Milner Baily Schaefer

Milner Baily ("Benny") Schaefer was born in Cheyenne, Wyoming, in 1912 and died at the age of 57 in San Diego, California in 1970. He is notable for his work on the population dynamics of fisheries.

Schaefer worked as a biologist at the Washington State Fisheries Department and from 1937-1942 as a scientist for the International Pacific Salmon Fisheries Commission in New Westminster, British Columbia, Canada. In 1946 he joined the United States Fish and Wildlife Service and held various posts at the Fishery Biology Headquarters at Stanford University. Later, he worked at the Pacific Oceanic Fisheries Investigations Laboratory in Honolulu, Hawaii and completed a doctorate in fisheries from the University of Washington in 1950. In 1951 Schaefer became Director of Investigations at the Inter-American Tropical Tuna Commission (IATTC). IATTC established its first headquarters at the Scripps Institution of Oceanography.

Schaefer short-term catch equation

During his period at the IATTC, Schaefer worked on the development of theories of fishery dynamics and published a fishery equilibrium model based on the Verhulst population growth model and an assumption of a bi-linear catch equation, often referred to as the Schaefer short-term catch equation:

$H(E,X)=q E X\!$

where the variables are; H, referring to catch (harvest) over a given period of time (e.g. a year); E, the fishing effort over the given period; X, the fish stock biomass at the beginning of the period (or the average biomass), and the parameter q represents the catchability of the stock. Assuming the catch to equal the net natural growth in the population over the same period ($\dot{X}=0$), the equilibrium catch is a function of the long term fishing effort E:

$H(E)=q K E (1-\frac{qE}{r})$

r and K being biological parameters representing intrinsic growth rate and natural equilibrium biomass respectively.

Schaefer published during the 1950s a range of papers of empirical studies based on the model. Other researchers also soon saw the potential of developing the model tools further into bioeconomic studies.

References

• Day, Deborah Cozort (1982) Guide to the papers of Milner Baily Schaefer (1912-1970). Archives of the Scripps Institution of Oceanography (SIO Reference series).

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Name	Schaefer, Milner Baily
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Date of birth	1912
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Date of death	1970
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