UNCOVER

1. UNCOVER WP 3: Trophodynamic control of stock dynamics Jens Floeter

2. WP 3: Trophodynamic control of stock dynamics

3. PAN-REGIONAL • Objectives • To identifythe physical and biological key processes that lead to historic changes in food webs • To quantifyhistorical changes in food web fluxes and trends in stock sizes • To estimate the impact of local high-intensity predation events on survival rates • To enhance the predictive capabilities of deterministic and stochastic ecosystem and multi-species assessment models • To predict the impact of trophic control, exerted by both direct and indirect predation under contrasting environmental and fishing regimes, on stock recovery paths. • Key output • a) Quantification of multi-species interactions by enhanced MS-Models • b) Estimation of how trophic controls will influence stock recoveries.

4. PAN-REGIONAL • Trophodynamic control of stock dynamics • What is it all about ? • Direct predatory effects • Indirect predatory effects

5. What`s it all about ? PAN-REGIONAL • Direct predatory effects • other species predate on early life stages and juveniles of recovery species • Barents Sea: Herring preys on capelin larvae • North Sea: Grey gurnard preys on cod juveniles • Baltic Sea: Cod preys on sprat and herring • cannibalism • Barents Sea: Cod • North Sea: Cod • Baltic Sea: Cod Sprat • Bay of Biscay: Hake

6. What`s it all about ? PAN-REGIONAL • Indirect predatory effects • predators affect prey of recovery species • Barents Sea: Herring preys on capelin larvae, main prey for cod • North Sea: Low pelagic sandeel recruitment due to predation by herring & mackerels ? affecting gadoids ? • Baltic Sea: Sprat preys on Pseudocalanus, which is an important prey for cod • predators affect a prey which is a predator on recovery species • North Sea: Gurnard preys on whiting, which preys on cod • Baltic Sea: Cod preys on sprat, which preys on cod eggs • depletion of alternative prey species increases the predation pressure on recovery species • Barents Sea: Low capelin stock – higher cod cannibalism • North Sea: Low pelagic fish biomass lead to increase in predation • on juvenile gadoids ? • Bay of Biscay: Low prey stocks lead to higher hake cannibalism ?

7. What`s it all about ? PAN-REGIONAL This addresses: • direct predatory effects (prey acts as predator on recovery species) • triangular predatory effects (predator affects prey which acts as predator on recovery species) • triangular competitatory effects (predator affects prey for recovery species) • cannibalism as density dependent regulatory mechanism There is clear evidence that these processes act at different scales, have a strong influence on stock recovery potentials, and that their magnitudes of impact often depend on the prevailing environmental conditions.

8. WP 3 Overall Structure PAN-REGIONAL • Task 3.1. Description of changes in entire food web structure. • Review changes in entire food web structures and fluxes • Deliverable • Review of the key physical and biological processes associated withslow or sudden historic changes in food webs and how these processes affect the potential for future stock recoveries (month 8).

9. WP 3 Overall Structure PAN-REGIONAL • Task 3.2 Resolution of switches in predatory control. • Analyse direct and indirect predation effects on recruitment in relation to their environmental dependence and spatio-temporal scale • Gained mechanistic understanding will provide enhanced process models • Deliverable • Time series of historical changes in food web fluxes and trends in stock sizes via application of improved deterministic and stochastic ecosystem and multi-species models (month 40). • Prediction of the impact of trophic control, exerted by direct and indirect species interactions under contrasting environmental and mixed-fishing regimes, on stock recovery paths (month 44).

10. WP 3 Overall Structure PAN-REGIONAL • Task 3.3 Determination of mesoscale predator-prey interactions impacting on population dynamics. • Develop appropriate methods to take small-scale, high-intensity predation events on early and juvenile life stages of target species into account • Use simulation models • Implement methods in large-scale, multi- species fisheries assessment models. • Deliverable • Methods to implement predation on early life stages and small-scale, high-intensity predation process within large-scale, multi-species models (month 36).

11. WP 3 Overall Structure PAN-REGIONAL WP 3 Person months & contributing partners 115 Person months ~ 18 % of total

12. Case Study 1: Cod and herring in the Barents/Norwegian Sea REGIONAL • Task 3.1. Description of changes in entire food web structure. • Fit GADGET & STOCOBAR* to historical data for cod, herring and capelin • Cod stomach data from 1984-present (IMR & PINRO) • Average of 9000 stomachs of cod sampled annually • BECAUSE will produce a Gadget model for cod, capelin, herring and minke whale (February 2007). *) STOCOBAR is a single-area multi-species model focusing on predation by cod and the effect of prey consumption on cod growth

13. Case Study 1: Cod and herring in the Barents/Norwegian Sea REGIONAL • Task 3.2. Resolution of switches in predatory control. • 1) Description of temporal and spatial changes in predation by cod

14. Case Study 1: Cod and herring in the Barents/Norwegian Sea REGIONAL • Task 3.2. Resolution of switches in predatory control. • Predation by cod on cod, capelin and herring including variation in space and time has been described by several authors, e.g. Bogstad et al. 1994 (cod), Bogstad and Gjøsæter (1998), Johansen (2003) (and Russian studies) • These studies will be reviewed using updated data • There is also a long time series, starting in 1947 of qualitative (frequency of occurrence, degree of fullness) Russian stomach content data for cod. •  These data will be used to enhance the understanding of the temporal and spatial changes in the predation by cod.

15. Case Study 1: Cod and herring in the Barents/Norwegian Sea REGIONAL • Task 3.2. Resolution of switches in predatory control. • Formulate stochastic SSB-R relationships for these species necessary for stock predictions • Validate and enhance process models for predation by cod in GADGET & STOCOBAR • Area definition (only Gadget) • Other food modelling • Prey switching formulation • Predator size/prey size preference model • Dependence of stock dynamics and growth rate, skipped spawning and cannibalism level of cod with food supply, water temperature and stock size (only Stocobar) •  TEST of Model Robustness

16. Case Study 1: Cod and herring in the Barents/Norwegian Sea REGIONAL • Task 3.3. Determination of mesoscale predator-prey interactions impacting on population dynamics. • PINRO • Study the frequency of occurrence of feeding hot spots in the Barents Sea. (data analysis) • Investigate whether the temporal scale used in the STOCOBAR model is appropriate

17. Task Expectedresults Participating Institution /Responsible Scientist Case Study 1: Cod and herring in the Barents/Norwegian Sea REGIONAL

18. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL Task 3.1 Description of changes in entire food web structure Key output a) Review on physical and biological key processes that lead to slow and sudden historic changes in the North Sea food web and how these affect future stock recovery potentials Literature Review .

19. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL • Task • 3.1 Description of changes in entire food web structure • Key output • b) Reconstruction of historical changes in the North Sea food web using ecosystem (ECOSIM), multispecies models (M4, SMS) and quantitative conceptual food web models •  4M / SMS hindcast runs •  identify typical system states • gadoid outburst • before the late 80´ies regime shift • new emerging predators (e.g. grey gurnard) • recovering predator stocks (e.g. mackerel) • declining of forage fish stocks (sandeel, Norway pout) •  define years of the time series which are representative for specific ecosystem states and use them as input to scenario predictions • .

20. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL Task 3.1 Description of changes in entire food web structure Key output b) Reconstruction of historical changes in the North Sea food web using ecosystem (ECOSIM), multispecies models (M4, SMS) and quantitative conceptual food web models  An existing Ecopath with Ecosim (EwE) model of the North Sea in 1991 will be used to reconstruct past abundances of species by fitting the 1991 model to stock assessment and CPUE indices from 1999-2004.  By treating the various processes and relationships as alternative assumptions, the reconstruction will evaluate how each contributes to explaining past patterns  ‘backward’ fitting where the 1991 model will be fit retrospectively to data prior to 1991. Changes in the North Sea food web due to the combined effects of human impact and environmental forcing at different stages of the hindcast time series will be analysed. .

21. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL Task 3.1 Description of changes in entire food web structure Key output b) Reconstruction of historical changes in the North Sea food web Assess the abundance and composition of the entire fish assemblage (i.e., target and non-target species), to estimate the gross production and fluxes occurring in the fish-ecosystem as a whole.  Pulling out the role of cod plaice and herring in the food web rather than aggregating to gross feeding groups. (Mike Heath, FRS) The methodology for how to integrate assessment data, landings, surveys, temperature and stomach data to calculate food web fluxes is established. However, the method needs enhancements regarding the assumption of a fixed diet composition for each species over time. This assumption will be overcome by developing a diet selection sub-model that takes the spatio-temporal coincidence of pretaor and prey into account. A focus will be on how to parameterise this sub-model in a spatially aggregated representation of the system. A technical issue concerns the analysis of species-specific catchabilities in trawl survey data. Diet and consumption data for key taxa in the system are to a large extent available from previous projects (MAFCONS, and ERSEM) but need an update. Species abundance and diet and consumption will be aggregated into functional groups, but key target species will be parameterized separately. The focus is on regime shifts in the food web fluxes caused, for example by the northerly shift in the distribution of horse mackerel and assess their implications for cod, herring and sandeel recruitment success in the North Sea.

22. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL Task 3.1 Description of changes in entire food web structure Key output c) Predict cod and plaice recovery paths and stock dynamics of their predator and prey species under different environmental and fishery scenarios using ecosystem (ECOSIM) and multispecies models (M4, SMS)  4M/SMS scenario predictions using the identified historic systems states as starting points  Evaluation of the effect of F-changes in various system states on medium term cod & herring stock development  Evaluation of existing cod recovery plans with 4M/SMS  Sensitivity analysis on recovery potentials of gadoids in the North Sea for different environmental frameworks and different parameterizations of process sub models (functional response, spatial predator prey overlap)  Formulation of management options taking multi species interactions and environmental variability into account  Input to WP4 & 5. .

23. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL Task 3.1 Description of changes in entire food web structure Key output c) Predict cod and plaice recovery paths and stock dynamics of their predator and prey species under different environmental and fishery scenarios using ecosystem (ECOSIM) and multispecies models (M4, SMS)  Explore alternative pathways for the future recovery of specific stocks and consequent biomass trajectories of other stocks using ECOSIM  Sensitivities of the predictions to model structure and parameter specification will be evaluated.  Comparison of ECOSIM and 4M/SMS results .

24. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL Task Task 3.2 Resolution of switches in predatory control. Key output a) Investigate temporal and spatial changes in direct and indirect predatory effects on cod, plaice and herring interacting with their prey and predator species. Develop and validate process sub-models for these critical interactions, which enable predictions covering periods of regime shifts. Models (4M, SMS) b) Enhanced multi species fisheries assessment models including validated process sub-models  Development of enhances predator-prey overlap process models  Address climate variation and stock size effects  Implementation of these into 4M/SMS .

25. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL Task Task 3.2 Resolution of switches in predatory control. Key output a) Investigate temporal and spatial changes in direct and indirect predatory effects on cod, plaice and herring interacting with their prey and predator species. Develop and validate process sub-models for these critical interactions, which enable predictions covering periods of regime shifts. Models (4M, SMS)  RIVO Case Study: Herring predation on cod eggs in southern North Sea New field data available .

26. Case Study 2: Cod, plaice and herring in the North Sea REGIONAL Task Task 3.3 Determination of mesoscale predator-prey interactions impacting on population dynamics Key output a) Review and simulation of the impact of local feeding hot spots on the basin-wide mortality of early and juvenile life stages of North Sea cod and whiting. Development of methods to realistically implement these local high-intensity processes in multispecies models.  Review of existing case study data sets (IBTS, GSBTS)  Develop appropriate methods to take small-scale, high-intensity predation events on early and juvenile life stages of target species into account when using large scale single area models.  Implementation of predation hot spot-effects into 4M/SMS .

27. Task Expectedresults Participating Institution /Responsible Scientist Case Study 2: Cod, plaice and herring in the North Sea REGIONAL

28. Case Study 3: Cod and sprat in the Central Baltic Sea REGIONAL • Task • Task 3.1 Description of changes in entire food web structure. • Key output • Review of key environmental and trophodynamic processes responsible for a regime shift in the Central Baltic ecosystem and a reconstruction of historical changes using ecosystem (ECOSIM) and multispecies models (M4, SMS) • Review of hydrography (water temperature and salinity) processes and fishery influencing on the regime shift in the South-Eastern Baltic and a reconstruction of historical changes. • Causal description of changes in food web structure in the South-Eastern Baltic on basis of 73060 stomachs, collected during 1992-2005. • Analyse time series data on ichthyoplankton abundance and production in relation to environmental forcing and predator abundance in order to resolve processes related to the regime shift in the Baltic Sea.

29. Case Study 3: Cod and sprat in the Central Baltic Sea REGIONAL • Task • Task 3.1 Description of changes in entire food web structure. • Key output • Review of key environmental and trophodynamic processes responsible for a regime shift in the Central Baltic ecosystem and a reconstruction of historical changes using ecosystem (ECOSIM) and multispecies models (M4, SMS) • Provide an updated, area disaggregated MSVPA run for the Central Baltic Sea in order to resolve changes in large scale abundance and distribution of Baltic cod, sprat and herring. • ECOSIM model

30. Case Study 3: Cod and sprat in the Central Baltic Sea REGIONAL • Task • Task 3.1 Description of changes in entire food web structure. • Key output • Predict cod recovery paths and sprat stock dynamics under different environmental and fishery scenarios using ecosystem (ECOSIM) and multispecies models (M4, SMS) ) • Gadoid recovery scenarios will be carried out with 4M/SMS for different future fishing strategies (including HCRs) and environmental scenarios. • ECOSIM model environmental scenario predictions of cod, herring & sprat • ??? !!!Scenenario modelling using ISIS fish model (as established in the frame of PROTECT to simulate MPA effects)??? !!! IfM-Geomar - IFREMER

31. Case Study 3: Cod and sprat in the Central Baltic Sea REGIONAL • Task • Task 3.2 Resolution of switches in predatory control . • Key output • Identification of temporal and spatial changes in predation pressure of cod on sprat, sprat on cod eggs, sprat on Pseudocalanus sp., and cod and sprat cannibalism. Develop and validate process-models for above critical interactions, which enable predictions of regime shifts • Predation on sprat: Provide process models on vertical distribution of cod and sprat to quantify predator prey overlap • Predation on cod eggs: Provide data on abundance and distribution of cod eggs, and sprat from area-disaggregated MSVPA and hydroacoustics • Cannibalism: provide sprat egg abundance and distribution patterns, area dis-aggregated cod and sprat stock sizes • Validation of existing and developed process sub-models by new data on meso- zooplankton structure, diet composition and food intake of sprat available from the national projects. • Implementation of enhanced process models into 4M/SMS

32. Case Study 3: Cod and sprat in the Central Baltic Sea REGIONAL • Task • Task 3.3 Determination of mesoscale predator-prey interactions impacting on population dynamics. • Key output • Review and simulation of the impact of local feeding hot spots on the basin-wide mortality of cod eggs by sprat predation as well as cod cannibalism • Impact analysis • The objectives of the impact analysis are to answer the following questions with respect to predation on 0-group cod in the Baltic Sea. • 1) What is the frequency of occurrence of feeding hot spots in existing data bases ? • 2) What is the probability to detect feeding hot spots in a routine large scale survey ? • 3) What is the frequency of occurrence of feeding hot spots in reality ? • Identification of local feeding hot spots in Gdansk Basin with small-scale, high-intensity predation events on early and juvenile life stages of target species in relation to key local physical processes and Basin-wide hydrography. • Development of a size- structured, dynamic and spatial individual based explorative simulation model, parameterized to the Baltic Sea ecosystem (in cooperation with IHF).

33. Task Expectedresults Participating Institution /Responsible Scientist Case Study 3: Cod and sprat in the Central Baltic Sea REGIONAL

34. Case Study 4: Hake and anchovy in the Bay of Biscay REGIONAL • Task • Task 3.1 Description of changes in entire food web structure. • Key output • Review on physical and biological key processes that lead to slow and sudden historic changes in the Bay of Biscay food web and how these affect future stock recovery potentials • Literature Review ? • Analyse, update and enhance diet data base for GADGET • Reconstruct past changes in ecosystem by fitting model predictions to • observed changes in the relative abundance of species. • The GADGET model will be fitted to historical data producing parameter • estimates for the process models used. As part of the fitting process, the • relative importance of different processes (single-species population • dynamics, fisheries, species interactions)inreconstructing the past • population dynamics for hake will be explored

35. Case Study 4: Hake and anchovy in the Bay of Biscay REGIONAL • Task • Task 3.2 Resolution of switches in predatory control. • Key output • Influence of temporal changes in the abundance of some juvenile hake preys (anchovy, horse mackerel, silvery pout and hake) in its diet composition and their influence on hake and anchovy dynamics using multispecies models (Gadget) • The hypothesis to investigate is: • The availability of hake prey fish has a signficant impact on the level of hake cannibalism. • Improve the BoB and IP GADGET model developed in BECAUSE • * Extend the information in GADGET for anchovy • * Improve the information in GADGET for hake diet and consumption •   * Diet and consumption data for Hake from the IEO • * Anchovy French datasets for GADGET • * Horse Mackerel datasets for GADGET • * If not available data will be used from ICES assessment Working Groups for Horse Mackerel, Anchovy and Blue Whiting.

36. Task Expectedresults Participating Institution /Responsible Scientist Case Study 4: Hake and anchovy in the Bay of Biscay REGIONAL

37. WP 3 – Task – Partner – Matrix

38. Thanks for listening !