Nature = Food Part 2: Fisheries

• The marine environment has been described as the last frontier on the planet

• Let us, for the sake of our discussion, assume the above statement is true

• Many scientists argue that we are harvesting marine fishes at a rate that greatly exceeds their rate of production

• Precautionary Principle – where there are threats of serious or irreversible damage, lack of scientific certainty should not be used as a reason for failing to take measures to prevent potential damage

Terms

• General locations of fishing– Inland– Marine

• Source of fish– Aquaculture – literally fish farming– Capture – one of variety of “fishing” methods

• By-catch – “Total fishing mortality excluding that accounted directly by the retained catch of target species.”– Depending on the fishing locality, the ratio of by-catch to

target species can range from 3:1 to 14:1 (in pounds)– By-catch roughly averages 30% of global landings

Trends in fish production• Capture fisheries and aquaculture provided the world

117 million tons of food in 2004 – Approximate per capita amount of food fish was 16.6

kg (roughly 36 pounds per person)– Largest amount on record

• Fish account for roughly 20% of the protein consumed by humans

Trends in fish production• Also during 2004, a grand total of 155 million tons were

harvested for all uses (human consumption, fish food, oils and other)– 40 million tons from inland sources– 104 million tons from marine sources– This total represents a total 12 million ton increase

over one year!– 50 year fisheries trend diagram– 50 year fisheries and population trends diagram

A world of consumers

• China is the largest harvester of fish– Fishing nations diagram– Per capita consumption in China is estimate at 56

pounds– Chinese statistics are notoriously wrong and viewed

by the international community with skepticism• In keeping with the Chinese predominance in fisheries

landings, the several Pacific regions top the list of principal fishing regions– Fisheries region diagram

Where do those fish go?

• The destination of the fished species is mixed• Some of the species are high value species (i.e., the

tunas) while others (i.e., mackerals, herrings, Peruvian anchoveta) are low value and are used to make fish meal for agriculture (to be fed to chickens and pigs plus as plant fertilizer) and aquaculture– Top Ten Species Diagram

• Some species get new names to increase appeal– Formerly – Patagonian Toothfish, Currently – Chilean

Seabass– Formerly – Slimeheads, Currently – Orange roughy

• Profound lack of understanding about the life cycles of most of the open ocean fish – Many have long lifespans and late reproductive

phases (i.e., Patagonian toothfish)

A History of Decline

• Historically, the Cod has been a fish that shaped nations and exploration– Very important in the history of many countries

including Spain, Canada, and Iceland– The search for cod led to exploration of the North

Atlantic• Cod was continuously fished in the North Atlantic for

over 500 years• Cod was fished with increasing intensity in the 1960s• The cod populations in the North Atlantic crashed (and

the fishery along with it) in 1992– Diagram of decline

What happens when they are gone?

• Species replacement occurs when one or more species are overfished/overharvested

• The niche does not remain empty for long before another species (or multiple species) takes up part or all of the niche

• In Newfoundland, the cod was replaced by shellfish• In Georgia, the cannonball jellyfish is replacing missing

species of former larget species• As the target species abundance declines, fishing down

the food web occurs; the average trophic level of target species declines (ex. in Georgia from higher trophic level fish to lower trophic level cannonball jellyfish) – Fishing down the food web diagram

The crime of by-catch

• By-catch accounts for roughly 30% of global landings• Included in this % are: dolphins, sea turtles, sharks,

seabirds• By-catch is typically thrown overboard and therefore

“wasted”• The non-target species are damaged by hooks and/or

drowned by being underwater too long• To reduce by-catch without reducing the yield of the

target, industry and government groups have created and deployed a number of devices to reduce by-catch:– Turtle Excluder Device (TED) – UGA researchers

were instrumental in construction– Bycatch Reduction Device (BRD) – variety of styles,

designed to allow non-target species to leave net

Laws

• United Nations International Law of the Sea– Covered many aspects of ocean law, most relevant

was the extension of national waters to 200 miles (from 12 miles)

– Removed fish from the international commons and placed them under the jurisdiction of nations

– Never ratified by US in its entirety

Laws

• Magnuson Act of 1976– Enacted the 200 mile limit as US Federal Law– 200 mile zone known as the Exclusive Economic

Zone (EEZ)– Amended in 1996 as Magnuson-Stevens Act, which

added requirements to rebuilt/restore damaged fisheries and the formation of regional fisheries management councils

– Reauthorized in 2006 adding ecosystem approaches to management

Sustainable fishing

• Ways to sustainably harvest fish:– Reduce habitat damage (more delicate fishing

methods)– Reduce by-catch quantity/percentage– Don’t feed wild caught species to aquaculture– Understand population dynamics of target species– Purchase and consume fish that are sustainably

harvested• A number of groups are banding together to emphasize

use of sustainably harvested fish– Monterrey Bay Aquarium Seafood Watch– Environmental Defense Sustainable Fishing and

Seafood

World Fisheries Trends

Fish Utilization Trends

Top Ten Producers

Top Capture Fisheries Areas

“The Marine Most Wanted”

The Cod Collapse

Fishing Down the Food Web

The Fate of Whales

TED in action

TED and BRD in action