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
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
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?
North Pacific Ocean current systems (Dodimead et al. 1963)
Approximate area of oceanic domains and prevailing current directions in the Northeast Pacific Ocean (Ware and McFarlane 1989)
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 = 199 10% 0% 55 54 53 52 51 50 49 48 47 45 44 44 42 41 39 38 36 Latitude
30 25 20 15 10 > 70% Coastal and inshore communities California Current: dominated by herring coastal inshore 5 0 70 60 50 40 30 20 10 0 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. 2007 AFS symposium 57
Common crustaceans eaten by salmon Euphausiids (krill) Thysanoessa longipes Hyperiid Amphipods Themisto pacifica 15 23 mm 2 8 mm
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
Fishes eaten by salmon (Puget Sound) Pacific herring Surf smelt Sand lance Northern anchovy
Pteropods Limacina helicina Mollusks eaten by salmon Berryteuthis anonychus Squid 2 3 mm Gonatopsis borealis
Gelatinous zooplankton: ctenophores, medusae, salps (tunicates) Beroe spp. ~45 mm TL Aglantha digitale ~15 mm TL Salpa sp. ~20 mm TL
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) 0 500 1000 1500 2000 2500 cal/g wet weight 0 500 1000 1500 2000 2500
Annual cycle of average zooplankton density at Ocean Station P Zooplankton (g/1000 m3) 300 250 200 150 100 50 0 Jan Feb Mar April May June July Aug (mean and standard error) Sept Oct Nov Dec Brodeur et al. (1996)
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 4 80 3 60 2 40 1 20 0 0 21-Mar 20-Apr 20-May 19-Jun Pink salmon (thousands)
Food habits of salmon vary among species, years, and among fish of different sizes Wakatake maru Nancy Davis
Salmon prey composition Bering Sea Basin, summer 1991-2003 Coho 100% 80% 60% no data no data Unid Other Gelatinous Fish Pteropod 40% Squid Crab larv 20% Amphipod Copepod 0% 91 92 93 94 95 96 97 98 99 00 01 02 03 Euphausiid Chinook 100% 80% 60% 40% 20% 0% 91 92 93 94 95 96 97 98 99 00 01 02 03 Unid Other Gelatinous Fish Pteropod Squid Crab larv Amphipod Copepod Euphausiid
Prey of salmon collected from the Bering Sea basin 1991 to 2003 Sockeye 100% 80% 60% 40% 20% 0% 91 92 93 94 95 96 97 98 99 00 01 02 03 Unid Other Gelatinous Fish Pteropod Squid Crab larv Amphipod Copepod Euphausiid Pink 100% 80% 60% 40% 20% 0% 91 92 93 94 95 96 97 98 99 00 01 02 03 Unid Other Gelatinous Fish Pteropod Squid Crab larv Amphipod Copepod Euphausiid Chum 100% 80% 60% 40% 20% 0% 91 92 93 94 95 96 97 98 99 00 01 02 03 Unid Other Gelatinous Fish Pteropod Squid Crab larv Amphipod Copepod Euphausiid
Diet overlap Bering Sea basin, summer 1991-2003 Low 0-24% Moderate 25-49% High 50-74% Very high 75-100% sockeye chum pink chinook sockeye 52 88 54 chum 52 26 pink 55 chinook
Ontogenic diet shift: coho and Chinook salmon consume a higher proportion of fish as they grow 100 75 % fish in the diet 50 25 coho Chinook 0 0 100 200 300 400 Daly et al. 2009 Body length (mm)
Diet vs. body size 100% 80% 60% 40% 20% 0% Chinook <500 500-999 1000-1499 1500-1999 % composition 2000-2499 2500-2999 100% 80% 60% 40% 20% 0% chum 3000-3999 4000 100% 80% 60% 40% 20% 0% sockeye other fi sq eu 1499 1999 100% 80% 60% 40% 20% 0% <500 500-999 1000-1499 2499 1500-1999 2999 pink 2000-2499 <500 500-999 1000-1500- 2000-2500- 3000-3999 2500-2999 4000 3000 unid other ge fi pt sq am co eu other <500 500-999 1000-1499 1500-1999 2000-2499 fi pt sq am co eu other fi pt sq am co eu Body Weight (g)
Sockeye: diel change in prey composition Euphausiids and copepods 40 30 20 Euphausids and copepods 10 Fish Prey wt (g) 40 30 0 0600-0800 Fish 0900-1100 1200-1400 1500-1700 1800-2000 Time of day 2100-2300 0000-0200 0300-0500 20 10 0 0600-0800 0900-1100 1200-1400 1500-1700 1800-2000 2100-2300 0000-0200 0300-0500 Time of day
Data storage tags record temperature and pressure (depth)
Attachment of the DST to salmon
16 Chum salmon diel vertical migration TD Tag 1565 - Hokkaido Chum Salmon Recovered: 9/24/02 Nemuro coast, Hokkaido, Japan Length: 655 mm, Weight: 3.4 kg 0 Temperature ( C) 14 12 10 8 6 Tagged: 7/9/02 Location: 56-30N, 179-00E Length: 618 mm, Age: 0.3 Depth 50 100 150 200 250 Depth (m) 4 300 2 0 Temperature 9 16 21 25 28 1 4 8 11 15 18 22 25 29 1 5 8 12 15 19 22 July August September = night 350 400 recuperation period coastal period
Growth of salmon at sea Pink Chum Chinook Sockeye Coho Steelhead Masu Smolt weight (g) Adult weight (kg) Full years at sea 0.22 0.4 5 to 18 10 18 50 18 1.63 3.73 7.22 2.69 3.02 3.48 1.45 1 2,3,4 2,3,4 2,3 1 2 1 Data from McGurk 1996, Groot and Margolis 1991, Bigler et al. 1996, Burgner et al. 1992, Kato 1991.
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 20 15 10 5 females males 0 370 390 410 430 450 470 490 510 530 Length (mm, MEH)
Males may also be heavier for a given length Woody Island sockeye salmon 5 4 Males Mass (kg) 3 2 1 Females 0 350 400 450 500 550 600 Length (MEH, in mm)
Factors affecting the growth of salmon at sea Density (intra-specific competition) Ocean conditions Productivity Temperature Inter-specific competition
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) 720 680 640 600 males age 4 females age 4 0 15 30 45 60 Chum salmon abundance (millions)
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) 540 530 520 510 500 490 480 1958-76 1977-97 1998-02 0 20 40 60 80 Millions of adult salmon
Hypothesized effects of ocean temperature and density on sockeye salmon growth rate Body Size at Age Temperature 2 Temperature 1 Abundance (Peterman 1984)
photo by Richard Bell
Growth History Fish Length Individual circuli Scale Radius
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 2 3 4 5 6 2 4 266 3 27 220 508 4 150 183 466 676 5 60 171 425 622 813 6 8 122 368 549 730 917
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Central Bering Sea Mean CPUE per tan 1991-2000 20 15 10 5 Sockeye Chum Pink Chinook Total 0 91 92 93 94 95 96 97 98 99 00
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
Stomach contents for salmon sampled in the Strait of Juan de Fuca < 40 cm 40-60 cm > 60 cm Total % stomach volume 0 40 80 0 40 80 < 40 cm 40-60 cm > 60 cm Total Coho Chinook Fish Crustaceans Miscellaneous
Stomach contents of salmon in the Strait of Juan de Fuca < 55 cm >55 cm Total % stomach volume 0 40 80 0 40 80 < 55 cm < 55 cm Sockeye Pink Fish Crustaceans Miscellaneous
Biomass of Salmonids Biomass (T x 1000) 600 400 200 0 Coastal shelf Coastal downwelling Coastal upwelling Domain
Comparison of Diet Overlap-Summer and Fall Summer, basin, even yrs 1992-2002 sockeye chum pink chinook sockeye 56 76 57 chum 58 26 pink 45 chinook Low 0-24% Moderate 25-49% High 50-74% Very high 75-100% Fall, basin, 2002 Fall, Aleutian Is., 2002 sockeye chum chinook sockeye 49 21 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
Diet overlap Bering Sea basin, summer All years, 1991-2003 Even years, 1992-2002 (low pink) sockeye chum pink chinook sockeye 52 88 54 chum 52 26 pink 55 chinook sockeye chum pink chinook sockeye 56 76 57 chum 58 26 pink 45 chinook Low 0-24% Moderate 25-49% High 50-74% Very high 75-100% Sockeye N=577 Chum N=1413 Pink N=156 Chinook N=274 Odd years, 1991-2003 (high pink) Sockeye Chum Pink Chinook Sockeye 44 83 54 Chum 40 28 Pink 63 Chinook Sockeye N=724 Chum N=1523 Pink N=1331 Chinook N=193
Relationship between the size of salmonids and the size of their prey 1000 Keeley and Grant (2001) Fishes (all environments combined) Prey length (mm) 100 10 Ocean invertebrates Freshwater invertebrates (streams and lakes combined) Keeley and Grant 2001. CJFAS 1 1 10 100 1000 Fish length (cm)