Bio 125 Ch 31 and 32 Fisheries, Pollution, Human Impacts

Fisheries, Pollution, Human Impacts

DDT

Dichloro-diphenyl-trichloroethane, pesticide, insecticidal action discovered by Paul Hermann Muller, can travel long distances in atmosphere, very long time for complete biodegradation, lipophilic (accumulates in fat)

Rachel Carson

Wrote about the dangers of DDT in her book Silent Spring

Effect of DDT in Brown Pelicans and correlation to biomagnification

decreased populations of pelicanus accidentalis (brown pelican) by making their eggshells extremely thin, a direct result of DDT’s biomagnification up the food chain, concentrating the pesticides to toxic levels in these fish-eating birds.

The role of EPA (environmental protection agency) in controlling the problem of DDT accumulation

banned DDT

biodiversity

All of the species living in an area and their interactions with each other.

Core threat to biodiversity

combination of human population growth and the resources used by that population.

3 greatest proximate threats to biodiversity

habitat loss, overharvesting, introduction of exotic species

fourth major cause of extinction

human-caused climate change

stock

how many individual fish make up the population

fecundity

how many offspring does an individual have, or how quickly do the fish reproduce?

fishing effort

number of boats, type of gear, hours invested in fishing, how many fishermen participate.

landings

how much is caught in commercial fisheries

maximum sustainable yield

how many individuals can be taken from a stock without causing a decline in the population.

common resource

available to anyone

tragedy of the commons

resources held in common will inevitably be over-exploited.

Climate change

long term shifts in temperatures and weather patterns

renewable resource

A natural resource that can replenish itself naturally over a relatively short time.

Where do most of out fishing resources come from and why?

90% of fishing concentrated in 7% of ocean sea, neritic. Due to higher primary productivity, shallower, and more accessible.

3 major fishing areas in the world and why they are so heavily fished

wide continental shelf, strong upwelling, historical fishing

kinds of data necessary in fisheries research to determine maximum sustainable yield

Logistic growth models

common problems in fisheries

overharvesting, indiscriminate catching devices, indirect catches, special markets, enforcing laws

indiscriminate fishing gear

drift nets, shrimp trawls, longlines, bycatch: any non-targeted animal caught

How do shrimp trawls work and effect of environment

they drag heavy cone-shaped nets across the seafloor, catching shrimp and other bottom-dwelling creatures but cause immense environmental damage, primarily through massive bycatch.

How are purse-seiners correlated to dolphin catches?

yellow-fin tuna often swim under dolphin pods, leading fishermen to set large nets around both causing dolphins to also get trapped.

characteristics of the California Sardine and what happened to the population in 1940s and why?

small, pelagic, schooling. population declined in the 1940s due to overfishing

decadal oscillation

long term climate pattern of ocean atmosphere variability that shifts between warm and cool phases over several decades.

How humans influence marine environments

pollution, overfishing, climate change, habitat destruction, invasive species, conservation and restoration, sustainable practices, research and monitoring, reduced emissions.