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Brooke Comprehensive Exam > Quantitative Conservation Biology and Quantitative Fisheries Stock Assessment > Flashcards

Quantitative Conservation Biology and Quantitative Fisheries Stock Assessment Flashcards

1
Q

population viability analysis

A

suite of population modeling and data-fitting methods for assessing extinction risk and guiding the management of rare or threatened species
-predict likely future status of population

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2
Q

What are the uses of PVA?

A
  • assess extinction risk of single pop
  • comparing relative risks of multiple pops
  • analyzing and synthesizing monitoring data
  • identifying key life stages or demographic processes as management targets
  • determine size of reserve to achieve desired level of protection
  • setting limits on harvest that is compatible with continued existence
  • determining how many and which populations are needed to achieve a desired overall likelihood of species persistence
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3
Q

What are the types of PVA?

A
  • count-based
  • demographic (account for differences in contributions and for percentage of each type currently in population. Structured population)
  • multi-site (includes 2+ local population patches of suitable haibtat)
  • spatially explicit, individually based PVAs
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4
Q

What are factors that can threaten a population?

A
  • life history
  • average environmental conditions
  • environmental stochasticity
  • demographic stochasticity (intrinsic variability caused by small population size)
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5
Q

What are the 3 vital rates?

A
  • birth rate
  • death rate
  • growth rate
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6
Q

net reproductive rate

A

average number of female offspring produced by a female over her entire life

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7
Q

lambda

A

annual population growth rate

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8
Q

When is demographic stochasticity important?

A

at low population sizes

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9
Q

negative density dependence

A
  • decline in average vital rates as population size increases
  • typically due to competition or predation
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10
Q

positive density dependence (Allee effect)

A

increase in growth rate as population size increase

  • improved mating success, group defense, group foraging
  • most important at small pop size (decreased growth at low pop size)
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11
Q

quasi-extinction

A

minimum number of individuals below which the population is likely to be critically and immediately imperiled by Allee effects, loss of genetic diversity, and imbreeding depression

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12
Q

cumulative distribution function

A

probability of extinction over certain time horizon

-most useful and robust extinction risk estimates

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13
Q

How to incorporate density dependence into count-based PVA?

A
  • can put threshold to pop size (K)
  • can use theta logistic model (allows from gradually changing growth rate)
  • can use Ricker model (linear growth) often used in fisheries (theta = 1)
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14
Q

How can you determine if there is density dependence in population?

A

plot population size vs log annual growth rate

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15
Q

observation error

A

variation in census counts (and thus pop growth rates) caused by our inability to count precisely the number of individuals

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16
Q

structured population

A

individuals differ in their contributions to population growth
-survival, reproduction

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17
Q

population projection matrix model

A

primary tool for assessing the viability of structured populations

  • divides pop into discrete classes
  • uses vital rates (survival, growth/transition rate, fertility rate) at each class
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18
Q

projection matrix

A

summarizes per capita contributions of all classes at one census to all classes in the next census

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19
Q

How do you get lambda of the projection matrix?

A

lambda represents the dominant eigenvalue

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20
Q

How do you get the reproductive values of each class in the projection matrix?

A

dominant left eigenvector

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21
Q

eigenvalue sensitivities

A

measure of how much changes in a particular matrix element will change the annual growth rate

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22
Q

sensitivity analysis

A

suite of methods to ask “how sensitive is population growth to particular demographic changes?”

  • can help with effective management plans
  • change values of vital rates and see how it affects growth rate
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23
Q

elasticities

A

rescales sensitivities to show proportional change in growth rate resulting from proportional change in vital rate

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24
Q

How is site-based PVA different than count-based or demographic PVA?

A

requires all info to do other types of PVA but ass data on movement rates between populations, and correlations in vital rates between populations

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25
Q

What is the most important component to include in PVA?

A

estimates of uncertainty and variability

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26
Q

stock assessment

A

use of statistical and math calculations to make quantitative predictions about the reactions of fish populations to alternative management choices

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27
Q

What is the purpose of fisheries management?

A

ensure sustainable production over time from fish stocks while still promoting economic well-being of fishers

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28
Q

overexploited

A

stock size has been driven to lower levels than would produce the largest annual biological surplus or net economic value

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29
Q

When can we detect overfishing?

A

when it’s already severe

30
Q

What are the stages of management decision?

A
  • stock assessment/modelling (for each possible management action, possible outcomes and their probabilities are assessed)
  • decide which of the possible actions is best in recognition of the outcomes that it may produce
31
Q

What are the objectives of fisheries management?

A
  • biological (MSY)
  • economic (max net profit)
  • recreation
  • social (jobs, food)
32
Q

When are profits maximized?

A

lower harvest rate (larger stock size) and lower effort than MSY

33
Q

discounting

A

value of fish in future is less than value today

-due to uncertainty of tomorrow

34
Q

population dynamics

A

birth, death, growth, and movement processes

35
Q

What are the 4 types of behaviors of exploited populations?

A
  • steady state (steady and sustainable yield, rare)
  • cyclical - periods of high catch followed by low catch
  • irregular - irregular periods of high abundance
  • spasmodic - produced major yields and then collapsed without major recovery
36
Q

globally stable

A

will always return to original state regardless of how much it is perturbed

37
Q

locally stable

A

will return to original state if pushed to certain limits, but if pushed beyond limits, won’t return

38
Q

depensatory mortality

A

predator causes prey mortality to degree that it cannot reproduce at same rate

39
Q

functional response

A

relationship between prey abundance and amount consumed by predator

40
Q

stock

A

arbitrary collection of pops that is large enough to be self-producing (abundance changes are not dominated by immigration and emigration) with members showing similar patterns of growth, migration, and dispersal

41
Q

biomass dynamics model

A

consider only a single indicator of population size (count-based)

42
Q

surplus production

A

catch plus net change in biomass over time interval

43
Q

What are the patterns of fishery development?

A
  • initiation (exploration)
  • growth and decline to bionomic equilibrium
  • innovation periods and development cycles
44
Q

catching power

A

determines how many fish a vessel will catch

-how often they fish, abundance where it fishes, crew skill

45
Q

How does commercial catch data relate to abundance?

A
  • it’s often not proportional
  • fish in high density areas
  • may not cover entire distribution
46
Q

What is CPUE based on?

A
  • spatial pattern of abundance
  • spatial pattern of fishing effort
  • relationship between abundance and capture success at the site
47
Q

constant density model

A

fish maintain a constant density by adjusting the area covered

48
Q

proportional density model

A

constant proportion of stock goes to each area so that the density in each area is proportional to abundance

49
Q

least squares method

A

parameter estimate minimizes the sum of squared differences between the predicted observations from the model and parameters and the observed data

50
Q

maximum likelihood method

A

maximizes the probability that the actual observations would have occurred if the parameters were true

51
Q

recruitment overfishing

A

the rate of fishing above which the recruitment to the exploitable stock becomes significantly reduced

52
Q

How does recruitment related to stock size?

A

recruitment tends to increase with higher spawning stock size (to a point), but there is greater variation at higher stock size

53
Q

compensation

A

relationship between stock size and recruitment limited by resources
-eventually stock-recruit relationship will flatten or decrease at high stock size due to egg survival

54
Q

overcompensation

A

when recruitment declines at high stock size

-due to cannibalism, disease

55
Q

depensation

A

increase in recruits as spawning stock increases. Due to:

  • predation held constant (% eaten decreases as recruits increase)
  • Allee effect - inability to find mates at low spawning stock
56
Q

recruitment

A

number of individuals still alive at a specified time (i.e. maturity) after the egg stage

57
Q

The One-Way Trip

A

fishery data with continuously increasing fishing effort and decreasing CPUE

  • k almost never known
  • better to have changes in effort to estimate parameters (how abundance relates to CPUE)
  • changing effort allows you to estimate catchability and intrinsic growth rate
58
Q

delay difference models

A

predicts this year’s biomass directly from the last few years biomass and parameters for survival, growth, and recruitment

59
Q

virtual population analysis/cohort analysis

A

calculates stock size based on catches with no underlying statistical assumptions
-calculate number of individuals for each cohort

60
Q

depletion estimators

A

examine how measured removals of fish (fishing) influence the relative abundance (CPUE or other abundance index) of fish remaining in total stock

61
Q

growth overfishing

A

taking too many fish when they are too small

62
Q

growth model

A

usually models relationship between body weight and age

-often use length vs age and weight vs length to predict weight vs age

63
Q

harvest strategy

A

plan stating how catch taken from stock will be adjusted from year to year depending upon the stock size, economic/social conditions of the fishery, conditions of other stocks, uncertainty, etc.

64
Q

F0.1

A

constant exploitation rate strategy with the fishing mortality (F) set equal to the value of F where the slope of the yield-per-recruit function is 0.1 times the initial slope

65
Q

Fmax

A

Fishing mortality (F) set equal to the value of F where the slope of the yield-per-recruit is 0 times the initial slope

66
Q

How to determine TAC for the year?

A

estimate stock size, then multiple stock size by desired exploitation rate

67
Q

When stock size is well know, what is the best harvest strategy?

A

TAC

68
Q

When vulnerability to fishing is well know, what is best harvest strategy?

A

effort limits

69
Q

optimization methods

A

used to find best fishing plan given:

  • specified quantitative objective
  • model of stock dynamics
  • specific management alternatives
70
Q

passive adaptive strategy

A

uses data to construct single “best guess” and act as though the model were true (or use conservative model) while assuming errors will reveal themselves in future assessments (most fishing stock assessments do this)

71
Q

trial-and-error adaptive strategy

A

try a variety of alternative policies at random in hopes of finding best option (usually happens in management)

72
Q

active adaptive strategy

A

construct range of alternative models that are consistent with historical evidence and identify a policy that offers some balance between probing for info (experimentation) versus caution about losses in short-term yield and long-term overfishing

Brooke Comprehensive Exam (9 decks)

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