Transcript Power Point
Today Schedule 1. 2. 3. 4. 5. Diversity of Wisconsin Fishes reproduction habitats Reproduction strategies Early life history- terms Ecology of early life history Lab – Wisconsin fishes part 2 Non-gaurding , Pelagic Alewife - inshore waters, eggs settle High fecundity High early stage mortality Gizzard shad - Often move up rivers, eggs drift down Non-gaurding , Pelagic Freshwater drum eggs float on surface until hatch Paddlefish eggs are sticky when fertilized, adhere to the first thing they touch Non-gaurding , Benthic – fine substrate Spottail shiners spawn on gravel and silt substrates Non-gaurding , Benthic - Crevice Spotfin shiners use rock crevices to hold eggs Non-gaurding , Benthic –vegetation Northern pike prefer flooded vegetation in backwaters Non-gaurding , Benthic –vegetation Banded killifish spawn gets entangled in aquatic vegetation Non-gaurding , Benthic – coarse bottom Lake trout and lake whitefish spawn over large broken coble areas Non-gaurding , Benthic – stream Pacific salmon and brown trout dig redds – clean gravel where stream water upwells Non-gaurding , Benthic – stream Brook trout exclusively use groundwater upwelling areas in lakes and streams Guarding , Nests – nests of plants Guarding means higher survival Sticklebacks make nests of algae and macrophytes and then lay eggs inside the nests Gaurding , Benthic – Underside of rocks Both round gobies and Johnny darters spawn under rocks, attaching the eggs to the underside of the rocks Aggressive defense can incur high costs to parents or death Gaurding , Nests – gravel Common in centrachids also lamprey, nests are often fanned to increase water flow and remove sediments American brook lamprey Smallmouth bass Gaurding , Nests – Holes and burrows Catfish and bullheads make burrows or use existing holes Noodling Time: http://www.yout ube.com/watch?v =zOjA8Puh1BM Gaurding , Nest – fine sediment Crappie nests associated with vertical vegetation in fine sediments Livebearers , (none native) Mosquitofish 60 -100 progeny per brood, born live, male has modified anal fin to impregnate female Why bear live young? Life history strategies Multiple strategies: Bluegill – parental care or Cuckolder Female mimic http://publish.uwo.ca/~bneff/research_beea.htm Life history strategies Multiple strategies: Pacific salmon ‘Jack’ – 2 year old male Normal 5-6 year old male Female mimic Spawning variants How often: Semelparous = once, Iteroparous = more then once Fish evolve to spawn in different locations Temiscamie – strain Little Tupper strain Tributary spawner Shoal spawner Assinica- strain Outlet spawner Why...think about the emerged fry! Early life history Same basic pattern Eggs Larvae (alevin) Juvenile Adult Snook Salmon Diverse Larvae Majority of mortality occurs in early life Most fish are r selected – lots of offspring, little care, few make it Verhulst equation Small changes in survival at any stage = big difference in year class strength Year class strength Measure or index at some point when fish can be easily caught. Long term data is critical since each year is only one data point What could influence year class strength? At what stages? Factors that influence early life survival Temperature -How quickly adult fish mature and spawn -How quickly eggs hatch -Growth rate of larvae and YOY Food availability -Is the right food available once yolk sac is used up? -As they grow does the food out grow them? Water level -Eggs can be left high and dry or smothered? Predation -Do larvae face a predator gauntlet? Match/Mismatch Hypothesis – Conditions match what is needed Year class strength: egg stage gravel size influences survival from egg to larvae Year class strength: YOY – young of year River flow influences survival of young of year Year class strength: temperature Food Abundance Fluctuations Predation Lake trout eat alewives…right? What about larval lake trout? Must fill swim bladder at surface (physoclistous ) Great lakes LT spawning reefs Match/Mismatch Yellow perch hatch Eat small copepods, then switch to Daphnia Yellow perch hatch Eat small copepods but Daphnia show up too late Wisconsin Fishes part 2 Esocidae (Pikes) Grass pickerel Muskellunge Northern pike ID’ing esocids Northern pike Pores Pickerel – 4 Pike – 5 Muskie – 6-9 Branchial. Rays Pickerel – 12 Pike – 14-16 Muskie – 16-19 Muskellunge Identify with pores and or branchiostegal rays Umbridae (Mudminnows) Central mudminnow Fin placement Homocercal tail Lottidae (Burbot) Homocercal tail Long continuous anal and dorsal fins Single chin barbel Aphredoderidae (Pirate perch) Big dorsal Starts here Ends here "Migrating anus" Percopsidae (Trout-perch) Trout-perch Big head, big eye, big mouth Adipose fin Centrarchidae – 4 genera, 8 species Ambloplites Micropterus Pomoxis Lepomis Micropterus Largemouth bass Maxilla beyond eye Maxilla to middle of eye Smallmouth bass Lepomis Green Sunfish Pumpkinseed Bluegill Ambloplites – rock bass Rounded pectoral Solid, no light margin Percidae – 5 genera, 8 species Perca Percina Sander Crystallaria Etheostoma Sander White tip Walleye More mottled No-White tip Sauger Darters Rainbow darter Johnny darter Fantail darter Crystal darter Moronidae (Temperate Basses) Broken and offset Yellow bass Not offset White bass Sciaenidae (Freshwater Drum) Elongated ray on pelvic fin Gobiidae (Gobies) Distinct head shape differences Round goby Tubenose goby Gasterosteidae (Sticklebacks) Uh…count the spines Ninespine stickleback Brook stickleback Fundulidae (Killifishes & Topminnows) Vertical bars on flank Blackstripe topminnow Faint horizontal bars on flank Starhead topminnow Ictaluridae (Bullheads) Yellow bullhead Yellow chin barbels Brown bullhead Mottled Saw like barbs Black bullhead Even color Ictaluridae (Catfish) Channel Catfish Deeply forked tail Osmeridae (Rainbow Smelt) Rainbow smelt Adipose fin Atherinidae (Silversides) Brook silverside Spots on back