Human and fish interactions?
- There are more species of fish than all other vertebrates combined (~32,000 known species)
- Fish are harvested from wild stocks as part of global fishing industries or grown under intensive aquaculture conditions
- Most common pet and are widely used for scientific research
- Fish not always given enrichment to express their natural behavioural patterns in captivity
- Fish live in complex environments (social and physical) -> high degree of behavioural plasticity
Reviews of fish cognition suggest fish show a rich array of sophisticated behaviours such as…
- excellent long-term memories
- develop complex traditions
- show signs of opportunist intelligence
- cooperate with and recognise one another
- capable of tool use
‘Wild’ vs ‘Hatchery’ Fish
‘wild’
* fish hatched and reared in a natural environment (regardless of parentage)
‘hatchery’
* fish are bred by genetic crosses. Hatched and raised in captivity until juvenile stage then released
- Most hatchery programs are meant to produce fish for harvest
- Increasing number of hatchery programs now have the explicit mission of restoring declining wild populations
What is fish stocking?
- Fish stocking = management tool that helps manage or change fish populations
- Stocking cannot sustain a fishery above the productive capability of the lake or the species
- Stocking lakes where game fish are capable of reproducing will not result in any improvement to the fishery
- The size of fish stocked in Saskatchewan typically
includes:
* Fry (few days old), Fingerling (8 to 12 cm in length), Catchable (20 to 30 cm in length), Adult (mature fish)
wild caught vs aquaculture
Wild caught:
* stocks are under pressure
Aquaculture:
* Farming of fish, shellfish, and seaweeds.
* Limited selection/ domestication, captive rearing of wild stocks
* Over 50% of the seafood we eat comes from farms — number continues to increase.
- Types: Fish spp, crustaceans, mollusks
- Intensive: man-made pools, tanks
- Extensive: net cages in open water
what are the fish in aquaculture?
Mostly Bony fishes-> Osteichthyes
Largest vertebrate class >29,000 species
* Carps, Tilapia
* Catfish
* Sea bass, Sea bream
* Salmonids - Rainbow trout, Atlantic salmon, Arctic char
* Flatfish- newer species, e.g. Turbot
Invertebrates:
* Mussels (mytilus edulis)
* Shrimp, crayfish
* Oysters
* Softshell clams
What is fish sensory perception?
- To get inside an animal’s head, to try to understand why it does what it does, we must first understand how it views the world around it
- Many fish species occupy an immense array of habitats à it is very difficult to generalise
- The environment in which a fish lives shapes the senses it relies on
- Water differs from air in a wide range of biologically important ways
- Ramifications for understanding the evolution of fish senses, behaviour and cognition
What is the fish vison like?
- The common goldfish has cones that absorb at 400, 450, 530 and 620 nm (Neumeyer 1982)
- Work in cichlids, guppies and sticklebacks show that ultraviolet (UV) is important for mate choice and species recognition
- Detection of UV can occur in some parts of the life cycle and then be reduced or lost entirely
- Certain spp. of fish use UV as a discrete channel for communication since their predators are unable to see in this part of the spectrum
- Various fish can see polarised light:
(1) increased contrast when foraging on small prey
(2) visual communication
(3) spatial orientation
What is chemosensory ability in fish?
- Chemosensory ability of most fishes is highly developed
- They use this information for a wide variety of behaviours: feeding, predator recognition, mate choice and navigation
- Sharks sense of smell is ~10,000 times more sensitive than ours
- Because fish are submersed in water -> no restriction on the location of their taste buds
- Variability in location and density of taste buds tells us about their environment and its feeding habits
- Cyprinids have ~300 taste buds per mm2 , and density is associated with the fishes’ feeding habits
- von Frisch (1941) discovered minnows showed an innate fright response when one of their conspecifics was harmed- (‘‘fright stuff’’)
- Now know this substance is held in special skin cells (club cells) in all ostariophysan fishes
- Plays a crucial role in enabling naïve fish to recognise dangerous predators via classical conditioning
- When a conspecific is hurt or killed by a predator, the alarm substance is released into the water resulting in anti-predator responses in the surrounding fish -> Fish can pair the appearance of a predator with an appropriate biological response (e.g. schooling or crypsis)
- One of the greatest examples of animal migrations = return of salmonids to their home streams - spend long time in in ocean and can go back to stream they were born in
What is cerebral lateralization in fish?
- Fish prefer to use one side of their brain over the other when analysing sources of information
- Pattern of laterality varies between species, between populations of the same species, and between individuals
- Sarasins minnows look at a familiar individuals with their left eye and use their right eye to view unfamiliar individuals
- Right eye is commonly used for looking out for predators or other potentially threatening objects
- Preference for using one eye or the other in social contexts influences the location rainbowfish prefer to adopt within a school
- Those that prefer to use their left eye to view school mates tend to prefer positions on the right side of the school and vice versa
- School would show faster responses to predators and prey on the periphery of the school while also rapidly responding to the behaviour of their school mates -> Shows fish can perform multiple complex tasks simultaneously and provides a non-invasive method to understand which hemisphere fish use when attending to various stimuli.
- Laterality varies with emotive content of stimuli and provides a method of studying emotional responses in fish
learning and memory in fish
- Associating time of day and location of feeding is known as time-place learning
- Time-place learning has been demonstrated in several fish species
- Typical approach is to feed the fish at one end of an aquarium in the evening and the other end in the morning
- Each day the location of the fish is recorded just prior to feeding
- If the fish show anticipatory behaviour by congregating at the feeding end, then they have learnt the task
- Shown to take 2-4 weeks to learn depending on species
Brown et al. (2015) examined the effects of rearing environment on learning using classical or Pavlovian conditioning…. what did they find?
- Fish learnt that when a light was turned on food would shortly be delivered down a feeding tube
- Wild rainbowfish showed rapid learning over 7 days (14 trials)
- A captive-reared population was initially slower to learn but they eventually caught up
Social learning in fish
- Occurs when information passes from one individual to another by observation or interaction
- Lead to a transfer of information through generations (vertical transmission) resulting in cultural traditions
- Hatchery-reared salmon could be taught to recognise novel live prey by pairing them with fish that already recognised the prey
- Naïve observers learn to eat the new food and also learn where to forage for it
- Guppies trained to use routes to locate a foraging patch
What is individual and kin recognition like in fish?
- Guppies can remember the identities of up to 15 individuals with little difficulty
- In small shoals, familiarity takes ~12 days to develop and may be maintained after 5 weeks of isolation
- When given a choice, fish prefer to shoal with familiar rather than unfamiliar individuals
- Shoals comprised of familiar individuals are better at avoiding predators than groups comprised of strangers
- Social learning is enhanced in groups of familiar fish
- Territorial cichlids show lower levels of aggression towards familiar than unfamiliar neighbours
- Fish may lose preference for familiarity after multiple generations in captivity and could have other consequences on social behaviours
- Fish may also be able to recognise kin using both visual and chemical information
What are the 3 social structures in fish and describe them
- Solitary
* Territorial fish
* Aggressive defense of feeding area
* Pike (Jack fish) and juvenile salmonids
* Need some refuge, such as weeds or banks - Schools (large, tight groups)
* Deep bodies of water
* Provide refuge to individual fish
* Predator detection
* Synchronization- flooding effect on predator
* Improved foraging - Shoals (small, loose groups)
* Intermediate between solitary and school
* “Aggregation but without synchronization”
what is cooperation and reconciliation in fish?
Cleaner wrasse and its clients
* Recognize each client individually
* Clients present themselves and perform a ‘clean me’ stance -> signals to the cleaner that they require a clean
* If the cleaner accidentally bites the client, the client will rapidly swim away
* But the cleaner has a mode of reconciliation -> they chase after the client and give them a back rub, thus, enticing them to come again
* Cleaner fish are selective about who they serve and classify their clients according to if they are local or transient or predator or nonpredator.
* Cleaners are partial to cheating – occasionally they nip the skin of clients to obtain a cheap meal (won’t perform this behaviour on predators) -> the cleaner wrasse recognises individual fish and can categorise different fish species based on their predatory tendencies
What is nest building in fish?
- Involves complex manipulation of external objects
- Associated with parental care (widespread among cichlids and gobies)
- Not clear what the extent to which building involves cognition
- Many nest building behaviours have strong innate motivation
- More species of fish (at least 9,000) nest builders than mammal species – for laying eggs or shelter from predators
- Nests vary in materials used and their shape and function
- Few studies examining nest building behaviour in fish – mostly in sticklebacks
What are nest building examples in fish?
- Male gourami (e.g. Siamese fighting fish) build nests out of bubbles which entice females to lay their eggs
- Various species of wrasse produce mucus cocoons which protect them from predators and parasites while they sleep
- Cutlips minnow collects ~300 identical pebbles and builds a mound (35 cm wide, 10 cm high) and tilefish make coral mounds up to 1 m high
- Jawfish gather small rocks from the sand floor to build a wall in front of its burrow - search for rocks that fit together like a puzzle and leave a hole big enough for it to go through
- Rockmover wrasse gathers up large bits of coral every night to make a house à spends the night sleeping and abandons the next morning
how do fish use tools?
- Many species of wrasse use rocks to crush sea urchins to access the meat inside
- Wrasse commonly use anvils to break open shellfish
- Study examining tool use in the wrasse family showed that tool use has either evolved multiple times or is a common behaviour
- Wrasse also have a larger than expected brain size, a theme that is also apparent in both tool-using birds and primates
- Cichlids and catfish often glue their eggs to leaves and small rocks and then carry them around when their nest is threatened
- Many fish (e.g. archerfish) squirt water from their mouths to dislodge prey items
What is unique reproductive behaviour in fish?
Cardinal fishes (355 species):
* mouth brooders: the males keep the fertilized eggs safe in their mouths until they hatch
* This strategy evolved convergently in several other fish families (e.g. African Cichlids and jawfishes)
* Prevents male cardinal fish from feeding
* Trade-off: starve, and risk future reproduction but keep the current batch of eggs alive, or swallow them, and live to breed another day (i.e., parental cannibalism)
* Occurs if the trade-off between breeding now and eating now vs breeding in the future does not look good
- Species of South American Cichlids
- Have evolved a way to feed their fry which is convergent with mammalian suckling
- Both the female and male produce a mucus which feeds the young fish
- Only produced when parents take care of fry
- Protein and mineral rich mucus
what is fish welfare?
- Evidence suggests hatchery fish exhibit differences from wild fish in predator avoidance and agonistic behavior
- Most people do not consider fish welfare to be important
- Scientific evidence shows that fish are behaviourally complex and feel pain
- Welfare of captive fish is influenced by fish health (water quality, stress and behavioural needs) and owner’s provision of care (knowledge, attitudes, social norms and media coverage)
“Whilst measures of welfare developed for other
animals are often relevant to fish, clearly defined
protocols for fish welfare evaluation are lacking”
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