Nutritional status of seals

The concept of using body condition of seals as core indicator for GES within Helcom is based on

- Blubber thickness is a commonly used indicator for the nutritional state of marine mammals

- The blubber (energy reserve) is important for survival of the individual and in females also for the survival of their offspring

- Changes in blubber thickness may be affected also by other stressors than prey depletion or poor quality of prey, such as contamination and disturbances affecting foraging

- top predator, highly exposed to persistent chemicals- sensitive for ecological changes in the fish communities- during the last decade, juvenile grey seals are leaner than earlier

Nutritional status of seals

• Blubber thickness, measured at sternum between skin and muscle

Blubber thickness in 1-3 year old grey seals

1993-2001 (N=21)

2002-2004 (N=39)

2005-2007 (N=69)

2008-2010 (N=38)

2011-2012 (N=32)

2010-2012 (N=17)

0

5

10

15

20

25

30

35

40

45

Hunt

Bycaught

GES

Hunt Finland

Bycaught Finland

GM mm

Nutritional status of seals

Stage of development Indicator type

Core State

Primary importance Secondary importanceBSAPSegment and Objective

Biodiversity- Healthy wildlife

Biodiversity:- Thriving and balanced communities of plants and animals- Viable populations of species

MSFD Descriptors and Criteria

D1. Biodiversity D1.3. Population condition

D1. Biodiversity D1.1 Species distribution (range, pattern, covered area) D1.2 Population size (abundance, biomass)D4. Food webs D4.1. Productivity of key species or trophic groups D4.3 Abundance/distribution of key trophic groups/speciesD8. Contaminants D8.2. Effects of contaminants

Other relevant legislation: WFD - Chemical quality, Habitat directive

Legislative linkage:

Nutritional status of seals

Concept/design

Coordinated monitoring Assessment

Research needs for operationalization (in

relation to needs stated under the

coordinated monitoring and

assessment columns)

Data arrangements

Monitoring strategy (method, frequency, spatial resolution) in relation to relevant indicator parameters Technical guidelines Geographic scale

Assessment method

GES / assessment criteria(currently all GES are provisional)

A ) in placeB) under developmentC ) not available, what needs - action level?

A ) monitoring in placeB ) monitoring needs revisionC ) monitoring not available, what needs - action level?

A ) in placeB ) needs revision, what needs doingC ) not available, what needs - action level?

HELCOM assessment units:A ) identifiedB) Identified not describedC) not identified, what needs - action level?

A ) available and describedB ) available not describedC ) not available, what needs - action level?

A ) proposed and describedB ) proposed but needs more supporting dataC ) not available, what needs - action level?

A ) in placeB ) needs revision, what needs doingC ) not available, what needs - action level?

B - relation between pressures and blubber thickness needs elaboration - TM

B- Time of year for measurements under conceptual discussion - task manager. Measurement during autumn decided for ringed and grey seals - ad hoc seal expert group

B - clarificaiton on sampling time needed - TM

B - currently does not cover entire Baltic Sea, assessment units to be clarified - TM

B - data pooling for valid assessments and other technical aspects need development - TM

B - suggested levels need more support - TM

Data collection procedures for all relevant species should be improved and ultimately operationalized

B - data submission arrangements to be incoorporated into the indicator to be discussed, preliminary strategy and schedual agreed among experts - TM, HELCOM

B – no change B- TMs discussed to start with juveniles 1-3 year olds and continue with adults next operationalization period. Time of year for measurements under conceptual discussion – TM

B – no change B -Proposal to remove the indicator from the core list in Latvia and Lithuania.

Indicator is not in use, but indicator should be kept in core list for EstoniaIt may be enough if some countries are monitoring the mobile species

B – no change B – no change No change B – no change

Curr

ent

situ

ation

(action level = who needs to complete the task)

Begi

nnin

g of

CO

RESE

T II

Nutritional status of seals - GES

• Bäcklin B-M (Sweden), Kunnasranta M and Isomursu M (Finland). Health assessment in the Baltic grey seal (Halichoerus grypus). HELCOM Indicator Fact Sheets 2008 (Ringed seals since 2010)

• In 2012 “Blubber thickness of Marine Mammals” was a proposed Core Indicator for Biodiversity

• The name changed from “Blubber thickness of Marine Mammals” to “Nutritional status of seals”

• TMs are discussing to start with juveniles 1-3 year olds and continue with adults next operationalization period.

• Time of year for measurements under conceptual discussion, seals from the summer will probably be excluded as they are lean after the moult.

• GES is determined when the blubber thickness is above a threshold level defined by Norwegian, Swedish hunted grey seals from 1999–2004 and Finnish seals. The reason for basing the proposed GES boundary to data from before 2005 is that since this year the available data indicates a trend of decreasing blubber thickness. Suggested reference levels for GES are the lower limit of the 95 % CI for the geometric mean.

Nutritional status of seals - GES

• For 1-3 years old grey seals (both sexes) the GES level will be ≥ 26 mm. In order to get enough data, assessment could be renewed every third year (i.e. pooling the data for each 3-year period) for grey seals

• by-caught and hunted grey seals are suggested to be presented separately since their proportions will influence the GES determination. Stranded seals are excluded.

• It has been discussed in the HELCOM SEAL health team that the lower 95 % CI could be used as the GES boundary for ringed seal as well. The lower limit of 95 % confidence intervals was 39.5 mm for young and sub-adult individuals before the year 2006 and 32.6 mm after the year 2005. The samples include both by-caught and hunted seals from August-February. (is there a difference between them?)

• GES limits for blubber thickness in ringed seals and harbour seals are still to be considered or investigated.

• People involved today: Britt-Marie Bäcklin, Charlotta Moraeus, Tero Härkönen, Swedish Museum of Natural History,

Kaarina Kauhala, Finnish Game and Fisheries Research InstituteMarja Isomursu, Finnish Food Safety Authority, EVIRAKarl Lundström, Swedish University of Agricultural SciencesUrsula Siebert, Institute for Terrestrial and Aquatic Wildlife Research (ITAW), University of Veterinary Medicine Hannover, Foundation

Nutritional status of seals

• HELCOM Assessment Unit Level: 1• The indicator is applicable in: For

grey seals, results are considered applicable for the whole Baltic Sea, whereas the ringed seal results may apply only to Bothnian Bay. For harbour seals data is applicable on the Swedish West coast.

• Currently data is available : From the Swedish and Finnish coast of the Baltic Sea and Swedish West coast.

Nutritional status of seals

List of issues that still need to be solved for the indicator

Describe what is hindering solving the issue

Developing the indicator for southern populations of ringed seals.

There is a lack of data especially for these populations. (Small change in original text, CM-please check it’s ok)

Harbour seal data to be compiled (Tero and Kaarina work with this)

The data has been difficult to access, but it is known where to get it from.

Determine GES in the Kalmarsund harbour seal population. Data has been scarce. Data from investigations on the western population of harbour seals could probably serve as normal data also to determine GES for Kalmarsund harbour seal population.

Suggested GES levels need more support Comparative studies of other populations of grey, harbour, ringed seals haven’t been done yet, but are now planned.

It is important to combine population and distribution investigations for the evaluation of the significance of decreased mean blubber thicknessclarification on sampling time needed The availability of samples needs to be considered against the

seasonal sampling, samples are few and may need some sort of statistical normalizing however doing this is difficult due to low number of samples??? CM-is this correct?

Look for differences between different areas in the Baltic Sea