Humans and the ocean Flashcards
(21 cards)
How long have humans been using marine environments for food
For over 150,000 years, dating back to early Homo sapiens in Africa
What are the main modern uses of the ocean?
Tourism, fishing, aquaculture, mining, energy, and cultural activities
How has our view of ocean resources changed since the 1800s?
Early views (e.g. Huxley, 1883) considered fish stocks inexhaustible; we now recognize their limits and need for regulation
What is “fishing effort”?
The magnitude or distribution of fishing activity in a specific area over time
e.g number of vessels, hours fished
What is CPUE (Catch per Unit Effort)?
A measure of fishing efficiency: catch amount per unit of effort (C/f = qN)
Used to estimate fish population sizes
What is a “stock” in fisheries science?
A discrete population that breeds separately from others and is largely self-sustaining
Basic unit for management
What is Maximum Sustainable Yield (MSY)?
The largest catch that can be taken from a stock annually without causing population decline
How much global fish production was reported in 2022?
185 million tonnes (worth $452 billion), including 79.7 million tonnes from marine capture and 35.3 million from marine aquaculture
Where are most marine fisheries located?
In coastal waters—95% of major fisheries, with >50% of catches coming from <7% of the ocean (especially upwellings)
What is the current average per capita fish consumption?
20.5 kg per year, with 88% used directly for human food and 9% for feed/oil
Which species dominate global catches?
Clupeoids (e.g., anchovies, sardines), Alaskan pollock, skipjack tuna, and Humboldt squid
What defines artisanal fishing?
Small-scale, low-tech fishing often for subsistence or local income
What defines commercial fishing?
Mechanized, profit-driven operations often supplying distant markets
Name five common industrial fishing methods
Trawling, purse seining, long lining, pots/traps, and gill nets
What is bottom trawling and why is it damaging?
Dragging nets along the seafloor—can remove 41% of biota in one pass and damage habitats >15 cm deep
Recovery may take years
What is “fishing down the food web”?
A trend where fisheries shift from top predators to smaller, lower-trophic species as the former are overfished.
Indicated by falling mean trophic level
What is bycatch?
The unintentional capture of non-target species
e.g gulf of Mexico fishers report 4:1 bycatch ratios
Which method has the lowest bycatch?
Pole-and-line fishing
Also allows selective harvest
What is Shifting Baseline Syndrome?
A gradual change in what we consider “normal” environmental conditions due to generational knowledge loss
Affects how we percieve ecosystem health
What is the purpose of Marine Protected Areas (MPAs)?
To conserve biodiversity and biomass by restricting or banning fishing in designated zones
Often more productive than non-protected areas
What makes an MPA most effective?
No-take, well-enforced, over 10 years old, large (>100 km²), and isolated by deep water or sand
