Recruitment Variability, cont’d: Ho: Delayed Development ... · K.E. Selph, OCN 621, Spring 2008 Density-dependent Population Regulation Potential contributing mechanisms: Reduced

K.E. Selph, OCN 621, Spring 2008

Recruitment Variability, contRecruitment Variability, cont’’d:d:HHoo: Delayed Development: Delayed Development

Houde Houde (1987) (1987) Fish early life dynamics and recruitment variabilityFish early life dynamics and recruitment variability::10-fold or greater fluctuations in fish recruitment can be due to10-fold or greater fluctuations in fish recruitment can be due tosmall variations in mortality rates or stage durations in the earlysmall variations in mortality rates or stage durations in the earlylife of fishlife of fish


Agents of Mortality for Young FishAgents of Mortality for Young Fish

Fuiman & Werner 2002


Density-dependent PopulationDensity-dependent PopulationRegulationRegulation

Potential contributing mechanismsPotential contributing mechanisms:: Reduced fecundity of adults due to foodReduced fecundity of adults due to food

limitationlimitation Predation of adults on larvae or juvenilesPredation of adults on larvae or juveniles Direct competition for food between juvenilesDirect competition for food between juveniles

and adultsand adults Indirect effects of adults on food supply forIndirect effects of adults on food supply for

larvae, e.g., adults reduce stocks of adultlarvae, e.g., adults reduce stocks of adultcopepods to low levels, resulting in lowcopepods to low levels, resulting in lowabundance of abundance of naupliinauplii


HHoo: Retention Area: Retention Area Survival depends upon being retained in areasSurvival depends upon being retained in areas

((““nursery groundsnursery grounds””) with specific hydrographic) with specific hydrographiccharacteristicscharacteristics vs vs. loss to offshore advection. loss to offshore advectione.g., Migration Triangle Hypothesise.g., Migration Triangle Hypothesis


CoastalCoastalConveyorConveyor

BeltBelt

Gulf of Maine

Atlantic herringspawning site

• Herring spawn in latesummer through autumn.• Extended larval stage,then complete transitionfrom larvae to juvenilewhen 5-8 months old.• Later, current turnsoffshore: into a cyclonicgyre, retaining larvae inarea.

Fuiman & Werner 2002


Pacific HakePacific Hake

Adults migrate south overshelf in winter

Spawn off So. Cal (deeperthan mixed layer and as faras 300 km offshore): larvaedrift inshore

High recruitment:weakupwelling


Member/Vagrant HypothesisMember/Vagrant Hypothesis

a.k.a. Larval Retention Hypothesisa.k.a. Larval Retention Hypothesis

Members able to remain in favorable geographic setting (i.e., allows them toMembers able to remain in favorable geographic setting (i.e., allows them tocomplete their life cycle)complete their life cycle)

Vagrants fail to reach appropriate habitat, generally donVagrants fail to reach appropriate habitat, generally don’’t reproducet reproduceKey element: larvae must reach & remain within the nursery sites afterKey element: larvae must reach & remain within the nursery sites after

spawningspawning

Menhaden off N.Carolina in winter:spawn

Eggs float, larvaefeed on µzp, enterestuaries and becomejuveniles in 30-90days

Same strategy:flounder, stripedmullet and Japanesesardine

Coral Reef FishCoral Reef FishBroadcast spawners --Larvae spend several weeks in the planktonHow do they find the reef, or any reef, after such dispersaltime?

Swearer et al. (Nature 1999) used the elemental compositionof Caribbean wrasse otoliths to show their origins (coastalvs. open ocean) and found that >50% of recruits were fromlocally spawned larvae

Jones et al. (Nature 1999) marked 10 million damselfishembryo otoliths. Later, examined 5,000 juvenile settlers andfound 15 marked fish. This translated to 15 - 60% ofjuveniles returning to same site, since only 0.5 - 2% of totalembryos were marked.

FishFish Otoliths Otoliths• fish “ear bones” -- bony fish have 3 pairs of these -- sense ofbalance and aid in hearing• natural data logger -- grow throughout the fish’s lifetime• daily and annual growth rings (like in trees)• composed mainly of calcium carbonate, but incorporatestrace elements, too.• composition records age of fish, growth patterns, and chemicalenvironment

• fossilized otoliths alsoused by paleontologists toinfer past conditions, suchas water temperaturethrough stable O2 isotopes.


Fish MigrationsFish Migrations Migrate to seek favorable food supply or idealMigrate to seek favorable food supply or ideal

reproduction sitesreproduction sites

Some migrations several hundred to severalSome migrations several hundred to severalthousand kilometersthousand kilometers

Some migrations between salt and fresh waterSome migrations between salt and fresh water(spawning (spawning feeding grounds).feeding grounds). Anadromous Anadromous fish: breed in fresh, spend most of rest offish: breed in fresh, spend most of rest of

life in the sea (e.g., salmon)life in the sea (e.g., salmon)

Catadromous Catadromous fish: breed in the sea, spend life in freshfish: breed in the sea, spend life in freshwater (e.g., freshwater eels)water (e.g., freshwater eels)


MigrationMigrationexampleexample

Pacific Albacore Tuna:from Pacific coast of the US,across the Pacific well north ofHawaii, then southward acrossalong the east coast of Asia toJapani.e., generally along majorcurrent systems.

And: within 14.4° - 16.1°C waters

How do they find their way?How do they find their way?Sun: Use the sun to aid orientation, “sun compass”

Geomagnetic and Geoelectric Fields: movement of oceancurrents through the earth’s magnetic field generates electricfields that some fish can sense (salmon, eels).

Random walks? Some studies show that if salmon swim inrandom directions in the open ocean, but then get near theriver mouth where they originated, and presumably can then“smell home”, then no other directional sense is required,other than maybe use of the sun for orientation

Conclusion: relatively low degree of orientation probablyinvolved in migrations and not all migrants make it “home”


OlfactionOlfaction•• ““smelling homesmelling home”” evidence evidence

•• many fish (eels, salmon, carp, trout) canmany fish (eels, salmon, carp, trout) candistinguish between home and non-homedistinguish between home and non-homewaterswaters

Hamdani et al. 2007

•• what chemicals? thosewhat chemicals? thoseassociated with sexassociated with sex(pheromones), food (amino(pheromones), food (aminoacids), and avoidance andacids), and avoidance andmigration behavior (e.g.,migration behavior (e.g.,bile salts)bile salts)


Summary: Why does fisheriesSummary: Why does fisheriesrecruitment vary so much even in therecruitment vary so much even in the

absence of fishing pressure?absence of fishing pressure?Basic species ecology with practical implicationsBasic species ecology with practical implications Vulnerability during early life historyVulnerability during early life history

Starvation -- first feedingStarvation -- first feeding Predation -- poor escape abilitiesPredation -- poor escape abilities(side topic: adaptive behavioral responses to predation)(side topic: adaptive behavioral responses to predation) Delayed developmentDelayed development

Oceanographic context - random componentOceanographic context - random component timing and magnitude of food availabilitytiming and magnitude of food availability

productive periods -- blooms & lagsproductive periods -- blooms & lags stable periods -- prey aggregationstable periods -- prey aggregation

timing and magnitude of predator outbreakstiming and magnitude of predator outbreaks Vagaries of ocean currents -- drift/retentionVagaries of ocean currents -- drift/retention

The role of the jellyfish - The role of the jellyfish - medusoidmedusoid• Increasingly important in many ecosystemsworldwide

regime shifts? over-fishing?

• Competitors and predators of fish: perhapsrepresent an alternate guild of predators to fish inmarine ecosystems

• Adapted to patchy and diffuse food resourcescan grow rapidly if food available or subsist on little or no food (able to shrinkwhen starved)

• Can survive at lower O2 levels than fish -indication of eutrophication


Benguela Benguela Upwelling Zone - shift from fishUpwelling Zone - shift from fishto jelliesto jellies

Lynam et al. 2006c,d = jellyfish, e,f = fish

jellyfish biomass = 12.2 MTfish biomass = 3.6 MT

mainly sardines/anchovies

105

SalpsSalps• Abundant in equatorial and Antarctic waters• Filter feeders with fecal pellets sinking ~1,000

m/day• Decrease in krill in Antarctica coincides with

increase in salps

Larry Madin, WHOI

• Why? Both consume similarfood but salps tolerate highertemperatures so can live inopen water whereas krill needsea ice to over-winter and asnursery grounds

CtenophoresCtenophores• “comb jellies”: carnivores --use tentacles to entangle prey• usually do not have a bigeffect on ecosystem function• Big exception: introduction ofa North Atlantic species into theBlack Sea -- out-competedanchovies for copepod prey andcontributed to collapse offishery

SiphonophoresSiphonophores

• colonial organism, carnivore• feed on fish larvae,crustaceans• movement: air bladderpushed by the winds/currents• most famous member:Portuguese Man O’War


ReferencesReferences

•• Bailey, K.M., R.C.C Francis, P.R. Stevens. 1982. The life history and fishery of Pacific whiting, Bailey, K.M., R.C.C Francis, P.R. Stevens. 1982. The life history and fishery of Pacific whiting, Merluccius productusMerluccius productus.. CalCOFI CalCOFI Rep. 23:81-98.Rep. 23:81-98.

•• Bone, Q., N.B. Marshall, J.H.S. Bone, Q., N.B. Marshall, J.H.S. BlaxterBlaxter. 1995. Biology of Fishes. 2nd edition, Blackie Academic & Professional, London.. 1995. Biology of Fishes. 2nd edition, Blackie Academic & Professional, London.

•• CheckleyCheckley, D.M., , D.M., JrJr., S. Raman, L. ., S. Raman, L. MailletMaillet, K.M. Mason. 1988. Winter storm effects on the spawning and larval drift of a pelagic fish. Nature, K.M. Mason. 1988. Winter storm effects on the spawning and larval drift of a pelagic fish. Nature335:346-348.335:346-348.

•• Cowan, J.H., E.D.Cowan, J.H., E.D. Houde Houde, K.A. Rose. 1996. Size-dependent vulnerability of marine larvae to predation: an individual-based numerical experiment., K.A. Rose. 1996. Size-dependent vulnerability of marine larvae to predation: an individual-based numerical experiment.ICES J. Mar. ICES J. Mar. Sci Sci 53:23-37.53:23-37.

•• Cushing, D.H. 1975. Marine Ecology and Fisheries. Cambridge University Press, Cambridge.Cushing, D.H. 1975. Marine Ecology and Fisheries. Cambridge University Press, Cambridge.

•• FuimanFuiman, L.A. & R.G. Werner. 2002. Fishery Science: The unique contributions of early life stages. Blackwell, L.A. & R.G. Werner. 2002. Fishery Science: The unique contributions of early life stages. Blackwell Scence Scence..

•• HjortHjort, J. 1914. Fluctuations in the great fisheries of northern Europe viewed in the light of biological research. , J. 1914. Fluctuations in the great fisheries of northern Europe viewed in the light of biological research. Rapports et Rapports et ProcesProces--Verbaux Verbaux DesDesReunions, Reunions, Conseil Conseil International pour International pour LL’’Exploration Exploration de la de la MerMer 20:1-228.20:1-228.

•• HoudeHoude, E.D. 1987. Fish early life dynamics and recruitment variability. , E.D. 1987. Fish early life dynamics and recruitment variability. AmerAmer. Fish. Soc. . Fish. Soc. SympSymp. 2:17-29.. 2:17-29.

•• Hunter, J.R. 1972. Swimming and feeding behavior of larval anchovy,Hunter, J.R. 1972. Swimming and feeding behavior of larval anchovy, Engraulis mordaxEngraulis mordax. U.S. Fish. Bull. 70:821-838.. U.S. Fish. Bull. 70:821-838.

•• LaskerLasker, R. 1975. Field criteria for survival of anchovy larvae: the relation between inshore chlorophyll maximum layers and successful first feeding., R. 1975. Field criteria for survival of anchovy larvae: the relation between inshore chlorophyll maximum layers and successful first feeding.U.S. Fish. Bull. 73:453-462.U.S. Fish. Bull. 73:453-462.

•• LaskerLasker, R. 1978. The relation between oceanographic conditions and larval anchovy food in the California Current: identification of factors, R. 1978. The relation between oceanographic conditions and larval anchovy food in the California Current: identification of factorscontributing to recruitment failure. Rapp. P.-v. contributing to recruitment failure. Rapp. P.-v. ReunReun. Cons. . Cons. intint.. Explor Explor. . MerMer, 178., 178.

•• Paine, R.T. 1969. A note on Paine, R.T. 1969. A note on trophic trophic complexity and species diversity . American Naturalist 100:91-93.complexity and species diversity . American Naturalist 100:91-93.

•• PaulyPauly, D., V. Christensen, J. , D., V. Christensen, J. DalsgaardDalsgaard, R. , R. FroeseFroese, F.C. Torres , F.C. Torres JrJr. 1998. Fishing down marine food webs. Science 279:860-863.. 1998. Fishing down marine food webs. Science 279:860-863.

•• PaulyPauly, D., J. , D., J. MacleanMaclean. 2003. In a perfect ocean: The state of fisheries and ecosystems in the north . 2003. In a perfect ocean: The state of fisheries and ecosystems in the north Altantic Altantic Ocean. Island Press, Washington.Ocean. Island Press, Washington.

•• Werner, E.E., J.F. Gilliam, D.J. Hall, G.G.Werner, E.E., J.F. Gilliam, D.J. Hall, G.G. Mittelback Mittelback. 1983. An experimental test of the effect of predation risk on habitat use by fish. Ecology. 1983. An experimental test of the effect of predation risk on habitat use by fish. Ecology64:1540-154864:1540-1548

•• Other good refs:Other good refs:

•• Jennings, S., M.J. Kaiser, J.D. Reynolds. 2001. Marine Fisheries Ecology. Blackwell Publishing.Jennings, S., M.J. Kaiser, J.D. Reynolds. 2001. Marine Fisheries Ecology. Blackwell Publishing.

•• IversenIversen, E.S. 1996. Living Marine Resources: Their utilization and management. Chapman & Hall., E.S. 1996. Living Marine Resources: Their utilization and management. Chapman & Hall.

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Recruitment Variability, cont’d: Ho: Delayed Development ... · K.E. Selph, OCN 621, Spring 2008 Density-dependent Population Regulation Potential contributing mechanisms: Reduced