1. Variation in fish condition within and between populations: the effect on their productivity and management implications (Mediterranean and North Atlantic) Josep Lloret (a), Hans-Joachim Rätz (b) and Montserrat Demestre (a) (a) Institut de Ciències del Mar (CMIMA-CSIC), Barcelona, Catalonia, Spain (b) Institut für Seefischerei, Hamburg, Germany UNESCO WORKSHOP June 2005. Varna (Bulgaria) LARGE-SCALE DISTURBANCES (REGIME SHIFTS) AND RECOVERY IN AQUATIC ECOSYSTEMS: CHALLENGES FOR MANAGEMENT TOWARDS SUSTAINABILITY

2. 1. Condition (fitness) is an important feature of fishes because it affects growth, reproduction and mortality 2. Two areas: Mediterranean and North Atlantic 3. Several commercial demersal species: cod, white seabream, hake, red mullet, etc 4. Several sampling methods: groundfish surveys, data from fishery vessels, spear fishing 5. Several condition indices: K, HSI, DSI, GSI, total lipids (muscle and liver) 6. Publications: 2005. H.J. Rätz and J. Lloret. ICES Journal of Marine Science (in press). 2005. J. Lloret, R. Galzin, L. Gil de Sola, A. Souplet and M. Demestre. Journal of Fish Biology 67:1 (July; in press). 2003. J. Lloret and S. Planes. Marine Ecology Progress Series 248:197-208 2003. H.J. Rätz, J. Lloret. Fisheries Research 60:369-380. 2002. J. Lloret, Gil de Sola, L., Souplet, A. and Galzin, R. ICES J. mar. Sci. 59:1215-1227. FISH CONDITION

3. CAUSES OF VARIABILITY IN FISH CONDITION

4. Habitat productivity

5. MEDITERRANEAN a) Condition is generally better in the north (Gulf of Lions: higher productivity) than in the south (Catalan Sea: lower productivity) b) Condition generally decreases with depth (deep waters: lower productivity) Rhône river Ebre river

6. K of Lophius budegassa MEDITERRANEAN

7. DSI of Pagellus acarne MEDITERRANEAN

8. (230) (38) -0.6 -0.4 -0.2 0 0.2 0.4 0.6 0.8 ln % lipid dry weight Gulf of LionsCatalan Sea Total lipids in the muscle of Pagellus acarne MEDITERRANEAN

9. Total lipids in the muscle of Mullus surmuletus MEDITERRANEAN

10. Interannual fluctuations of K of Lophius piscatorius MEDITERRANEAN

11. Bottom characteristics

12. MEDITERRANEAN

13. (84) (46) 0 1 2 3 4 5 Muscle lipid Liver lipid Rocky unprotected Sandy unprotected Condition of juvenile Diplodus sargus is better in the rocky coast than in the sandy coast % dry weight MEDITERRANEAN

14. Habitat protection

15. MEDITERRANEAN

16. (19) (41) 0 0.5 1 1.5 2 HSI Muscle lipid Rocky protected Banyuls Rocky unprotected Condition of post-spawners D. sargus is better in the rocky protected area of Banyuls than in the adjacent rocky unprotected area Index (HSI) or % dry weight MEDITERRANEAN

17. (43) (32) (42) 0 2 3 Muscle lipidLiver lipid Rocky Protected Cap Creus Rocky unprotected …and the same in the rocky protected area of Cap de Creus % dry weight 1 4 MEDITERRANEAN

18. Water temperature

19. Northwest Greenland Labrador Grand Bank Golf v. St. Lawrence Georges Bank NORTH ATLANTIC Northeast Northeast Arctic Iceland West of Scotland North Sea Irish Sea

20. NORTH ATLANTIC

21. SPATIAL VARIABILIY IN TEMPERATURE AND CONDITION r 2 =0,67, p=0,0036. NORTH ATLANTIC Cod stocks living in temperate waters are better conditioned than those living in cold waters

22. R 2 =0.28 Mean K= 0.89 INTERANNUAL VARIABILIY IN TEMPERATURE AND CONDITION IN GREENLAND NORTH ATLANTIC Condition is better when water temperature is higher than average

23. Stock density

24. NORTH ATLANTIC The strong year class 1984 of cod off Greenland experienced a low condition during the following years

25. Sex and reproductive stage

26. 0 1 2 3 4 5 6 HSI M. barbatus DSI M. barbatus Juveniles Adult males Adult females HSI P. erythrinus Sex differences in condition Females are better conditioned than males; and adults better than juveniles MEDITERRANEAN

27. Differences in condition between different reproductive stages of D. sargus (Gulf of Lions) Post-spawners are better conditioned than spawners MEDITERRANEAN

28. Size (age) of fish

29. HSI of cod during resting (Greenland, autumn 1998; males + females) The bigger are better conditioned NORTH ATLANTIC

30. GSI of Mullus barbatus during spawning (NW Mediterranean; spring 2000&2001; females) MEDITERRANEAN The bigger are better conditioned

31. GSI of Diplodus sargus during spawning (Gulf of Lions; spring 2001; males) MEDITERRANEAN The bigger are better conditioned

32. CONSEQUENCES OF THE VARIABILITY IN CONDITION: EFFECTS ON STOCK PRODUCTIVITY AND MANAGEMENT IMPLICATIONS

33. Stock productivity

34. Growth of cod ( weight at age 4) r 2 =0,79, p=0,0006. Well conditioned cod stocks are more productive because they grow faster NORTH ATLANTIC

35. r 2 =0,49, p=0,0234. Well conditioned cod stocks are more productive because they recruit more successful at decreased stock sizes Recruitment potential of cod ( Ricker’s a-coefficient from the SSB-R relationships) NORTH ATLANTIC

36. Growth of cod off Greenland is faster when condition is better; r 2 = 0.50 NORTH ATLANTIC

37. Management implications

38. 1.Poor conditioned populations are more susceptible to overexploitation 2.Low condition values recorded in given years can precede negative events in stock productivity in the following years: condition can be monitored to detect regime shifts and forecast changes in the productivity of stocks 3.Additional management measures are needed when poor condition values are recorded (in given years or habitats) In this sense, the protection of habitats can help to preserve the condition and status of fish stocks. NORTH ATLANTICMEDITERRANEAN TAKE CARE WITH POOR CONDITIONED FISH!