Testing spatial heterogeneity with stock assessment models
|Author(s)||Jardim Ernesto1, Eero Margit2, Silva Alexandra3, Ulrich Clara2, Pawlowski Lionel4, Holmes Steven J.1, Ibaibarriaga Leire5, de Oliveir Jose A. A. A.6, Riveiro Isabel7, Alzorriz Nekane1, Citores Leire5, 9, Scott Finlay1, Uriarte Andres8, Carrera Pablo7, Duhamel Erwan4, Mosqueira Iago1|
|Affiliation(s)||1 : European Commiss, JRC, Via Enrico Fermi 2749, I-21027 Ispra, VA, Italy.
2 : Tech Univ Denmark DTU AQUA, Natl Inst Aquat Resources, Charlottenlund, Denmark.
3 : IPMA, Av Dr Alfredo Magalhaes Ramalho 6, P-1449006 Lisbon, Portugal.
4 : IFREMER, Lab Technol & Biol Halieut, 8 Rue Francois Toullec, F-56100 Lorient, France.
5 : AZTI Tecnalia, Marine Res Div, Sukarrieta 48395, Bizkaia, Spain.
6 : CEFAS, Lowestoft Lab, Pakefield Rd, Lowestoft NR33 0HT, Suffolk, England.
7 : IEO, Ctr Oceanog Vigo, Subida Radio Faro 50, Vigo 36390, Spain.
8 : AZTI Tecnalia, Marine Res Div, Pasaia 20110, Gipuzkoa, Spain.
9 : BCAM, Mazarredo 14, E-48009 Bilbao, Basque Country, Spain.
|Source||Plos One (1932-6203) (Public Library Science), 2018-01 , Vol. 13 , N. 1 , P. e0190791 (1-23)|
|WOS© Times Cited||7|
This paper describes a methodology that combines meta-population theory and stock assessment models to gain insights about spatial heterogeneity of the meta-population in an operational time frame. The methodology was tested with stochastic simulations for different degrees of connectivity between sub-populations and applied to two case studies, North Sea cod (Gadus morua) and Northeast Atlantic sardine (Sardina pilchardus). Considering that the biological components of a population can be partitioned into discrete spatial units, we extended this idea into a property of additivity of sub-population abundances. If the additivity results hold true for putative sub-populations, then assessment results based on sub-populations will provide information to develop and monitor the implementation of finer scale/local management. The simulation study confirmed that when sub-populations are independent and not too heterogeneous with regards to productivity, the sum of stock assessment model estimates of sub-populations’ SSB is similar to the SSB estimates of the meta-population. It also showed that a strong diffusion process can be detected and that the stronger the connection between SSB and recruitment, the better the diffusion process will be detected. On the other hand it showed that weak to moderate diffusion processes are not easy to identify and large differences between sub-populations productivities may be confounded with weak diffusion processes. The application to North Sea cod and Atlantic sardine exemplified how much insight can be gained. In both cases the results obtained were sufficiently robust to support the regional analysis