lecture15

Ichthyology
Spring 1999
T. Turner

Lecture 15 -- Protacanthopterygii

lecture15 For Thursday: Key to Families from Sublette et al. 1990 (1st lab)

Division Teleostei

Infradivision Euteleostei

Superorder Protacanthopterygii --

Major revisions of this group have occurred and will continue to occur

Prot (original) - acanth (spine)- pterygii (fin)

Order Esociformes -- 2 families; 10 spp.; circumpolar; freshwater

Maxillary bone included in gape, but toothless
All predatory on fishes (Esocidae) or invertebrates (Umbridae)

Family Escocidae

pike, pickerel, musky -- genus Esox
Large-bodied (can be 1.5 meters)
northern pike (Esox lucius) circumpolar distribution
sit-and-wait predators, solitary, no nest construction or guarding, highly fecund (200,000 eggs)
lakes, backwater areas-- flooded vegetation for nursery areas

Family Umbridae

NA, Eurasia
Mudminnows -- genera Umbra, Novumbra, Dallia

Can survive for days in moist surroundings
Small-bodied (rarely larger than 20 cm)
Remarkable adaptation to ice-covered, low oxygen freshwaters (high latitudes)

Order Osmeriformes -- 13 families, 236 spp. worldwide; marine and fw

Most have adipose fin
Maxillary bone included in upper jaw
Cycloid scales with no radii

Deepsea smelts -- 7 families

Agentinidae (herring smelts) Opisthoproctidae (barreleyes)
Silvery or black in color, a few species possess photophores
Possess epibranchial organ for grinding food

Family Osmeridae (true smelts) -- ex. Osmerus mordax

Half the species in the family support commercial fisheries
Enormously abundant in coastal areas
Marine to anadromous to completely freshwater existence
Pelagic carnivores -- zooplankton, ichthyoplankton, have teeth on maxilla
Smell like cucumbers

Family Galaxiidae

Southern hemisphere only, interest to biogeographers

Galaxias maculatus found in all regions except SA, has planktonic larvae; spawning ecology (lunar cycles -- eggs stranded in grass for up to 2 weeks)
Occupy same ecological niche as salmonids
Some species burrow in mud to prevent dessication
Introduction of salmonids in New Zealand have had a detrimental impact on galaxids

Family Lepidogalaxiidae

Southern Australia only
Inhabits acidic, ephemeral waters
Burrows in sand and/or mud to prevent dessication; emerges after rains

Order Salmoniformes -- 1 family; 66 spp.; native to northern hemisphere; FW and marine; many circumpolar

Anadromous or freshwater, landlocked populations
Ecology, physiology, reproduction, genetics among the best-studied among fishes == 26183 papers since 1977 on LANL SciSearch (keywords: Salmonidae or Salmon or Trout)
Reproductive Ecology/Life History

Redd - nest
Alevin - yolk-sac larvae; retained in gravel interstices
Fry - yolk sac absorbed, active, emerge from interstices
Parr - juveniles with parr marks (lateral bars)
Smolt - transformation from fw to marine physiology and ecology
Jacks, grilse - males that mature/spawn at 1 to 2 years (may not migrate to sea)
Kelt - spawned out adult

Graylings -- genus Thymallus; Sexually dimorphic dorsal fin, large scales

Whitefishes -- genus Coregonus, large scales, ecological diversity

Salmon, Char, and Trout -- genera Oncorhynchus, Salmo, Salvelinus; small scales

Gila trout -- Oncorhynchus gilae -- New Mexico - Arizona endemic

Found in the Verde River and Gila Drainage
Conservation efforts began in the 1920's
Named as a species in 1950 -- R.R. Miller
Habitat loss from mining, agriculture, grazing (minor effect) reduced population sizes
Hybridization (with rainbow and brown trout) is primary factor reducing genetic variation and population numbers in the Gila R.
Management efforts include stocking, construction of barriers to migration, and removal of non-natives
Listed as federally endangered in 1967, state endangered in 1975
Downlisted to state threatened 1987
Fires eliminate populations of Gila trout
Sabotage

Slides:

Esociformes

Esox americanus grass pickerel

Esox lucius - northern pike

Esox masquinongy - muskellunge

Umbra limi - central mudminnow

Osmeriformes

Argentina silas - Atlantic argentine

Spirinchus thaleichthys - longfin smelt

Salmoniformes

Onchorynchus gorbusha - pink salmon (male)

Onchorynchus gorbusha - pink salmon (female)

Onchorynchus clarki - Rio Grande cutthroat trout

Onchorynchus mykiss - steelhead (rainbow) trout

Salmo trutta - brown trout

Coregonus clupeaformis - lake whitefish

Thymallus arcticus - arctic grayling

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Updated 26 March 1999, T. Turner