Dan Minchin Marine Organism Investigations, Ireland Coastal Research and Planning Institute, Univeristy of Klaipeda, Lithuania. September/November 2013

Technological developments Efficient searching methods Efficient gear Deep-freezing of catches Processing on-board Good port infrastructure Good berthing and servicing Efficient business management

Commercial fishing: 500 species regularly caught Employs 200 million people worldwide In 2002 the world fishing fleet numbered about four million vessels. In 2005: 100 million tons taken $70 billion

 Doubling of fleet over 30 years  Does not take account of vessel size  Does not take account of fishing efficiency  The result: a huge increase in fishing effort

Tropic levels Variability Complex webs

World Commercial Catch of Marine Fishes, Crustaceans, and Mollusks (1995) cod Species Group Millions of Metric Tons, Live Wt. Herrings, sardines, anchovies22.0 Jacks, mullets, sauries11.2 Mollusks11.0 Cods, hake, haddock10.6 Redfish, basses, conger eels 7.0 Crustaceans 4.8 Tunas, bonitos, billfish 4.7 Mackerel, snooks, cutlass fishes 4.7 Flounders, halibut, soles 0.9 Miscellaneous marine fishes17.7 Total (excluding marine mammals) 83.6 (39.4)

To be cost-efficient: Large volumes of fish need to be captured The volume depends on the market price: food fishes- industrial fishes (fertilizer,fish meal, pet food, novelty items) Industrial fishes must have high abundance

With technological developments – large catches Sardinops sagax Engualis encrasicolis Catches subsequently declined Trophic changes Jellyfish dominant Chrysaora hysoscella Aequorea forskalea Sufflogobius bibarbatus

Purse seine Used for pelagic species Selects fish according to their schoaling behaviour Food and industrial fishes Surround shoals Tighten the foot of the net Then draw net aboard

Mid-water trawl Acts like a bottom trawl but off the bottom Has boards to spread the net entrance The height above the bottom is known Electronic equipment identifies the shoal

The Humboldt upwelling El Niño Anchovy more abundant than pilchard Production depends on oceanography Large bird population Guano on islands mined

La Niña El Niño El Niño - La Niña events Low production on coasts

Peru Anchovy Fishery Upwelling zone off Peru Fishery began 1950 Greatest fish catches for any single species Fish exported for domestic animal feed Fishery collapsed due to El Niño and overfishing

Bottom trawling In deep water and shallows for benthic and epi-benthic fishes (demersal) Long time to set in deep water Other trawls: beam trawls

Off-bottom trawl for orange roughy o Distribution: world wide, high concentrations in New Zealand o Found: m depth o Life span: slow-growing, long-lived, ~150 years o Size: cm o Diet: prawns, fish, & squid o Reproductive age: years old o Captured in spawning aggregations Hoplostethus atlanticus

Potential harvest = million MT/yr Economic cost of fishery high Patchy distribution complicates location Depths may be m Single net haul may collect 10 MT Ecological consequences of removal poorly understood Estimated 500,000,000 tonnes (~x2 human biomass) Trawl fishery for krill Euphausia superba

Krill Fishery Annual consumption by natural predators = 470 million MT 1972: Japan and Russia began harvesting krill

Gill nets Gill nets are selective by size Used in all waters Bottom nets, surface nets, drift nets Hemp & bark to monofilament nets

Crystal crab fishery (Australia) Red king crab (N. Pacific) King crab in US has a short timeline fishery

Longlining Mainly for large species, i.e. cod, halibut, tilefish Limited entry to many fisheries N Pacific 1930s

Global swordfish catch cfin/hi/dar/Pages/hi_fish_2.ph p Ave. wt. in lbs year

Bycatch by Gear Type for 2002/2003

‘Inshore’ trap fishery These are baited Serviced regulary Different entrance sizes and designs

Surface to near surface fishing with lures Often used for migrating fishes Large fast swimming fishes targeted

Mainly for squid Different lures can be used for fish