When ice covers lakes, there is less oxygen to breathe, and most fish sink to the bottom. They remain very quiet but awake. Carp, however, flap their tails to cover themselves with mud and they go to sleep. When the lake ice melts and the oxygen levels rise they awaken.
Synchronised spawning
Synchronised spawning Trout naturally spawn over a 2 month period and
this makes it difficult for fish farmers to efficiently harvest
their eggs. However, a team of European researchers has now
developed a hormone-laced food that makes fish spawn predictably.
The food was originally developed with troublesome trout in mind,
but the same technique could also be used in salmon farming. Fish
fed the hormone-rich food will not end up on supermarket shelves.
The feed is given only to brood stock, those fish used exclusively
for egg production. However, inducing spawning in fish is risky -
there is the chance of getting poor quality eggs. Convincing fish
farmers to try the food is another hurdle. There are fears that
using feed to manipulate the natural spawning of the fish would
leave a poor impression on the industry’s public
image. 15 JANUARY 2000, P. 16
Cool Articles
