

ones [1987, 1958, and 1963 year 

classes] which totally dominate the 

story—and that’s another problem 

which makes all these calculations 

rather tricky, which is the actual 

biomass and the actual catches 

were very much influenced by very 

few extremely large year classes. 

But, if you say they can’t be relied 

upon to come along just when we 

want them, there’s very slight 

proof there, if anything. The replacement rate [for North Sea 

plaice] is at the moment at about 

an F of around about 0.4 or 0.5. 

Figure 26. Stock-recruitment diagrams 

for North Sea plaice (A) and North Sea 

sole (B). 

146 
Lecture 3: Reflections on 100 Years of Fisheries Research 

The yield curve for plaice (black 

solid line, Fig. 27A), as produced 

by the ICES North Sea Flatfish 

Working Group (ICES, 1992b), the 

yield-per-recruit curve, because I 

suppose recruitment is not thought 

to be a problem in plaice, gives you 

an F max somewhere around 0.2. 

But, if you take this seriously, this 

question, and try and get the biomass up, you look as if you are going to be suffering a significant 

drop in recruitment (F = 0.25 line, 

Fig. 27B). Now, if that were to happen, then you’d get a yield curve 

looking much more like [the gray 

solid line] (Fig. 27A). So, actually, 

in terms of total yield, you 

wouldn’t be getting what you’d 

think you would. You’d be down 

there [about F = 0.2 on the gray 

solid line] (Fig. 27A). You’d still be 

better off in terms of catch per unit, 

of course, but not as well off as you 

thought you would. Now, Andy, if 

you put this in, this is a real risk 

now. This is sort of the decision it 

seems to me to be how we are going to interpret the cluster (Fig. 

26A). They’re all in the 1960’s. The 

data set so far in that range has 

never been there twice to check 

whether you again get a reduced 

recruitment if you let the biomass 

go up. I don’t know that there’s an 

answer to that one, because I can’t 

see how you can. The 1960’s was a 

funny decade. You’ve seen all the 

things that we talked about yesterday about the peculiarity of the 

1960s. If the high biomass was 

causing the low recruitment, then 

we have some problems just to 

know whether we’re right to try 

and get back in, which is what the 

advice is at the moment. 

Andy Rosenberg 

In simple terms, if you had to 

advise on that, I think you would 

be ill-served if you said, without a 

caveat, “Reduce the fishing mortality rate to F max.” On the other hand, 

you clearly can’t certainly say that 

if you allow the higher fishing mortality rate, then you will see that 

benefit of higher recruitment in the 

long term. In a sense, that would 

highlight, to me, that you need to 

put an uncertainty caveat which 

says, “Proceed cautiously. If you’re 

going to reduce the harvest rate 

towards Fmax, then you need to 

watch out for recruitment, and the 

only way you can do that is to do 

it very cautiously. On the other 

hand, there are good reasons to reduce the harvest rate aside from 

just yield, and that would be because you have such a poor picture 

of stock and recruitment on what 

appears to be the right hand side 

of the curve only.” It’s rather surprising for plaice to have all that 

data that appears to be on the right 

hand side or descending limb of 

the stock-recruitment curve. 

Ray Beverton 

I hadn’t realized it was coming 

out so clear-cut as that. Of course, 

this is only data from 1957 onwards, and this is why it’s so important to go back and put in the 

historical data. There’s no doubt 

there have been big changes in 

plaice. The center of spawning is 

changed from the Southern Bight 

just off Lowestoft to the German 

Bight, as Adriaan Rijnsdorp has recorded in the Flatfish Working 

Group report (ICES, 1992b). Completely switched over. There is a lot 

of spawning way out in the center 

of the North Sea, which there never 

was in the old days, so things have 

been changing in a big way. Over 

and above all that, there is no doubt 

that the production has gone up 

considerably, which you saw from 

the other one. Of course, the question then is who’s going to be suffering what, if we did, say, go back 

to there [around F = 0.60, Fig. 27A] 

and what you’ve got was that drop 

[difference in yield per recruit between the two yield curves at F = 

0.2, Fig. 27A]. 

If that were really true, you’d be 

losing (compared with what you 

thought you were going to get, in 

terms of yield) not much, only a 

small percentage, if the gray solid 

curve were the right one. The problem is you would have had to dismantle some fishing capacity to do 

it, and that’s the painful thing. It 

would be easy enough if you could 

divert the fishing for a few years 

and say, “Well, go and fish something else while we see what happens to the stock and recruitment 

147 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

Plaice 

9 

Yield SSB 

0.35 

? 

? 

A 

F0.1 Fmax Fmed F90 Fhigh 7 

8 

7 

0.30 6 

6 

0.25 5 

5 

? 

? 

F = 0.5 

F = 0.25 

B 

0.20 4 

4 

0.15 3 

3 

0.10 2 2 

0.05 1 1 

0.00 0 0

0 1 2 3 4 5 

? ? 

F = 0.55 

F = 0.25 

D 

F SSB (10–5 t) 

Figure 27. Possible longterm assessments for North 

Sea plaice (A and B) and Sole 

North Sea sole (C and D). 

Data from ICES (1992b). Yield SSB 

2.0 

0.20 5.0 

0.18 4.5 

0.16 4.0 1.5 

0.14 3.5 

0.12 3.0 

0.10 2.5 1.0 

0.08 2.0 

0.05 1.5 

0.5 

0.04 1.0 

0.02 0.5 

0.00 0.0 0 

0 50 100 150 

F SSB (10–3 t) 

? 

? 

F0.1 Flow Fmed F90 Fhigh 

C 

Yield per recruit (kg) 

Yield per recruit (kg) 

SSB per recruit (kg) at spawning time SSB per recruit (kg) at spawning time 

Recruitment at age 1 year (1

0–8) Recruitment at age 1 year (1

0–8) 

0.0

.20

0

0.10

0.20

0.30

0.40

0.50

0.60

0.70

0.80

0.90

1.00

1.10 

1

0.00 0.10 0.20 

0.30 

0.40 

0.50 

0.60 

0.70 0.80 

0.90 

1.00 

1.10 

148 
Lecture 3: Reflections on 100 Years of Fisheries Research 

situation.” But that takes quite a 

few years for this sort of fishery to 

do it. I don’t think, in financial 

terms, it would be very much to 

worry about, providing you are 

there [at F = 0.2 in Fig. 27A] instead 

of there [F = 0.6], because who’s going to measure the total catch anyway. I mean, total catch is what we 

all talk about with these curves, but 

in reality when does the total catch 

matter? It matters to a country 

which is totally dependent or very 

heavily dependent on fishing, but 

it doesn’t really matter. What much 

more matters is something like the 

catch-per-unit-effort rate or the 

stock-recruitment level. In the sole 

(Fig. 27C, D), the tendency would 

be much weaker and it wouldn’t 

make much difference. I think the 

difference between the two yield 

curves is so small, quite honestly, 

and I don’t think you would worry 

too much. 

Andy Rosenberg 

If you thought that those 1960’s 

and early 1970’s points were from 

different productivity regimes, if 

you like, hydrographic issues, and 

you looked at a stock-recruitment 

curve in that upper left quadrant 

which only included the later 

points, you would draw a curve 

that would be rather flat topped. 

That would suggest that the current fishing mortality rate, if you 

maintain it there, is probably much 

riskier. In other words, it’s rather 

closer to the tangent to the line 

since you have no equilibrium 

point. Then the risk of being close 

to recruitment overfishing that 

stock is, in a sense, much more severe than the risk of losing a little 

bit of yield if that were the true 

stock-recruitment relationship. 

But, I guess the problem with the 

uncertainty analysis is whether it 

is better to point out the two possibilities and to try to make the argument for caution by pointing out 

the two possibilities, or better not 

to confuse people and give what 

appears to be much clearer or more 

certain? 

Ray Beverton 

I think the trouble, of course, in 

putting across the cautious approach is that it will be seized upon 

by those who would have to make 

sacrifices, whichever section of the 

industry that would be, to do nothing. But, I don’t think, in that case, 

that one would worry too much. If 

we really are fishing here [F max on 

the gray yield curve, Fig. 27A] instead of there [Fmax on the black 

yield curve], I don’t think it’s all 

that serious, but there might be another way of looking at it. 

I’ve been trying to see how we 

could reconcile harvesting strategies, in ideal terms, with what we 

would like to see happen, with all 

the modern ideas about biodiversity and all the rest of it. It seems to 

me that, although for once, economics and that sort of thing are 

marching hand in hand, the more 

timely way of taking that sort of 

objective would be to say, “Well, 

we will sacrifice deliberately 5% [of 

the yield].” That’s a loss of 5 or 6 

or 7% of yield which is not going 

to be tangible to anybody. I suppose, theoretically, the processing 

side, the marketing side, would 

say, “There’ll be 5 or 6 or 7% less 

fish going through our hands,” but 

that’s a pretty intangible sort of 

thing. But what is tangible is that 

there is no doubt that the catch per 

unit effort, put into whatever terms 

you want to, will be substantially 

greater if you were there [F0.1 on the 

gray yield curve] compared with 

there [F max on the same curve], and 

what’s more, the biomass would be 

much greater. That’s the way I 

think, nowadays, we ought to try 

and talk about it, so there’ll be no 

worry about F0.1 in economic 

terms, but in terms of, “Look, our 

fishing industry’s contribution to 

(if you like to put it in simple terms) 

the ‘Rio principles.’”14 It’s, “Okay, 

we’ll deliberately fish nevertheless 

to get the maximum. We’ll deliberately underfish to the extent that 

14The United Nations Conference on Environment and Development (UNCED) 

was convened in Rio de Janeiro in June 

1992 to discuss a comprehensive range of 

environmental issues and to promote the 

policy of sustainable development. The 

Conference proclaimed a set of 27 principles (Rio Principles) on the environment 

and development, designed to promote international cooperation for sustainable development. 

149 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

we need only lose 5 or 6 or 7% yield 

in order to gain more than double 

the biomass.” That seems to me the 

sort of argument that we might 

have to think about in future. 

Leave the economics [out] on that 

one. The fishermen would be quite 

happy with that, except those who 

are going to lose out. It will be those 

concerned with the shipbuilding 

side, with the gear, all that has to 

do with the catching side, who will 

miss out because they’ll have to 

run with a smaller fleet, and smaller 

manpower, and everything else. 

I’m talking [here of] a long-term 

objective. I’m not talking of something you’d get at straightaway. 

But it does seem to me that those 

sort of redefinition of familiar objectives may be timely if we’re going to keep pace with some of the 

modern attitudes to the way certain of our environmental lobbyists 

are thinking in terms of attitudes 

that anything to do with commercial fishing is anathema. We may 

have to find ways [to reduce fishing pressure], and if so, then it 

points to literally aiming at a point 

like that [F0.1 on the gray yield 

curve in Fig. 27A] while we’re trying to get to the sustainable maximum. Don’t you think so, Andy? I 

know it’s all a lot of theoretical talk. 

Andy Rosenberg 

I don’t think it is, in fact. Unfortunately, I think that sometimes the 

argument does come down to 5%. 

People will make a fierce stand 

around here at 5%. They start 

bringing their children into it, and 

their houses, having to eat dogfood, and everything else. But in 

principle, I don’t anticipate at all a 

sensible way to approach it. 

Steve Murawski 

I think it almost comes full circle 

to Bob Edward’s comments about 

the role of scientists in defining 

societal objectives and certainly 

pushing societal objectives in a 

much more of an advocacy role. 

Based on the first century of population dynamics research, I think 

we understand the effect of singlespecies fisheries regimes on quantities such as yield maximization, 

effect on biomass ability, and a variety of single-species parameters. 

The traditional optimization points 

have been places on the eumetric 

fishing curve, but they come at 

great risk. We understand these 

things to a much greater degree 

than our para-professional managers, who are out there, and certainly the general public. I think we 

are almost obliged to “take it on the 

road,” as it were, and to at least get 

the public more familiar with the 

great risks that the managers seem 

to be willing to accept in terms of 

the collapse of these stocks and 

their impacts on society in general. 

I know we have a very uneasy time 

dealing with ourselves as scientists, in an advocacy role. On the 

other hand, if it wasn’t for the 

dawn of the environmentalist, we 

would be on one end of the lever 

and all the fishing industry would 

be on the other end. I think the nice 

thing about having this great interest by environmentalists is that we 

can sort of subtly shift to the center and play more of a fair-brokerof-information role, or try to. I 

know Vaughn and I have, in the 

last 5–10 years, really gotten ourselves into some tight pickles trying to encourage this without really having ourselves perceived as 

being very strident in this whole 

area. 

Vaughn Anthony 

There is a big gap though, I 

think, in this kind of advice and 

however we come forward with 

advice to the managers and [with] 

what they really need to manage. 

Managers are not having any problem with what we say in its accuracy. They think we know what’s 

going on; they agree with what we 

say. We’re not giving them the 

information they really need to 

manage, because they want to 

know how they’re going to get 

over the social problems of managing, recovering the stocks, reducing catches, and so forth. I think 

we’re making a big mistake in not 

giving them the information they 

need to manage, which is the social aspect. How do you lay on a 

management program and have 

people “survive” or change their 

lifestyle or move into a different 

150 
Lecture 3: Reflections on 100 Years of Fisheries Research 

way of operating when there’s a 

little less fish out there than there 

used to be? How do they function, 

how do they live, how do they 

change their lifestyle? We don’t 

even give them any information on 

any of that stuff, so they’re afraid 

to move forward to do what’s 

responsible because they don’t 

know how to do it. 

There’s a big gap between science and biology and fish management, and I think we’re making a 

mistake if we think there’s not 

much of a gap between management and biology. I think biology 

is straightforward and easy and is 

not much of a problem. Even these 

things [the science] are not much 

of a problem. No one will give us 

grief about them, but trying to get 

managers to actually put something in place that affects people’s 

lives and how they do their dayto-day activity requires a lot more 

information, different kinds of information, not just economic, but 

social information which we are 

not giving them and helping them 

manage. I think that’s where somebody’s making a mistake. It’s not 

the stock assessment science. We 

are not socially oriented to do that, 

but it’s a whole area we are not providing information on, and they 

don’t know how to proceed. Somebody has to step in and give them 

the information and say, “If you 

want to manage along these lines, 

here’s some information, here’s 

what will happen, here’s the responses, and here’s a lot of data 

dealing with the lives of people.” 

We’re not doing it, and that’s where 

the problem is with fish management, as far as I’m concerned, not 

whether it’s F max, or growth overfishing, or recruitment overfishing. 

Steve Murawski 

If I could be so bold, I’d say that 

the first century of fisheries research has basically been a golden 

age of single-species population 

dynamics. I think Vaughn is exactly right that we’ve come to the realization that we can’t manage fisheries for the sake of fish. The issues 

seems to be relatively clear to the 

point where we are trying to clean 

up and evaluate our variances, etc. 

But, there is a whole realm of fisheries science in which, even in 

terms of the evolution of this laboratory and some of the new people 

who have come on, a whole realm 

of science in economics and social 

science which, even though seminal papers were written in the 

1950’s, has a long developmental 

period that perhaps, I hope, is not 

as long as the developmental period in population dynamics. But, 

I think we may have actually seen 

the height of population dynamics 

research on a single-species basis. 

Now we may be entering into an 

era of social and economic analysis. 

Vaughn Anthony 

[Fishery management] council 

people say to us all the time, “We 

don’t argue with anything you 

guys say. We believe everything 

you say. So what! We’re scared to 

put in a management program because we just don’t know how to 

get it done. We just walk away.” 

Marvin Grosslein 

It isn’t a lack of information so 

much as it is a lack of political will. 

I think the environmental movement is gradually, perhaps, empowering administrators, and we 

recognize that the public does 

eventually see the environmental 

policy as an issue of sustainability. 

I think we’re becoming more understood by the public, and perhaps the political-will issue may be 

overcome more easily, we hope, in 

the future. Until that happens, no 

amount of information is going to 

change anything. 

Ray Beverton 

I think Steve has put his finger 

on the button, really. I’ve been talking about two species there, but 

they can probably be perfectly well 

treated as a single species. But if 

you did it on some of the gadoids, 

and I must admit I haven’t fully 

thought out to myself what you 

would aim at, you would probably 

assume, “Well, we’ll aim at something on the safe side of F max.” 

What is that in a mixed fishery? Is 

there such a thing in an interacting 

species complex? 

151 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

There is such a thing, I expect. 

I’ve asked Lowestoft, I’ve asked 

John Pope15, “Can you give me sort 

of a combined yield curve?” He 

said, “Oh, I can’t do that. We’ve already looked at that and can’t think 

along those lines now.” I know 

what he means. It depends which 

mix of fishing effort is going to be 

on which species, as well as the 

interaction between them. But 

there has to be something there. I 

mean, they will fish the mix in 

some way or other, and there is 

going to be a response, and it seems 

to me that we’ve got to have somewhere a hand in that situation. The 

Norwegians will, but there are only 

three species to balance. They’re 

going to do a three-ball juggling act 

of the three major species. Whether 

we can do it in a more complex one, 

I don’t know. 

Andy Rosenberg 

A couple of things. In the multispecies case, the question has to be 

much more specific. You can no 

longer say, “What’s the optimum 

or maximum sustainable yield?” 

We’re not to the point where we’re 

being asked specific questions until somebody says, “Well, how 

should we fish?” You have to say, 

“What do you mean? After you 

fish, what do you want to achieve?” 

That objective has to be very specific in a multispecies case, whereas 

15Fisheries scientist at Lowestoft Laboratory, U.K. 

we could generally, in a single-species case, say, “Well, at least you 

want to get as much catch as you 

can out of this thing without being 

too risky about it.” I don’t disagree 

with the importance of the economic information for the economic analysis, but I don’t think 

we should lose sight of the fact that, 

in general, the managers, being either political managers or, in our 

case, the [fishery management] 

councils, say that they’re the ones 

who know the fishing industry and 

the fishing business and the fishing communities. They’re there to 

represent those communities and 

those social factors and economic 

factors within the interest groups. 

In a sense, they’re supposed to be 

providing that side of the equation, 

given the biological advice. 

I don’t disagree with Vaughn 

that, in many cases, they’re now 

saying, “OK, give us more, we 

need more, we need more information.” But it’s certainly true that 

that was the information that fishery management councils were intended to bring to the table in making their management decisions. It 

was not viewed as, “Well, the scientists didn’t give us enough.” 

They weren’t viewed as a collection of twelve reasonably bright 

people who would assimilate any 

of the information that came to 

them. They came to the table with 

expertise. So, I’m not quite sure 

that it’s the case that none of that 

information was in front of them 

by which to proceed. The difficulty 

was that it all focused on the biological information for a long time, 

and they essentially were not accepting the biological principle and 

then getting on with the issues of 

management. 

Steve Murawski 

I think ultimately, for example, 

in the case of New England groundfish (which I’m sure you’re alluding to), getting over the hump of 

actually making a management 

decision was based on whether or 

not, in an economic sense in the 

long term, it paid off, because 

people make a lot of money on collapsed stocks because the value per 

pound is quite high. Ultimately, 

there was a technical question 

whether or not the net benefits to 

society exceeded the tremendous 

economic cost, not necessarily the 

social cost. So, I think there is room 

for technical analysis. 

Andy Rosenberg 

I think there is too. I’m not saying that there isn’t, but I do not 

think that it’s been left out. 

Fred Serchuk 

I just want to follow up on what 

Andy said, because I think the economics are not up front, nor are the 

social [sciences], but they are in 

there of a sort. When you say management makes short-term decisions, they are just externalizing a 

152 
Lecture 3: Reflections on 100 Years of Fisheries Research 

socioeconomic cost away. That is, 

they are responding to the political exigencies of the day. To close 

down a fishery? No, politics comes 

in to play. Nobody has actually 

considered the long-term cost. 

What Ray is basically saying is, if 

you go back and take a retrospective look, you might be able to say, 

“Had we taken this action, then 

you would get an idea of the magnitude of what the benefits would 

be and what the costs would have 

been at that point [by] doing it over 

the long term.” So, I think that retrospectively is really quite a nice 

way to go. 

In terms of fisheries or fisheries 

science only being a small component of it, I recall a remark that 

Jakob Jakobsson16 made several 

years ago at an ICES meeting 

where he said, “When we try to 

predicate our management based 

on a strong scientific basis, as they 

did for herring, as they did for 

capelin and other stocks, and in 

many cases had very modest fishing mortality levels, such as F0.1, or 

very substantial minimum biomass levels, we get into trouble. 

When we deviated from a biological basis, as we did for the cod 

stock, and put most of the decision 

weight on socioeconomic factors, 

we got into problems.” Here’s a 

case where, in Iceland, fisheries are 

16Director of the Icelandic Marine Research 

Institute in Reykjavik. 

important and they deal with 10 or 

15 different stocks, and the cod 

stock is one of the most important. 

When they started basing decisions 

on socioeconomic information, at 

least discounting it in the long 

term, they got themselves into a 

mess. 

Ray Beverton 

If I can just comment on the 

multispecies [issue], it seems to me 

that it blurs the range of clarity in 

the middle, but it doesn’t blur the 

extremes. If you’re up to an F of 1 

on cod, irrespective of whether it’s 

a multispecies [fishery] or not, it’s 

almost certainly not going to be a 

very sensible thing to do. Conversely, there’s no point in getting 

too far back the other way. It does 

mean that there’s a wider area in 

the middle which you have to say, 

if you know enough about it, “Well, 

you can have a certain proportion 

of that plus that plus, or if you do 

that, you can have that, plus that, 

etc.” It doesn’t alter the general 

impression, though, that excessive 

fishing is almost certainly going to 

be undesirable on every ground, 

and that there’s quite a lot of present situations we’re in whether it’s 

your haddock—I mean your haddock is not a single species, but you 

can be jolly sure you’re overfishing it [or another species]—so, I 

don’t think we should allow the 

multispecies [issues] to frighten us. 

It’ll blur the middle, but it won’t 

prevent the really brink side of science from being pretty realistic. It 

may be just a little more difficult 

to be sure where you are at the 

edges, but you know where you 

are already on some of them. You 

don’t need to worry about multispecies [management] for that 

point. Isn’t that fair, Andy? 

Fred Serchuk 

What about protection? I’m 

thinking about marine mammals 

now—the seals. This is a real big 

problem that we have in fisheries. 

Ray Beverton 

We haven’t seen it quite as 

strong as you have, or potentially 

have. I think the Norwegians are 

going to have to now put the minke 

whale and the others into their 

equation in a big way. They won’t 

be able to leave them out of their 

Barents Sea story. Of course, I think 

we must, as fisheries scientists, put 

this into the equation really to 

make sure we have it right. What 

is done about it is another matter. 

[As for] the question of the economics and the politics, I think 

what we have to get across is that, 

unlike farming, the only way that 

we can influence the future replenishment of a stock is by controlling the harvesting rate. The 

trouble is that the harvesting rate 

is played fast and loosely by the 

economists who don’t realize 

that—they think you can manipulate whatever you like and it 

doesn’t make any difference in the 

153 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

long term. We seem to fail to get it 

across, and it does matter, and, 

unlike farming, you can’t step up 

effort. 

I don’t know whether you have 

yet read Mike Holden’s book on 

the Common Fisheries Policy 

(Holden, 1993). If you haven’t, 

you’d be well advised to do so. It’s 

an extraordinary book because it’s 

a mixture of the factual account, the 

pretty glaring account, and he’s 

drawn aside the curtains and 

shown you some of what he called 

ultimately “horse dealing,” [which] 

was going on all the time. It was 

an apologia, for clearly he feels he’s 

failed [as a fisheries manager]. He 

thinks he’s being criticized for failing, which I don’t think was true 

actually, but he feels he’s responsible. He tries to make a gloss of it, 

that it wasn’t really a failure, but 

in fact it was a ghastly failure. The 

reasons for it were very special. 

They’re not the sort of reasons you 

would place here. I won’t go into 

details, but will just say that when 

NEAFC collapsed because of the 

200-mile extension in the mid 

1970’s, the E.C. hadn’t really gotten a common fisheries policy at 

all. The U.K. only had just joined, 

and Denmark had only just joined 

in 1974 or 1975, so we were new 

boys in it, and yet we were powerful players in any fisheries policy. 

The move to have a fisheries 

policy came from the Italians and 

the French who wanted a marketoriented expansion. The idea was, 

“Look, we said we’ve got to make 

ourselves self-sufficient in the European Community in agriculture 

and fisheries. We’ve done it for 

agriculture.” What they’d done 

was to create enormous surpluses, 

of course, which were grossly, entirely wasteful. I mean, it was 

ghastly business really, when you 

have mountains, millions of tons, 

of butter that nobody can do anything with. But, leaving that aside, 

at least economically, provided you 

subsidize your farming, which was 

heavily unraveled, it was at least a 

coherent exercise. They set out to 

do the same for fishing. “Let’s 

double the fishing.” So, we doubled 

the fishing power. So, everything 

was subsidized. Countries were 

building new ships with E.C. 

money when they should have 

done the opposite. They took not 

the slightest notice of decades of 

ICES advice through NEAFC, 

through the Overfishing Convention17. 

There wasn’t even a [fisheries] 

scientist in the Directorate until 

Mike Holden went there. Because 

the influential countries were only 

17The 1946 Convention for the Regulation 

of Meshes of Fishing Nets and the Size 

Limits of Fish, which came into force in 

1953 and led to the establishment of the 

Permanent Commission, which was renamed 10 years later the North-East Atlantic Fisheries Commission (NEAFC). 

really on the edge at that point, presumably we didn’t exercise our responsibility—I say “we,” the U.K. 

for a start—I wasn’t there. I was 

with NERC; I wasn’t at Lowestoft 

then. I know Cushing got totally 

and utterly frustrated with what 

was going on there and really almost opted out of it half the time. 

The net result was, not for that reason but for other reasons, the 

whole thing was set up on an expansionist policy when the exact 

opposite should have happened. 

They [the fisheries] should have 

been contracting, and it’s only now 

[mid 1990’s] that they’ve had to 

“bite the bullet” and are starting to 

offer subsidies for removal of a few 

percent of fishing power. So, there’s 

a case, maybe it’s a special case, 

that wouldn’t be repeated in most 

other countries. It’s a special case 

of market-oriented and political 

forces actually dominating [fishery 

management decisions]. It wasn’t 

a question of where on the yield 

curve you were. There’s no such 

thing as a yield curve; you just expand. It’s a terrible lesson and a 

tragic lesson really, as far as the 

North Sea is concerned, not as bad 

as a truly collapsed fishery then, 

but still as an exercise in sensible 

husbandry of natural resources, a 

pretty poor record. 

Steve Clark 

We have an identical one; a 

pretty poor record. 

154 
Lecture 3: Reflections on 100 Years of Fisheries Research 

Ray Beverton 

So, somehow or other, there was 

obviously no scientific message 

getting through. Who’s fault it was 

I don’t think you can say, because 

it was a special situation. It wasn’t 

the scientific message not getting 

through at all. It wasn’t that it was 

being disregarded, or it wasn’t a 

question of no risk analysis, it was 

just not there at all. 

Steve Murawski 

I think one more question from 

Paul. I think we’ve exercised your 

capacity as long as we can. 

Paul Rago 

I just wanted to ask you one of 

the questions you partially answered. I would like to hear your 

thoughts on the idea of multispecies management and, before 

we completely understand it, if we 

ever will, the idea of managing on 

the basis of the weakest species or 

a weak species which is collapsed 

and managing around that. One 

that comes to mind is Pacific halibut and the idea of other fisheries 

being restricted on the basis of the 

bycatch of that species in those 

fisheries. When those situations 

occur, everyone else benefits. Perhaps haddock or yellowtail flounder would be an appropriate species here from which you could 

base a multispecies management 

on the weakest component and 

then bring everybody else up along 

the way. 

Ray Beverton 

That might prove to be quite a 

useful way into it. If you’re talking 

about using your haddock as an 

example, as I was saying, I hardly 

think you need worry initially 

about the multispecies aspect to it. 

You just get cracking on it somehow or other. It’s way outside the 

range of sensitivity on a multispecies basis, but when you are 

getting everything growing back 

from the brink and getting more towards being generally abundant, I 

think in a really complex fishery, 

of which yours may not be even the 

most complicated, some of the 

tropicals would be much more so, 

I don’t think there is any way you 

can manage without extraordinary 

difficulty and complexity and expense trying to pick out individual 

species and trying to treat them 

separately. You have to try and take 

a by-and-large level not too excessive of fishing effort and let them 

go. What they’ll do is overfish to 

some extent, depending on market 

demands and local temporary 

abundance or shortage, and underfish others. After a bit, they’ll 

change around and switch another 

way. If you can get it to that sort of 

situation and let the fishermen go, 

you don’t have to interfere with 

their activity; we can let them go. 

As long as there aren’t too many 

of them, they can’t do dramatic 

harm. If they do, they’ll soon realize that they’re not getting much 

out of that and they’ll switch to 

another one once they can be 

taught to switch around. 

I think there comes a point in 

some of these complicated fisheries when expecting to get an objective that is too sharply defined, trying to fine-tune it by management, 

becomes an unreal objective. Trying to do it, I think, will make our 

science less credible than need be. 

We’re asking too much, just as we 

would refuse to make a prediction 

of what the yield curve would be 

10 years off, because we know we 

can’t. I think we just have to 

acknowledge that there are some 

things we can’t predict and it 

would be foolish to try and do so. 

One of the difficulties with all 

the TAC business that we’ve had 

on the European scene, and you’ve 

probably had the same, is that you 

get a prediction wrong and that 

destroys the credibility. The 1985 

year class in North Sea haddock 

was much stronger than we thought 

it was and it upset all the quotas 

and TAC’s. They had haddock running out of their ears and fishermen said, “These bloody scientists, 

they’re telling us there are no haddock, they don’t know what they’re 

talking about.” It was on television, 

it was everywhere; I was down at 

Lowestoft not long ago, and they 

said it has done more harm, that 

one miscalculation, than the decades of attempts to try to get it 

right. So, to some extent, we should 

155 
The Raymond J. H. Beverton Lectures at Woods Hole, Massachusetts 

only aim at targets which we can 

reach scientifically as well and not 

try and pretend that we can be absolutely precise about what the 

catch is going to be, even for a short 

time. 

All of this comes back to not 

having to make TAC’s the dominant idol that everybody goes to. I 

know it’s easy to say and difficult 

to do, but in the end, if only we can 

get there, it would be worth it. 

TAC’s will no longer be the absolute sort of cutting edge so sharply 

as it is at the moment. You can let 

them get on with it and have a review every few years of what has 

happened to F—that’s what matters—on the understanding that if 

it’s gone up above a certain point, 

there’d have to be a redistribution 

or running-down schedule put in 

over the next 5 years. There’d be 

the money, if you have a good 

rental system, to pay for that. I 

think that’s the sort of schedule. In 

the meantime, you let them get on 

with it, and they’re not hedged 

about by this, that, or the other 

thing and they can get on and fish 

as they like. It won’t be perfect, but 

it won’t be a disaster, and it may 

be that’s the best way of gradually 

edging them into a more sensible 

husbandry approach, which will 

satisfy some of the more reasonable 

members of the environmental 

lobby. 

Steve Murawski 

I think that’s a long argument 

for effort control. Thank you. 

Ray Beverton 

I hope you found it enjoyable 

and helpful, and thank you for being such a good audience, yesterday as well. 

Steve Murawski 

On behalf of the NMFS Northeast Fisheries Science Center, I’d 

really like to thank you for obliging us with three outstanding lectures. I know we have all been impressed, certainly, by your endurance and putting up with us for 

two grueling days and a couple of 

parties. 

Ray Beverton 

Thank you, Steve. 

156 
Lecture 3: Reflections on 100 Years of Fisheries Research 

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158 
Appendix 

Common and Scientific 

Names of Species 

The following is a listing of the common and scientific names of fish, shellfish, and marine mammals mentioned 

in this book. The species are listed in the order first mentioned. The scientific names printed in each lecture use 

the same spelling of Raymond Beverton’s original figures and of the figures from the cited literature. 

Atlantic herring, Clupea harengus


Pacific herring, Clupea pallasi


European pilchard, Sardina pilchardus


Sprat, Sprattus sprattus


California sardine, Sardinops sagax caerulea


Spanish sardine, Sardinella aurita


South African pilchard, Sardinops ocellatus


Peruvian anchoveta, Engraulis ringens


European anchovy, Engraulis encrasicolus


Pacific anchoveta, Cetengraulis mysticetus


Pacific or chub mackerel, Scomber japonicus


Atlantic mackerel, Scomber scombrus


Bluefin tuna, Thunnus thynnus


Cape hake, Merluccius capensis


Silver hake, Merluccius bilinearis


Haddock, Melanogrammus aeglefinus


Pollock or saithe, Pollachius virens


Whiting, Merlangius merlangus


Atlantic cod, Gadus morhua


Pacific cod, Gadus macrocephalus


Greenland cod, Gadus ogac


Polar cod, Boregadus saida


Poor cod, Trisopterus minutus


Norway pout, Trisopterus esmarkii


Redfish, Sebastes spp.


Pacific ocean perch, Sebastes alutus


Silvergray rockfish, Sebastes brevispinis


Yellowtail rockfish, Sebastes flavidus


Canary rockfish, Sebastes pinniger


Yellowmouth rockfish, Sebastes reedi


Sharpchin rockfish, Sebastes zacentrus


Redstripe rockfish, Sebastes proriger


Puget Sound rockfish, Sebastes emphaeus


Olive rockfish, Sebastes serranoides


Acadian redfish, Sebastes fasciatus


Deepwater redfish, Sebastes mentella


Plaice, Pleuronectes platessa1


North Sea sole, Solea solea


American plaice, Hippoglossus platessoides


Greenland halibut, Reinhardtius hippoglossoides


Atlantic halibut, Hippoglossus hippoglossus


Pacific halibut, Hippoglossus stenolepis


Yellowtail flounder, Limanda ferruginea2


Witch flounder, Glyptocephalus cynoglossus


Common sole, Solea vulgaris


Petrale sole, Eopsetta jordani


Large-tooth flounders, Paralichthys spp.


Long-snouted flounder, Ammotretis rostratus


Japanese flounder, Paralichthys olivaceus


Starry flounder, Platichthys stellatus


Winter flounder, Pleuronectes americanus


Greenback flounder, Rhombosolea tapirina


Flatfish (flounder species)


Common skate, Raja batis


Spiny dogfish, Squalus acanthias


Striped bass, Morone saxatilis


Capelin, Mallotus villosus


Sandeel, Ammodytes spp.


Atlantic salmon, Salmo salar


Trout, Salmo spp.


Walleye, Stizostedion vitreum


Prawns, Pandalus borealis


Harp seal Phoca groenlandica


Hooded seal, Cystophora cristata


Minke whale, Balaenoptera acutorostrata


1

Now Platessa platessa 2

Now Pleuronectes ferrugineus. 

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