WMAN 445 Exam 1

shifting baseline theory

perceive overfishing changes with generations; things that are → extinct (not perceived as big loss not aware about abundance)

first evidence of fishing

harpoons

fishing down marine food web

fish near top (long-lived, large) tend to decline faster than smaller (short-lived) fish w/ lower trophic levels

fishing down process (inland)

disappearance of larger species + their replacement by smaller species, not linked to trophic levels but to species length

Thomas Huxley

Darwin’s bulldog, fisheries are inexhaustible, nothing we do affects fish numbers 

Walter Garstang

bottom fisheries aren’t exhaustible, rate at which sea fishes multiply + grow is exceeded by rate of capture 

Kyle

mathematician might be able to calculate precise point where overfishing begins 

Emmeline Moore 

first female president of AFS; watershed characteristics 

fisheries manager

control fishing pressure using various regulations at a level that sustainable catch levels could be achieved perpetuity 

tragedy of the commons

self interest, little incentive to conserve the resource 

Hardin’s solutions to ToC

externally imposed regulation; private rights to ensure that the common remained whole

fisheries co-management

interdisciplinary, flexible + cooperative management, responsibility of resource is shared, decision making, implementation + enforcement 

3 components of fisheries management 

aquatic fauna, habitat, users

adaptive management 

systematic approach for improving resource management by learning for management outcomes; iterative process

iterative learning process def

management adjusted based on improved scientific understanding 

iterative process

inventory, strategic, operational, monitoring + evaluation

inventory

describing current status of the fishery; identify + assemble stakeholders; collect data 

strategic planning 

utilizing data to develop management goals 

goals 

broad statements of benefits desired from resources 

SMART

specific, measurable, achievable, realistic, time bond

operational planning

identify limitations, design + implement strategies

monitoring + evaluation

provides the feedback loop for determining whether selected strategies have intended effects

the management process

assemble stakeholders; assess current conditions; set goals; set objectives, ID limitations; design strategy/actions, evaluate progress; revise/adapt 

population

group of individuals of the same species living in the same area at the same time + sharing common gene pool, with little immigration/emigration 

stock

part of fish pop. which is under consideration from the pov of the actual/potential utilization 

why pop dynamics 

detect changes, diagnose problems, identifying management actions

basic pop dynamics

recruitment + growth → biomass → death

biomass

mass/weight of living biological organisms in a given area at a give time

endogeneous

relating to the fish’s environment, physiology + behavior

exogenous

determined by the fish’s environment + external influencing factors

recruitment

appearance of new young organisms in a population following a previous reproductive event when a new individual can be detected 

natural mortality

death of fish in a population due to natural causes such as predation + disease; removal of fish from the population

fluctuations in M w/age

M tends to decrease with age as fish out grow predators but many increase again in older fish due to stress associated with reproduction

growth

considered a change in fish size or weight with age

why does the pop fluctuate around k 

changing enviro. conditions; changes in habitat quality + quantity; changes in mort; recruitment variability

MSY assumptions + limitations

pop/stock being harvested at equilibrium; pop fluctuates; variations in pop parameters 

density dependent processes

changes in pop demographic rates (births+deaths) related to pop density

density independent processes

changes in demographic rates that are due to abiotic/enviro forces

catch curve 

decline in individuals with age can be theoretically modeled with continuous exponential pop. model 

passive tagging

tagging with external tags + obtaining anglers’ reports of harvesting tagged fish

active tagging

use of telemetry techs to assess mortality

3 main factors of growth

max average size/weight a species can obtain; average rate at which fish size/weight changes with age; how big/heavy it is when it begins to grow 

how is growth measured + summarized

growth curve: ages to length; weight-length relationships

von-bertalanffy growth curve

describes growth rate (length) that decreases with age

what are parameters that are influenced by variation in recruitment 

pop. abundance, age structure (# of large fish), fish growth rates 

how do we measure recruitment 

sampling regimes targeted at juveniles, size specific indices of abundance from catch effort data, assume a relationship with adult stock size