Salmonid Feeding and Growth at Sea

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1 Salmonid Feeding and Growth at Sea 1. Habitats and communities of salmon 2. Diet of salmon 3. Patterns of feeding 4. Growth 5. Density and temperature

2 Feeding and growth of salmon at sea Salmon time their seaward migration to take advantage of marine prey Salmon grow rapidly and achieve > 99% of their total weight at sea Salmon diets reflect their size and species, and the prey available to them Growing conditions vary among years, with ocean conditions and salmon density

3 Salmon in the central North Pacific and Bering Sea Alaska Asia British Columbia The distributions are large, and overlap broadly between species and populations. What is the nature of the region that they occupy?

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5 North Pacific Ocean current systems (Dodimead et al. 1963)

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7 Approximate area of oceanic domains and prevailing current directions in the Northeast Pacific Ocean (Ware and McFarlane 1989)

8 Catches of fishes and squid in gill nets along 155 o W by the Oshoro Maru, July 1984 Salmonids Open ocean communities Percent of Total 70% 60% 50% 40% 30% 20% Pacific Pomfret Blue Shark, Albacore, Ommastrephes bartami Tuna, billfish, Mackerel, mahi mahi, Yellowtail n = 3999 n = 2897 n = 694 n = % 0% Latitude

9 > 70% Coastal and inshore communities California Current: dominated by herring coastal inshore herring salmonids herring salmonids anchovies sticklebacks anchovies % of fishes caught, by family, in two current systems Alaska Current: dominated by salmon sticklebacks sharks sharks other other squid sand lance squid sand lance atherinids coastal inshore atherinids smelt smelt gadids gadids rockfish rockfish jacks jacks Orsi et al AFS symposium 57

10 Common crustaceans eaten by salmon Euphausiids (krill) Thysanoessa longipes Hyperiid Amphipods Themisto pacifica mm 2 8 mm

11 Some fishes eaten by salmon at sea Northern smoothtongue - Bathylagidae Northern lampfish (lanternfish) Leuroglossus schmidti ~135 mm SL Stenobrachius leucopsarus ~90 mm SL Pleurogrammus monopterygius ~40 mm SL Atka mackerel Hemilepidotus spp. ~15 mm SL

12 Fishes eaten by salmon (Puget Sound) Pacific herring Surf smelt Sand lance Northern anchovy

13 Pteropods Limacina helicina Mollusks eaten by salmon Berryteuthis anonychus Squid 2 3 mm Gonatopsis borealis

14 Gelatinous zooplankton: ctenophores, medusae, salps (tunicates) Beroe spp. ~45 mm TL Aglantha digitale ~15 mm TL Salpa sp. ~20 mm TL

15 Energy density of salmon prey organisms Salpa, Beroe Salpa sp. (35 mm TL) Clione limacina (16 mm TL) Sebastes sp. (11 mm SL) pteropods, Themisto; juv. fish, euphausiids juv. squid <2 cm Squid (22 mm ML) Hippoglossus stenolepis (19 mm SL) Limacina helicina (3 mm TL) Fish-sticklebacks, Tarletonbeania, juv Atka mackerel 3-4 cm; euphausiids 2 cm, Anonychus 4 cm Parathemisto pacifica (Females w/ young) Thysanoessa longipes (19 mm TL) Tarletonbeania crenularis (43 mm SL) Thysanoessa longipes (23 mm TL) Hemilepidotus sp. (21 mm SL) Juv. sculpin 2 cm, Anonychus 8-9 cm Berryteuthis anonychus (86 mm ML) Berryteuthis anonychus (82 mm ML) Stenobrachius leucopsarus (64 mm SL) deep sea smelt 11 cm Stenobrachius 4-11 cm Stenobrachius leucopsarus (112 mm SL) cal/g wet weight

16 Annual cycle of average zooplankton density at Ocean Station P Zooplankton (g/1000 m3) Jan Feb Mar April May June July Aug (mean and standard error) Sept Oct Nov Dec Brodeur et al. (1996)

17 Synchronous downstream migration of pink salmon fry and density of zooplankton in Prince William Sound, Alaska (Cooney et al. 1995). Zooplankton (ml/m3) 5 zooplankton 100 pink salmon Mar 20-Apr 20-May 19-Jun Pink salmon (thousands)

18 Food habits of salmon vary among species, years, and among fish of different sizes Wakatake maru Nancy Davis

19 Salmon prey composition Bering Sea Basin, summer Coho 100% 80% 60% no data no data Unid Other Gelatinous Fish Pteropod 40% Squid Crab larv 20% Amphipod Copepod 0% Euphausiid Chinook 100% 80% 60% 40% 20% 0% Unid Other Gelatinous Fish Pteropod Squid Crab larv Amphipod Copepod Euphausiid

20 Prey of salmon collected from the Bering Sea basin 1991 to 2003 Sockeye 100% 80% 60% 40% 20% 0% Unid Other Gelatinous Fish Pteropod Squid Crab larv Amphipod Copepod Euphausiid Pink 100% 80% 60% 40% 20% 0% Unid Other Gelatinous Fish Pteropod Squid Crab larv Amphipod Copepod Euphausiid Chum 100% 80% 60% 40% 20% 0% Unid Other Gelatinous Fish Pteropod Squid Crab larv Amphipod Copepod Euphausiid

21 Diet overlap Bering Sea basin, summer Low 0-24% Moderate 25-49% High 50-74% Very high % sockeye chum pink chinook sockeye chum pink 55 chinook

22 Ontogenic diet shift: coho and Chinook salmon consume a higher proportion of fish as they grow % fish in the diet coho Chinook Daly et al Body length (mm)

23 Diet vs. body size 100% 80% 60% 40% 20% 0% Chinook < % composition % 80% 60% 40% 20% 0% chum % 80% 60% 40% 20% 0% sockeye other fi sq eu % 80% 60% 40% 20% 0% < pink < unid other ge fi pt sq am co eu other < fi pt sq am co eu other fi pt sq am co eu Body Weight (g)

24 Sockeye: diel change in prey composition Euphausiids and copepods Euphausids and copepods 10 Fish Prey wt (g) Fish Time of day Time of day

25 Data storage tags record temperature and pressure (depth)

26 Attachment of the DST to salmon

27 16 Chum salmon diel vertical migration TD Tag Hokkaido Chum Salmon Recovered: 9/24/02 Nemuro coast, Hokkaido, Japan Length: 655 mm, Weight: 3.4 kg 0 Temperature ( C) Tagged: 7/9/02 Location: 56-30N, E Length: 618 mm, Age: 0.3 Depth Depth (m) Temperature July August September = night recuperation period coastal period

28 Growth of salmon at sea Pink Chum Chinook Sockeye Coho Steelhead Masu Smolt weight (g) Adult weight (kg) Full years at sea to ,3,4 2,3,4 2, Data from McGurk 1996, Groot and Margolis 1991, Bigler et al. 1996, Burgner et al. 1992, Kato 1991.

29 In many cases, male salmon grow faster than females (i.e., are longer at a given age) 25 4-yr old sockeye salmon from Woody Island, Iliamna Lake Percent of fush measured females males Length (mm, MEH)

30 Males may also be heavier for a given length Woody Island sockeye salmon 5 4 Males Mass (kg) Females Length (MEH, in mm)

31 Factors affecting the growth of salmon at sea Density (intra-specific competition) Ocean conditions Productivity Temperature Inter-specific competition

32 Mean fork length of Hokkaido chum salmon as a function of the number of adult chum salmon (catch plus escapement) that year (from Kaeriyama 1998). 760 Fork length (mm) males age 4 females age Chum salmon abundance (millions)

33 Mean length (males and females combined, for fish spending two years at sea) of adult Bristol Bay sockeye salmon as a function of the number of adults returning to spawn that year. Mean length (mm) Millions of adult salmon

34 Hypothesized effects of ocean temperature and density on sockeye salmon growth rate Body Size at Age Temperature 2 Temperature 1 Abundance (Peterman 1984)

35 photo by Richard Bell

36 Growth History Fish Length Individual circuli Scale Radius

37 Back-calculated lengths of chinook salmon (in mm) at different ages, as a function of their final age at maturity (data from Parker and Larkin 1959). Age at maturity AGE Sample

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39 Central Bering Sea Mean CPUE per tan Sockeye Chum Pink Chinook Total

40 No. freshwater winters Age notation: 1. 2 No. ocean winters Species Common ages & maturity in catch Sockeye 1.1, 2.1, 1.2, 2.2 immature, maturing Chum 0.1, 0.2, 0.3 immature, maturing Pink All maturing 0.1 Coho All maturing 1.1, 2.1 Chinook 1.1, 1.2, 1.3 immature

41 Stomach contents for salmon sampled in the Strait of Juan de Fuca < 40 cm cm > 60 cm Total % stomach volume < 40 cm cm > 60 cm Total Coho Chinook Fish Crustaceans Miscellaneous

42 Stomach contents of salmon in the Strait of Juan de Fuca < 55 cm >55 cm Total % stomach volume < 55 cm < 55 cm Sockeye Pink Fish Crustaceans Miscellaneous

43 Biomass of Salmonids Biomass (T x 1000) Coastal shelf Coastal downwelling Coastal upwelling Domain

44 Comparison of Diet Overlap-Summer and Fall Summer, basin, even yrs sockeye chum pink chinook sockeye chum pink 45 chinook Low 0-24% Moderate 25-49% High 50-74% Very high % Fall, basin, 2002 Fall, Aleutian Is., 2002 sockeye chum chinook sockeye chum 28 chinook sockeye chum sockeye 80 chum Sockeye N=78 Chum N=360 Chinook N=84 Sockeye N=32 Chum N=58 Fall, EBS shelf, 2002 chum chinook chum 30 chinook Chum N=54 Chinook N=16

45 Diet overlap Bering Sea basin, summer All years, Even years, (low pink) sockeye chum pink chinook sockeye chum pink 55 chinook sockeye chum pink chinook sockeye chum pink 45 chinook Low 0-24% Moderate 25-49% High 50-74% Very high % Sockeye N=577 Chum N=1413 Pink N=156 Chinook N=274 Odd years, (high pink) Sockeye Chum Pink Chinook Sockeye Chum Pink 63 Chinook Sockeye N=724 Chum N=1523 Pink N=1331 Chinook N=193

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47 Relationship between the size of salmonids and the size of their prey 1000 Keeley and Grant (2001) Fishes (all environments combined) Prey length (mm) Ocean invertebrates Freshwater invertebrates (streams and lakes combined) Keeley and Grant CJFAS Fish length (cm)