1. Introduction to the Circumpolar World The marine environment #2 Hreiðar Þór Valtýsson, MSc in Fisheries Biology Assistant Professor, Faculty of Business and Science, University of Akureyri Director, the Fisheries Sciences Center at the University of Akureyri Borgir (2 nd floor, office 228), Norðurslóð, 600 Akureyri Tel.: 460 8920 (office) E-mail: hreidar@unak.ishreidar@unak.is Office hours: By appointment

2. Iceland and surrounding waters NOR0173 Hreidar Thor Valtysson The webThe web Situated close to the Arctic Circle in the North Atlantic. Right at the boundaries of the cold temperate and arctic zones

3. The ecosystem – water masses INJFU03 Hreiðar Þór Valtýsson The web The battle of the currents Productivity of the ocean around Iceland is high Biomass and biomass production high on all levels of the food chain Due to regular mixing of sunlit surface and nutrient rich deep water The mixing of the cold currents from the north and warm from the south increases this mixing However highly variable between years

4. Iceland and surrounding waters NOR0173 Hreidar Thor Valtysson The webThe web Greenland halibut Oceanic redfish Capelin Herrring Blue whiting Blue fin tuna Scallop Shrimp Lobster and monkfish Cod and haddock

5. The effects of warming What will happen with a warming climate? In general Cold water (arctic) species mostly suffer Intermediate water (Sub-arctic) species mostly gain Warmer water species (temperate) species will arrive NOR0173 Hreidar Thor Valtysson The webThe web

6. Arctic species Greenland halibut The second largest predatory fish in high Arctic waters Mostly fished N and NW of Iceland Low stock size Warming or overfishing ??? NOR0173 Hreidar Thor Valtysson The webThe web

7. Arctic species Northern (or pink) shrimp Invertebrate fisheries began in the middle of the 20th century, initially on shrimp and lobster Shrimp fisheries mainly north of Iceland => cold water species For a time the second most important commercial species in Iceland Then a disaster........ NOR0173 Hreidar Thor Valtysson The webThe web

8. Arctic species Northern shrimp and cod The stock collapsed and the catch collapsed Reason, warming trend in waters north of Iceland However not directly the temperature => more cod in the area north of Iceland (the shrimp can actually well tolerate this temperature) but... => the cod eats shrimp What about Greenland ? Newfoundland ? NOR0173 Hreidar Thor Valtysson The webThe web

9. Arctic species Scallop Chlamys islandica – the Icelandic scallop Important fisheries in western Iceland Unexpected collapse of the fishery Now no fishery....... Why? The climate became warmer but the scallop is supposed to tolerate warmer waters ! Studies revealed a protists disease that killed them In normal (cold) conditions it is to cold for the protists It came with the warmer waters and wiped out the scallop stock NOR0173 Hreidar Thor Valtysson The webThe web

10. Arctic species Capelin A small cold water species and very abundant north of Iceland. However spawns in shallow and warmer waters off the south coast. It is during these migrations that it becomes the most important food for many other marine species in Icelandic waters Usually spawns at the age of 3 and then dies. NOR0173 Hreidar Thor Valtysson The webThe web

11. Arctic species Capelin Annual caches more than 1.000.000 t, almost as high as all other species combined Even if it is a cold water species the effects of warming climate are uncertain as it depends on warm waters for spawning In previous warm periods it has simply shifted from spawning and spawned in the waters north of Iceland. We do not know if the stock was smaller NOR0173 Hreidar Thor Valtysson The webThe web

12. Sub Arctic species Herring One of the most abundant fish stock in the world when the stock is in good conditions, probably the largest in the N. Atlantic Fisheries very important for many nations throughout the centuries. Was for a time the most important fish species in Icelandic waters Most stocks did collapse due to heavy fisheries between 1965 and 1975 NOR0173 Hreidar Thor Valtysson The webThe web

13. Sub Arctic species NOR0173 Hreidar Thor Valtysson The webThe web Herring Cooling climate also to blame?

14. Sub Arctic species NOR0173 Hreidar Thor Valtysson The webThe web Herring The herring stock will probably increase in size in northern waters if the warming climate will continue Given that the fishery is restricted And diseases will end

15. Sub Arctic species Cod Economically the most important species during most of the centuries, a valuable species per kg Since the stock is quite large and he fish is greedy it also has a great ecological impact Many stocks in the N. Atlantic Historically the largest off Newfoundland (now collapsed), Barents Sea and Iceland All around Iceland NOR0173 Hreidar Thor Valtysson The webThe web

16. Sub Arctic species Cod Main spawning grounds (meginhrygningarstöðvar) are off the south coast Egg and larvae drift west and then north, occasionally also to Greenland Main juvenile grounds (meginuppeldisstöðvar) are off the north coast Main feeding areas after they are mature are where the cold and warm currents meet off the west and east coast NOR0173 Hreidar Thor Valtysson The webThe web

17. Sub Arctic species NOR0173 Hreidar Thor Valtysson The webThe web Cod Very small native cod stock in Greenland During warm periods cod can however become very abundant new grounds open up Due to larval drift from Icelandic grounds Is self sustained during warm periods but collapses in cold A large part of this stock migrates back to Iceland to spawn and stays there Very good for the Icelandic cod fisheries Mainly because of that it has been predicted that the cod stock in Icelandic waters will grow with warming climate Has not happened (yet?)

18. Sub Arctic species Northern shrimp and cod This relationship between shrimp and cod now well known in many other areas These species just don't mix, you cannot have both in abundance Warming climate will (given that the cod stocks are not heavily overfished) drive shrimp stocks down or further north NOR0173 Hreidar Thor Valtysson The webThe web

19. Sub Arctic species Capelin and cod However …….. The sub Arctic cod depends heavily on the arctic capelin as food If the capelin stock will be reduced due to warming it will have adverse effects on the cod stock This causes great uncertainties on the fate of the cod stock because warmer waters might either mean larger cod stock as cod in warmer waters generally grows faster (such as in the North sea) or it might mean smaller cod stock if the capelin stock collapses NOR0173 Hreidar Thor Valtysson The webThe web

20. Temperate species NOR0173 Hreidar Thor Valtysson The webThe web The winners, Temperate species Blue- fin tuna Mackerel Monkfish or anglerfish Norway lobster

21. Iceland and surrounding waters NOR0173 Hreidar Thor Valtysson The webThe web Summary if warming continues Valuable species added to the Icelandic fisheries (temperate) – Blue fin tuna – Mackerel Valuable species will increase in abundance (sub Arctic and temperate) – Herring(not in Greenlandic waters but might if warmer) – Haddock (not in Greenlandic waters but might if warmer) – Monkfish – Lobster Valuable species will decline in numbers (high Arctic) – Shrimp – Scallop Valuable species that are great uncertainties about (high an sub Arctic) – Cod(probably increase) – Greenland halibut(probably decline)

22. Iceland and surrounding waters NOR0173 Hreidar Thor Valtysson The webThe web Norwegian and Barents Seas The same species and the same consequences