1. A history of whaling 10th Century – records of whaling
Atlantic Arctic fishery – targeting the right whale
the Pacific fishery
– more right whales
s Sperm whale fishery
Quantity of oil in a sperm whale made it an attractive target
Innovation: Possible to make margarine of almost 100 percent whale oil.
Atlantic Northern Right Whale – the right whale because it’s slow, and floats when you kill it. A sinking whale is no use to a hunter.
First whaling mostly Europeans and Scandinavians

2. Sperm Whale (Physeter macrocephalus)
toothed whale. Sperm whales feed mainly on squid, including the giant squid.
Sperm Whales as the epitome of a species that has been K-selected, low birth rate, slow maturation and high longevity.
Females give birth once every four to six years
Spermaceti was much sought after by 18th, 19th and 20th century whalers. The substance found a variety of commercial applications; also produce ambergris, which is like a big ball of mucus and is used widely in perfume. Nice.
Population and hunting
Crude estimates, obtained by surveying small areas and extrapolating the result to all the world's oceans, range from 200,000 to 2,000,000 individuals.

3. 1712 – Americans hunt sperm whale
Americans discover the sperm whale is not impossible to catch, although complicated. When technology increased in the 1860s, they fished out all the near shore whales, then headed for deeper and further waters. Once it became possible to “shoot” a whale with an explosive harpoon, it became worth shooting blue whales and humpbacks as well.
1860 – Norwegians introduce steam-powered boats and explosive harpoons
Factory ships and newer technologies
more species, more oceans, more countries

4. Whales caught and logged between 1910 and 1990

5. Blue whale
Sei whale
Minke whale
Fin whale

6. 1949-1960 – IWC sets annual “fixed” quotas for all whaling
1946
17 nations signed a license where the International Whaling Commission (IWC) set a maximum catch in the Antarctic.
– IWC sets annual “fixed” quotas for all whaling
the United Nations called for a cessation of whaling and the United States Congress passed an Endangered Species Act
whale sanctuaries were declared in the 1970s and ’80s, and a general moratorium on commercial whaling, adopted by the IWC in 1982, took effect in 1987
By WWII, whale numbers had plummeted, and the recognition that regulation was needed became prevalent in the 1930s.
International moratorium on whaling is disputed by the Japanese and Norwegians – aboriginal whaling is still permitted at very low levels, “research” whaling is not actually permitted by IWC, but they can’t do anything about it.

7. Populations III: Harvest Models
Clupea harengus
Odocoileus virginianus
Populations III: Harvest Models
Who can name the organisms?
Harvesting models can be used in many ways
Most visible is fisheries – setting catch quotas, managing stocks
Terrestrial hunting quotas based on same models
Logging forests, planning timber plots
Biocontrol – invasive insect infestations
Oncorhynchus tshawytscha
Pinus sylvestris

8. Review r – intrinsic or per capita growth rate
dN/dt = r*N – exponential growth
Nt=N0*ert
(We’re keeping it discrete)
Nt – population at time t (now)
N0 – initial population at t=0
E = approximately 2.71 – inverse natural log
Rt are the exponent – hence exponential growth
Bye bye fuzzy duckling!!

9. Rabbits in Australia – invasive species can grow exponentially at first

10. Review Logistic growth – S-shaped or sigmoid curve
K – carrying capacity
Modify with “unused” component of K
(K-N)/K = (1-N/K) – used interchangeably
dN/dt = r*N*(1-N/K)
Logistic growth
r=0.25
K=100

11. Review
Ceratotherium simum
Exponential
K=100
Logistic

12. Review
Environmental resistance
Exponential
K=100
Logistic

13. How do we use this information to create harvesting quotas?
Two types of mortality:
Additive – added mortality causes a reduction in survival
any hunting is added mortality
if we want to control a population of invasives
Compensatory – added mortality does not affect survival,
up to a threshold
harvesting/ hunting is mortality “that would have happened anyway” e.g. starvation, predation, disease
We assume that a “compensatory” decrease in non-harvest mortality occurs – perhaps due to extra food availability

14. K Inflection point K/2 Logistic growth r=0.25 K=100
K/2 is the inflection point of the logistic curve – where the curve starts to “slow down” approaching K.

15. MSY = Maximum Sustainable Yield
K/2 K
MSY
K/2 gives us the maximum growth rate – the point at which the most production occurs
MSY – maximum sustainable yield – maximum production point; best yield for the harvest.
Logistic growth
r=0.25
K=100

16. OSY – Optimal Sustainable Yield? ?
K/2 K
MSY h
OSY – not a biological concept – it is the MSY modified by economical, political or gear reasons. If your stock is already depleted, but people rely heavily on it, you can’t just tell them that the season is off; so regulatory agencies create OSYs instead.
Low quota – at high population, this is stable, at low population, unstable.
Logistic growth
r=0.25
K=100
OSY – Optimal Sustainable Yield

17. Problems with setting quotas
Estimating numbers is not easy
hard to obtain reliable MSY
You can’t just stop people that easily
noncompliance is a huge issue
K varies with environment = MSY changes N
Recruitment
MSY? K K K

18. Factors that affect K Density-independent factors
Weather (storms, cold, drought)
Density-independent diseases (DDT poisoning)
Density-dependent factors
Food
Space (territories, denning sites, nest cavities)
Density-dependent epizootics (rabies, SARS)

19. Trophic effects on K – remove large fish, remove fish waste, removes fertilizer, removes smaller fish, up the food chain, less fish to catch

20. Yield = efficiency*Effort*Population
Fixed Effort harvest
H=q*E*N
Yield = efficiency*Effort*Population E2 E1
EMSY
E2 > E1 > EMSY

21. Hindsight always helps – the Allee effect
Low population density is prone to sudden extinction
Fewer mating opportunities; simply too few to be fit enough N
Logistic
dN/dt
Allee model
The assumption that populations are most “fit” closest to extinction proves to be a little problematic in practice.
A decline in fitness, or in per capita population growth rate at low density is called an ALLEE EFFECT. It is named after the ecologist who came up with the idea in the 1930s – Warder Clyde Allee from the University of Chicago.

22. Peruvian anchoveta (Engraulis ringens)
– world’s largest fishery
MSY estimated at 10 million tonnes/year
Expanded fishing fleet plus El Niño events meant collapse
20,000 people relied on it, so politically harmful to close
Repeated collapses – 1973, 1986 – still not recovered.
Makes great fishmeal for fertilizer

24. Making a better model Fish, deer, trees are not all one size or age
We prefer adult or mature organisms
Life-history events – reproduction, growth occur at different times
Next Lecture: life-tables and age-structure