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Comparing size-limit strategies for exploitation of a self-thinned stream fish population

Nordwall, F; Lundberg, Per LU and Eriksson, T (2000) In Fisheries Management and Ecology 7(5). p.413-424
Abstract
There is increasing evidence that territorial stream fish populations exhibit some degree of self-thinning. Four size-limit strategies were examined, under which a size-structured model population exhibiting self-thinning was exploited. The effects of: (1) increased minimum-size limits; (2) protection of spawners; (3) decreasing maximum-size limits; and (4) slot limits (prescribe lower and upper size limits of fish that must be released) were analysed in terms of population size and mean body size in the population after harvest. Biomass and numbers harvested, mean size of fish taken and proportions of different sizes in the population after harvesting were also analysed. Combinations of high exploitation rates and high minimum-size limits... (More)
There is increasing evidence that territorial stream fish populations exhibit some degree of self-thinning. Four size-limit strategies were examined, under which a size-structured model population exhibiting self-thinning was exploited. The effects of: (1) increased minimum-size limits; (2) protection of spawners; (3) decreasing maximum-size limits; and (4) slot limits (prescribe lower and upper size limits of fish that must be released) were analysed in terms of population size and mean body size in the population after harvest. Biomass and numbers harvested, mean size of fish taken and proportions of different sizes in the population after harvesting were also analysed. Combinations of high exploitation rates and high minimum-size limits maximized both the number and biomass harvested while it favoured post-harvest abundance and the proportion of larger sizes in the population. When harvest rates and minimum-sizes were increased, the combinations of these that maintained or increased yield were successively narrowed. Protection of spawners and slot limits did not come close to reaching the levels of post-harvest abundance, yield, positive size structure and endpoints of harvest rates that were obtained with a high minimum size applied to the fishery. Maximum-size limits favoured the abundance of smaller size-classes. The results emphasize the advantages of setting the largest sizes of fish in the population as a minimum size that can legally be retained. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Fisheries Management and Ecology
volume
7
issue
5
pages
413 - 424
publisher
Wiley-Blackwell
external identifiers
  • scopus:0033778947
ISSN
0969-997X
DOI
10.1046/j.1365-2400.2000.00227.x
language
English
LU publication?
yes
id
e7588b54-503e-48df-b301-27b74d953999 (old id 147577)
date added to LUP
2007-07-03 15:00:16
date last changed
2017-01-01 07:07:42
@article{e7588b54-503e-48df-b301-27b74d953999,
  abstract     = {There is increasing evidence that territorial stream fish populations exhibit some degree of self-thinning. Four size-limit strategies were examined, under which a size-structured model population exhibiting self-thinning was exploited. The effects of: (1) increased minimum-size limits; (2) protection of spawners; (3) decreasing maximum-size limits; and (4) slot limits (prescribe lower and upper size limits of fish that must be released) were analysed in terms of population size and mean body size in the population after harvest. Biomass and numbers harvested, mean size of fish taken and proportions of different sizes in the population after harvesting were also analysed. Combinations of high exploitation rates and high minimum-size limits maximized both the number and biomass harvested while it favoured post-harvest abundance and the proportion of larger sizes in the population. When harvest rates and minimum-sizes were increased, the combinations of these that maintained or increased yield were successively narrowed. Protection of spawners and slot limits did not come close to reaching the levels of post-harvest abundance, yield, positive size structure and endpoints of harvest rates that were obtained with a high minimum size applied to the fishery. Maximum-size limits favoured the abundance of smaller size-classes. The results emphasize the advantages of setting the largest sizes of fish in the population as a minimum size that can legally be retained.},
  author       = {Nordwall, F and Lundberg, Per and Eriksson, T},
  issn         = {0969-997X},
  language     = {eng},
  number       = {5},
  pages        = {413--424},
  publisher    = {Wiley-Blackwell},
  series       = {Fisheries Management and Ecology},
  title        = {Comparing size-limit strategies for exploitation of a self-thinned stream fish population},
  url          = {http://dx.doi.org/10.1046/j.1365-2400.2000.00227.x},
  volume       = {7},
  year         = {2000},
}