It follows, therefore, that when a field is complex, when it is beset with 
a swarm of gadfly variables, it is subject to personal opinion, to the develop- 
ment of statements unsupported by fact or at least only partially supported by 
fact, and subjectivity is likely to replace in part the more desired objectivity. 
Workers in the physical sciences often speak of an apocryphal ‘‘fourth 
law’’ of thermodynamics to express the perversity of inanimate objects. Con- 
servation biologists, in turn, have real need for an additional ‘‘fifth law’’ to ex- 
press the fact that they seldom know what is going to happen when man starts 
tinkering with nature. 
The Great Lakes are a resource upon which it would be hard to place a 
true value. This value is not only biological; it involves sociology and econom- 
ics as well, and in these fields the plethora of variables makes biology look like 
apiker. However, it is the purpose of this paper to develop some of the conser - 
vation problems, largely biological, with as much objectivity as possible. And 
this assignment is no Sinecure. 
THE AQUATIC ENVIRONMENT 
The aquatic environment in the Great Lakes is of greater importance to 
us than most persons realize. We haul iron ore over its surface from Minne- 
sota to the various steel centers on the Lakes. This highway use is most im- 
portant. But in time we may find that this use is a transitory thing. There will 
be no more ore to haul. ‘The fisheries of the Lakes are another thing. They 
can be self perpetuating, and can continue into the future as long as nature or 
man allows the Lakes to continue. 
Fish don’t just happen in the nets of Great Lakes fishermen. Their oc- 
currence is no accident. They hatch and grow up, and the growth cycle begins 
to gather the variables which we have referred to. There is an interdependence 
in this process which is highly complex, and years of study by several highly 
competent workers have done little else than gather important basic statistics. 
The philosophy of complexity in inland waters is dramatically illustrated by an 
article written by one of my predecessors, Dr. Stephen A. Forbes (1925). This 
paper, now 65 years old, is a biological classic, and should be read by biolo- 
gists and physical scientists alike. Its title is ‘‘The Lake as a Microcosm,”’ 
and in part it says: 
A lake is to the naturalist a chapter out of the history of 
a primeval time, for the conditions of life there are primitive, 
the forms of life are, as a whole, relatively low and ancient, and 
the system of organic interactions by which they influence and 
control each other has remained substantially unchanged from a 
remote geological period... . It forms a little world within it- 
self--a microcosm within which all of the elemental forces are 
at work and the play of life goes on in full, but on so small a 
scale as to bring it easily within the mental grasp. Nowhere 
can one see more clearly illustrated what may be called the 
