1. Knowledge-based solutions, for sustainable choices Kaarina Kauhala & the Ecoseal group Finnish Game and Fisheries Research Institute Photo: Mervi Kunnasranta ECOSEAL– Balansing between sustainable seal population management and fisheries

2. Knowledge-based solutions, for sustainable choices 2012-2013 Cooperation between Finnish, Swedish and Estonian researchers, hunters and fishermen Varsinais-Suomen elykeskus

3. Knowledge-based solutions, for sustainable choices Aim of the project ECOSEAL-project aimed at diminishing the seal – fishery conflict. We collected samples and information of both by-caught and hunted seals to reveal their numbers, demographic structure, diet and the seal-induced damage to coastal fisheries.

4. Knowledge-based solutions, for sustainable choices Demographic structure and body condition of Baltic grey seals: are the problem seals a random sample of the population? Kaarina Kauhala & ECOSEAL group Finnish Game and Fisheries Research Institute Photo: Markus Vetemaa

5. Knowledge-based solutions, for sustainable choices Who are the problem seals? Three seal groups: Seals hunted during normal hunting mainly from the outer archipelago ’Problem seals’: seals shot near fishing gear seals by-caught in fishing gear.

6. Knowledge-based solutions, for sustainable choices Are the problem seals a random sample of the population? Age? Sex? Body condition? Long-term diet?

7. Knowledge-based solutions, for sustainable choices The samples from hunters and fishermen included : the lower jaw: age determination from lower canine teeth Reproductive organs: sex and birth rate Body length: body size Blubber thickness (measured from posterior end of sternum): an index of body condition Pieces of blubber, liver and muscle: long-term diet

8. Knowledge-based solutions, for sustainable choices

9. Age and sex of seals Age structure did not differ between seal groups (p = 0.208).

10. Knowledge-based solutions, for sustainable choices Age structure differed between seal groups (p = 0.006).

11. Knowledge-based solutions, for sustainable choices Comparison between the samples and the population

12. Knowledge-based solutions, for sustainable choices Sex ratios (males/females) of the samples HuntedShotBy-caughtTotal Spring1.2 (91)2.3 (10)1.4 (50)1.3 (151) Autumn1.2 (50)1.7 (16)3.5 (68)2.0 (134) Total1.2 (141)1.9 (26)2.3 (118)1.6 (285) Difference between seasons: p = 0.060 Difference beween hunted, shot and by-caught: p = 0.034

13. Knowledge-based solutions, for sustainable choices Blubber thickness: condition index among marine mammals

14. Knowledge-based solutions, for sustainable choices Blubber thickness of original data

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16. We tested the effects of seal group (hunted, shot, by- caught), age (pup, subadult, adult), sex and month, and their interactions on the blubber thickness. ____________________________________________________ Effect df F p ____________________________________________________ Seal group 2, 225 5.5 0.005 Age group 2, 225 2.1 0.119 Month 1, 225 23.2 <0.001 Sex 1, 2250.04 0.840 Age group*month 2, 225 7.8 0.001 Sex*age group 2, 225 5.0 0.007 ____________________________________________________

17. Knowledge-based solutions, for sustainable choices Model predicted values

18. Knowledge-based solutions, for sustainable choices Effect of month adult males: hunted: Y = 55.4 - 6.0 X + 0.55 X 2, by-caught: Y = 54.9 - 9.0 X + 0.75 X 2.

19. Knowledge-based solutions, for sustainable choices Are the problem seals a random sample of the population? No In spring, most problem seals were by-caught pups, and the sample of by-caught seals was biased to pups. In autumn, most problem seals were subadult and adult males, and the the sample of seals shot near fishing gear was biased to adult males. By-caught seals were in poor condition.

20. Knowledge-based solutions, for sustainable choices Do seals come to fishing gear because they are starving? Probably, because the long-term diet of by-caught adult males seems to differ to some extent from that of hunted seals. Hungry seals in poor condition may become bold and incautious and easily go into the traps. In spring, pups probably go into the traps because they are inexperienced.

21. Adult males: long-term diet based on fatty acids Comp. 1 (48.0%) Comp. 2 (25.4%) -5.11-2.420.282.975.67 -4.68 -1.98 0.71 3.41 6.10 29MA3m1605O 30MA3m1594D 30MA4m1497N 30MA5m5643O 30MA6m5902O 32MA4m1586N 32MA5m1606D 29MA3m1561O 29MA4m5922N 29MA5m1598D 29MA5m1613D 29MA5m1618N 29MA5m1620N 29MA6m1616N 29MA6m1619N 29MAUm1615N 30MA3m1519O 30MA3m1588D 30MA3m5467O 30MA3m5644O 30MA4m5083D 30MA4m5514O 30MA5m1610D 30MA6m1629D 30MA7m5955O 32MA2m1553N 32MA3m1524N 32MA3m1574D 32MA3m1593N 32MA4m1596D 14:0 16:1n-7 18:1n-9 18:2n-6 18:3n-3 18:4n-3 20:4n-6 22:6n-3 Sprat & Salmonids Bay predator fish Herring Hunted Shot Near Traps By-caught

22. Knowledge-based solutions, for sustainable choices What can we do to prevent damage and by-catch? Hunt more males in autumn? Hunt more often near fishing gear? More research is needed on the long-term diet and movements of seals to see, whether only some adult males specialise in catching fish near fishing gear. Use seal-safe traps to prevent by-catch.

23. Knowledge-based solutions, for sustainable choices What is the impact of human-induced mortality to the seal population? By-catch mortality may not be totally additive to natural mortality, because by-caught pups were small and in poor condition. At least some of them would probably have died anyway. By-caught adult males were in poor condition. Were they subordinate males which would not have reproduced?

24. Knowledge-based solutions, for sustainable choices By-catch may not be a so severe threat to the population as expected but it is a serious ethical problem. When estimating the impact of by-catch on the population, we must take into account not only the numbers but also the quality of by-catch, because different individuals have different reproductive values.

25. Knowledge-based solutions, for sustainable choices The effect of hunting Both pups and adults are hunted in spring. In autumn, most hunted seals are adults, many males (in good condition) but also mature females, i.e. reproducing individuals. The mortality rate of females < 10 years of age is important for the population growth, i.e. not too many young females should be hunted. Hunting should be targeted more on males, especially those in poor condition.

26. Knowledge-based solutions, for sustainable choices Thank you for your attention!