| |
BASIC TIPS FOR SUCCESSFUL SPAWN TAKING
Neil
Van Gaalen
Former Hatchery and Brood Station Manager Colorado Division of
Wildlife
During my tenure with the Colorado Division of Wildlife I accrued
more than 30 years experience in taking spawn. I found that good
techniques will result in less than a 10% pick-off. These tips
cover two categories; wild fish spawning in natural conditions
and domestic spawners raised in a hatchery environment.
The natural diet of wild fish gives them high quality eggs which
will result in a very low pick-off. These fish are caught in fish
traps placed at inlets or outlets of lakes or they are caught
in rivers. When taking eggs in an open environment the sunlight
shining on the spawning pan can have a negative impact on the
fertilization process. This is particularly true in the late spring
or summer when the sun is very strong. During this time it is
advisable to construct a small shelter to protect the spawning
pan from direct sunlight.
The fish should be presorted to separate the ripe females from
the green ones before the spawn taking begins. Normally, when
a female is ready her belly will become very soft. Separating
the ripe females ahead of time enables the spawning process to
proceed at a fast rate. The reason, of course, is to reduce the
time that it takes for the eggs and sperm to come together. I
have always used a glove on my left hand (I am right handed) in
order to be able to hang onto the tail of the fish better while
using my right hand to strip the eggs. Forcing the eggs from an
unripe female is bad news.
For optimum fertilization, eggs from a couple females may be stripped
into the pan and then be fertilized with a couple of males. More
eggs may be added with additional sperm. Then the eggs should
be rinsed in clear water to remove the sperm, placed in a container
of clear water and allowed to water harden.
|
 |