Fishing

categories of commercial fishing

artisanal-subsistence fishing

recreational fishing

commercial-macro scale fishing

BUT economy drives commercial fishing, so economy might dictate it anyway (fuel prices)

fishing conflicts

many national/international conflicts over fishing

what belongs to who, socal especially (populations oscillate in phases b/s temp can change so much), CA current makes norcal + above perpetually cold

provinces along wc (south to north)

panamic, callifornia, oregonian, aleutian

management

state: <3 nautical miles offshore

federal: 3-200 nm

international: rest

history of fishing in CA

fishing increased after marine mammals fished out, sardine fishery was one of the biggest in the world before it collapsed, now it’s mostly hake

rockfish

inverse relationship between stock size and catch

historically lots of rockfish

crashed in 1980s-90s (started to protect rockfish and once stocks went up, the fisheries are starting to regain

how to manage fisheries so you can catch them and also have a large stock?

target biomass —> use the 40% rule

ricker recruitment curve

strong density dependence, increasing geometrically over a certain range of stock densities. potential dd mechanism = cannibalism of young by adults

beverton-holt recruitment curve

Implies an arithmetically progressive reduction in the recruitment rate as

stock density increases. A ceiling of recruit abundance is imposed

by available food or habitat (resources limitation)

recruitment

ecological definition: settlement + recruitment can have a gap, but mostly in CA terms exactly same

fisheries literature: recruitment means accessible to fishery (sized based), try to have a few years where fish can reproduce before fishery

logistic curve

maximum sustainable yield

right half is not helping the fishery

surplus yield

CPUE

catch per unit effort

the easiest way to measure effort is # of people fishing

msy-schaefer model fitted for peruvian anchovy

no data on the right side b/c it would be too dangerous to fish

but then how do we predict the curve? need to be able to predict the future

msy model issues

regime shifts (oceanographic variation)

annual + recruitment + spatial variability

need to overshoot MSY to predict it

need to switch target if fish populations low

data is expensive to collect

single species management doesn’t work

40% rule

fisheries management set a target (40%) and a limit

if stock falls below 40% —> adjust fishing

if stock falls below 10% —> close fishery

get the first dots, if we get all the dots then yay but any more is overfishing

MLMA

establishment of MPAs in CA

MLPA

have to manage fisheries in ecosystem

prop 132

gill net ban (but CA is still the only state that allows gill nets in federal waters)

soupfin sharks

started being caught in WWII for fish oil, fished out by the end of the war, after gill net closure they came back (!!)

same w/ leopard sharks and giant black sea bass