Term
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Definition
N=CR/r
N= pop est
R= # marked fish
r = # marked in next sample
C= # fish in next sample
Assume: all survived, equal odds of being caught, no immigration or birth, marks not lost, random dispersal. |
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Term
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Definition
| N=∑CR/∑r, sample over time. larger percentage marked, better estimate |
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Term
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Definition
can handle addition and deletion to pop, keeps track of when each fish was last seen, can get an idea of population size change, mortality, etc.
tags must be individualized |
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Term
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Definition
| computer program to estimate pop variables (size, recruitment, survivorship, mortality) |
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Term
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Definition
| often a concern instead of numbers. weight per area (kg/ha) Standing crop - amount of biomass at a given point in time |
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Term
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Definition
| Max sustainable standing crop affected by community. If pop exceeds CC - reduced growth increased mortality. can reduce standing crop to bring below CC |
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Term
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Definition
| amount of fish removed from the system. active fishing is a big economic plus, fish often removed for game and food. management must figure out how much can be removed (0.966)*SqRt of MEI |
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Term
| optimal sustainable yield |
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Definition
| most fish you can remove without reducing yield in following years. younger fish grow and replace biomass of removed fish, if not enough are left then the biomass WILL decline. |
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Term
| System Productivity is affected by: |
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Definition
| nutrients, harvest rates, bathymetry (littoral zone is most productive, larger area = more productive) |
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Term
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Definition
| length of shoreline/circumference of a circle of equal area. higher # = more shoreline and more littoral zones. |
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Term
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Definition
| total dissolved solids/mean depth. both tell you something about expected productivity of a lake. TDS - how much material is held in water column, indicator of nutrient load in a lake. |
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Term
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Definition
| usually based on weight of prey and predatory fishes |
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Term
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Definition
ways to look at balance of populations. forage to carnivore species. young to carnivore species. (some fish are so small they are not considered predators).
Proportion of weight composed of harvestable fish. |
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Term
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Definition
| unbalanced populations can lead to a situatoin where the population is dominated by small fish with low growth and reproduction. Remedies - stock predator, disrupt reproduction, alter habitat to increase predation. |
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Term
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Definition
| bass-bluegill-channel catfish in typical farm pond. gov't will give you fish to stock in proper ratios. Rate depends on nutrient status in lake typically 50/500/50 per acre for B/BG/CCF. Stock BG in fall. Bass and Caats in spring. time depends on size stocked. |
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Term
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Definition
| large range in sizes for fish of the same age. Size frequency of cohort is bimodal due to differences in timing of change to piscivory. |
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Term
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Definition
by increasing phytoplankton: decrease light penetration, decrease macrophyte growth, decrease litorral zone.
Fertilization is a valuable tool in management of oligotrophic systems. |
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Term
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Definition
| controlling community structure through the introduction of augmentation of upper levels of the food web. trophic cascade. |
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Term
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Definition
| species indigenous to an area |
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Term
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Definition
| a species put into an area by humans. species released into non-native areas. |
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Term
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Definition
| an introduced species reproducing on its own. non-native species that is reproducing naturally -established. |
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Term
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Definition
| a species (normally introduced) that is expanding its range. non-native species naturally expanding into an area. |
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Definition
| reserved for introduced species that are not native to the biogeographic region they have been put in. species not native to NA. |
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Term
| Mechanisms of introduction |
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Definition
| Intentional, Pets, Food fish, Bait Bucket release, Commerce (boats, canals), Most introductions are not successful but some that are successful are devastating to native fauna. |
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Term
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Definition
| Cyprinus carpio - introduced in 1877 ubiquitous in SE, less common in west. |
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Term
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Definition
| Petromyzon marinus - entered Great Lakes through St. Laurence sea way - reduced large fish, especially lake trout |
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Term
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Definition
| Channa sp - from Asia, extermiated by MDNR, in South they are established - release by aquaculture |
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Term
| Introduced - Northern Pike |
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Definition
| Esox lucius - introduced to western waters as game fish - reduce native salmonids. |
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Term
| Introduced - Rainbow trout |
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Definition
| Beloved. Oncorhynchus mykiss - native to Pacific drainages - stocked throughout US |
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Term
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Definition
| Beloved. Salmo trutta - native to Europe - introduced throughout US and world |
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Term
| Introduced - Striped bass |
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Definition
| Beloved. Morone saxatilis. native to Atlantic/gulf drainages - introduced to reservoirs through south. |
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Term
| Introduced - Largemouth bass |
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Definition
| Beloved. Micropterus salmoides - introduced into central and south america. |
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Term
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Definition
| Beloved. Lates niloticus - large piscovore native to Nile, but excluded from Lake Victoria by Victoria Falls. Released by manager in 50's. Let to loss of estimated 200 species of Chichlid. Indirect effects. Let to deforestation and poverty - indirect effects. |
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Term
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Definition
some species have effects on the physical environment in which they live
Many times introduced species have greatest effects by changing the physical habitat rather than through predation or competition. |
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Term
| Carp (Ecosystem Engineer) |
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Definition
| increase turbidity, decrease light penetration, increase temperature, decrease primary prod. |
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Term
| Stonerollers (ecosystem engineers) |
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Definition
| build nest mounds, crop algae with their mouths |
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Term
| Temperature - why an issue for fish? |
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Definition
| With freezing temperatures ice can form in the body and puncture cells walls (cell death) |
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Term
| How do I keep my cells from freezing |
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Definition
| Supercooled state (rare) or lower freezing temperature (with anti freeze) |
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Term
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Definition
A-F Glycoprotein (AFGP) - Cod
A-F protein: Type 1 - right eye flounders, sculpin. Type 2 - Sea raven. Type 3 -?
These inhibit the growth of ice crystals along a-axis. |
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Term
| AF(G)P's are not like normal anti freezes... |
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Definition
| do not work on proportion to concentration (minimizes effect on osmotic pressure) |
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Term
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Definition
| difference between the freezing and melting points. value is a function of AF(G)P |
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Term
| AFP produced all the time? |
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Definition
| NO! levels vary with season except with antarctic fish. |
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Term
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Definition
| seen most in antarctis notothenioids. high concentrations see in digestive tract (ice crystals from food, produced in pancreas) Most are produced in the liver - direct access to bloodstream. First discovered in insects. Used to help develop an ice cream additive that prevents the formation of ice crystals. |
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