Reviews in Fish Biology and Fisheries 11: 95–111, 2002.
© 2002 Kluwer Academic Publishers. Printed in the Netherlands.
Recruitment models: diagnosis and prognosis
Coby L. Needle
FRS Marine Laboratory, PO Box 101, Victoria Road Aberdeen, AB11 9DB Scotland
Accepted 12 November 2001
Abstract page 95
Recruitment modeling 95
Uses and abuses of recruitment models 96
The purpose of recruitment modeling
The uses of recruitment models in ﬁsheries management
Choices and problems 101
Problems with stock-recruitment models
Ongoing research directions 106
The need for improvement
Some current approaches
An atttainable solution?
Key words: ﬁsheries, models, recruitment
Probabilistic projections of future ﬁsh population dynamics and the determination of many management reference
points are both driven by ﬁshery recruitment models. In turn, these projections and reference points largely govern
perceptions of the likely response of a population to ﬁshery management action. Hence, recruitment modeling
is a vital component of stock assessment as carried out for the purposes of strategic ﬁsheries management. This
review presents a synopsis of the types of recruitment model that are currently utilised in stock assessments, the
reasons that certain models are habitually selected and the problems inherent in their use, and some of the key
ongoing research efforts that are attempting to improve the validity of recruitment models. The need for increased
multidisciplinary symbiosis in the development of recruitment models is emphasized.
“The most important and generally most difﬁcult
problem in biological assessment of ﬁsheries is
the relationship between stock and recruitment ...
Fisheries managers simply cannot ignore the fact
that if you ﬁsh hard enough on any stock, you will
reduce recruitment” (Hilborn and Walters, 1992,
Fish are a ﬁnite resource. Unlike farmers or foresters,
marine ﬁshermen can do little to replace or reju-
venate the stock that has been removed by ﬁshing,
and must rely on the natural ability of the ﬁsh popu-
not, and whether recruitment (that is, the number of
young entering the ﬁshed population) will be enough
to meet the demands of the ﬁshery in the medium- to
long-term, are the subjects of recruitment modeling.