Cod and fmounder (seasonal) habitat mapping Berthe Vastenhoud - - PowerPoint PPT Presentation
Cod and fmounder (seasonal) habitat mapping Berthe Vastenhoud Alexandros Kokkalis Sofja Ferreira Elliot Brown Josianne G. Stturup 12 December 2018 Map fjsh habitats to contribute to the FishHab II project knowledge basis for Maritjme
Berthe Vastenhoud Alexandros Kokkalis Sofja Ferreira Elliot Brown Josianne G. Støturup
12 December 2018
Map fjsh habitats to contribute to the knowledge basis for Maritjme Spatjal Planning 10 commercially important species in the inner Danish waters
Mapping of habitats Explore seasonality of the spatjal distributjons, relatjve to life stage (juvenile, adult) habitats
KASU dataset
Sampled twice a year Q1 : February/March Q4 : October/November/December
Danish part of Baltjc Internatjonal Trawl Survey (BITS)
SEASONAL DISTRIBUTIONS
Fitued maturatjon ogive Additjonal sampling campaign in 2016 (Q3) 2005 – 2015: checked to validate 2016
6 maturity stages
1. Virgin - Immature 2. Maturing - Mature 3. Spawning - Mature 4. Spent - Mature 5. Restjng- Mature 6. Abnormal - Mature Separate analysis juveniles/adults
Habitat distributjon models:
habitats
Main model including all possible (environmental) variables, reduce stepwise removing the least signifjcant variable untjl all are signifjcant
Generalised Additjve Models (GAMs)
(Separate models for juveniles and adults) Environmental factors
Spatjotemporal factors
Ofgset efgort Number of individuals
Results - Adults
Quantjles: cut points dividing the range of observatjons into intervals with equal probabilitjes
Signifjcant variables:
Uncertainty - Adults
Declining stock: many of the earlier spawning sites are no longer observed & changed to:
Sound
(Vitale et al., 2008; Börjesson et al., 2013)
Spawning: Q1 (& Q2)
in the Katuegat and the Sound
Skälderviken and Laholmsbugten
Western Baltjc stock: Kiel Bight
Can we use 2016 as an example for other years?
Model for 2005-2015 Similar selectjon process to 2016 model Predict numbers at statjons in 2016
Compare
Average of weighted positjon coordinates of the distributed mass
Dispersion of weighted point observatjons along two
Signifjcant environmental variables:
Results - Juveniles
Uncertainty - Juveniles
Results - Juveniles
Associated to habitats that provide refuge (greater structural complexity than sand/mud)
substrate/mixed sediment
improved
Other studies:
Can we use 2016 as an example for other years?
Compare
Average of weighted positjon coordinates of the distributed mass
Dispersion of weighted point observatjons along two orthogonal axes
Adults vs. Juveniles ADULTS JUVENILES
What has been done?
Next steps
Results - Adults
Quantjles: cut points dividing the range of observatjons into intervals with equal probabilitjes
Signifjcant variables:
Uncertainty - Adults
Signifjcant variables:
Results - Juveniles
Uncertainty - Juveniles