Lecture 21 fisheries and overfishing

fishery

a unit determined by an authority or some power that handles and engages w people raising/catching fish. TYPES: commercial , subsistence, recreational, artisanal

artisanal

small scale local fishery. local sale! and low tech

discriminatory/non discriminatory fishery

discriminatory you are trying to catch a specific type of fish and usually your fishing method is picky somehow(net) and you can target what your target is. non discriminatory usually ends up with a lot of bycatch and the method of fishing you do will catch anything that might get hooked/caught/whatever

drift net

type of fishing where you have a net that you set and wait for the fish to get cuahgt(passive , non discriminatory)

longline

type of fishing where you have a long line with massive hooks that can catch large things like sharks. unfortunatly this is non discriminatory/passive and all sorts of bycatch can get caught

purse seine

a seining method usually done from a boat where you basically swing around and swoop fish up in the net. active capture, discriminatory bc you can target specific schools of fish

trawling

type of fishing where you drag a towed net on the ocean floor and get whatever is down there. this is pretty problematic for habitat on the ocean floor. non discriminatory, active

trolling

recreational fishing where you sit around with a fishing pole and wait until something gets hooked. hook selection is important for this! circle hooks help reduce fish mortality! J HOOKS SUCK! WAY OF THE PAST

fish pound

net method that basically guides fish into series of net fences that collects a bunch of fish. then fisherppl can filter thorugh and get rid of bycatch without killing them! really a decent way to go about it. some of these in chesapeake bay!

haul seine

same thing as a beach seine! scoop fish by swooping around but this can be done by ppl on either end on the beach or sometimes it can be helpful to have one on beach and the otehr swoop around in the boat

gear selectivity

ability to target specific type of fish!!larger mesh lets small fish through, more selective for specific bigger fish maybe

industrialized fishing

started in 1930s, boomed in 1980s due to population pressure and affordability of cheap gear! not so awesome for habs and environment

serial depletion

serial depletion = depletion of one individual stock at a time. when you fish out one region or one species so you just move. onto the next region or next species. switch to enxt most profitable species. usually region THIS IS NOT ABOUT FISHING DOWN THE FOOD CHAIN

PATTERNS IN world fisheries

populations hugeling increasing…eating more seafood, need more fish. wild caught kind of plateaued in 90s, aquaculture increasing still, abt eaqual at this pt. us and europe laggin in aquaculture bc labor is not cheap

fishieries productivity model

includes top down and bottom up elemetns. “top down” stuff = mortality(FISHING MORTALITY and natural). “bottom up” stuff = reproduction and growth . takes into accound life history stuff like longevity, growth rate, fecundity, size at maturity, etc etc

more fisheries yeild stuff

less trophic levels, more production. more primary productoin, also more production

habitat degradation due to overfishing

ruined spawning grounds:(. also pollutants, and blockages to migrations(dams and such). ex: trawl damage to soft benthos

bycatch

catch that is not retained(dead or alive). usually stuff that gets caught with a non discriminatory fishing method like longline

overfishing

when a species population is knowcked out by fishing at a faster pace than it can be replaced(esp problematic with things that have long generation times low fecundity slow growth rate etc)

overfishing and altered food web

when a species is overfished an dit might knock out a trophic level and impacts the entire ecosystem. this can contribute to something liek fishing down the food web. surge in lower trophic species which throws everything though. basically big trophic cascade.