Fish biology and fieldwork

sagittal line

top line of fish

dorsal fin

fin/s along the sagittal plane

can be more than one, can be spiny or soft (rays)

anal fin

located on the ventral side of the fish along the medial plane

caudal fin

tail, single fin

pelvic fins

bilaterally paired fins located anterior to the anal fin

pectoral fins

paired fins located posterior to the head

tread water

adipose fin

featureless bump, important for ID

located posterior to the dorsal fin

operculum

forms the gill cover

shape can be important for ID

lateral line

along side of fish, ID for shape

generally has dashes or dots

organ of sense, can note changes in pressure, or electrical potential

caudal peduncle

base of caudal fin, shape can be ID

types of mouth shapes

terminal - at end of fish

upturned, downturned/subterminal, ventral

upturned fish

ideal for grabbing food from surface of water when swimming below surface

subterminal mouth

slightly downturned

ideal for feeding below the eye

barbel

organ for taste? or touch - feeling in turbid water or for organisms which live along the bottom of rivers
size, shape, presence imp for ID

ventral mouth

underslung or inferior for feeding on the bottom surface

fin spines

defensive

can accompany softer fins or no

fin rays

support fins, slightly softer but still bone

bony armour

like scales but larger plates

homocercal tail

caudal peduncle is symmetrical and therefore usually so is the caudal tail

heterocercal tail

the caudal peduncle is not symmetrical and therefore neither is the caudal fin

dorsal spines

anti predator structures located along the dorsal sagittal plane

maxilla

prominent bone which bears upper teeth, used for ID

same as mammals

how to measure length of fish

start at tip of upper jaw/maxilla and to the fork of the caudal fin

fork length

aquatic fieldwork

to better understand limnology, food for different species, ecology, connectivity between other species, etc.

triangular net

can scrape along the bottom of a water body and pick up bottom dwellers better than other nets

heavy duty dip to keep small organisms from passing through

field supplies

triangular net, white pan for identification of bugs against a clean background

waterproof gear and bag, waders

aquatic habitats

can be streams or lakes

or can be small and short in duration such as plant pots left outside, tracks from cars,

water quality factors

temperature, dissolved oxygen (cold water increases), flow rate, clarity, TSS - hardness, conductivity/salinity, pH (diversity)

concentrations of toxins, nutrients, etc

secchi disk/depth

black and white disk attached to a marked cord (in length)

you drop the disk slowly unless it disappears from view (algae, sediments, tannins, etc)

next raise it to the point it reappears

the depth is midway between the bottom and where it reappears

surber sampling

a standard sized box is place in a flowing river anchored in the mud

stir up the mud to pick up things to catch within the net behind the contraption

often white pan for ID

funnel traps/gee traps

rigged set up with rocks to hold down into the current

based on principle that animals which get in cannot understand how to get out

how did crayfish get across rivers in AB

either they swam up stream to all rivers

or people brought them

unconclusive evidence