history

Fishery Science

FW8448, Fall Semester, 2007

A Brief History of Fisheries Science

FISHERIES MANAGEMENT, PAST, PRESENT & FUTURE

It is entirely inappropriate for a set of class notes to begin as these do. A recitation of history can do nothing to inform a pilot, no matter how watchful, of how next to steer. Only with a sense of purpose, even modestly formed, can we hope to achieve a course of action that will sustain our interest in management of living resources. But often the purpose is not a single thing, or is in contradiction of another dearly held belief or interest. How then may we accommodate disparate objectives in exposition of a subject so complex as fishery management? One approach would be to develop the subject fully at the outset. That would be appropriate, in my view, but contrary to the practice of most authors of modern textbooks. Many scholars are so interested in recent developments in their discipline that they prefer to jump into the subject with only a cursory treatment of the history, and no philosophical foundation for the topic. That is the course of action embodied here, although I think it is less than optimal. The final chapter of these notes should properly be the initial chapter, as it attempts to expose the student to a variety of different approaches and philosophies underlying current practice in fishery management. So please regard the following historical account as a cursory one that may ultimately be fleshed out as you become more conversant with alternative approaches (philosophies) of resource management. The subjects treated here are, in my view, among the most important currently employed in real-world fishery management. But, having said that, neither of us, the reader, or the writer, is absolved of a personal responsibility for finding a philosophical underpinning for these practices.

We begin by asking what is the importance of fisheries biology? The answer surely rests with what has happened and is happening in the world's fisheries as evidence on a major scale of the consequences of removing animals from natural communities. Forest management is the botanical analogue of fisheries whereas the European style of "Gamekeeping" is the terrestrial vertebrate analogue. Other branches of applied ecology, notably horticulture and applied "economic" entomology have made outstanding contributions to our understanding of the magnitude of interspecific interactions. All of these sub-disciplines have their artificial propagation constituents, and these reproduction-oriented technologies, agriculture, silviculture and aquaculture, have a role in the management of many economically important species. But the mainstay of fisheries biology has been an emphasis on population dynamics, i.e. the understanding of population processes in those species of fish that are the targets of the world’s capture fisheries. This is partly because we recognize that recruitment-overfishing, i.e. the extraction of so large a proportion of the adult stock that too few remain to replace them, is only one element of a broader set of phenomena influencing a population's capacity to sustain a yield.

Motivation to continue to harvest fish springs from a growing human population which is, regionally, protein limited. The motivation to maximize the annual harvest springs from the economic incentives provided by a world protein market. Examples--Perurian Anchoveta harvests influencing soybean prices and livestock feed prices from 1972-74.

The following brief chronology defines our perception of the progress of fisheries management.

I. Impact -- until about a century ago there were local instances of a decline in abundance of some species that aroused suspicions: man might, in part, be responsible. In some cases, changes (pollution) in water quality were thought to be the causes of declining fish stocks.

1. SCOL Symp. Vol. - Ryder discusses limnology of North American pre-cambrian shield lakes. Toivonen discusses Fenno-Scandian lakes. These cases discounted a strong influence due to changes in water quality.

2. Marine environment - In the Sea of Japan, several local stocks of herring (Clupea harengus) disappeared during the prosecution of an intense fishery.

3. Pacific salmon were no longer as abundant as they once were.

4. The first concrete example of the effects of fishing on a large scale occurred as a consequence of WWI. Prior to 1914, the average individual size of demersal stocks became progressively smaller in the North Sea and they became harder to catch. The four-year respite was immediately apparent when fishing resumed. It didn't take long to fish down the stocks to their pre-war levels. Russell's paper in 1942 discussed “the overfishing problem” (Cambridge Univ. Press, London, 132 pp.).

II. Development of fishery science

1. The interwar period - Fishery statistical data were being gathered in many important fisheries.

2. A 'stock concept' was developing among fishery workers which suggested that some species were functionally organized into groups of discrete "stocks" upon which the fishery acted. Pacific salmon management was the stronghold for application of the stock concept in North America for nearly half a century. A Great Lakes synthesis of the ‘stock concept’ was compiled in concert with the “Stock Concept International Symposium,” sponsored by the Great Lakes Fishery Commission and published as a Special Issue of the Canadian Journal of Fisheries and Aquatic Science, Vol. 39, No. 12, December, 1981: 1457-1921.

3. The MSY concept was solidified after WWII. The fisheries literature began to aim at techniques for collecting fisheries statistics. Ricker (1948) formalized the ideas of Baranov (1918) for combining statistics of growth and mortality to estimate the "critical age" or mean age of capture that would give maximun yield for a specified rate of harvest.

4. In 1954, Ricker added a model for "stock and recruitment."

5. In 1957, Beverton and Holt synthesized the North Sea experience into a general model of the dynamics of exploited fish populations.

6. From 1948-1970, world fish catch rose from 20 to 70 million metric tons.

7. Much of the increase in landings involved a shift in emphasis from predators at the top of the food chain to more plentiful fishes at lower trophic levels. Anchoveta (Engraulis ringens) catches increased from 200,000 metric tons in 1955 to 12 million tons in 1970. (Approx. 12 trillion fish). Ecologically, this meant that the fish were not being taken by guano-producing sea birds, but by chickens and other livestock.

8. Distant-water fleets were developed by Japan, Russia and several European countries and 200-mile limits were declared shortly after the 1974 Law of the Sea Conference (200m was probably mis-read as "200 miles from shore" rather than 'out to a depth of 200 meters' as originally intended). These designated coastal nations as responsible for management.

9. 1974-1980 - The central problem for fisheries science remains: how to manipulate a fishery for social and economic advantage within the constraints of ecological prudence.

III. Ecological rationalization for the fall of MSY

1. The most importrant characteristic of fish is that they are opportunistic carnivores. - Lake trout generally eat fish, but can subsist in perpetuity on plankton alone. While there may be a selection of certain food items, it is the kind of selection which can be quickly modified with a change in circumstances--even the morphometry of the animal can change (adapt) very quickly -- Svardson's coregonine gill-raker lengths and counts. Generally speaking, fish are characterized by a place in which they feed, rather than by a type of food (in spite of our efforts to maintain the old typologies).

2. Another important characteristic of fish is that they grow throughout their lives. Because they keep growing, they change diets as they get larger--this is due to feeding energetics (Kerr and Martin) and behavior. Associated with change in diet may be a change in habitat, thus we may find the young of some species in shallower water than the older fish.

As a consequence of their flexible diets, the food webs of fish are exceedingly complex. Pacific salmon may eat herring, but herring also eat salmon fry. There is no simple "predator-prey" system to match that of terrestrial communitiies--lions eat zebras, zebras do not eat lions. Lynx eat snowshow hares; hares do not eat lynx.

3. Fish have highly flexible growth rates and can gorge themselves (or starve) in response to local feeding conditions. Their maturation schedules are more closely related to size than to age. This allows a population to respond quickly to changes in circumstances.

4. Flexibility in food habits combines with continuous and flexible growth rates to limit competition among age-classes. Older fish in a population may be so ecologically separate that they are essentially different species from their juveniles.

5. Fish have relatively high fecundities which allow them to respond dramatically to changes in environmental conditions. Thus, it is not clear whether density dependent factors are more or less important than density independent factors.

6. From an evolutionary perspective, aquatic environments are a geographic inverse of terrestrial environments.

6.1. Oceans are like a single continent, only partially divided by land masses into basins. Vast and continuous currents disperse fish throughout the basins. Many species are cosmopolitan. Exterminations in local areas may be of small long-term consequence.

6.2. By contrast, lakes are small and (geologically) ephemeral. Magnuson (1976) develops this analogy fully. Lakes are zoogeographic equivalents of islands, being connected to other lakes by streams, (analogous to peninsulas) as winds and currents connect oceanic archipelagos. Smaller lakes tend to support fewer species of fish as smaller islands support fewer species of birds.

This presumably reflects both their lesser accessability to immigrants and the greater intensity of ecological interaction among species within small areas. It is not common to find fish species endemic to particular lakes--exceptions occur only in lakes which have been geologically isolated for long periods of time -- Baikal in Siberia and Lake Victoria in Africa, for example.

6.3. The smallest lakes and aquacultural ponds intensify interspecific and intraspecific interactions so greatly as to provide little insight into interactions in larger lakes or more natural communities. Thus, our experience in aquaculture is no more informative of the community dynamics of trout than agriculture is of the dynamics of pheasants.

7. These characteristics of aquatic environments, together with the attributes of fish combine to suggest a broader view of fish population dynamics:

7.1. Density-dependent processes are most evident in the smallest and most-confined environments, less important in larger lakes and least evident among wide-ranging marine species.

7.2. Density-dependent regulation (where it occurs) may include: suppression of growth rate, delay in maturity, decline in fecundity, cannibalism, predation, and parasitism and diseases.

7.3. The size of a year-class is usually determined in its first year, and the entire population is best viewed as the sum of a number of successive cohorts. How to harvest a population is a problem in cropping contemporaneous cohorts.

IV. Conventional Population Models

The substance of our technical discussions of logistic growth population estimation methodologies and stock-recruitment relationships has been to provide estimates of the parameters of conventional exploitation models.

1. We began with an analytic theory of fish populations--Baranov, Russell, Beverton and Holt.

2. Refined it - Gulland, Ricker, Schaefer, Jones, Cushing, Deriso, Schnute, Kimura.

3. Recognized it's inadequacies by virtue of collapse of most of the world's stocks being managed by MSY. See the ASPY volume, Can. J. Fish. Aquat. Sci. Supplement 2, 1987 for a modern characterization of the problem and recent management responses to it.

V. What lies ahead for fisheries science?

1. We now appreciate the power of analytic models and the statistical and mechanical machinery for their solution, manipulation and simulation.

2. We can use simulation to produce familiarity with a system that may facilitate conceptualizations of some analytical analog.

3. Modelling a system can sharpen our appreciation of the priorities that should be attached to different kinds of research if the model and its management consequences are to become more sophisticated.

VI. Optimization -- The question has come to be "what do we want to optimize?" rather than simply, how do we do it.

In the final analysis, it has become clear that we need to consider every exploited species of fish or shellfish in the context of its own habitat and ecology, being especially cognizant of the impact that fisheries have on non-target species. A few attempts have been made to broaden our conceptual models, but progress has been very slow. Following are a few examples of attempts to remedy this situation.

1. A need persists for conceptual models for multispecies fisheries.

Some examples of multipsecies models include: Marten 1979 -- Used an historical time series to show by a mutiple regression analysis that fish catches (by a native peoples’ fishery) were best where predator populations had been reduced by fishing.

Y = 48 Xsm + 50XL + 10XE + 110XH

s = small mesh gill nets 3.8-5.1 cm.

L = large mesh gill nets 10-12 cm.

E = extra-large mesh gill nets 13-20 cm.

H = hooks.

S = seines

Gill nets of 6.2-9.8 cm., and seines had regression coefficients not significantly different from zero. Clarias, Bagras, Protopterus were large predators on Tilapia and Haplochromis .

Y Tilapia = 4.8Xs + 6.2XL + 8.8XE + 29XH

YHaplo = 21Xs + 8.8XH + 124XS

Tilapia and Haplochromis are not caught by hooks, so why the significant coefficients? Bagrus consumes more than 10X as many Haplochromis as are caught by fisherman. Also, there is an inverse relationship between catches of Bagrus and Tilapia. Marten’s recommendation was to “remedy the overfishing” by increasing fishing pressure on predators.

2. A need persists for analytical methods to deal with multi-species exploitation problems. Optimal exploitation -- Walters’ 1975 and 1976 papers address this problem. Also Hilborn 1976.

Silvert and Smith 1977 - Give a model for maximizing present value of several species in a marine community. This underscores the point that fishery exploitation problems have an economic dimension as well as biological ramifications.

3. We need a harvesting strategy which is responsive to rapid changes in the fish community and which reflects the fact that the coef. of var. in yield increases as the MSY is approached. Beddington and May, 1977. Adaptive control of fishing - Walters and Hilborn.

4. Ecological thinking in fishery science has, in the past, focussed upon the general principles of ecology as propounded during the first half of the Twentieth Century. These "principles" have proven to be little more than common sense interpretations of predator-prey interactions, singling out individual pathways as the "explanation" for how managed animal populations will respond to exploitation or other management activities. Such approaches are insufficient because, 1) they do not allow useful prediction; 2) they ignore broader system effects; 3) they are based on linear models, and, 4) they fail to anticipate the self-organizing character of living systems. We need to supplant this approach with the "new" ecology of James Kay and Eric Schneider who interpret organisms and living systems as entities that collectively dissipate the gradients of energy and nutrients that they encounter in the natural world. Fishery management models based on this paradigm have only recently begun to appear. See, for example, Spangler, G. R. and J. H. Peters. 1995. Fisheries of Lake Huron: An Opportunity for Stewardship. In: The Lake Huron Ecosystem: Ecology, Fisheries and Management. Munawar, M., T. Edsall, and J. H. Leach (Eds.). Ecovision World Monograph Series. SPB Academic Publishing, Amsterdam, The Netherlands. Pages 103-123.

5. Although we have alluded to it above in the "rationale for modelling" we should make explicit our acceptance of exploratory modelling as an integral component of scientific endeavor. We can no longer view science as narrowly construed by Karl Popper's notion of empirical falsification. We find ourselves increasingly confronted by situations in which we are unable to construct experiments to falsify hypotheses. Does this mean that we should ignore these questions and move on to more tractable problems? Certainly not. To do so is to abdicate the scientist's fundamental responsibility to expand the frontiers of knowledge. Stephen Wolfram has taken a giant step forward in providing for us both the analytical machinery (Mathematica) and the rationale for using it to further broaden our understanding of the universe.

6. Finally, we need further recognition of the common property resource aspect of fish stocks and their inevitable demise in the face of a profit motivated free enterprise system.