Abstract
Demographic analyses can be quite useful for effectively managing elasmobranch fisheries.
However, they require valid estimates of age-specific mortality and natality rates, in addition
to information on the distribution, abundance, habits and reproduction of the population, to
produce reliable estimates of population growth. Because such detailed ecological information
is usually unavailable, complete demographic analyses have been completed for only four shark
species: the spiny dogfish, Squalus acanthias; the soupfin shark, Galeorhinus australis; the lemon
shark, Negaprion brevirostris; and most recently the sandbar shark, Carcharhinus plumbeus.
In California, reliable estimates of age, growth, mortality, age at maturity, and fecundity are
available only for the leopard shark, Triakis semifasciata. A demographic analysis of this
species yielded a net reproductive rate (Ro) of 4.467, a generation time (G) of 22.35 years,
and an estimate of the instantaneous population growth coefficient (r) of 0.067. If the mean
fishing pressure over 10 years (F= 0.084) is included in the survivorship function, Ro and r
are reduced considerably, especially if leopard sharks first enter the fishery at early ages.
A size limit of 120 cm TL (estimated age 13 years), especially for female sharks, is tentatively
proposed for the leopard shark fishery.
Subject
Ecology,Aquatic Science,Ecology, Evolution, Behavior and Systematics,Oceanography
Cited by
42 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献