PERCH. 
31 
gating its species until three or four years old". This 
may be very much influenced, however, by the abun- 
dance or scarcity of its food, which consists of small 
fry, roe, insects and worms. 
The spawning-season varies according to the depth 
of the water; in shallow lakes it is often earlier than 
the middle of April, but in deeper water, in Lake Wetter 
and the island-belts for example, not before the middle 
of May, and generally towards the end of that month. 
It is also much influenced by the temperature and the 
earliness or lateness of the spring. When the spawning- 
season has arrived, or, more correctly, some days before 
its arrival, the Perch leaves the deep water where it has 
passed the winter, and, collected in large shoals, wanders 
to points along the shore where the water is shallow 
and the bottom consists of stones or sand covered with 
reeds ( Arundo phragmites), or where it can find sunken 
twigs and branches. If it fails to find any spots of 
this nature, it deposits its spawn among tufts of rushes 
( Scirpus ) and horse-tail ( Equisetum ). The roe of the 
Perch is not made up, as is generally the case among 
fishes, of loose grains covered only with a viscid mucus 
and easily detached from each other as soon as the roe 
is deposited, but is enveloped in a netty membrane 
which holds the grains more closely together, and ren- 
ders it necessary for the female to make greater effort 
and to have recourse to special expedients in order to 
free herself from the roe. It is said 6 that in the spawn- 
ing-season the female rubs her belly against a sharp 
stone or a piece of wood, until she succeeds in fastening 
the roe-string to this object, whatever it may be. She 
then darts suddenly forward with a winding motion, 
and thus draws out the roe in the form of a string 
which in some way resembles the strings of spawn which 
certain batrachians deposit. Now and again, however, 
the roe is found lying loose on some water-plant 0 or 
drifting about in the water L The eggs are numerous, 
but their number varies considerably in proportion to 
the size of the fish. In a female weighing about 255 
grammes Lund estimated the number of the eggs to be 
26,880, and in another weighing about 584 grammes, 
66,150. In a female 2 lbs. 9 1 / 4 oz. in weight Bloch 0 
estimated the number of the eggs to be 268,800. From 
these estimates we may imagine how quickly the Perch 
might multiply. That it does not do so, may be 
ascribed to the fact that the roe is in one mass, and is 
thus more liable to be devoured by fishes of prey and 
waterfowl, or in stormy weather cast on the shore, 
where it dries up, etc. It is also probable that it is 
impossible for the milt of the male to fertilize all the 
eggs enclosed in the roe-sheath. 
As a general rule, the males seem to be less nume- 
rous than the females — among twenty perch bought 
at the same time in a market-place in Stockholm, there 
were only three males, and all three were among the 
smallest of the twenty. No external distinction as to 
sex was visible at this time (in December). The opinion 
that the female (according to others, the male) has a 
greater depth of body or a smaller head, was not borne 
out by fact. It is during the spawning-season that the 
difference of sex first becomes apparent in the brighter 
and more vivid colouring of the male and the deeper 
shape of the female, which is perhaps always visible at 
this season'. 
The courage with which it defends itself, and the 
formidable weapons against fishes of prey which it pos- 
sesses in its spinous fins, tend to preserve the Perch 
from attack as soon as it has reached an age when it 
can defend itself. It swims rapidly, but not continuously. 
After each dart forwards it stops for a moment. It 
generally keeps close to the bottom, and sometimes 
half-way between the bottom and the surface. It is 
only on bright and calm summer days that it disports 
itself at the surface. About midsummer comes the time 
In the beginning of Dec., 1886, among females with eggs about 1 mm. in size, we have found 
the weight of specimens 266 mm. long to be 281 grin., the weight of specimens 288 mm. long to be 361 grm., 
» » » » 278 » » » » 276 » » » » » 305 » » » » 361 » 
» » » » 281 » » » » 332 » » » » » 330 » » » » 553 » 
a Norback (Fiskevard och Fiskafvel , p. 359) and Maklin (1. c.) state that the Perch is capable of propagating itself when two years 
old. That this holds good in the case of the males, is undoubtedly true, at least if the estimate of age given above be correct, for in Lilia 
Vartan (a firth of the Baltic near Stockholm) on 12th of May, 1887, males 127 mm. in length (measured to the end of the middle rays in the caudal 
fin) were found to have fluid milt. The smallest female ready to deposit its spawn, which was caught on the same occasion, measured 154 mm. in length. 
b Lund, Vet.-Alcad. Handl. 1761, p. 188. 
c Malm, Gbgs, Boh. Fn., p. 377. 
d Sundevall, Vet.-Akad. Handl. 1855, p. 9. 
e Naturg. Fische Deutschl., 2 Th., p. 68. 
f The truth of this statement is most clearly shown by the fact that in the case of 3 males and 4 females the least depth of the body, or the 
least depth of the tail was more than 30 % of the greatest depth of the body, while in the females it was less than 30 %. 
