Class The Oceans FOOD RESOURCES OF THE OCEANS World Fish Catch Dynamics of fish populations and fishing Over-exploited fisheries Management to get maximal harvest of fish

FOOD RESOURCES World fish catch increased 4-fold from l950 to 1995 in 1953: 23 Million Metric Tons in 1953: 23 Million Metric Tons in 1970: 50 Million Metric Tons in 1970: 50 Million Metric Tons in 1995:85 Million Metric Tons in 1995:85 Million Metric Tons

FOOD RESOURCES World fish catch plateau??? in 1995:85 Million Metric Tons in 2003:85 Million Metric Tons

Open Ocean Areas- Small Harvest Fisheries near upwelling zones: High trophic level fish, e.g., Tuna

Coastal Areas: Large Harvest Often good nutrient supply Shorter, more efficient food chain

Upwelling Areas -- e.g., West coasts Very high primary productivity. Harvest small, fast-growing, phytoplankton- eating species

What is the "maximum sustainable yield?” Not well known for most commercial fish stocks. Estimates: 1/3 to 2/3 of “total production”

If the harvest is too large, the population shrinks and reproduction slows - then next year’s harvest will be smaller and everyone suffers The goal: Harvest as much as possible while still allowing sufficient reproduction for the future A sustainable harvest OVER-EXPLOITATION

1. Peruvian anchovies. Over-fished at peak harvest (l970; 12 million metric tons) Devastating 1972 El Nino Decrease to 2 million metric tons per year Recent recovery… EXAMPLES OF OVER-EXPLOITATION

Anchovy harvest… declined drastically in 1972, and stayed at low levels for more than ten years. Harvest increased after the El Niño , and reached a maximum level of 9.7 million tons in 1994, a level which was the highest since the collapse of the fishery in Harvest fell after the El Niño of , but this decline was followed by a rapid recovery in 1999 and The species has been declared as fully exploited. The main fisheries management measures are: Total Allowable Catch, minimum harvesting size and reproductive closed seasons. SOME SHARED FISH STOCKS OF SOUTH EASTERN PACIFIC (by Jorge Zuzunaga, GOV’T OF PERU, 2002)

Note 1997 El Niño

2. Pacific Salmon -- Overfishing and environmental degradation. Degradation of spawning streams: –dams –altered stream banks (reduced shade) –water quality

3. Grand Banks Cod Fishery-- Overfishing and environmental degradation

2008 UN Report: The world economy could be $50 billion richer if fisheries were managed better Half the world fishing fleet could be scrapped, and the remaining half would catch as much fish.

Fisheries management: The individual “right to fish” versus long-term health of the fish population Other environmental damage: Logging, dams, etc....Mortgage......Tuition Bills..

Ecosystem-based fisheries management

Effectiveness of the world's fisheries management

One way to harvest more from the oceans: Harvest lower on the food chain Antarctic krill? Harvest phytoplankton directly?

Slow reproduction/ Overharvesting: Chilean sea bass (toothfish) Shark- Mercury hazard also Monkfish (like Anglerfish) Orange Roughy Bluefin tuna (sushi) Fish to avoid m.org/cr/seafoodwatch.aspx

Whales Some species hunted to near- extinction e.g., GraySome species hunted to near- extinction e.g., Gray Whaling banned; Numbers have reboundedWhaling banned; Numbers have rebounded Others still perhaps 100x less than pre- whaling numbersOthers still perhaps 100x less than pre- whaling numbers