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Fishing, reproductive volume and regulation: population dynamics and exploitation of the eastern Baltic cod

Wikström, Anders LU ; Knape, Jonas; Casini, Michele; Gardmark, Anna; Cardinale, Massimiliano; Hjelm, Joakim and Jonzén, Niclas LU (2016) In Population Ecology 58(1). p.199-211
Abstract
The relative importance of exploitation rate and environmental variability in generating fluctuations of harvested populations is a key issue in academic ecology as well as population management. We studied how the eastern Baltic cod (Gadus morhua) is affected by fishing and environmental variation by using a newly developed single species state-space model. Survey data and auxiliary environmental data were used to estimate the model parameters. The model was then used to predict future development of the eastern Baltic cod under different fishing mortalities and abiotic conditions. Abiotic condition was represented by an index: reproductive volume which is the volume of water suitable (in terms of salinity and oxygen content) for the... (More)
The relative importance of exploitation rate and environmental variability in generating fluctuations of harvested populations is a key issue in academic ecology as well as population management. We studied how the eastern Baltic cod (Gadus morhua) is affected by fishing and environmental variation by using a newly developed single species state-space model. Survey data and auxiliary environmental data were used to estimate the model parameters. The model was then used to predict future development of the eastern Baltic cod under different fishing mortalities and abiotic conditions. Abiotic condition was represented by an index: reproductive volume which is the volume of water suitable (in terms of salinity and oxygen content) for the successful development of the early life stages of Baltic cod. The model included direct density dependence, fishing, and a lagged effect of reproductive volume. Our analysis showed that fishing rate is approximately three times more important than reproductive volume in explaining the population dynamics. Furthermore, our model suggests either under- or over-compensatory dynamics depending on the reproductive volume and long term catch levels. It follows that fishing can either reduce or increase temporal oscillations of the cod stock depending on whether the dynamics is over- or undercompensatory, respectively. The sustainable level of fishing rate is however dependent on reproductive volume. Our model predicts a dual role of fishing rate, stabilizing when reproductive volume is high and destabilizing when it is low. Exploitation rate may therefore increase or decrease the risk of the population of cod dropping below a given biomass reference point depending on the environmental conditions, which has practical implications for fisheries management. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Climate, Harvesting, State-space-model, Stochasticity, Temporal, variation
in
Population Ecology
volume
58
issue
1
pages
199 - 211
publisher
Springer
external identifiers
  • wos:000367807500018
  • scopus:84953638949
ISSN
1438-390X
DOI
10.1007/s10144-015-0520-3
language
English
LU publication?
yes
id
b396d81e-8d9c-400d-93e2-b8e1064ea8f1 (old id 8761366)
date added to LUP
2016-02-22 14:38:16
date last changed
2017-10-08 03:14:00
@article{b396d81e-8d9c-400d-93e2-b8e1064ea8f1,
  abstract     = {The relative importance of exploitation rate and environmental variability in generating fluctuations of harvested populations is a key issue in academic ecology as well as population management. We studied how the eastern Baltic cod (Gadus morhua) is affected by fishing and environmental variation by using a newly developed single species state-space model. Survey data and auxiliary environmental data were used to estimate the model parameters. The model was then used to predict future development of the eastern Baltic cod under different fishing mortalities and abiotic conditions. Abiotic condition was represented by an index: reproductive volume which is the volume of water suitable (in terms of salinity and oxygen content) for the successful development of the early life stages of Baltic cod. The model included direct density dependence, fishing, and a lagged effect of reproductive volume. Our analysis showed that fishing rate is approximately three times more important than reproductive volume in explaining the population dynamics. Furthermore, our model suggests either under- or over-compensatory dynamics depending on the reproductive volume and long term catch levels. It follows that fishing can either reduce or increase temporal oscillations of the cod stock depending on whether the dynamics is over- or undercompensatory, respectively. The sustainable level of fishing rate is however dependent on reproductive volume. Our model predicts a dual role of fishing rate, stabilizing when reproductive volume is high and destabilizing when it is low. Exploitation rate may therefore increase or decrease the risk of the population of cod dropping below a given biomass reference point depending on the environmental conditions, which has practical implications for fisheries management.},
  author       = {Wikström, Anders and Knape, Jonas and Casini, Michele and Gardmark, Anna and Cardinale, Massimiliano and Hjelm, Joakim and Jonzén, Niclas},
  issn         = {1438-390X},
  keyword      = {Climate,Harvesting,State-space-model,Stochasticity,Temporal,variation},
  language     = {eng},
  number       = {1},
  pages        = {199--211},
  publisher    = {Springer},
  series       = {Population Ecology},
  title        = {Fishing, reproductive volume and regulation: population dynamics and exploitation of the eastern Baltic cod},
  url          = {http://dx.doi.org/10.1007/s10144-015-0520-3},
  volume       = {58},
  year         = {2016},
}