From chapter "Primary Perception and Biocommunication"
One reason fish strike at hooks is that they, like all of us, make decisions based on cost/benefit and risk/reward analyses. I’m hungry and need food. Some food chunks are fatal, but nearly all are nutritious. I need to weigh the risk of this particular piece of food killing me versus the gain of nutrition.
Humans make similar decisions every day. I’m hungry, so I’m going to drive to the grocery store. I’m going to get into a big metal missile and hurtle myself frighteningly close to other big metal missiles at high rates of speed. More than 30,000 people died in the United States last year in automobile accidents. I’m making a calculated decision, risking my life to get some food. And then there are the risks assumed once I’ve reached the grocery store, like buying potato chips and chicken nuggets.
We all make these sorts of decisions, so it’s not a sign of stupidity on the part of fish when the decision ends up killing them.
That’s one of the heartbreaking things about life: one decision can change everything. This was true when I was in the car wreck that broke my mom’s neck; had we decided to stop for the evening five miles earlier, she would not now be functionally blind. Likewise, had a fly I earlier heard buzzing frantically as she was progressively bound by sticky silken threads decided a few moments earlier to go left instead of right, she would not have been caught by a spider. Had the snail not been exactly where she was and had I not unwittingly put my foot where I did . . .
Fish are really smart. They have good memories. Fish who have been caught are generally more difficult to catch again. And if fish are nearly caught by a predator at a specific place, they may avoid that place for several months. There are fish who can remember the human call announcing food for at least five years. We’ve been told that gold fish have a two-second memory. Not true. They can remember the color of a tube for dispensing food a year later. Other fish can remember signals associated with food for months. They can learn how to avoid traps, and if presented with the same trap eleven months later, still know how to avoid it.
Fish have complex social relationships. They remember the behavior of others in their groups and change their own behavior accordingly, for example avoiding fish who have bullied them. They also choose to associate with fish who are better rather than worse foraging partners.
Fish understand properties of transitivity. Scientists set up fights between males of a certain species of cichlid, and had other males watch. They learned that if the fish in question witnessed fish A beat up fish B who beat up fish C who beat up fish D who beat up fish E, they would consistently choose to associate with fish D over fish B, even though each had beaten up another once and been beaten up once. They choose to associate with the least dominant one.
Also, fish can deceive each other.
And they can learn from each other. Scientists captured some French grunts and released them in a new spot. Many grunts travel daily from sleeping to eating areas and back. The newly transplanted grunts followed the native grunts, and when the scientists removed the native grunts, the transplanted grunts continued to forage and rest at the places they’d been taught. Fish also learn from each other what are good food sources, and how to avoid predators. They can learn the scent of a predator by being exposed to that smell at the same time they see another fish who is frightened.
Of course fish can cooperate, swimming in shoals or schools, and hunting in packs. They sometimes and in many contexts work with fish of other species. For example, if a roving coralgrouper sees prey hiding somewhere the grouper can’t get to, she might visit a local moray eel and shake her head outside the eel’s lair. The eel knows this is an invitation to hunt. The grouper leads the eel to the hiding place, the eel heads on in, and either catches the prey or flushes it out for the grouper.