Episode 217: How To Catch A Sleeping Fish

Key Messages

• Like all animals, fish DO sleep. All animals sleep to enable their brains to process the data (memories, learnings etc) from their day. Fish don’t have eyelids or show facial expressions, so it can be tricky to tell if they are asleep, but they have periods of low activity with lowered metabolic rates and a high threshold to stimulus that signifies they are sleeping.
• Sharks, rays and some larger pelagic species such as tuna continue to swim while they are sleeping, although at a slower pace than when they are awake. Many bony fish species will seek refuge in a cave, log, weedbed or other structure while they sleep. Others sleep near the water surface. 
• Like humans (and other animals), fish aren’t completely unconscious while they sleep. Their brain filters out unnecessary information, but they will wake if there is a threatening noise, vibration or other indicator.
• We don’t know if fish dream, but it’s considered likely that they do. Recent video of a sleeping octopus displaying hunting colours suggests that it was dreaming about hunting. It’s not hard evidence but it does point to the possibility that fish might dream.  
• Most animals when woken from a deep sleep will initially exhibit a fleeing response, so waking a fish up by banging lures through a snag may cause it to spook. However, all species are different and continuously waking a fish that is trying to sleep might well cause an aggressive strike. 
• It is possible that sometimes when fish are showing on your sounder but not responding they might actually be sleeping. 
• Doc’s theory: When fishing to shut down fish try using subtle surface lures to start with then progressively switch to more aggressive lure styles and get them closer to the fish. The idea is that gently waking the fish with vibrations and sounds that aren’t to threatening is less likely to spook them. Getting closer to them with noisier lures might then be more successful because you’re not waking the fish with a jolt. It’s just a theory – put it to the test and let me know how it goes.