ichthyology final exam

red muscle

rich in myoglobin, oxygenated, suited for sustained swimming

ammonia

nitrogenous waste that fish secrete

countercurrent exchange

water flows over gills opposite of blood flow, creates gradient that maximizes oxygen diffusion where water always has more oxygen than blood

adaptations for high pressure

flexible bones, reduced skeletal structures, enhanced eyesight, bioluminescence, slow metabolism, specialized swim bladders

types of behavior

camouflage, schooling, territorialism

anadromous

fish that live in saltwater but move to freshwater to spawn

factors that affect distribution

stream flow, temperature, oxygen levels

coral reefs have high biodiversity because…

…structural complexity and diverse microhabitats lends to niche diversity and reduced competition

confusion effect

schooling behavior reduces predation and individual threat risk

effects of habitat fragmentation

population isolation, limited gene flow and genetic diversity, prevention of migration and spawning

adaptations for seasonal changes

thermal refuge (migrating to warmer/deeper water in winter), torpor/reducing metabolism, timing spawning/growth with food availability

effects of climate change

warm habitats shifting up, altered seasonal migrations → mismatched spawning cues, food availability, disrupted ecosystems, invasive species expansion/immigration

Maximum Sustainable Yield (MSY)

maximum yield of fish stock without reducing future stock

Catch-per-unit-effort (CPUE)

method for fish stock assessment, estimates fish abundance by dividing catch by amount of effort

cause of overfishing

use of small mesh nets, which allows for catching juvenile and non-target fish

FAO Code of Conduct for Responsible Fisheries

promotes responsible fishing practices, conservation, sustainable use of resources

open-access fisheries

fisheries that allow anyone to fish, prone to overexploitation (“tragedy of the commons”), lack of regulation

aquaculture

reduces pressure on wild stock and controlled supply BUT can contribute to pollution, habitat degradation, risk of disease, escape of non-native species

wild-caught fish

natural behavior and diet, usually healthy BUT potential to overfish, bycatch, habitat destruction

turtle excluder devices (TEDs)

a form of bycatch reduction, allow turtles to escape trawl nets

effects of overfishing

removing key predators, algal blooms, sudden abundance of prey species, collapse of dependent species

methods of monitoring fish populations

scientific surveys, CPUE, stock modeling, acoustic tagging

methods of controlling fishing pressure

size limits, gear restrictions, seasonal closures, quotas, marine protected areas (MPAs)

illegal, unreported, unregulated (IUU) fishing

undermines conservation, reduces fish stock sustainability, harms legal fishers economically, destabilizes local economies